COMPARISON OF RADIATION

AND FUSION REACTORS

Yu. V. Sivintsev

H A Z A R D F R O M F I S S I O N

UDC 621.039.58

An at tempt was made in the paper by Hafele and Starr* to compare the advantages and disadvantages of two types of nuclear devices for the production of e lec t r ica l power: fast r e a c t o r s based on the f ission of heavy nuclei (FIR) and thermonuclear r e a c t o r s based on the fusion of light nuclei (FUR).

In a comparison of FIR and FUR, a decisive factor is the est imate of the radiation hazard for staff and population and the potential effect on the environment . However, the approach and resul t s of the analy- sis descr ibed in the paper cited call for several cr i t ical r e m a r k s . This is all the more necessa ry because a repr in t of the Hafele and Starr paper is being prepared as an official repor t of the International Institute of Applied Systems Analysis (tASA).

This paper d i scusses the text of the third vers ion of the repor t distributed by IASA. The r e m a r k s re la te fo rmal ly only to Sec. IIt in which the questions of radiat ion hazard and environmental protect ion are d iscussed .

Statement of Purpose and_Area of Invest igation. The proble~a of comparison of the radiation hazards of FIR and FUR is formulated co r rec t ly in the repor t . However, the authors confine themselves to an analysis of only a single aspect -- exposure of the population under accident conditions and as the resu l t of disposal of was tes . These important questions do not encompass the entire problem. Therefore , one should refine the formulation of the purpose and expand the area of investigation for such a compar i son . Obviously, the problem in one of the corresponding sections of the new text of the repor t is more advanta ~ geously formulated in the following manner: "Quantitative evaluation of the degree of radiation hazard from FIR and FUR (of identical thermal power) ."

In accordance with the ba sic concepts developed by the International Commission on Radiation P r o - tection (ICRP) [1] and the analogous national commiss ion (NCRP) [2], the radiation hazard for three popula- tion groups -- occupational workers (A), individuals in the general population (B), and the general popula- (C) -- is subject to evaluation for such a c o m p a r i s o n . In the appropriate calculations, the dose f rom ex te r - nal and internal radiat ion should be evaluated.

*W. Hafele and C. St~rr, J . Bri t . Nucl. Energ'y Soc. , 13, 131 (1974).

TABLE I . Long-Lived Radioactive Isotopes (Half-Lives > 10 yr) in FUR and FIR [3]

FUR

FIR

Radioactive Tff2, yr Production of radioactive isotopes t . . . . . - . . . . .-r----v----- ,Mt'~. m water,

Ci/MW(t)in Ci/MW(t).yr [10~y r ]~Ci/limr

9amNb ~4Nb V (containing Nb)

90Sr iaTCs ~Tc 2a~p u

19,6 2,9.104

40,4 43,4 3. i05

128

I 8 800 I i73 000 2,9 t 2 900

670 930 0,i2 0,9

27 000 40 000

~20 t20

[ 4.t0-a 3.10-~

3.10-7 2. t0-5 2.i0-~ 5.i0-6

Hazard factor. kma/MW (t)

0,4 1,0

i ,4.i0-a--i0-4

2,0 6. ~ff-a

2,5-i0-a

Translated f rom Atomnaya ]~nergiya, Vol. 39, No. 3, pp. 173-176, September, 1975. Original ar t ic le submitted May 16, 1975.

I " �9 76 Plenum Publishing Corporation, 227 West 17th Street, New York, N. Y. 1001t. No part o f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission o f the publisher. A copy o f this article is available from the publisher for $15.00.

779

Fig. 1. Paths for the e f f ec t s of radioact ive d i scha rges on the human body.

In Russ ian scientif ic l i t e ra tu re , the t e r m " r a d i - ologh'" has a na r rower meaning (the science of the use of ionizing rad ia t ions in medicine) than i~ A n g l o - A m e r i - can publ icat ions. The re fo re , it is p r e f e r ab l e to use the t e r m radia t ion hazard instead of radiological hazard in the English text of the r e p o r t .

R e m a r k s within the Bounds of the Tradi t ional Approach . Evaluat ion of the re la t ive radia t ion hazard was ca r r i ed out by the authors in t e r m s of the t radi t ional approach: an ac t iv i ty A (curies) built up in the r e a c t o r or d ischarged into the envi ronment (the a i r , for example) is re la ted to the value of the m a x i m u m p e r m i s s i b I e con- centrat ion ~:[PC, C i / l i t e r ) . The r e su l t is a volume of a i r needed to dilute the analyzed radioact ive ma te r i a l to the It{PC, which is taken as a quanti tat ive c r i t e r ion of radia t ion haza rd .

In compar ing FIR and FUR with r e s p e c t to the amount of tongLlived rad ioac t ive isotopes contained ia the r e ac to r a f te r an extended opera t ing per iod, the authors of the paper being discussed did not consider t37Cs and SgTc in Table 6. We note that such e s t i m a t e s were made in [3], which is cited as r e f e r ence 7 in the paper , According to this data, the radia t ion hazard of laTCs is twice as g rea t as that of ~Nb, and SgTc is c o m - parab le to vanadium containing an admixture of niobium with r e spec t to this p a r a m e t e r (Table 1).

We also d i rec t at tention to the inconsis tency of the data for 9~ given in Table 1 [3] and in Table 6 of the subject pape r . According to the data in [3], the re la t ive radia t ion hazard 9~ +UNb) =90/1.4=50; f r o m the data in the second column of Table 6, where a mixture present ing a g r e a t e r rad ia t ion hazard -- atl f i ss ion products (FP) - - is being cons idered , ZFP/(~3Nb +~Nb) =104/1.7 * 104~0 .6 , This difference ( a lmos t two o rde r s of magn i tude )demands a detailed explanation.

In the s ame Table 6, the ana lys i s of the radia t ion hazard f r o m was tes is not c a r r i ed out to the po in t where values of A/MPC are obtained, In the third row of Table 6, one should take into account the abun- dance of radionuclide components in the f iss ion f ragment sum.

The FIR/FUR compar i son was made for only a pa r t of the volati le gaseous m a t e r i a l s (iaiI and all). In no rma l operat ion of the FIR and under accident conditions, however , one of the main sources of r a d i a - tion hazard is the rad ioac t ive isotopes of the noble gases (argon~ krypton, xenon) and their daughter a e r o - sol products (rubidium, s t ront ium, ba r ium, cesium,, e t c . ) . The f o r m e r a r e predominant ly r e spons ib le for ex terna l fl and 3f i r radia t ion of the body and the la t te r (together with 3H, i~c, and 85Kr) for internal i r r a d i a - tion [4]. These isotopes should be included in the appropr ia te ca lcula t ions .

In making the compara t ive evaluat ion, liquid rad ioac t ive was tes of low and medium speci f ic act iv i ty , which a re constantly d ischarged f rom an FIR, were a lso not taken into account . T h e authors of the r epor t , without taking these was t e s into considerat ion, s ta r ted f rom the assumpt ion that the c r i t e r ion of I m r e m / y r ,would be met in any ca se . However , the convers ion f rom the evaluation of A/MPC Values to the calculat ion

of dose r equ i r e s a study of the so-ca l !ed "c r i t i ca l " path

TABLE 2. Relat ive Radiat ion Iflazard of Rad io - act ive Wgstes f r o m FIR and FUR

Radioactive eIement

Yie ld'~f radio - active isotopes Ci/MW (t) m ' [108 sec

t Relative MPBB, gCi hazard

t t ] 35 90 [ 4.t05 94N b

~gPu [ 35 0,04 [ 9-10 s

of a radioact ive isotope in the envi ronment including f ac to r s of d i spers ion and concentra t ion . A cIass ica l example is the food chain a i r - g r a s s - c o w - - m i l k - - h u - man thyroid gland for the f iss ion product i3iI. When all the l inks on this c r i t ica l path a r e considered, the: con- cent ra t ion fac tor of ialI is e s t imated to be 700 [5, 6].

The bioaccumulat ion fac tor for ce r t a in radioa ctlve m a t e r i a l s in the bodies of fish amounts to t03 (cesium,

7 8 0

cobalt , zinc, e t c . ) . Jus t as g rea t a concentrat ion was r eco rded in expe r imen t s on r o e . These exper imen t s showed that radionucl ides r e l a t ed to the group of r a r e - e a r t h e lements as well a s z i rcon ium, niobium, ru thenium, and other e l emen t s a re concentra ted predominant ly in the cover ing of i~he r o e . g t ront tum, ba r i um, and ces ium a re main ly concentra ted in the contents of the roe [7, 8].

Unfortunately, the values for p e r m i s s i b l e concentra t ions r ecommended by [CRP and NC~P [2] were es tab l i shed without cons idera t ion of food chains and b ioaccumuls t ion f a c t o r s . In addition, they were a c c e p - ted on the bas i s of r e com m enda t i ons f r o m national commi t t ee s and may contradic t one another . Thus, the content of rad ioac t ive m a t e r i a l s (25 pCt / I i t e r in f r e sh water) which is acceptable in West Germany exceeds the s tandard es tab l i shed tn Hungary [9].

F r o m what has been said, it ts p r e f e r ab l e f r o m our point of view to use for an e s t ima te of the r e l a - t ive radia t ion hazard RH the r a t io

RH---- A/ I O -6 q,

where A has i ts previous meaning and q is the m a x i m u m p e r m i s s i b l e content of a rad ioac t ive isotope in the body (MPBB in the t e rmino logy of ICRP) , t~Ct. The ra t io given is a d imens ion less quantity which c h a r a c - t e r i z e s (in a r b i t r a r y units of radia t ion hazard) the number of people who may be exposed to p e r m i s s i b l e doses if the considered ac t iv i ty A is d i spe r sed into the env i ronment . Applying this approach to some of the data in the a forement ioned Table 6, we obtain fl~e values given in Table 2. A compar i son of re la t ive haza rd s gives theva lue ~agPu/~Rrb~--2 �9 10 -a .

Need for Expansion of Sys tems Approach . In the analys is of radia t ion hazard f r o m specif ic nuclear r e a c t o r s , e i ther FIR or FUR, for people in ca tegory B,one should evaluate the effect of gaseous , liquid, and solid rad ioac t ive m a t e r i a l s including poss ib le paths of migra t ion in the envi ronment and all types of i r rad ia t ion of the body. The scheme proposed in [10] {see Fig . 1) can be used as a ba s i s for th i s . The r e p o r t [11] can se rve as an example .

I t is convenient to accompNsh a quanti tat ive evaluation by calculat ion of the in tegral radia t ion effect (in units of m a n - r e m / y r ) . This m a k e s it poss ib le not only to compare FIR and FUR but a l so to make a compar i son with the natural radia t ion background. A technique for such calculat ions has been proposed [12]. It is e x t r e m e l y des i r ab le to evaluate the genet ical ly and leucogentcal ly significant doses s epa ra t e ly (GSD and LSD).

New complexi t ies have been observed for th~s p rob lem recen t ly . Thus, it was noted a t a mee t ing of IAEA exper t s in Budapest (September 1973) that the d ischarge wa te r s f r o m a nuclear r e a c t o r with a t h e r - mal power of 237 MW at Gundremingen which were emptied into the upper r eaches of the Danube R ive r con- tained 18 iso topes (up to 98% 3H, 89, 90Sr ' 134, laTCs ' l a l i , 140Ba_140La, 58, ~0Co ' and o thers) , but the radia t ion dose produced by them in the poput ation of the adjacent a rea did not exceed 1 t o r e r o / y r . T h i s is 1/170 of the cor responding m a x i m u m dose. By 1977, however , the total t he rma l power of the nuclear power s tat ions d ischarging the i r was te wa t e r s into the Danube will inc rease to 12,800 MW, i . e . , by a fac tor of 50 [9], which can br ing the i r rad ia t ion dose to the population close to a dangerous leve l . In addition, cons iderable misca lcu la t ion has occur red in p r e c i s e l y this a rea of radia t ion protec t ion in the r ecen t pas t . Thus~ the amount of liquid rad ioac t ive was tes produced during the operat ion of the Shipping P o r t n u e l e a r power stat ion was underes t ima ted by a fac tor of 15 [13]. In the design of a r ad ia t ion - sa fe ty sy s t em for the f i r s t nuclear i c e b r e a k e r , a s i m i l a r unde res t ima te by a fac tor of 10 was accepted [14]. T h e r e f o r e , it is advisable to sup- p lement the m a t e r i a l in the r e p o r t with a new sect ion containing quanti tat ive e s t i m a t e s of the radia t ion hazard f r o m e lec t r i ca l power s y s t e m s using FIR or FUR in a given geographical a rea (for example , Wes te rn Europe or the Miss i ss ipp i R ive r basin) as was done recen t ly [10, 15].

The radia t ion b_~zards of FIR or FUR under no rma l operat ion and in accident situa~:ions should be c o m - pared for s e v e r a I des igns for specif ic r e a c t o r s . As examples of FIR, it is convenient to consider the BR-350, "Phoen ix , " and PFR; as examples of FUR, designs ca r r i ed out to a high degree of engineer ing development (for example , the RTPR [16] and o thers ) .

tn the subject m a t t e r of such a compar i son , it is e x t r e m e l y des i r ab le to include quest ions concerning the min imiza t ion of the rad ia t ion hazard f r o m individual a s s e m b l i e s in FIR and FUR as w a s done [17] for FUR blankets of niobium, vanadium, and a luminum.

A compar i son of the rad ia t ion haza rds of FIR and FITR can only be complete when the global a spec t s the effect of pescefut power based on fas t and t he rma l r e a c t o r s and on fusion r e a c t o r s a re subjected to

ana lys i s , tt is then n e c e s s a r y to consider the ent i re technological chain (from ore t r e a t m e n t and enr ichment ,

781

refinement and preparation of fuel, to burial of radioactive wastes) and to take ~nto accoun~ the effect of other harmful factors accompanying the use of ionizing radiation and radioactive mster ials (radium, rador~ and daughter aerosols in uranium mines; silica and lead dusts in ore-processing, plan~s; chemically cor- rosive media at radiochemical plants, e tc . ) . Along with this~ it is extremely dezir~ble to evaluate the radiation hazard to the biosphere from FIR and FUR, considering it as a total system with the human popu- lation a subsystem. Such studies might reveal subtle, and as yet unobserved, mutual effects between, radia- tion and other natural or artificial factors . Typical examples are the known dependence of the harmful effects of ionizing radiation on the partial p ressure of oxygen [18] and on the ambient temperature [ 1 9 ] , the previously published extraordinarily high values for the relative biological efficiency of 3H included in DNA [20], etc.

Perhaps the last of the studies we have mentioned cannot possibly be included in the new text of the repor t . In that case, one should exert every effort to organize such a multifactor systems analysis under the aegis of the IASA. It seems to us that these studies particularly fit the spirit and approach of the IASA What has been said still does not furnish a basis for considering FIR and FUR equivalent from the viewpoint of radiation safety. The conclusion that a signifiean/difference between them is irl f~vor of the fusior~ r eac - tor rather comes to mind.

1.

2.

3. 4. 5. 6.

7.

8.

1

i0. 11. 12. 13. 14.

15. 16.

17. 18. 19. 20.

LITERATURE CITED

Recommendations of the International Commission of Radiological Protection ([CRP Publ, 9), Oxford (1966). Radiation Safety Standards (NRB-69) [in Russian], Atomizdat, Moscow (1972). D. Steiner and A. Fraas, Nucl. Safety, 13, 353 (1972). Yu. V. Sivintsev, Radiation Safety st Nuclear Reactors [in Russian], Atomizdat~ Moscow (1967). T. Barnett, Health Phys . , 18, 73 (1970). L. A. II'in, I . A. Likhtarev, and Yu. D. Konstantinov, Radioactive Iodine in Radiation Safety ~in Russian], Atomizdat, Moscow (1972). N. I. Mashneva, S. Ya. Sukal'skaya, and A. I . Tikhonova, Radiobiol0giya, 12, 156 (1972). V. P. Shvedov, G. G. Polikarpov, and I, A. Sokolov, in: Rsdioecology of Aquatic Organisms [in Russian], No. 2, Zinatie, Riga (1973), p. 263. G. V. Shishkin et a l . , At. Energ . , 3__6, 154 (1974). J . Kastner, Trans. Amer . Nucl. Soc., 17, 535 (1973). P . McGrath, KFK-1992 (1974). J . Pensko, Nukleonika, 19, 47 (1974). C. Abrams et aL, Chem. Engng. P rogr . 5~8, 70 (1962). Yu. Sivintsev and A. Stefanovitch, Bull. of the Permanent Intern. Association Congress, 2., No. 8,

5 (1963). Nucl. Safety, 15, 56 (1974). T. Coultas et a l . , in: Proc . IAEA Conf. on Rusion Reactor Design Problems, Culhum, 29 Jan.-15 Feb. , 1974, p. 151.

J . Powe11 et a l . , ibid, p. 343. Pr imary Radiobiologtcal P rocesses [in Russian], Atomizdat, Moscow (1973). V. Ya. Aleksandrov, Cells, Macromolecules, and Temperature [in Russian], Nauka, Leningrad (1975)~ Yu. I . Moskalev, in: Tri t ium Oxide [in Russian], Atomizdat, Moscow (1968), p. 366.

782