The article estimates the time required to achieve radiation and radiological equivalence between radioactive waste and natural uranium raw materials, assuming that all thermal reactors will be fully replaced by fast reactors by the year 2130. Radiation equivalence will be reached when the carcinogenic risks of radioactive waste and natural raw uranium have the same value according to effective dose technologies. The estimated time required for this radiation equivalence is 250 years. Additionally, radiological equivalence can also be achieved if the carcinogenic risk associated with radioactive waste and raw natural uranium has the same values as those of lifetime attributable risk (LAR) technologies. The estimated potential time for this radiological equivalence is 78 years. Furthermore, the potential time for the burial of radioactive waste is also considered. It is estimated that this event will occur after the year 2208.

Economic and radiological advantages of the closed nuclear fuel cycle with fast neutron reactors in view of radiological equivalence, i.e. the equalization of carcinogenicity of radioactive waste and the natural uranium ore materials are considered in the paper. Potential cancer risks of the spent nuclear fuel (SNF) from the WWER-1000 reactor and radioactive waste from the BR-1200 reactor generating 1 GW of electric power per year have been estimated. It is assumed that the SNF from WWER-1000 reactor will be sent to 10 or 30-year storage. In the closed nuclear fuel cycle radioactive wastes, the products of SNF reprocessing, consisting of 0.1% of Sr, Cs, Tc, I, U, Np, Pu, Am, Cm of their content in SNF and all other radionuclides are disposed. Over a period of 10,000 years, the total radiation detriment from SNF from the WWER-1000 reactor is more than 132 times higher than the radiation detriment from radioactive waste from the BR-1200 reactor. The time of radiological equivalence achievement was evaluated. It is assumed that if WWER-1000 and BR-1000 generate 1 GW of electricity per year, radiological equivalence of carcinogenicity of radioactive waste (BR-1200 reactor) and natural uranium ore material will be achieved in 100 years of radioactive waste storage. The equivalence of carcinogenicity of SNF storage and natural uranium ore materials will be achieved after 15,600 years storage. When disposing of spent fuel from a WWER-1000 reactor without achieving radiological equivalence, socio-economic losses due to excess mortality from cancer are estimated at 129 billion rubles/GW year.

The paper presents for the first-time comparison of radiation safety for the population between spent nuclear fuel (SNF) irradiated in water-water power reactor with thermal neutrons (WWER-1000) and radioactive wastes (RW) from lead cooled fast neutrons reactor (BREST-1200). The re-actors generate equal amount of electric power 1 GW per year. Composition and radiation param-eters of long-lived radiation wastes sent to disposal is reviewed. Potential biological hazards from SNF and RW for about 10,000-years disposal were estimated as effective doses (Sv). To assess potential radiation-induced carcinogenic risk as estimates of lifetime attributable risk (LAR) new ICRP methodology was used. New ICRP methodology was used as the basis for the computer code for the program “Radiological protection of the population” (ROZA-N) developed by the Proryv Project of the Rosatom State Corporation. The project was registered at the Unified Register of Russian Software in 2021 (registration number 2442). It was found that potential radiation-induced carcinogenic risk for the population associated with WWER-1000 reactor SNF was 132 times high-er than the risk associated with BREST-1200 reactor RW. Radiological equivalence of carcinogenic risks associated with SNF WWER-1000 and natural uranium material was proven to be achieved in about 15,600 years (significantly more than 10,000 years), the radiological equivalence of risks associated with RW BREST-1200, on the other hand, to be achieved only in 120 years.

Abstract The radiological hazard of spent nuclear fuel and radioactive waste slows down further development of nuclear energy systems. The authors evaluate timescales required to reduce the radiological hazard of accumulated waste to the reference level of natural uranium that had been consumed by the nuclear energy system. The estimate of this time scale depends on the radiological hazard metric used in the calculations. In this study, two metrics are compared: (1) the committed effective dose based on ICRP Publication 72 and (2) the lifetime radiation risk calculated with use of organ doses and recent radiation risk models recommended by ICRP. The effective dose of the waste reaches the reference level 300 y after the accumulation of waste, while lifetime attributable risk of waste converges to natural uranium in 100 y. Thus, the lifetime attributable risk (LAR) metric is more appropriate to estimate the time requirements for radioactive waste storage and disposal. The effective dose metric significantly overestimates this timescale as it is not intended for quantifying radiation-related risks.

The Russian Government approved the Energy Strategy of the Russian Federation (Government Decree No.1523-r of June 9, 2020). The Strategy envisages the use of both thermal (TR) and fast (FR) reactors. The Strategy points out that the problems of nuclear power are associated with po-tential high expenses for irradiated fuel and radioactive wastes management. The previously de-signed model of the Russian nuclear energy development suggested that fast reactors only would operate at NPPs after 2010. Radiological equivalence, expressed as the equivalence of lifetime radiation risks to the public from radioactive wastes and from primary uranium ore, was shown to be achieved after 100-year storage. The burnup of 241Am, 237Np и 242Сm in closed nu-clear fuel cycle with fast reactors is a key part in the achievability of radiation risks equivalence. Scenarios of the Russian nuclear energy development through to 2100 with account of uncertain-ty factors in the measurement of contribution of fast and thermal reactors to the electric energy production are considered in the paper. The following three scenarios were developed: uncer-tainty is replaced by FRs; uncertainty is replaced by TRs; 50 per cent of FRs and 50 per cent of TRs replace uncertainty. If the energy is produced by fast reactors only (scenario 1) radiological equivalence was found to be achieved in 412 years. In two other scenarios radiological equiva-lence will be achieved after more than 1000 years. Contribution of main dose-forming radionu-clides and relevant ratios of potential biological hazards is included in models regardless of whether uncertainty in nuclear energy development is taking or not taking into account. Results of the study of conditions for radiological equivalence achievement should be used for amending Strategic plan of Russian nuclear power development through to 2100 that meets requirements of radiation ecology and radiation protection of the public.

The radiological hazard of spent nuclear fuel and radioactive waste slows down further development of nuclear energy systems. The authors evaluate timescales required to reduce the radiological hazard of accumulated waste to the reference level of natural uranium that had been consumed by the nuclear energy system. The estimate of this time scale depends on the radiological hazard metric used in the calculations. In this study, two metrics are compared: (1) the committed effective dose based on ICRP Publication 72 and (2) the lifetime radiation risk calculated with use of organ doses and recent radiation risk models recommended by ICRP. The effective dose of the waste reaches the reference level 300 y after the accumulation of waste, while lifetime attributable risk of waste converges to natural uranium in 100 y. Thus, the lifetime attributable risk (LAR) metric is more appropriate to estimate the time requirements for radioactive waste storage and disposal. The effective dose metric significantly overestimates this timescale as it is not intended for quantifying radiation-related risks.

The article presents analysis of safety of long-lived high level radioactive waste (RW) disposed for permanent storage in a deep geological repository. According to the study protocol it is necessary to estimate the human and environmental health safety of RW, generated in different nuclear fuel cy-cles, during their long-term stay in the repository. To estimate biological effects, RW composition from thermal reactors in open nuclear fuel cycle (“TR”) and from simultaneously operated thermal and fast reactors in closed nuclear cycle (“TR+FR”) in different time after their disposal have been evaluated. It is suggested that RW to be safe to humans and the environment if committed effective doses from RW components including minor actinides and fission products and from natural urani-um are equivalent (radiation equivalence) or lifetime attributable risks of cancer mortality from RW and natural uranium are equivalent (radiological equivalence). For this purpose it is important to evaluate the time of achievement of radiation or radiological equivalence. To evaluate health effect of RW containing radio-nuclides on the public and the environment their migration activity has been evaluated with the use of distribution coefficient and retardation factor. Probable annual effective doses to the public from exposure to the radionuclides released from the repository to the biosphere at different time after the RW disposal have been estimated. Radiation doses to the public following the consumption of water from the well installed on the repository, and lifetime attributable risk (LAR) of cancer mortality associated with the exposure to radionuclides contained in “TR” and ”TR+FR” generated waste have been evaluated. It turned out that LARs of cancer mortality from “TR+FR” radionuclides is lower than LAR from natural uranium, it means that radiological migration equivalence after its achievement will exists until the repository conditions allow, about 1 billion years. We have found that LARs from “TR+FR” waste is about 100 times lower than the negligible level, 10-6, established in the Russian National Radiation Safety Standards (NRB-99/2009). Estimat-ed LAR of cancer mortality from “TR”-generated waste is 360 times higher than LAR from “TR+FR”-generated waste. As evaluated for the waste from TR radiological equivalence will be achieved not earlier than 1 million years after permanent disposal. If RW is generated in the closed cycle estimat-ed LAR value from consumption of well water does not exceed 10-5 year-1, if RW is generated in open fuel cycle, the LAR value is 10-3 year-1, this is socially unacceptable risk. In the first 10 thousand years after the disposal the major dose- and risk-forming radionuclides in the well water will be 241Am, 239Pu и 240Pu. Estimates of radiation detriment from ”TR” generated waste put to the perma-nent deep geological disposal are given in the article.

Сравнительный анализ уровней «радиотоксичности» отдельных радионуклидов ОЯТ реакторов БРЕСТ и ВВЭР при различных временах выдержки на основе современных

 1 МРНЦ им.А.Ф.Цыба -филиал «НМИЦ радиологии» Минздрава России, Обнинск; 2 ООО «НПК «Мединфо», Обнинск; 3 АО «НИКИЭТ» им.Н.А.Доллежаля Госкорпорации «Росатом», Москва; 4 Частное учреждение «ИТЦП «Прорыв», Москва В статье рассмотрены два подхода к расчёту времени выдержки отработавшего ядерного топлива (ОЯТ) в условиях реализации принципа радиационной эквивалентности -по отношению ожидаемых эффективных доз от ОЯТ и природного урана и по отношению соответствующих пожизненных радиационных рисков, рассчитанных для российского населения