Authors & Affiliations
Tykleeva K.V., Zabrodskaya S.V., Seliverstov I.N., Tsikunov A.G.
A.I. Leypunsky Institute for Physics and Power, Obninsk, Russia
The given work presents the results of calculation of the 14C radionuclide contents in the BN-1200 reactor process media. The obtained calculation results and their analysis testify to the fact that sodium-cooled fast reactor specific features in design and physics make it possible to ensure radiation and radio-ecological safety in terms of radioactive carbon in the course of these reactors operation both with oxide and nitride fuel, with natural contents of nitrogen isotopes. In calculations of 14C radionuclide contents in the various BN-1200 reactor process media as well as in the ambient environment in the course of a long-term reactor operation with different types of fuel, it is assumed that only the 14C radionuclides that are produced in the failed fuel and in the primary sodium can find their ingress to these media. It was found out that in about 10 years of BN-1200 reactor operation in certain process media of a reactor with nitride fuel the maximum possible 14C activities will be reached: in the primary sodium ~ 1.0·1011 Bq; in the primary cover gas ~ 2.0·1010 Bq. Based on these data, consideration is also given to the results of calculation of local staff radiation exposure in NPP rooms and that of the local population as a result of the radiation effect from 14C that is released to the ambient environment under normal operation conditions of BN-1200 reactors with mixed oxide and nitride fuel. The normalized 14C emission rate at NPPs with BN-type reactors with nitride fuel to the ambient environment was estimated to be equal to ~ 0.02 TBq/GW(e)·year, that is lower than the values typical of VVER and RBMK reactors. As for the BN reactors with oxide fuel, their 14C emission to the ambient environment and radiation effect of this radionuclide on the personnel and population is expected to be an order of magnitude lower. However, it should be noted that some of the data used in this paper are not sufficiently studied and verified experimentally. So the obtained results should be considered as preliminary estimations which could be specified if necessary. The problem of radioactive carbon as a global pollutant of the biosphere goes beyond studying the stage of BN-type reactor operation with nitride fuel and should be traced up to the stage of fuel reprocessing at the radiochemical plant. The issues of ensuring radiation and radio-ecological safety at radiochemical plants under conditions of increased 14C production in the nitride fuel are worthy of special consideration.
High-power BN-type reactor, reactor process medium, nuclear fuel, 14C isotope, actinides, nitride fuel, neutron reactions, MOX fuel, impurities activation
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