SOVIET ATOMIC ENERGY - VOL. 34, NO. 5
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Russian Original Vol. 34, No. 5,"May, 1973
November, 1973
SATEAZ 34(5) 4177530 (1973)
SOVIET
ATOMIC
ENERGY
'-ATO.MHAfl 314E1)114H
(ATOMNAYA iNERGIYA)
- TRANSLATED FROM RUSSIAN
CONSULTANTS BUREAU, NEW YORK
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??
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SOVIET
ATOMIC
ENERGY
Soviet Atoinic Energy is a' cover-to-cover translation of Atomnaya
EnergiY a, a publication of the Academy of Sciences of the USSR.
An arrangement with Mezlidunarodnaya Kniga, the Soviet, book
export agency, makes evadable both advance Copies of the Rus-
sian journal and original glossy phatographs and artwork. This
serves to decrease the necessary time lag between publi'cation
of the original and publication of the translation and helps to im-
prove the quality of the latter. rhe translation began with the first
issue of the,Russian journal.
Editorial Board of Atomnaya energiya:
Editor: M. b. Millionshchikov
Deputy Director ? ,
I. V. Kurchatov Institute of Atomic Energy
Academy of Sciences of the USSR
Moscow, USSR
Associate Editors N. A. Kolokol'tsov
A. Vlasov
A.)A. BochVar V. V. Matveev
N. A. Dollezhal' M. G. Meshcheryakoy
V. S. FUrsov P. N. Plei
I. N. Golovin V. B. Shevchenko
V. F. Kalinin Simonenko
A. K. Krasin V. I. Smirnoy
A. I. Leipunskii A. P. Vinogradov
A. P. Zefirov
Copyright01973 Consultants Bureau, New York, a division of Plenum Publishing
Corporation, 227 West 17th Street, New York,'N. Y. 10011. All rights reserved.
No, article contained herein may be reproduced for any purpose whatsoever ,
iw thout permission of the publishers.
Consultants Bureau joUrnals appear about six months after the publication of tile
original Russian iesue. For bibliographic accuracy, the English issue published by
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from which it Was translated. For example, a Russian issue published In Decem-
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The material you will receive will be a translation of that Russian volume or Issue.
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'CONSULTANTS BUREAU NEINYORK AND LONDON
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Published monthly. Second-class postage paid at Jamaica, New York 11431.
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SOVIET ATOMIC ENERGY
A translation of Atomnaya Energiya
November, 1973
Volume 34, Number 5 May, 1973
System for Monitoring the Energy Distribution in the RBMK Reactor
? I. Ya. Emel'yanov, L. V. Konstantinov, V. V. Postniko4, V. K. DenisoV,
CONTENTS
Engl./Russ.
and V. Ya. Gurovich
417
331
Reliability Accounting of Process Channels in Nuclear Power Station Costs Accounting
? S. V. Bryiniin, Yu. I. Koryakin, and V. Ya. Novikov
421
335
Emergency Cooldown of the BOR-60 ? 0. D. Kazachkovskii, G. K. Antipin,
V. A. Afanas'ev, V. F. Bai, V. A. Borisyuk, E. V. Borisyuk,
V. M. Gryazev, V. N. Efimov, V. P. Kevrolev, V. I. Kondratt ev,
N. V. Krasnoyarov, and A. M. Smirnov
428
341
The Effect of Added Zirconium on the Surface Tension of Copper?Aluminium Alloy and
the Interphase Tension with Uranium Dioxide ? G. V. Pastushkov,
P. P. Novoselov, and G. B. Borisov
432
345
Neutron Spectra from Isotopic (a, n) Sources ? N. D. Tyufyakov, L. A. Trykov,
and A. S. Shtan'
436
349
Thermal and Epithermal Neutron Cross Sections for Vanadium Isotopes
? V. P. Vertebnyi, M. F. Vlasov, N. L. Gnidak, R. A. Zatserkovskii,
A. I. Ignatenko, A. L. Kirilyuk, E. A. Pavlenko, N. A. Trofimova,
and A. F. Fedorova
441
355
Neutron-Radiation Analysis of Rocks and Ores Using Ge(Li) Spectrometer
? A. M. Demidov, V. A. Ivanov, and N. K. Tarykchieva
445
359
Yields of Fragments of the Spontaneous Fission of Cf252 ? N. V. Skovorodkin,
G. E. Lozhkomoev, K. A. Petrzhak, A. V. Sorokina, B. M. Aleksandrov,
and A. S. Krivokhatskii
449
365
REVIEWS
Development of Nuclear Energy and Problems of Environmental Protection in
Czechoslovakia ? J. Neumann
456
373
Problems of Radioecology in Connection with the Development of Nuclear Power
? M. Zaduban
460
376
Current Problems in the Radioecology of Soils and Plants ? G. Plitakova, T. Sabova,
and M. Zaduban
465
380
ABSTRACTS
Mathematical Model for the Optimization of the Parameters of the Power Section of an
Atomic Electric Power Plant with a Fast Sodium Reactor ? V. M. Chakhovskii
and Yu. S. Bereza
476
391
Determination of Oil Impurities in CO2, Used as a Coolant in Gas-Cooled Reactors, by
the Methods of IR and UV Spectroscopy ? M. I. Ermolaev, L. G. Savenko,
K. V. Goryachev, I. B. Strel'nikova, E. F. Kozyreva, P. I. Kondratov,
and T. I. Kirienko
477
391
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CONTENTS
Deactivation of Radioactive Off-Gases from a Single-Loop Boiling-Water Reactor
Power Plant by Exposure in a Circulation Tube ? G. Z. Chukhlov,
(continued)
Engl./Russ.
E. K. Yakshin, Yu. V. Chechetkin, and Yu. A. Solov'ev
478
392
Angular Distributions of Neutrons behind an Iron Shield ? A. I. Kiryushin
and Yu. P. Sukharev
479
393
Thermal Flux Measurements in Neutron Capture Therapy ? AT. E. Zaichik,
V. N. Ivanov, V. M. Kalashnikov, Yu. S. Ryabukhin, and V. F. Stepanenko
480
393
Ratio of Cs137?Sr90 in Ocean and Sea Water ? A. G. Trusov, L. M. Ivanova,
and L. I. Gedeonov
481
394
LETTERS TO THE EDITOR
On the Possibility that Certain Isotopic Anomalies on the Earth May be Due to an
Annihilation Explosion ? N. A. Vlasov
483
395
Neutron Flux Integrator ? Yu. K. Kulikov, Yu. T. Dergachev, G. Ya. Voronkov,
M. A. Sunchugashev, and V. V. Fursov
484
396
Effect of Intense Reactor Irradiation on the Shear Modulus and Viscosity of Iron
? E. U. Grinik, A. I. Efimov, V. S. Karasev, V. S. Landsman,
and M. I. Paliokha.
?487
397
Electron Currents Excited by y -Radiation in a Substance ? A. V. Zhemerev,
Yu. A. Medvedev, B. M. Stepanov, and G. Ya. Trukhanov
490
399
Type EPG-10-1 Electrostatic Acceleration with Charge Reversal ? A. S. Ivanov,
G. F. Kirshin, V. M. Latmanizov, A. V. Lysov, V. D. Mikhailov,
G. Ya. Roshalf, and S. A. Subbotkin
493
401
Yield of Ti" when Scandium is Irradiated with Protons or Deuterons ? P. P. Dmitriev,
G. A. Molin, and N. N. Krasnov
497
404
Yields of Sen and Se5 in Nuclear Reactions with Protons, Deuterons, and Alpha
Particles ? P. P. Dmitriev, G. A. Molin, I. 0. Konsta.ntinov, N. N. Krasnov,
and M. V. Panarii
499
405
INFORMATION
A Naturally Occurring Uranium Chain Reactor on the Earth ? N. A. Vlasov
501
407
CONFERENCES AND CONGRESSES
Third International Congress on Peaceful Uses of Underground Nuclear Explosions
? I. D. Morokhov, K. V. Myasnikov, V. N. Rodionov, and A. A. Ter-Saakov
502
407
Present Research on the Physicochemical State of Radioisotopes in Sea Water
?A. G. Trusov
505
409
Symposium on Neutron Dosimetry for Radiological Protection ? M. M. Komochkov
508
411
Unscheduled Meeting of the ICRP Leading Body ? Yu. I. Moskalev
510
412
December Session of the CERN?IFVE Scientific Commission ? A. V. Zhakovskii
511
412
V /0 ifIzotop" Seminars and Conferences
513
413
Nuclear Power Seminar at Zittau ? K. Meier
515
413
EXHIBITS
Third Internation Atomic Industry and Atomic Engineering Exhibit (Basel, October 1972)
? V. I. Mikhan
516
414
NEW EQUIPMENT
Vint-20 Single-Helix Torsatron Machine with Three-Dimensional Magnetic Axis
? A. V. Georgievskii, V. A. Suprunenko, and E. A. Sukhomlin
518
415
GU-200 Versatile Modulp.r Gamma-Irradiation Facility ? S. A. Kell tsev,
V. P. Smirnov, G. I. Lukishov, and M. S. Kuptsov
520
416
Pilot Radiation Facility for Production of Tetrachloroalkanes ? G. M. Karpov
and G. I. Lukishov
522
417
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BIBLIOGRAPHY
CONTENTS
(continued)
Engl./Russ.
New Books
525
421
BOOK REVIEWS
R. D. Vasilev. Fundamentals of the Metrology of Neutron Radiation ? Reviewed by
V. S. Yuzgin
527
422
M. L. Feltdman and A. F. Chernovets. Special Features of the Electrical Equipment
in Nuclear Electric Power Stations
529
423
The Russian press date (podpisano k pechati) of this issue was 4/20/1973.
Publication therefore did not occur prior to this date, but must be assumed
to have taken place reasonably soon thereafter.
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SYSTEM FOR MONITORING THE ENERGY DISTRIBUTION
IN THE RBMK REACTOR
I. Ya. Emel'yanov, L. V. Konstantinov,
V. V. Postnikov, V. K. Denisov,
and V. Ya. Gurovich
UDC 621.039.564
A knowledge of the distribution of energy evolution in the nuclear reactor is a vital condition for the
economically effective and danger-free exploitation of a nuclear power station. At the present time the
problem is usually solved by means of a set of sensors placed discretely in the active zone 11]. The analy-
sis of the signals arising from these sensors by data-processing equipment facilitates the operative monitor-
ing of the reserve of each fuel channel relative to the critical thermal load, and hence allows the field of
energy evolution to be optimized in such a way as to increase the power, the heat-technological reliability
of the reactor, and the average integrated power development of the charge.
The purpose of the system used for monitoring the energy distribution in the RBMK reactor (which we
shall subsequently call simply the "monitor") is that of measuring the flux of radioactive radiations char-
acterizing the energy evolution in the reactor.
The monitor analyzes the signals arriving from the energy-distribution sensors, compares these with
the specified limiting (optimum) values, and then advises the operator as to how to reshape the field of en-
ergy evolution. The optimum positioning of the sensors inside the reactor is calculated in an external elec-
tronic computer. '
For the additional correction of the field of energy evolution, making due allowance for the particular
work being carried out in the reactor, provision is made for a connection between the monitor and a data-
processing unit, so as to facilitate the periodic calculation of the energy evolution from each fuel channel.
Description of the System
The monitor is a complex of instruments and devices which facilitate the operative monitoring of the
distribution of energy evolution. The monitor incorporates the following main components: a sensor for
monitoring the energy release with respect to the radius of the reactor; a sensor for monitoring the energy
release with respect to the height of the reactor; a calibrated sensor for monitoring the total energy evolu-
tion; an auxiliary system for measuring the induced activity in the steel cables and the activity of fuel as-
semblies withdrawn from the reactor; the secondary part of the system; a signalling circuit.
In order to estimate the principal metrological characteristics of the monitor and obtain various re-
lationships between the signals arising from the sensors, the burn-up of the fuel in the fuel assemblies, the
positions of the control rods, etc., provision is made in the reactor for measuring the strength of 60 tech-
nological reference channels, furnished with steam-content sensors, flow meters, and temperature sensors.
In order, to monitor the energy evolution, special provision is made for the establishment of 153 fuel
assemblies with suspensions under a calibrated monitoring sensor, in which miniature fission chambers
may be placed during physical experiments and calibrated sensors (y chambers) during the shutdown period
of the reactor. The neutron distribution is determined in the first of these, and the residual energy evolu-
tion in the second; the corresponding data are used in order to determine the principal metrological char-
acteristics of the system and the coefficients required for calculating the power of the channels.
Translated from Atomnaya nergiya, Vol. 34, No. 5, pp. 331-334, May, 1973. Original article
submitted February 2, 1973.
o 1973 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York,
N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without
permission of the publisher. A copy of this article is available from the publisher for $15.00.
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Radial Energy-Evolution Sensor. The principle underlying the energy-evolution monitor of the reactor
is based on the so-called physical monitoring technique (i.e., the measurement of the fluxes of radioactive
radiations, which are related to the energy evolution in accordance with known relationships).
The neutron density constitutes the principal parameter for the monitor. For monitoring the radial
neutron density distribution in the reactor, 117 0-emission neutron sensors are distributed uniformly over
the active zone.
The energy-evolution sensor is placed in the central aperture of the fuel assembly ? it consists of
three main parts; a sensitive element made from a cable-type sensor, a protective sleeve with a head sec-
tion, and a coupling line made from a high-temperature cable with magnesian insulation. The sensor cable
is a high-temperature cable 3 mm in diameter with magnesian insulation, a central silver filament, and an
outer casing of stainless steel. The length of the sensitive part of the sensor is equal to the height of the
active zone of the reactor. The outer diameter of the protective stainless steel sleeve is 6 mm.
The operating principle of the energy-evolution sensor is as follows. When the silver (emitter) is ir-
radiated with neutrons, radioactive silver isotopes are formed. When these decay, high-energy 0-particles
escape from the emitter, as a result of which the latter becomes positively charged. The short-circuit cur-
rent from the emitter to the collector (the sleeve or sheath of the cable) is proportional to the neutron den-
sity.
The measured sensor current fluctuates according to the disposition of the sensor in the active zone
(from 3 to 10 ?A).
The sensor is changed by means of the lifting crane in the central reactor room. Laying of the cable
run is effected when the reactor is being assembled. The actual cable of this run is analogous to the sensor
cable, except that its central core is made of stainless steel. In laying the run, special measures are taken
to.ensure resistance to interference.
Height Energy-Evolution Sensor. For monitoring the neutron density distribution with respect to the
height of the reactor, twelve seven-section 0-emission neutron sensors are used. These are arranged uni-
formly in the central (with respect to radius) part of the reactor, close to special control rods intended for
correcting the height distribution of energy evolution.
The height energy sensor is a hollow sleeve made of an aluminum alloy, 70 mm in diameter and 2 mm
thick. Inside the sleeve at equal distances from one another are seven elementary 13-emission neutron de-
tectors (sections). The centers of the lower and upper sections are displaced relative to the boundaries of
the active zone by 500 mm in the direction of the center. The sensitive element of each section is made in
the form of a spiral 62 mm in diameter and 115 mm high; the total length of the cable with the silver core
in each sensitive element is 7000 mm. The signal from the sensitive element is conveyed to the top of the
sensor by means of a high-temperature magnesian cable with a steel central core. The whole construction
is supported by a Special central tube, which at the same time serves for passing the cable to be activated
into the reactor.
The signal from individual sections of the sensor may vary from 3 to 10 ?A, depending on their posi-
tion in the active zone.
In laying the cable lines, special measures are taken to ensure resistance to interference.
The Secondary Part of the System. The secondary part of the system is made in the form of individ-
ual functional units. As regards purpose and .execution it may be divided into two parts; the secondary part
of the height energy-evolution monitor, and the secondary part of the radial energy-evolution monitor of the
reactor.
The Secondary Part of the Radial Energy-Distribution Monitor. The instrumental part of the system
provides for the analysis of signals arriving from the 117 sensors. Successive questioning of the sensors
is employed; thus common units may be used repeatedly and the data corresponding to each monitoring point
processed in a uniform manner, so increasing accuracy and simplifying the use of the system.
The signals from the sensors pass through a circulating system to a normalizing device, in which the
signal from each questioned sensor is divided (normalized) by the total current from all the sensors, this
being proportional to the average power of the reactor. Normalization ensures a constant sensitivity of the
system at all levels of power, eliminates the necessity of changing the reference signals (settings) of the
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specified distribution of energy release in accordance with the power level of the reactor, and greatly re-
duces the effect of the delay which occurs in /3-emission sensors during transient processes on the opera-
tion of the system.
From the output of the normalizing converter the signal passes to the deviation?detection unit; in this
it is compared with a standard signal, the magnitude of which is set by means of the reference-signal sen-
sor and the individual setting sensors.
Provision is made in the reference-signal sensor for smoothly varying all the reference signals by
?12% at the same time; this enables the operator to judge the extent to which the energy distribution ap-
proximates the specified (optimum) distribution.
When there is a deviation from the specified distribution, a light signal appears on a special display,
corresponding to deviations of +5%, + 10%, and ?10%. When there is a deviation of +10% a hooter also op-
erates.
Provision is made for detecting that part of the active zone having the greatest deviation (in the sense
of increasing power) and for automatically recording this deviation, as well as recording all the normalized
and total signals at the will of the operator.
For continuous monitoring, five normalized samples from any sensors may be measured directly by
means of measuring instruments; any sensor may be directly connected to a measuring instrument.
For carrying out periodic calculations on the data-processing system the latter is connected directly
to the monitor.
Irregularities leading to the emission of a signal representing too high a power ("excess" signals) are
automatically monitored.
The Secondary Part of the Height Energy-Distribution Monitor. This system is based on successively
running through the various sections of the sensor; the results are normalized to the total signal of all the
sections of the sensor being monitored. Any deviations of the sensor section signal so normalized from the
specified (optimum) value are recorded on a light display. For deviations of more than +5% a red light
shows, for deviations of more than ?5% a green light. For a deviation of more than +10% the red light
flickers. In continuous monitoring, provision is made for connecting the seven sections of any sensor to
the measuring (indicating) instruments. At the will of the operator the readings of all the sensor sections
may be recorded.
In order to use the resultant data in subsequent optimizing calculations, the system is connected to
the data-processing machine.
Irregularities are monitored and indicated by signals.
Auxiliary Energy Monitoring System
The purpose of the auxiliary system lies in making periodic measurements of the field of energy evo-
lution over both the radius and the height of the reactor. The data resulting from these measurements are
used to find the principal metrological characteristics defining the system as a whole. The auxiliary sys-
tem consists of a device intended to monitor the energy distribution along the radius of the reactor, based
on measurements of the 7 -activity inside the fuel assemblies of the shut-down reactor by means of y -cham-
bers, and a device intended to calibrate the energy-distribution sensors and measure the activity of the fuel
assemblies.
Device for Monitoring the Distribution of Energy Evolution along the Radius of the Reactor. In view
of the fact that the y -activity in the fuel assemblies of the shut-down reactor is proportional to their power
before the shut-down, the results of activity measurements in fuel assemblies distributed uniformly over
the active zone of the reactor, adjusted for the time which has elapsed between the instant of shutting down
and the instant of measurement, as well as certain other specific corrections, provide useful information
as to the distribution of energy evolution with respect to the reactor radius.
The measurements are made with the aid of y-chambers placed in 153 specially provided central
apertures of the fuel assemblies and constituting ionization chambers with two cylindrical electrodes. The
length of the sensitive part is equal to the height of the active zone of the reactor. The external diameter
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of the y -chamber is 6 mm. The y -chambers are installed and removed with the aid of the crane in the
central hall.
In order to simplify the computing algorithm it is recommended that measurements should be made
6-10 h after shutting the reactor down.
Device for Calibrating the Sensors Monitoring the Energy Evolution and Measuring the Activity of the
Fuel Assemblies. This device is intended to measure the neutron density distribution with respect to the
height of the fuel assembly while the reactor is working and the activity of the fission fragments in the fuel
assemblies extracted from the reactor. In the first case, a special coaxial 7-chamber with a collector is
used to determine the induced y -activity of a stainless steel cable passing through the central aperture of
the 7-chamber, this cable being let down into the central aperture of the sensor monitoring the energy dis-
tribution over the height of the reactor. Using the same chamber, the induced activity of the fuel assem-
blies passing through the central aperture of the chamber is also measured. The results are used for the
mutual calibration of the sensor sections, and for obtaining additional data required to determine the princi-
pal metrological characteristics of the system.
Algorithms for Calculating the Settings and the Field of
Energy Evolution from the Sensor Readings
In the monitoring system under consideration, provision is made for comparing the sensor readings
with specified settings. It is considered that if the settings match the measured signal then the energy dis-
tribution is at its optimum. For calculating these settings, the criteria employed include the fact that the
power in any fuel assembly must not exceed a certain limiting value, and that the integrated power of the
reactor should be as great as possible. In calculating the settings the method of linear programming is
employed.
The energy distribution over all the fuel assemblies is calculated by a computing + experimental tech-
nique, based on the simultaneous use of the results of a physical calculation and the data emerging from
discrete monitoring points.
The computing + experimental method [2] is based on the determination of a quantity V(r) for each sen-
sor, this being the ratio of the sensor signal to an analogous quantity derived from a physical calculation of
the neutron fields or fields of energy evolution. The relative power distribution of the fuel assemblies W(r)
is in this case defined as the product of the energy distribution derived from the physical calculation and the
distribution V(r) interpolated over the whole active zone. The distribution of V(r) is determined by a statis-
tical interpolation method based on the theory of random functions, and gives better results than any other
methods [3].
The method here considered has been verified in relation to the reactor of the I. V. Kurchatov Beloy-
arsk Atomic Power Station.
LITERATURE CITED
1. I. Ya. Emel'yanov, At. Energ., 30, 275 (1971).
2. W. Legget, Trans. Amer. Nucl. Soc., 9, 484 (1966).
3. I. Ya. Emeryanov et al., At. Energ., 315, 423 (1971).
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RELIABILITY ACCOUNTING OF PROCESS CHANNELS
IN NUCLEAR POWER STATION 'COSTS ACCOUNTING
S. V. Bryunin, Yu. I. Koryakin, UDC 338.4:621.039.516
and V. Ya. Novikov
A broad range of design solutions considered at the stage of engineering design of the reactor core
prompts the need for engineering costs comparison of different design variants which feature contrasting
degrees of reliability. Raising the reliability of the reactor core is generally a task involving changes in
the physical design parameters and cost parameters, such as: percentage burnup of fuel, dimensions and
number of fuel elements in a fuel assembly, specific cost of the fuel. The intimate relationship between
the engineering cost figures and reliability figures results in neglect of the latter in engineering cost calcu-
lations leading to severe errors in some instances, and on occasion even to conclusions that are fundamen-
tally unsound.
In the nuclear power industry [1, 2], reduced losses incurred at nuclear power stations are broken
down into two components: the fuel component of the reduced costs and a constant component. The fuel com-
ponent of the reduced costs 12] allows us to arrive at a correct solution to the problem of how effectively the
nuclear fuel is utilized, particularly from the vantage point of reliability. This cost accounting criterion
can be used independently, when application of different fuel loadings would not entail design changes in the
nuclear power station or related changes in the volume of basic production capital.
Let us consider some expressions for the fuel component of the net cost of electric power and of capi-
tal investments in the circulating capital of nuclear power stations figured as component parts in the expres-
sions for the fuel component of the reduced expenses.
The fuel component of the net cost of electric power characterizes instantaneous expenses in fuel con-
sumed by the nuclear power station, and is arrived at by transferring the cost of the nuclear fuel, materials,
and preparation of fuel assemblies over to the electric power released to the power grid.
Power station performance, fuel utilization and fuel expenses, can be represented most fully when we
consider the entire design service life of the power station. In that case the fuel component of the net elec-
tric power cost is expressed in terms of the ratio of integrated expenses to the integrated volume of power
generated over the service life of the power station.
Two methods for calculating the fuel component of the net cost of electric power are found in use in
engineering cost calculation practice: one for the performance of the nuclear power station in a fuel cycle
incorporating chemical reprocessing of spent fuel, and the other without consideration of fuel reprocessing
("discard").
Let us consider these two cases more closely, starting with the first.
Here we introduce the notation: / for the total number of channels loaded into the reactor over a time
equal to the service life of the nuclear power station; n for the number of channels loaded into the reactor
over the service life of the nuclear power station and experiencing no damage or accidents (surviving for
the rated on-power lifetime); m(t)dt is the number of channels loaded into the reactor during the service
life of the nuclear power station and experiencing no accidents over the time interval (t, t + dt) of its rated
campaign; yo is the utilization factor of the installed power; TK is the design campaign of the channel, in
years; gK is the uranium load on the channel, in kg; Ni, is the thermal power output of the channel, in kW;
Translated from Atomnaya Energiya, Vol. 34, No. 5, pp. 335-339, May, 1973. Original article sub-
mitted December 14, 1972.
1973 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York,
N. Y. 10011. All rights reserved: This article cannot be reproduced for any purpose whatsoever without
permission of the publisher. A copy of this article is available from the publisher for $15.00.
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n is the efficiency; C is the initial specific cost of the fuel, in rubles per kg U. The following formulas are
applicable:
TO)
m n = /; m (t)dt m;
0
-8 4000-
,5000-
a)
+
7u, 5000 -
C, 03
CD
U
11 3 0 0 0
U
i.,. 4000-
0) ..
=
'Cl
VA al
a 2
..
;
-a vl 46. 2000- vs
f.s.4 Lsa
1.
0 1- >
0) E a
co o ?,-. r-
r-
0 Z >
> 0, Z ...%
4)
E >
6/ ,..% >
D CV Z
Z ..X ,(1) ll.) 0r-0
> >
2000- to Cl . . X 11.) 03 Cb
1-1
co CV.v e-,u) 1...") co-- ..) >
C'D CD ....., C- CO ..X ..
CV CI CV
1000- 4414441NVA023:- t-
600
c'g
.700
8525
800
8996
.900
9278 keV Fe
1000 MO 1200 1300 1400 1500
Channel number
Fig. 2. y -Ray spectrum for Cu?Ni ore (sample number 2).
1600
1700
1800
1900
The mercury-ore samples were analyzed only in an isolated beam of thermal neutrons in the IRT-M
reactor. Five samples with various mercury content were studied. Since the base of the sample was Si02
(98% by chemical analysis), it was convenient to determine the content relative to the very intense silicon
radiative-capture y -line E = 4936 keV = 61%). There are many intense mercury y -lines in the spec-
trum:post of them appeared in the investigated samples: 4676, 4740, 4759, 4843, 5050, 5388, 5658, 5907,
and 6458 keV. For quantitative determination of the Hg content in these samples, it is convenient to choose
those y -lines close to the silicon 4936 keV line, i.e., 4740 keV + 4759 keV (I y = 6.81% + 2.46%), 4843 keV
y = 5.24%), and 5050 keV (I = 5.35%). Unfortunately, the most intense Hg line ? 5967 keV y = 15.5%)
? is of little use for determining Hg content, because the total-absorption peak for the Si line 4936 keV is
energetically close to the peak for double emission of the Hg line 5967 keV.
For the sample whose spectrum is shown in Fig. 3, the Hg content is 0.28 ? 0.05%. Here the accu-
racy is determined mainly by the size of the errors in nuclear data (thermal-neutron capture cross sections
and absolute values of y-line intensities). Under the given conditions, we can reliably determine Hg con-
tent higher than 0.03%. By improving the experimental conditions, we can lower this figure by about a factor
of 3
When ores containing rare-earth elements are studied, main attention is given to gadolinium, whose
content can be determined with high sensitivity by the neutron-radiation method because of its very large
thermal-neutron capture cross section. Measurements were made using a Cf252 source and the reactor
neutron beam. The gadolinium content was determined from the 5584 keV y -line. The more intense lines
with energies 6750 and 5903 keV were not used, since the former is close in energy to the very intense
titanium line 6762 keV, and the latter coincides with a calcium line. Besides this, the analysis is complicated
TABLE 1. Relative Content of Elements in the Samplies Studied
Sample No.
s
Na
Ca
Ti
Al
CI
Cu
Cr 1 Ni
Fe
1
13
?
,
4,5
1,8
30
0,5
u235 u238, K40 > sm1.47, Nd1.44 > v50, Bi209 >in115, sb123
Natural unstable nuclides are present in different quantities in different media. Their total activity
is assumed to be 1011 Ci [2]. The amounts of natural unstable nuclides present in the soil are shown in
Table 1. The amounts of natural unstable nuclides in the waters of rivers are different; for example, the
Danube near Gundremingen carries approximately 8 Ci of K4", 1.4 Ci of Ra226, and 0.4 Ci of U238 per year.
2. Unstable nuclides produced in nuclear reactions, such as (a, n), (a, p), (a, 1/), (n, 2n), (n, p),
etc., for example, K38, A38, Le, C14, u237, etc.; their activity is very low.
Faculty of Natural Sciences, P. J. Saktrik University, Kaice, Czechoslovak Socialist Republic.
Translated from Atomnaya Energiya, Vol. 34, No. 5, pp. 376-380, May, 1973.
o 1973 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York,
N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without
permission of the publisher. A copy of this article is available from the publisher for $15.00.
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SO ( krd en C E".1 026 Y 34(J 73
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105 107
108 fo4
?
7
(.)
fo5
io3
2
.of
??????????
,
iO3
tut
102 1-1 ILI! 111iII1 100
1956
1960 1964 1968 1972 1976 1980 Yr
Fig. 1
Fig. 1. Amounts of the most important decay products formed in the processing of
thorium and uranium in different years, including amounts predicted for the years up to
1980: 1) ionium, radium; 2) protactinium; 3) actinium; 4) RaD; 5) MsTh, RdTh; 6) total
amount.
10 4
102
10 II I I I I I103
1956 1960 1964 1968 1972 1978 '1980yr
Fig. 2
Fig. 2. Cumulative amounts of decay products formed in the processing of thorium and
uranium, including amounts predicted for the years up to 1980: 1) ionium, radium; 2)
protactinium; 3) actinium; 4) RaD; 5) MsTh; 6) RdTh; 7) total amount.
3. Unstable nuclides produced by nuclear reactions of cosmic-ray products ? for example, H3, Be7,
C14, Na22, P32, p33, S35, and C139; the nuclides formed in the largest quantities are H3 and C14 (the amount of C14
so formed is 7.5 ? 2.7 pCi/g of carbon).
4. Nuclides heavier than uranium; the only such nuclides known in nature thus far are neptunium and
pu224.
Artificial Unstable Nuclides. The sources of these nuclides are: indicator methods used in the in-
vestigation of biospheric processes; waste products of nuclear, radiochemical, and other laboratories;
nuclear explosions, which have introduced large amounts (of the order of gigacuries) of fission products in-
to the biosphere, mainly Sr39 and Cs137, with the formation of so-called global fallout; and waste products
from the nuclear-power Odustry, as well as waste products formed after the burial of radioactive sub-
stances.
Waste Products from the Nuclear-Power Industry. Waste products are formed at each step of the
following sequence: extraction of thorium and uranium; processing of thorium and uranium; production of
fuel elements; nuclear reactor; processing of irradiated fuel elements; burial of radioactive waste products.
Quantitative data concerning the waste products formed in the first two steps of this sequence are
shown in Table 2. According to the data of [4], the activity of decay products formed during the extraction
and production of thorium and uranium and present in the biosphere today is in excess of 105 Ci; in 1971
alone, the activity of decay products entering the biosphere was more than 2 .104 Ci. The amount of thorium
and uranium decay products will increase in the future (see Figs. 1 and 2). Theactivity of thewasteproducts
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TABLE 1. Amounts of Natural Unstable
Nuclides Present in Soil [3]
Nuclide
distsec per kg of
oil
Ci/km2
K4?
R b87
Ra225
Th232
U235
U238
120-920
20-550
10--75
0,4-50
10-110
10--110
0,73-5,6
0,12-3,3
0,06-0,46
0,0024--0,3
0,06-0,67
0,06--0,67
TABLE 2. Quantity and Activity of Fun-
damental Radioactive Nuclides Formed in
the Extraction and Production of 1,000 kg
of Uranium (Equilibrium state)
Nuclides
Amount, g
Activity, Ci
Io
18,5
0,349
Pa
0,31
0,014
Ac
2,06.10-4
0,015
Ra
0,35
0,35
RaD
4,89.10-5
0,382
MsTh
4,80.10-4
0,113
RdTh
1,37.10-4
0,114
Po
8,52.10-5
0,387
ThX
7,17.10-7
0,116
of a modern uranium plant amounts to several curies of
long-lived unstable isotopes; in particular, according to
the data of [5], this activity amounts to 2-3 Ci/day (Th230,
Ra226, pb210, p0210, etc.).
The radioactive wastes produced by a nuclear reactor
consist of many nuclides (from zinc to dysprosium), trans-
uranium elements, and neutron-activation products formed
in the technological part of the reactor. Among the fission
products most dangerous from the viewpoint of radiation
hygiene are the unstable nuclides (mainly long-lived nu-
clides) of strontium, yttrium, zirconium, niobium, ruth-
enium, rhodium, iodine, cesium, barium, lanthanum, cer-
ium, praseodymium, and promethium. The activation pro-
ducts include tritium, 04, F18, Na24, A128, C138, Ar51, Cr61
Mn54, Mn56, Fe55, Co58, Co60, Cu64, Zn65, etc. The gaseous
waste products consist predominantly of inert gases, the
most important of which is Kr85.
Gaseous waste products formed by nuclear-power re-
actors, depending on the type of reactor, consist chiefly
of radioactive nuclides of tritium, A41, krypton, xenon,
1131, and 1129. The activity of the gaseous waste products
also depends on the type of reactor; for example, for a
pressurized-water reactor the activity is less than for a
boiling-water reactor (the order is reversed only in the
case of tritium). On the basis of the investigations of Mar-
tin et al. [6] and Beck et al. [7], it was found that the activity values of the gaseous waste products of nuclear
power stations were between 10-4 and 0.6 times the maximum permissible amount; tritium wastes amounted
to 14,000-15,000 Ci/year, inert-gas and activated-gas wastes to 2.1-2.6 ? 106 Ci/year, halogen wastes to
about 6 Ci/year, and A41 wastes to 650 Ci/day. The activity of the liquid waste products of the nuclear
power stations investigated in 1970 amounted to 91 Ci [7], and for individual nuclear power stations the
amount ranged from 20 to 100 pCi/liter [8].
The variation of waste-product activity with operating time is not uniform; the activity may increase
or decrease.
If we consider a nuclear power station from the viewpoint of the quantity and quality of classical power-
generation waste products, the advantages of nuclear power are obvious. Electric power stations operating
on mineral fuel are also sources of radioactivity, depending on the amount of thorium and uranium in the
fuel. The average activity of the gaseous waste products of thermal electric power stations is 102-102 mCi
/year (chiefly Ram).
A wide spectrum of artificial unstable nuclides enters the waters of the seas and oceans, where, under
the influence of a number of factors, there is considerable accumulation of nuclides (up to 102-103 pCi/g
for such nuclides as Zr, Nb, Rai?, and Ce144).
Prognosis for the Possibilities of Contamination
of the Biosphere
A reactor producing 1,000 MW (elec.) produces, on the average, 108 Ci of activity. The amount of
fission products will increase continuously, in accordance with the increase in the number of nuclear reac-
tors. According to Eisenbud's data [9], the radioactivity of fission products amounted to 18 GCi in 1970,
and in 1980, 1990, and 2000 the value will reach 56 GCi, 150 GCi, and 380 GCi, respectively (Fig. 3).
However, there are other hypotheses as well. For example, Sousselier and Pradel [2] predict that in the
year 2000, nuclear power stations will produce 400-600 GCi of waste products, of which 2025J- GCi will be
Sr" activity and 30-40 GCi will be Cs137 activity; in addition, they assert, 300-400 MCi of tritium and C14
will enter the biosphere, and the waste products will include 6-8 tons of plutonium per year. If there will
be 5,000 nuclear-power reactors operating in the year 2000, then approximately 5 kCi of 1131, 30-140 Ci of
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Cs137, 4-7 Ci of Sr", andabout 1 Ci of Sr" will enter
/of 704
the atmosphere annually. The plants processing ir-
radiated fuel elements may discharge 3 GCi of Kr83 as
waste products 110]. Today the activity of the global
104 fallout is 0.2-6 GCi; according to hypotheses, in the
year 2000 the waters of the seas and oceans will re-
ceive about 30 MCi of industrial wastes, which amounts
to 10-3 times the total activity of the sea and ocean
1026 waters [li].
Particular attention should be paid to Kr", which
is found in the gaseous waste products of reactors and
102 101 of irradiated-fuel-element processing plants. The
amount of Kr83 in the atmosphere is increasing year by
year: in 1959 the amount was 64.5 dis/min/mrnole, in
1969 it was 99.5 dis/min/mmole [12], and today the
2000
/0? value ranges from 2 -10-2 to 3 .10-1 mCi/m3 [13]. Trit-
ium, formed in quantities of 10-30 Ci/MW, is also dan-
103
(.)
1900
1970 1980
. yr
1990
Fig. 3. Assumed amounts of the most impor-
tant fission products (MCi) of nuclear-power
reactors [1) Xein; 2) Zr33, N1335, Bai", ee141,
pr143; 3) V31; 4) Gel"; 5) Sim; 6) Ru103, I131; 7)
Nd147; 8) P147; U.-ss
) ST"; 10) CS137; 11) Tei"; 12)
Rum] and their total activity (- - -) in GCi.
gerous because of its capacity to be metabolized. When
nuclear power stations have an installed capacity of 100
GW (elec.), we shall have to take account of the forma-
tion of 1123 and xenon isotopes. After 1970, we may ex-
pect the rate of Ii31 formation to increase to 100 GCi
/day, while the amount of tritium in sea water will reach
1 MCi/year [14].
Experience gained in the operation of nuclear-power reactors indicates that there is a satisfactory
safety level, achieved by the application of technological measures based on present standards. We may
expect these standards to become more rigorous and the maximum permissible concentration values to de-
crease. Even today, the value of the risk factor in normal reactor operation is between 10-3 and 104 of
the possibility of an industrial accident, and for breakdown situations the factor is between 104 and 10-7.
According to the data of Beck et al. [7], the irradiation of persons working at nuclear power stations in the
United States amounted to 1.25 rem or less for 5,352 persons, 1.25-2 rem for 160 persons, 2-3 rem for
144 persons, 3-4 rem for 70 persons, and 4-5 rem for 26 persons; only 7 persons were subjected to more
than 5 rem of radiation, and nobody to more than 7 rem.
Nevertheless, it is essential that we begin at once to investigate the behavior of unstable nuclides in
the biosphere, since by the year 2000 the influence of nuclear power stations will have extended to an area
of about 107 km2, which amounts to 6.7% of the earth's land area. The situation will be more complicated
if the scientific and technological revolution is accompanied by an increase in population density (it is as-
sumed that in 2030-2050 there will be approximately 12 billion people living on an area of 3000 million ha,
constituting 2% of the earth's land area). In that case mankind will be faced with problems of energy pro-
duction, the dispersion and discharge of heat, the dispersion of radioactivity, etc. Radioecological prob-
lems will arise in different forms in different countries; these problems must now be solved by taking ac-
count of the specific situation of each state from the geographical, geological, hydrological, dendrological,
industrial, and agricultural viewpoints, and also in accordance with each country's population density. The
purposes of these investigations will be: to prevent breakdowns; to work out rapid methods for indicating
the presence of unstable nuclides in soil, water, plants, and animals; to determine critical objects and cri-
tical organs in biological objects; to determine the factors influencing the accumulation of nuclides in ob-
jects; to select agricultural crops suitable for cultivation in the vicinity of a nuclear reactor; to study the
movement of unstable nuclides along the food chains and the possibility of stopping them; to develop moni-
toring methods; to determine the effect of small doses of chronic irradiation on plants and animals; to deter-
mine the minimal value of a genetically significant dose; to develop methods of rapid analysis for monitoring
purposes, etc.
Radioecological investigations are of an interdisciplinary nature and very complicated, but they are
absolutely essential for a knowledge of the processes in which unstable nuclides participate in individual bio-
spheric systems; they are important for the preservation of the environment in which mankind lives.
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LITERATURE CITED
. J. Pelikan, 0 quce ekologie na vysok3ich gkolah. Seminar, Kogice (1971).
2. Y. Sousselier and J. Pradel, Fourth Geneva Conference (1971), Report No. 49/P/766 (France).
3. M. J. H. Bowen, Trace Elements in Biochemistry, Perg. Press, London (1966).
4. B. I. Spinrad, Symp. IAEA "Environmental aspects of nuclear power stations," Vienna (1971); JadernA
energie, 17, 205 (1971).
5. P. R. Kamath et al., Fourth Geneva Conference (1971), Report No. 49/P/536 (India).
6. J. E. Martin et al., Symp. IAEA "Environmental aspects of nuclear power stations," Vienna (1971).
7. C. F. Beck et al., Fourth Geneva Conference (1971), Report No. 49/P/038.
8. C. E. Kent et al., Symp. IAEA "Environmental aspects of nuclear power stations," Vienna (1971).
9. M. Eisenbud, Environmental Radioactivity, McGraw?Hill, New York (1963).
10. Yu. A. Izraer and E. N. Teverovskii, At. Energ., 31, 423 (1971).
11. M. Saiki et al., Fourth Geneva Conference (1971), Report No. 49/P/850 (Japan).
12. J. Schroder et al., Nature, 233, 614 (1971).
13. M. M. Hendrickson, Symp. IAEA "Environmental aspects of nuclear power stations," Vienna (1971).
14. A. Preston et al., Fourth Geneva Conference (1971), Report No. 49/P/512.
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CURRENT PROBLEMS IN THE RADIOECOLOGY
OF SOILS AND,PLANTS
G. Plitakova, T. Sabova,
and M. Zaduban
A biocenosis is characterized by complex processes taking place in the earth's biosphere. The in-
vestigation of the effects of various factors on organisms under natural conditions is known as ecology.
One of the new factors affecting the biosphere is the rise in the quantity of unstable nuclides in nature,
resulting from the current development of nuclear industry and also from the testing of nuclear weapons.
This factor may upset the equilibrium of the biosphere and pose a threat to mankind.
The main task of the relatively new scientific discipline known as radioecology is to investigate the
laws governing the migration of radioactive substances in the biosphere and the effects of ionizing radiation
on living organisms and on the earth's biosphere as a whole. From the fairly abundant experimental ma-
terial already available today, we can conclude that mankind cannot afford to disregard the presence of
radionuclides in nature.
The problem of the contamination of food products by radionuclides is one of the most important prob-
lems in the field of public health. This is so because we do not yet clearly understand the role of the bio-
logical effects of small doses of radiation; we have not yet established the magnitude of the doses caused
by the presence of radioactive substances in our daily diet, we do not know how much is contributed to the
dose by various ionization sources, we have not reached agreement on the assessment of food comtamina-
tion, etc.
The introduction of radioactive substances into the links of the biospheric chain depends on the loca-
tion and nature of the sources of unstable nuclides.
The fission of heavy nuclei, chiefly those of U235, Pll239, and Th232, gives rise to unstable nuclides (fis-
sion products), beginning with 30Zn72 and ending withseDYiel, making a total of about 340 nuclides, of which
92 are stable.
In nuclear explosions and in "total" breakdowns of nuclear reactors, the important parameters of the
radioactive fission products are their half-lives and the chemical properties characterizing their participa-
tion in the physiological processes of the living organisms of the biosphere. The fission products on which ,
the greatest amount of research has been done are: Sr89, Sr98?Y98, Zr"?Nb", Rui98?Rhi88, 1131, CSi37
?Ba137 ce144_pr/44,
111 Bal"?La.14? and PMI47.
Depending on the conditions of the nuclear explosion or breakdown, other unstable nuclides, arising
chiefly from the neutron activation of elements of the external environment, may also be of interest from
the viewpoint of radioecology.
In the normal operation of a nuclear reactor and in breakdowns of a local (technological) nature, the
group of unstable nuclides entering the atmosphere in the form of gaseous or liquid wastes differs from the
spectrum of unstable nuclides produced in a nuclear explosion. The gaseous wastes, depending on the types
of nuclear reactors involved, consist of radioactive inert gases and also of iodine and cesium, with traces
of strontium, barium, and other elements. Gaseous wastes may also contain corrosive products formed
during the neutron activation of structural and technological components of a nuclear reactor. The most
important of these are H3, C14, and others (Ar41, unstable isotopes of chromium, manganese, iron, tantalum,
Faculty of Natural Sciences, P. J. gafarik University, Kogice, Czechoslovak Socialist Republic.
Translated from Atomnaya Energiya, Vol. 34, No. 5, pp. 380-390, May, 1973.
0 1973 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York,
N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without
permission of the publisher. A copy of this article is available from the publisher for $15.00.
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tungsten, etc.) [1]. What we find in the biosphere today are mainly long-lived fission products formed in
nuclear explosions (Sr"?Y", Cs137); they are part of the so-called global radioactive fallout.
As a result of the development of nuclear power, fission products are entering the hydrosphere in
increasing quantities; the amount of such fission products in some parts of the oceans and seas in 1967 was
several times the amount of Sr" and Cs137 resulting from global radioactive fallout [2].
We shall discuss below the biospheric processes in which there is participation by long-lived fission
products formed in nuclear explosions. The results obtained in investigations of processes involving Sr",
Cs137, Ce144, and other long-lived fission products formed in nuclear explosions can be used in studying the
potential contamination of the biosphere and hydrosphere by installations operating on irradiated nuclear
fuel. Other significant processes, which will not be dealt with in this article, are those involving partici-
pation by fission products of uranium, protactinium, and thorium
(Ra226 Ra228 Ac227, Th230 P0210, etc.),
contaminating the biosphere and hydrosphere in the vicinity of installations where uranium and thorium ores
are extracted and processed.
The isotopes that have been most thoroughly investigated are the radioisotopes of strontium, cesium,
and iodine (the last has been studied chiefly in the thyroid gland). In the radioecology of plants, the most
detailed research has been done on Sr" and Cs137, as evidenced by an abundant literature. Less information
has been accumulated concerning Ii 31 , C el", RUM ?Rhi" , Z T95 ?Nb95 , and others.
The contamination of plants by radionuclides may take place in two ways: through the leaves and
through the roots; in the latter case the contamination depends on the characteristics of the environment
? soil system.
The task of radionuclide agrochemistry is to investigate the interrelationships between radionuclides,
plants, and soil. In order to carry out such investigations, we must know the principles of sorption and
desorption.
The Radioecology of Soils. The radioecology of soils is being developed today on the basis of bio-
physics, physics, and soil chemistry. It deals with the laws governing the way in which uranium fission
products and nuclides resulting from soil activation interact with the soil, their sorption, desorption, and
migration in the soil, as well as the migration of these products in the soil?plant system and the deactiva-
tion of soils.
Soils are components of the biocenosis which are directly involved in the life of various organisms.
In the investigation of the sorption of elements from aqueous solution by the soil, we must investigate
the concentration of the element in question in the aqueous solution (a change in concentration may affect the
processes of sorption, desorption, and migration of individual elements in the soil); the chemical form of
the element in the solution, which determines the nature of the sorption of the element in each individual
case; and the nature of soil absorbing the element (large differences in the properties of soils cause quanti-
tative changes in sorption and desorption).
In investigating the desorption of elements from the soil into an aqueous solution, we must take into
consideration the desorbing action of the ions present in the aqueous solution, the complex-forming capacity
of organic substances, and the variation in the pH and oxidation?reduction potential of the medium.
The migration of elements in soil, from the physicochemical point of view, is a continuous succession
of repeated processes of sorption and desorption of elements. In order to characterize the behavior of an
element, we must know how strongly it is sorbed by the soil and know the influence of the external and in-
ternal factors determining its migration capability. The internal factors affecting migration include the
chemical properties of the individual element, its concentration, and its chemical form, which is deter-
mined both by the nature and concentration of the element and by the properties of the medium. The most
important external factors affecting migration are the presence of extraneous ions in the aqueous solution,
the value of the pH, the oxidation?reduction potential of the medium, the presence of migrating colloids in
the solution, and the complex-forming capacity of the organic substances involved.
The data available in the literature are most complete in the case of Sr". Its coefficient of distribu-
tion and percentage of sorption increase with the number of exchange cations contained in soils. The coef-
ficient of distribution depends on the pH of the soil. The migration of Sr" has been investigated in cherno-
zem soils containing moderate amounts and low amounts of .podzol. The migration of Sr" is more intensive
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in soils with a lighter texture. The larger the amount of exchange calcium in the soil the more Sr90 is fixed
in it [3].
The coefficient of distribution and the percentage of sorption (up to 92%) are also rather high in buro-
zems (brown soils), although this type of soil contains a lower concentration of exchange cations. In experi-
ments with brown forest soils it was found that as the pH increases to 5, the sorption of Sr90 increases be-
cause there is less competition from H+ and A13+. As the pH varies from 5 to 8, the sorption remains ap-
proximately constant. For pH values increasing above 8, the absorption of Sr90 depends on the cation con-
tained in the added alkali; the absorption remains constant for sodium, potassium, and NH4 but decreases
for calcium and strontium.
In soils with turf and low podzol the amount of exchange cations is low, and therefore the distribution
coefficient and the percentage of sorption of Sr90 are low (86%).
Sandy forms of podzol have a lower cation-exchange capacity than loamy and clayey forms, and it may
be said that the concentration of Sr90 in the upper layers of the soil is inversely proportional to its cation-
exchange capacity. As the cation-exchange capacity of podzols decreases, the concentration of Sr90 will de-
crease. Strontium is accumulated in the top 5 cm of podzols. The lowest distribution coefficient and per-
centage of sorption for Sr90 (77%) has been found in sierozem (gray soil).
The desorption of Sr90 from turfy meadow soils by univalent cations is low. The highest percentage
of sorption is attained in soils with Ca2+ (70.3%) and aluminum (90%) [4].
The vertical migration of Sr" depends on the type of soil and the amount of fertilizer used. The effect
of fertilizers on migration can be explained by the fact that the rate of vertical migration depends essential-
ly on the concentration of cations in the soil solution.
The transfer of Sr90 is also affected by the percentage of organic substances in the soil, the type of
clayey minerals present, and the value of the pH. Such processes also include transfer with water and dif-
fusion, but the avilable data on these phenomena are very scanty [5].
The vertical migration of Sr90 and Ce141 is affected by the texture of the soils. In lighter textured
soils the migration of Sr90 is more intensive than the migration of Ce141 [6]. Essentially, however, the fis-
sion products are contained in the top 5-10 cm of the soil, which contains the largest amount of organic sub-
stances.
Investigations of horizontal migration have shown that surface runoff removes less than 5% of the Sr90
falling on plowed ground. We do not have sufficient information concerning the horizontal migration of Sr90
after it has fallen on ground planted in agricultural crops. In observations made 3 years after the introduc-
tion of Sr90 into pastures, the isotope was found at points 60-65 cm from the point of introduction. It is not
yet clear what role is played in horizontal migration by diffusion and by transfer through the root systems
of plants.
A fairly large number of reports are available concerning the behavior of Y91, whose sorption by cher-
nozem is 87-97% at acid pH values of 3-5, 84-89% at pH values of 6-7, and 85-94% at pH values of 8-10.
This isotope is most strongly absorbed by chernozem. Its sorption by krasnozem (red soil) increases as
the pH increases from 3 to 10. In the pH = 6-8 range the percentage of sorption remains unchanged. The
highest percentage of sorption (95%) has been observed for pH = 9. The absorption in the Ai stratum of
podzols is 90-95%, and the absorption in the A2 stratum is 89-94%. The highest percentage of sorption (97%)
was observed in the Bi stratum. In turfy meadow soils the highest percentages of sorption were observed
at pH = 3-6. The lowest sorption was observed at pH = 7 (89%).
The desorption of Y91 was carried out by means of 0.1 N solutions of NaC1, Al2(SO4)3, and FeC13. In
chernozem the lowest desorption was observed when the yttrium was displaced by sodium; aluminum dis-
placed 6% of the Y91, and iron displaced 65%. The desorption by sodium from krasnozem was 1%, while
aluminum displaced 42% and iron displaced 78%. The desorption of Y91 by aluminum in the three strata of
turfy podzols is rather high: in the Ai stratum aluminum displaced 27% of the yttrium and iron displaced
77%, in the A2 stratum the corresponding values were 54% and 77%, and in the Bi stratum the values were
43% and 75%. The lowest desorption of Y91 was observed in turfy meadow soil (8% by aluminum and 45% by
iron) [7].
Some radionuclides, e.g., Zr, are so strongly sorbed by the soil that their desorption is very low
(less than 10%). The soil may contain Zr 95 and Nb95 chiefly in the form of radiocolloids. The sorption of
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these elements reached its maximum value at pH = 4-8; at pH = 8 there was a decrease in the sorptive capa-
city, followed by an increase at pH values greater than 11 [3].
In contrast to strontium and cesium, Rut" occurs in the soil in anion form, but information on its
chemical compounds is very scanty. Different authors give different interpretations of the characteristics
of the sorption behavior of Rut". Some authors assume that sorption is caused by the colloidal state of
radioactive ruthenium in solutions [8], while others believe that in the sorption process the ruthenium com-
bines with the organic substances present in the soils [9]. The low sorption of ruthenium may be due to its
presence in the solutions in the form of anion complexes.
Relatively little has been published in the literature concerning the soil chemistry of short-lived nu-
clides, such as 1131. It is known that iodine is very rapidly absorbed from soil solutions and transferred to
the leaves. The results of investigations of 1131 sorption by soils from the Iolo and Aiken regions indicate
that the isotope is fixed in the organic mass. The amount of 1131 sorbed by kaolinite and bentonite is very
low. Anion exchange plays only a very slight role in the sorption of 1131.
Experiments with turf from which the mineral fraction has been removed have shown that the organic
fraction strongly sorbs 1131: turfy soil sorbed 85.7%, while the extracted organic mass sorbed 80.6%. In the
pH range from 4.5 to 8.5, Iolo soils sorbed 60% of the iodine, and Aiken soils sorbed 80-90% [10].
The bond between Cs137 and soil is different from the bond between strontium and soil, and this is why
Cs137 and strontium move in different ways along the soil?plant chain. The Cs137 is sorbed onto leached
clayey minerals low in potassium. The capacity of cesium to exchange with other cations is low, and it
has its specific characteristics if it is present in the soil in microconcentrations. Cesium introduced into
mineral soils in low concentrations is sorbed so strongly that it becomes inaccessible to plants. The degree
of sorption of Cs137 depends on the soil and on physicochemical factors, so that it is impossible to draw any
definite conclusions, but it is known that illites and vermiculites sorb cesium very strongly, while mont-
morillonites and kaolinites sorb it more weakly.
Investigations have determined the ratio between the amount of Cs137 sorbed by plants and the organic-
substance content of soils caused by Cs137 cation exchange [11].
The absorption of Cs137 is 98% in chernozem, 95% in krasnozem, and highest of all (99%) in meadow
soils.
Very little Ce111 in the dissolved state is found in soils; an exception is observed in the case of soils
with low pH values. In addition to the pH, the nature of the clayey minerals in the soil also affects the
strength of sorption [11]. Molchanova [12] asserts that for neutral and alkaline pH values the sorption of
cerium decreases. The absorption value of Ce111 in chernozem is 74%. The sorption is strongest in turfy
meadow soil and chernozem. Sorbed cerium is easily desorbed from the soil by salts of iron, aluminum,
and copper. When iron colloids in solution are present in the soil, the cerium sorption is lower. The sorp-
tion of Ce111 by soils decreases as the concentration of iron in the solution increases. In the sorption of
cerium by chernozem, microquantities of cerium are sorbed onto the most active part of the chernozem:
humic acid and substances similar to it.
In [9] it was found that radionuclides may be arranged in the following order with respect to mobility
in soils: Ru > Sr > Ce > Y > Co > Cs for sorption, and Sr ? Ru > Ce > Co > Cs for desorption.
On the basis of the available data, we may conclude that insufficient research has been done on the
sorption and desorption of uranium fission products (separately or mixed) by soils, on the effects of pH
upon sorption and desorption, and on the effects of the physical and mechanical properties of the organic
part of the soils. Very little research has been conducted on individual types of soils from the viewpoint
of the above-mentioned requirements.
An analysis of the literature on the radioecology of soils for the planning of further experiments in the
Czechoslovak Socialist Republic enables us to draw the following conclusions:
1. In the investigation of soil processes involving Sr", studies must be conducted on desorption and
migration caused by burozem, brown forest soil, podzol, meadow soil, and turfy soil; consideration must
be given to the effects of physicochemical properties on migration, sorption, and desorption, due to meadow
soil, turf, and sierozem; and account must be taken of the effect of pH on sorption and desorption due to
podzol, meadow soil, turfy soil, and sierozem. We have not yet determined the role of the organic part
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of the soil in the absorption and migration of strontium in chernozem, burozem, brown forest soil, and
sierozem in individual geological strata. Experimental data must be supplemented by information on the
deactivation of burozem, brown forest soil, podzol, meadow soil, turfy soil, and sierozem.
2. Extremely little information is available concerning the behavior of Zr95 and Nb 95 in soils. Investi-
gations have been conducted on sorption and desorption by turfy meadow soil and the effect of pH on these
processes. For both of these fission products, experimental investigations must be conducted on migration,
sorption, and desorption, as well as the effect of pH upon sorption and desorption in the soils mentioned
under 1.
The effect of physicochemical and mechanical properties of soils, as well as of their organic part,
on migration and adsorption must be determined for all types of soils.
3. It is assumed that Ru196 occurs in soils in anion form. Its chemical form must be determined. At-
tention must be given to the processes of sorption and migration and to the effects of pH, physicochemical
properties and mechanical properties of soils on migration and sorption. The deactivation of all types of
soils must also be investigated.
4. In the case of yttrium, experimental research must be conducted to determine its migration and
the effect of physicochemical and mechanical properties on sorption and migration in the soils mentioned
under 1. Additional information must be obtained concerning sorption and the effect of pH on sorption by
burozem, brown forest soil, turfy gley, rendzina (humus carbonatic soil), solonets (alkali soil), and siero-
zem.
5. For Cs137 a high percentage of sorption is characteristic. Data about this isotope must be supple-
mented by information concerning its behavior in burozem, brown forest soil, podzol, turfy gley, solonets,
rendzina, and sierozem. Attention must be given to the processes of desorption and migration, the effects
of pH on sorption and migration, the effects of physicochemical and mechanical properties of soils on these
processes, and the question of deactivation of all types of soils.
6. The soil chemistry of 1131 requires further research. We must explain the questions of sorption
and migration and the effects of pH and of physicochemical and mechanical properties, as well as of the
organic part of the soil, on sorption by soils.
7. The authors of this article have found no information whatever in the literature with regard to the
behavior of Bai" and Lau?. The behavior of these products in soils must be determined experimentally.
8. For Ce144, we must determine experimentally its sorption and desorption, as well as the effect of
pH on sorption and desorption by burozem, brown forest soils, turfy gley, rendzina, solonets, and siero-
zem, and we must supplement our information with data on the effect of soil properties upon the behavior
of this element.
9. We must clarify the behavior of fission products in all types of soils when different anions are pre-
sent in them.
10. We must explain the effect of large quantities of mineral fertilizers, as well as the effects of pro-
longed fertilization with manure and industrial fertilizers, on the behavior of fision products in soils; we
must solve the problems of chemical and biological deactivation.
11. We must work out general criteria characterizing the horizontal and vertical migration of fission
products and corrosion products, develop appropriate methods for monitoring soils, etc.
Radioecology of Plants. Radioactive contamination results only from those fission products which are
deposited in plants during their vegetative period, when their penetration through the root system depends
on the total amount of fission products in the soil.
The quantity of radionuclides in the soil may increase if fallout takes place over a long period with
relatively constant intensity (for example, during the operation of a nuclear reactor). Radioactive sub-
stances settle on the surface of the earth together with particles, vapors, or solutions, they are held by the
vegetative cover, and in many cases they are absorbed. Such contamination processes have been fairly
thoroughly studied in the literature (see, for example, [11]).
Questions of special interest in the direct contamination of plants by radionuclides are where the
radionuclides enter the tissue and what factors influence the rate of absorption. Three ways of direct
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Fig. 1. Mechanism of contamination
of perennial forage plants.
Fig. 2. Mechanism of contamination
of annual crops.
absorption are known (see Figs. 1-3): 1) contamination through the leaves; 2) floral contamination (through
the flowers); and 3) contamination from the sod (through the basal parts of the plant, or the surface parts
in the case of plants which are not in contact with the soil).
When it rains, there is not only absorption of radioactive products but also a washing away of these
products from the upper parts of plants and their transfer into the lower parts. Similarly, after radionu-
clides have been washed out of the basal zone into the soil, the absorption from the sod is replaced by as-
similation through the roots. The latter method plays an important role in perennial forage plants. Con-
tamination through leaves and through flowers can result only from those radionuclides which were'intro-
duced into the plant during the time of growth of the leaf or flower in question.
While absorption through leaves and flowers depends on the amount of fallout taking place during a re-
latively short period of time, absorption from the sod continues for a considerably longer time. When
enough time has elapsed after the fallout of the fission products, the contribution of direct contamination is
reduced, and the contamination of man's food by long-lived isotopes begins to depend increasingly on their
absorption through the root systems of plants. The rate of root assimilation of radioactive substances from
the soil, which is the principal reservoir of radionuclides, depends not only on the physiological properties
of the plants but also on processes taking place in the soil. It must be noted that plants absorb only water-
soluble substances. The concentration of electrolytes in the aqueous phase of the soil is so low that the
electrolytes are in a dissociated state. Radionuclides are absorbed by plants in the form of ions. The ab-
sorption of a nuclide by plants which are in the growing stage is substantially affected by the concentration
of the ion in the nutritive medium, its chemical properties, the pH value, the concentration of other ions in
the nutritive medium, and the degree to which the ion participates in metabolic processes. It has been found
that plants which have grown under identical conditions in the same pasture may exhibit definite differences
in the rates of migration of radioisotopes.
Especially important from the agrochemical point of view are investigations on the accumulation of fis-
sion products in the harvest of agricultural crops. The absorption of a radioactive isotope in the organs
which are above the ground amounts to 90% of the total quantity of the isotope contained in the plant in the
case of strontium and to 60% in the case of cesium [131.
Radionuclides such as Y9I, Cel", Ru196, Zr, and Nb 95 are concentrated mainly in the root systems
of plants (90-99%). In the above-ground part of the plant the bulk of the radionuclides is concentrated in the
vegetative organs (90-98% of the total above-ground mass), and the amount in the generative organs is con-
siderably less.
The accumulation of fission products increases with the above-ground mass of the plant, but the nu-
clide content per unit weight decreases as the organic mass increases, i.e., the laws governing this pro-
cess are similar to those governing the absorption of nitrogen, potassium, phosphorus, and other elements
of biological importance.
The soil constitutes a definite boundary which prevents the fission products from entering the plant,
and therefore from entering the food chain. The nuclides interact with the soil, and a smaller amount of
nuclides enters the plants from soil than would enter from sand or from aqueous solution. This difference
is much greater for Sr% than for CsI37, since radioactive strontium is sorbed by the soil in the metabolic
form, while radioactive cesium is sorbed in the nonmetabolic form.
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Atmogle re
f
?
?
a 3
3
? ? ? 00
Bodies of-
water
c:4
Fig. 3. Direct and indirect contamina-
tion of plants. From the atmosphere: 1)
floral contamination; 2) contamination
through the leaves; from the soil; 3) con-
tamination through the leaves by soil dust;
4) basal contamination; 5) root contamina-
tion.
The properties of soil strongly affect the migration of radionuclides. For example, Sr" migrates in-
to plants from turfy podzols to a very large extent, but there is much less migration from krasnozem, siero-
zem, and chernozem. The strongest radionuclide transfer has been observed to be that from turfy podzol.
The types of soil may be classified according to the Sr" and metabolic-calcium content of the plants.
For example, the absorption of Sr" decreases as the amount of metabolic calcium in the soil increases.
The Csiu content of plants in turfy podzols and in krasnozems is 10-100 times as much, and sometimes
even 200 times as much, as that of plants in sierozems; this is due to the presence of metabolic potassium
in the soil. The accumulation of Cs137 depends on the presence of metabolic potassium in the soil; as the
amount of potassium increases, the cesium content will decrease. In some cases, however, this relation
is not observed.
The absorption of Sr" and Cs137 is strongly dependent on the texture of the soil.
The presence of silt is thought to be of great importance. Experiments have shown that the accumula-
tion of strontium and cesium decreases if silt particles are added to silica sand. The presence of certain
minerals in the soil also affects the absorption and accumulation of radioactive nuclides by plants. Askanite
and bentonite (representatives of the montsnorillonite group of minerals) are characterized by a high sorptive
capacity: they strongly sorb Sr" and reduce its accumulation in plant crops.
In addition, the intensity of absorption of radionuclides depends on the biological properties of plants.
We know the relationship governing the accumulation of radionuclides and their chemical analogs. Plants
containing large amounts of potassium will accumulate more Sr". Plants containing little potassium will
absorb more Cs137. Plants may be arranged in descending order of the amount of nuclides absorbed in in-
dividual organs as follows: Viciaceae > Solanaceae > Asteraceae > Graminae (for the above-ground part)
and Viciaceae > Graminae > Asteraceae > Solanaceae (for the root part).
It has been determined that the largest amount of Sr" is found in radishes, which are followed by beets,
vetch, potatoes, and peas, with wheat and oats absorbing least of all. This sequence changes if the Se"
content is expressed in terms of the amount per gram of calcium.
On the basis of experimental studies concerning the absorption of radionuclides from the soil by plants,
the following sequence has been set up: Sr89 and Sr" ? Cs137 > Rul > el44 > ?8 Zr98 > PU239. In all soils,
the absorption of Sr89 was considerably higher than the accumulation of other radionuclides. The absorption
of Ru188 is higher than the absorption of Cs137 in all soils except heavy sandy soil. The accumulation of Ce144
is considerably lower than that of the radionuclides preceding it, except in the soil with the most acid re-
action (loam). The absorption and distribution of radionuclides are affected to a considerable extent by the
properties of the soil, namely: the concentration of other ions in the soil solution, the presence of stable
isotopes of the same element, the migration of fission products in the soil profile, etc.
The amount of radionuclides that is assimilated by plants may be expressed in three ways: 1) the ratio
of the amount of radionuclide per unit weight of plant biomass to the amount of the same radionuclide per
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unit weight of soil; 2) the amount of radionuclide accumulated by the plants growing on a unit area of soil,
expressed as a percentage of the total amount of this radionuclide in the soil; 3) the ratio of the amount of
a nuclide to the amount of a chemically similar ion in the plant biomass, divided by the ratio of these two
ions in the soil.
The concentration of a fission product in plants (particularly in the root system) per unit weight is,
as a rule, higher than the analogous concentration for the soil. Some researchers have proposed that this
ratio should be called the "coefficient of accumulation," but calculations of this kind have only a limited
value from the standpoint of physics. If the coefficient of accumulation is greater than 1, this still does
not mean that the ions migrate from the soil into the plants against the concentration gradient. In order to
prove this, we must compare the concentration of the ions present in free ionic form in the aqueous phase
within the plants with the analogous concentration for the soil. Finding this last value is particularly diffi-
cult. The value of the coefficient of accumulation depends on the rate of growth of the plant and on the
amount of soil. A calculation of the type mentioned is suitable for a comparison of the amounts of fission
products accumulating in plants in cases where the conditions of the external environment are specified;
such calculations are, therefore, of relatively little importance. Similar limitations apply to a determina-
tion of the quantities excreted by plants.
The results of laboratory experiments in which plants have been grown in small vessels may give a
completely different picture of the introduction of radioactive substances into plants than the results of ex-
periments with field plants, since the distribution of plant roots in the soils differs from one case to the
other.
There are only scanty data on the accumulation of fission products by plants under field conditions
when ordinary methods of cultivation are used. The isotopes most thoroughly studied have been Sr89 and
Sr88. It has been found that, depending on the type of plants and type of soil involved, 0.2-3% of the Sr"
content of the soil is accumulated in the total mass of the harvest in one year. On the basis of these data
and of laboratory experiments, it may be expected that under natural conditions the amount of any other
radionuclide accumulated in an agricultural crop will be less than 0.1% per year.
We cannot recommend any one method for measuring the accumulation of fission products by plants
from the soil; the proper choice of such a method will depend on the observation conditions and on the pur-
pose of the research.
Methods for Predicting the Contamination of the Vegetative Cover by Fission Products. In ecological
experiments with radionuclides and in the investigation of the radioactive contamination of the external en-
vironment, it is often necessary to determine the total amount of radionuclides contained in various parts
of the system, the amounts of radionuclides contained in individual components, and the extraction and ac-
cumulation of radionuclides. These processes have been investigated quantitatively by means of analog
computers [14]. The migration of fission products in an ecological system was studied at the Oak Ridge
National Laboratory in 1961. The investigators successfully overcame the difficulties involved in the cal-
culations and the construction of small models. Interpretation of the data on the rate of migration of radio-
nuclides between the components of ecological systems made it possible to construct mathematical models
of the physical processes involved.
The first models described the migration of carbon, energy, and biomass. The migration of carbon
includes its separation from organic compounds, its transfer into the atmosphere in the form of CO2, and
its displacement together with atmospheric carbon; this process is repeated after the incorporation of car-
bon in the biomass as a result of photosynthesis. A large proportion of the biomass of organisms and of
organic substances in the soil migrates in the same way as carbon, i.e., from the photosynthesizing organs
of plants into the root system, or else it goes into the ground cover and the soil. Nutritive substances mi-
grate from the soil into the root system and are transported into the above-ground organs; after those or-
gans die, the nutritive substances may again migrate into the ground cover and the soil. Radionuclides
migrate in the same manner.
Some nuclides, such as cesium, are strongly sorbed by the soil (the form in which they are found in
the soil is not very soluble) but become incorporated into the cycle through the action of plants. These
models are important because they enable us to investigate and calculate the migration of a nuclide if we
have a knowledge of at least some parts of the ecological system (Fig. 4).
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;Atmospheric ,
;radioactive i
Ifallout
k u U. I
k U
2
x,
_ kX
xe,9 x.9,8 X g
'Radioactive I
'wastes r?
UsX6 L
Fig. 4. Migration of inorganic nutritive substances or radio-
nuclides in an ecological system: X, g/m2) quantity of the
element on the surface; L, g/m2) rate of fallout; U, g) total
amount of the element [the subscripts after X and U denote
the following: 1) amount of the element present in grass; 2)
in roots; 3) in herbivorous organisms; 4,5) in carnivorous
organisms; 6) in organic ground cover; 7) in organisms
which decompose the ground cover; 8) metabolic form of the
element or isotope in the soil; 9) relatively inaccessible form
of the element or isotope in the soil]; kux and kxu) coefficients
of transfer from U to X and vice versa.
General Appraisal of Experiments in the Field of Radioecology; Some Conclusions. In experiments
investigating the migration and accumulation of fission products in plants, the nutritive media used were
nutritive solutions and sand and soil cultures. On the basis of a comparison of the absorption of fission pro-
ducts from aqueous solutions and from the soil, we can conclude that fission products are absorbed more
intensively from aqueous solutions. This can be explained by the fact that the fission products are sorbed
in the soil.
The amount of radionuclides accumulated in crops depends on the biological properties of the plants
concerned. Plants of the family Viciaceae accumulate a considerably larger amount of fission products than
do representatives of the family Graminae. The distribution and accumulation of fission products in plant
organs are affected by many ecological factors, e.g., the soil factor. Light-textured soils are of higher
quality from the agricultural standpoint, but the amount of fission products transported from them is larger
also. In addition to being affected by the texture of the soil, the absorption of nuclides is affected by the
amount of organic substances in the soil, the amount of calcium, the pH, and other characteristics. If we
compare soils according to the amount of fission products absorbed by plants, we obtain the following se-
quence: clayey sand > podzol -type sandy loam > podzol -type average loam > podzol -type heavy loam > cher-
nozem.
On the basis of other data, the following sequence has been established for Sr": sandy loam > loam
> sierozem > solonchak (saline soil) > turf > chernozem. The absorption of Sr" and Cs137 from the soil by
plants depends on time. The concentration of Sr90 in plants depends on its concentration in the soil, although
it is absorbed differently by different kinds of plants: peas > beans, alfalfa, clover > tubers and root crops
> table beets, potatoes > grains and cereal grasses > flax.
Factors in the external environment affect the accumulation more than biological properties do.
The absorption of Sr" by plants from the soil is limited by the amount of calcium present. In experi-
ments in which identical quantities of Sr" were introduced into 1-kg samples of various soils, the amount of
Sr" present in the above-ground organs was found to decrease in the following order: clayey sand > average
loam > heavy loam > chernozem. A similar relationship was found between Cs137 and potassium.
The absorption of Sr" depends on the amount of stable strontium present, the properties of the soil,
and the biological properties of the plants concerned. The absorption of nuclides is expressed by the
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coefficient of accumulation. Some radionuclides accumulate in plants in large quantities (yttrium, zircon-
ium, niobium, selenium, and prometheum), whereas others (e.g., cesium) have a low coefficient of accumu-
lation. These coefficients vary widely in value. The highest coefficients of accumulation are found in algae
(about 104), bacteria, and aquatic angiosperms (103). Very high coefficients of accumulation are character-
istic of the plants and animals in plankton.
Physicochemical properties also affect the absorption of fission products.
Living organisms in bodies of water provide good indicators of the contamination of natural water
surfaces. The technology of biological deactivation is being built up on the basis of high accumulation of
nuclides by the bottom materials, the mud, and the living organisms in the water.
We must systematize our knowledge of the laws governing the behavior of nuclides in different geo-
chemical regions and different types of biogeocenoses (forest, pasture, and other assemblages), in accor-
dance with the properties of these assemblages. Little research has been done on such radionuclides as
selenium, praseodymium, zirconium, yttrium, ruthenium, rhodium, lanthanum, prometheum, and pluto-
nium. The migration and circulation of radionuclides in natural biocenoses constitute a complex process
consisting of many cycles of radionuclide transfer, repeated many times, between individual components
of the biogeocenosis. One of the practical problems of radioecology is predicting and describing the ac-
cumulation and distribution of radionuclides, or mixtures of them, as functions of the time elapsed after
single or repeated emission of gaseous radioactive wastes into the environment.
In experiments designed to investigate how the vegetative cover of horizontal and inclined surfaces
affects the migration of a mixture of uranium fission products and isotopes of strontium, cesium, ruthen-
ium, and selenium, it was found that the mixture of fission products does not remain at the fallout site but
migrates in a horizontal direction whether or not there are any plants present. When there are plants, the
migration is twice as rapid as when there are none. It was also f6und that strontium and cesium are more
mobile than ruthenium and selenium.
It was established that the enrichment of soils in calcium and organic substances changes the sorbing
capacity of the soils and, at the same time, affects the absorption of nuclides by the plants. Acid soils can
be neutralized by other salts, such as carbonates, which considerably reduces the absorption of Sr". The
introduction of potassium into the soil also reduces the absorption of fission products (chiefly Cs137) by the
plants. Some agrochemical measures, e.g., deep plowing, combined with the enrichment of the soil in
calcium and fertilizers, can reduce the absorption of nuclides.
When the same nuclide Sr" was introduced into the soil in various chemical forms, it was found that
the amount absorbed by the plants depended on the anions associated with the Sr" and decreased in the fol-
lowing order: Cl- > NO3- > S034- > CrOi- > F- > OH- > CO > HP0i-. The biological sorption of Rui" and
its migration in the soil are also strongly affected by the chemical form of the nuclide; ruthenium in the
chloride form is absorbed less than strontium or cesium.
To sum up, we may state the following conclusions.
1. The isotopes most thoroughly studied in the radioecology of plants are those of the following se-
quence: Sr" and Sr" > CS137 ? RU106 > ce144.
2. Many studies have been devoted to investigating the behavior of fission products in the biosphere
after a nuclear explosion. It is known that the spectra of nuclides emitted by nuclear power stations are
different from those of nuclides emitted by a nuclear explosion. Not enough research has been done on the
processes in which the radioactive wastes of nuclear-power reactors may participate. The results of
studies conducted on processes in which a mixture of fission products resulting from a nuclear explosion
may participate are useful only as a rough guide in determining the effect of gaseous radioactive wastes
near a nuclear reactor or near a processing plant for irradiated nuclear fuels.
3. The largest amount of research has been conducted on long-lived uranium fission products in the
soil?water?plant system. The results of such investigations can be used in predicting the fission-product
content of agricultural plants.
4. Uncertainty in the assessment of experiments, lack of sufficient experimental data, differences
between experimental conditions, and an insufficiently clear classification system can often lead to contra-
dictory experimental results which cannot be generalized.
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5. Relatively little research has been done on lin, which is an important component of the emissions
of nuclear-power reactors.
6. There is a growing need for working out radiological methods for the selection and inspection of
plants
7. It is essential to find plants which can be used for deactivating contaminated areas and which are
characterized by a high capacity to absorb fission products in their above-ground organs.
8. It is essential to develop methods which can be used for monitoring the effect of a nuclear-power
reactor on the environment and which will make possible within a few years of the time the reactor is put
into operation a comprehensive estimate of the situation at the points subjected to the greatest contamina-
tion. These methods must furnish a sufficient amount of experimental data for making predictions.
9. It is also essential to construct a model of biospheric processes that will make it possible to make
predictions for areas with one or more nuclear reactors. The model must include all of the qualitatively
important elements that can be characterized quantitatively in the system consisting of fuel element, tech-
nological section of nuclear reactor, wastes, air (including fallout and including ground water, natural
water, flow-through water, and drinking water), plants, animals, and humans. This must be done not only
for nuclear-power reactors but also for installations processing uranium and thorium ore and irradiated
fuels. Special attention must be given to the air-water-soil-plant system.
LITERATURE CITED
1. Yu. V. Sivintsev, Radiation Safety at Nuclear Reactors fin Russian], Atomizdat, Moscow (1967).
2. V. M. Vdovenko et al., At. Energ., 31, 4, 409 (1971).
3. R. M. Aleksakhin, Radioactive Contamination of Soil and Plants [in Russian], Izd-vo AN SSSR, Mos-
cow (1963)
4. Radioactivity of Soils and Methods of Determining It [in Russian], Nauka, Moscow (1966).
5. H. M. Squire and L. J. Middleton, Report, ARCRL, 10, 78 (1963).
6. V. M. Bochkarev and Z. G. Antropova, Pochvovedenie, 9, 56 (1964).
7. I. V. Molchanova, Problems of Radiation Biogeocenology [in Russian], Izd. UFAN, Sverdlovsk (1965).
8. D. W. Rodes, Soil Sci. Proc., 21, 389 (1957).
9. N. A. Timofeeva and A. A. Titlyanova, Trudy Ural'skogo Otdelenia MOIP, 2, 195 (1959).
10. M. E. Raja and K. L. Babcock, Soil Sci., 91, 1 (1961).
11. R. Russel, Radioactivity and Human Nutrition [Russian translation], Atomizdat, Moscow (1971).
12. I. V. Molchanova, Behavior of Radioisotopes in Model Systems of Terrestrial and Fresh-Water Bio-
cenoses [in Russian], Izd. UFAN, Sverdlovsk (1968).
13. I. V. Gulyakin and E. V. Yudintseva, Doklady TSKhA, 139, 259 (1968).
14. V. Schultz and A. W. Klement, Radioecology, Proc. of 1st National Symposium on Radioecology,
held at Colorado State University, Fort Collins, Colorado, Sept. 10-15, 1961.
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ABSTRACTS
MATHEMATICAL MODEL FOR THE OPTIMIZATION OF
THE PARAMETERS OF THE POWER SECTION OF AN
ATOMIC ELECTRIC POWER PLANT WITH A FAST
SODIUM REACTOR
V. M. Chakhovskii and Yu. S. Bereza UDC 621.039.526
In the study we describe the fundamental systematic position and we give a construction for a calcula-
tion-optimization model for choosing the parameters of the power section of an atomic electric power plant
with a fast sodium-coolant reactor, having a three-loop thermal circuit and a steam-power cycle with a
single superheating of the vapor.
Assumptions are made for constructing the model and determining the accuracy with which the model
indicates the physical and economic relations characteristic of actual installations.
An expression is obtained for the integral function, which is the sum of the specific given expenditures
over all the elements of the power plant, and depends on the following optimizable parameters of the power
section of the power plant: temperature drop in the reactor core, temperature head in the heat exchangers,
temperature of the live vapor and the supply water, and pressure of the live vapor. The parameters to be
optimized are interrelated by the balance equations. We superimpose some constraints on the parameters:
technical and technological, based on the limiting temperature of the covering of the fuel elements, and
based on the minimum temperature head in the heat exchangers.
The turbogenerator set is represented in the model in the form of its efficiency as a function of the
parameters to be optimized. The dependence was obtained from preliminary calculations of the thermal
circuit of the turbogenerator set for various combinations of the initial parameters of the turbine cycle,
and then was approximated by power polynomials using a computer.
In the formulation discussed here, the problem of calculating the optimal parameters is an extremal,
nonlinear problem, with constraints on the vector of the control parameters.
To solve the formulated problem we develop a calculation-optimization complex of "Kaskad" pro-
grams for a "Minsk"-type computer, which uses efficient methods for solving such problems (1, 2].
Based on the model and programs developed, we carried out optimization calculations for the power
section of the atomic electric power plant. The initial data were taken for the BN-600 reactor 13].
The calculation results are represented in the form of curves, which show the dependence of the opti-
mal parameters of the power plant on the coolant temperature at the reactor output, and the relative expen-
ditures in the separate elements of the power plant. The model allows us to give answers to questions deal-
ing with the determination of the conditions of the optimal operation of the technological scheme of a power
plant and fast reactor.
The calculations showed the efficiency of using the developed algorithm and programs for optimizing
the promising scheme of a power plant at various stages of development and design.
The authors are grateful to L. A. Kochetkov, A. A. Rineiskii, and Yu. E. Bagdasarov for useful dis-
cussions and comments, which were taken into consideration in this work.
Translated from Atomnaya t'nergiya, Vol. 34, No. 5, p. 391, May, 1973. Original article submitted
November 19, 1971; revision submitted November 14, 1972.
C 1973 Consultants Bureau, a division of Plenum Publishing Corporation, 227 West 17th Street, New York,
N. Y. 10011. All rights reserved. This article cannot be reproduced for any purpose whatsoever without
permission of the publisher. A copy of this article is available from the publisher for $15.00.
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LITERATURE CITED
1. L. A. Krumm, Elektrichestvo, No. 5, 6 (1963).
2. G. B. Leventall and L. S. Popyrin, Optimization of Thermal-Power Installations [in Russian], En-
ergiya, Moscow (1970).
3. A. I. Leipunskii et al., At. Energ., 25, 403 (1968).
DETERMINATION OF OIL IMPURITIES IN CO2, USED AS A
COOLANT IN GAS-COOLED REACTORS, BY THE METHODS
OF IR AND UV SPECTROSCOPY
M. I. Ermolaev, L. G. Savenko,
K. V. Goryachev, I. B. Strel'nikova,
E. F. Kozyreva, P. I. Kondratov,
and T. I. Kirienko
UDC 543.42:661.973.4:665.4.062
When carbon dioxide is used as a coolant in nuclear reactors, the need arises to determine impurities
of mineral oils in the gas. The IR and UV absorption spectra of solutions of oils used in industrial carbon
dioxide apparatuses, both new and after operation and subjection to temperature influences, pressure, and
neutron irradiation, as well as samples of oils extracted from gas phases, were studied. It was established
by the method of UV spectroscopy that: the first of the two maxima of the spectrum of oils, with greater in-
tensity, corresponds to the wavelength ?230 nm, the second, with intensity lnc = 3.3-3.5, corresponds to
the wavelength 257-261 nm in pentane, hexane, ethanol, and n-octane, and 265 nm in CC14.
A ratio of the hydrocarbons with composition differing from the initial oils is observed in the gas
phase; even for the same oil it differs from the time and conditions of its operation. Thus, the ratio of the
coefficients of extinction for the two observed absorption maxima for all the oil samples lies within the
range 1.9-2.3, while for oil samples extracted from carbon dioxide cylinders, it reaches 5.6. In this case
a shift of the absorption maximum into the long-wave region of the spectrum, with a wavelength of 276 nm,
is observed. The method of determination of impurities in mineral oils in carbon dioxide according to cali-
bration coefficients of extinction of standard solutions prepared from oils isolated from the products of
sample collection, is evidence of the insufficient use of this method. It was established by the method of
IR spectroscopy that the nature of the IR spectra of various oil samples is identical. The greatest absorp-
tion is observed in the band 2926 cm-1, corresponding to the antisymmetrical valence vibrations of the CII2
group (k = 2.52 liters/g ? cm). Bands close to 2962 cm-1 (k = 1.63 liters/g ? cm) and 2860 cm-1 (k = 1.31
liters/g ? cm), corresponding to the antisymmetrical valence vibrations of the CII3 group and the symmetri-
cal valence vibrations of the CH2 group [1], have also been demonstrated for all the spectra. For these
bands the integral value of K = 1.82 liters/g ? cm. In this case the relative error is 1.5-3%. A band is
noted at 2872 cm-1, corresponding to the symmetrical valence vibrations of the CII3 group.
For samples of oils extracted from gas phases, an increase in the absorption is observed at the bands
2872 and 2962 cm-1. The differences in the IR spectra are evidence of a different ratio of the hydrocarbons
in the gas phase and in the initial mineral oils. Therefore, it is suggested that the oil impurities in carbon
dioxide be determined according to the integral intensity of the valence vibrations of the C?H groups. This
method is absolute, and does not require preliminary calibration according to artificial mixtures.
Translated from Atomnaya Energiya, Vol. 34, No. pp. 391-392. May; 1973. Original article sub-
mitted May 18, 1972; revision submitted November 23, 1972; abstract submitted September 26, 1972.
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LITERATURE CITED
1. L. Bellamy, Infrared Spectra of Complex Molecules [Russian translation], IL, Moscow (1963).
DEACTIVATION OF RADIOACTIVE OFF-GASES FROM A
SINGLE-LOOP BOILING-WATER REACTOR POWER PLANT
BY EXPOSURE IN A CIRCULATION TUBE
G. Z. Chukhlov, E. K. Yakshin, UDC 621.039.524.4-97.621.039.72
Yu. V. Chechetkin, and Yu. A. Solovtev
In cases where the pressure seal of fuel elements breaks down, radioactivity carried by off-gases in
a nuclear power station based on a boiling-water reactor can attain levels of ?100 Ci/(days ? MW). Expo-
sure of those gases in a circulation tube prior to venting them to the atmosphere can result in a 2-fold to
70-fold reduction in the activity. That requires a tube of volume
v= tbG?,/{p (T)/[i ?x (T)1} ay. (1)
where Gm is the mass rate of flow of dry gas through the ejector blower, in kg/ h; T is the gas temperature
in the specific cross section through the tube; p is the density of the gas, in kg/m3; xis the steam content
of the gas, in kg steam per kg dry gas.
The recommended exposure time texp for the gas is the root of the equation (2) in t:
c,? ex, (??0? E ciii exp A.110,
i=1 1=7,1+1
(2)
where cinr is the concentration of the n-th term in the decay chain of the i-th original gaseous isotope at
the r-th end of the exposure tube for the case of the maximum possible probability of fission-fragment
gases escaping from the fuel elements, in Ci/m3; i is the number assigned to the parent gaseous isotope
taken in order of increasing decay constants; n is the number assigned to the isotope in the decay chain
when the original gaseous isotope is taken as the first in the chain; r is a subscript referable to the en-
trance (r = 1) or exit (r = 2) of the tube; Ain is the decay constant of the n-th term in the decay chain of the
i-th original gaseous isotope, in sec-4; m is the least number assignable to the original isotope with a de-
cay constant greater than that of Xe138; 1 is the total number of isotopes present in the original gas mixture.
Free gravitational-thermal convection and concentration-related convection through the horizontal
tube can shorten the effective exposure time by three or more times. Two free convection streams in the
tube must be removed in order to utilize the tube volume to complete advantage. One of these two streams
is eliminated when the exit hole is located beneath the tube and the tube end is closed. The other stream
can be minimized by precooling the gas to the ambient temperature or by increasing the aerodynamic drag
presented to the stream, within limits in which ejector performance will not be impaired. That is achieved
by shortening the tube diameter. The fraction A of aerosols in the total radioactivity vented from the tube
is
1 q 1 q
ci?,)/(EE cifl2), (3)
1=1 n=2 i=1 n=1
where q is the maximum number of terms in the decay chains of the gaseous isotopes in question, and
Translated from Atomnaya Pnergiya, Vol. 34, No. 5, p. 392, May, 1973. Original article submitted
February 17, 1972; revision submitted December 26, 1972.
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IL
Cin2 Ciii II Xii) 2 lexp(?Xiit.) 1
?
jII
=1 k*i
Calculations performed for the VK-50 fast reactor show that the value of A can attain ?0.6. Installation of
an antiaerosol filter at the end of the tube is recommended on that account.
ANGULAR DISTRIBUTIONS OF NEUTRONS BEHIND
AN IRON SHIELD
A. I. Kiryushin and Yu. P. Sukharev UDC 539.125.52:621.039.58
The Monte Carlo method has been used to calculate the angular distribution behind an iron shield of
fast and intermediate neutrons from an infinite plane source of fission neutrons. The algorithm of the cal-
culation uses the method of conditional probabilities, which takes account of absorption by and the emergence
of neutrons from a layer by introducing the statistical weight. The algorithm of the calculation was des-
cribed earlier [1].
Angular distributions of fast (E > 1.0 MeV) and intermediate (0.1 MeV E 1.0 MeV) neutrons were
calculated for shield thicknesses of 0.5, 1, 5, 10, 20, 30, and 40 cm for isotropic, cosine, and monodirec-
tional sources of fission neutrons.
The results show that the angular distribution of the neutron flux behind thin shields (