This paper assesses the time to radiation (radiotoxicity) and radiological (radiation risk) equivalence between natural uranium and radioactive waste of thermal and fast reactors at an increasing content of Np, Am, and Cm in radioactive waste. We calculate radiation risk by adapting models of the ICRP and other international organizations for the Russian Federation, taking into account background epidemiological indicators including cancer incidence, cancer mortality, and overall mortality. The radiation risk of internal exposure considers both the time after radionuclide intake and equivalent dose dynamics in human organs and tissues. To determine the time to radiological equivalence, we estimate the lifetime attributable risk of a single intake of natural uranium radionuclides and radioactive waste. An increase in the Np, Am, and Cm content of radioactive waste within 0.1-0.4% causes no effect on the radiological equivalence time, equal to similar to 100 years. However, a further increase from 0.5-0.8% prolongs the time to 300 years. A problem for optimizing the time to radiological equivalence is posed providing for waste storage costs and content of Np, Am, and Cm in long-lived radioactive waste.

The leading design organizations of the Russian nuclear industry develop nuclear power facilities to satisfy almost any segment of the energy market. Within the framework of the Proryv project direction, a new technological platform for nuclear power is being created based on nuclear power plants with high-capacity reactors and a closed nuclear fuel cycle. Demand for fast reactors in the Russian Federation was thoroughly justified in the 2018 Strategy for the Development of Nuclear Power in the Russian Federation until 2050 and Prospects for the Period until 2100, as well as its updated 2022 version. It should be noted that the role of fast reactors in the energy system may vary depending on the goals and objectives set in terms of the fuel supply and adopted approach to spent fuel and waste management. The article examines various prerequisites that influence the parameters of fast reactors, taking into account these factors in the context of strategic planning along with the latest computational and analytical studies.

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.

The Fundamentals of State Policy in the Field of Nuclear and Radiation Safety of the Russian Federation, approved by the President of the Russian Federation, indicate that the goal of state policy in this area is to ensure the protection of the population, considering modern requirements. The IAEA Fundamental Safety Principles emphasize the need to protect both current and future generations from radiation risks. The achievement of these safety goals is ensured by the development in Russia of new nuclear energy system based on a closed nuclear fuel cycle (CNFC) and fast neutron reactors (FNR). One of the objects of the new nuclear energy system is the Experimental Demonstration Energy Complex (EDEC) consisting of the BREST-OD-300 FNR, a reprocessing module and a fuel fabrication/refabrication module, located on the territory of JSC «SHK» in the Tomsk region. This article provides assessments of radiation carcinogenic risks for the population living in the 30-km zone of JSC «SHK» under normal operating conditions and for workers after potential emergency situations at EDEC facilities. The conditions for ensuring the protection of future generations of people are also justified. Radiation risk assessments are obtained directly from the dynamics of equivalent doses in human organs and tissues and modern risk models recommended by ICRP Publication 103. The predicted values of the risks of radiation carcinogenesis for the population and personnel are significantly lower than the current limits of NRB-99/2009 for both normal operation and potential exposure during accidents. It has been shown that transmutation of minor actinides during the development of CNFC based on FNR ensures the safety of future generations of people: it reduces the carcinogenic risk of americium by 213 times, neptunium by 101 times, and curium by 47 times. The effect of radiological equivalence of radioactive waste and natural uranium raw materials is achieved after 99 years of radioactive waste storage. Thus, the priority direction for the development of new nuclear power is the energy sector of the CNFC based on the FNR.

According to the strategy for the development of the nuclear power industry in Russia for the first half of the 21st century, the nuclear power industry complex should undergo the initial stage in the formation of a two-component nuclear power system and a closed nuclear fuel cycle (NFC) infrastructure. All elements of such a nuclear power system, including NPPs, facilities for the fabrication of uranium and uranium-plutonium fuel, processing of spent nuclear fuel, and radioactive waste management, must be organically linked for producing competitive electricity in both domestic and foreign markets. The present article demonstrates the systemic benefits from a large-scale introduction of fast reactors for the Russian nuclear power industry in terms of a sustainable resource provision and a solution to the key problems of the final NFC stage, which is associated with the accumulation of spent fuel and transuranic actinides. The study proposes an optimum NFC closure scenario, in which the described problems can be solved without increasing the high parameters of the BR in a fast reactor and using special burners.

This article continues the debate on choosing a sequel to a strategy for the development of nuclear energy in the country. The provisions set forth in articles by the National Research Center Kurchatov Institute on the transition to a thorium-uranium nuclear fuel cycle are analyzed and compared with the Strategy for the Development of Nuclear Energy in Russia to 2050 and Prospects for the Period to 2100, which the Presidium of the Scientific and Technical Council of Rosatom State Corporation approved in 2018. The environmental impacts of nuclear power under these two approaches are compared. It is concluded that in an open nuclear fuel cycle thorium-uranium fuel has no significant advantages, including in the sphere of radiation safety.

The purpose of the program was to validate the resource dependability of fuel rods with mixed uranium-plutonium nitride fuel, the consistency of the reproduction of characteristics and quality required for this pilot technology for manufacturing pellets, fuel rods and experimental fuel assemblies for testing in the BOR-60 and BN-600 reactors, as well as optimization, in terms of the results of reactor testing, of the design and manufacturing technology of fuel rods for BN-1200 and BREST-OD-300. The article presents key results of the investigations: methods, codes, and criteria have been developed to validate the performance of fuel rods with nitride fuel, the necessary set of pre-reactor properties of mixed nitride fuel and cladding materials has been obtained, a cycle of reactor tests of experimental fuel rods in BOR-60 and BN-600 has been completed, the maximum fuel burnup 9% h.a., damaging dose 107.6 dpa, technical designs of fuel rods for initial loading have been developed, and the manufacturing technology for fuel and fuel rods has been developed and optimized.

The work performed on the creation of the BREST innovative reactor technology based on a lead-cooled fast reactor, mixed uranium-plutonium nitride fuel, operating in a closed nuclear fuel cycle is reviewed. It is shown that a safe and competitive large-scale nuclear energy with practically unlimited fuel resources can be developed based on the BREST reactor technology. The choice of mixed nitride fuel for the BREST reactor as compared with other types of nuclear fuel (oxide, metal, and carbide) is substantiated. The main technical solutions implemented in the BREST-OD-300 project are considered. The results of tests of nitride fuel, computational and experimental substantiation of the core, reactor vessel, operability and safety of the steam generator, development of automated monitoring and control systems, a study of the properties of the coolant and structural materials are presented. The results obtained made it possible to commence designing a commercial high-power BREST-type reactor for large-scale nuclear energy.

The project Proryv [Breakthrough] now being implemented in our country is aimed at achieving a new quality of large-scale nuclear power, development, origination, and industrial implementation of a closed nuclear fuel cycle with thermal and fast reactors. Here the current status of the technologies for reprocessing spent nuclear fuel and recycling plutonium fuel is analyzed, and it is shown that the prerequisites for closing the nuclear fuel cycle in two-component nuclear energy in the mid-term from the mid-2030s are present.

The development of nuclear energy Russia to 2050 is examined in keeping with the recommendations of various strategic planning documents. The technological factors of making NPP more competitive by improving their technical and economic metrics are evaluated. The possibility and economic feasibility of increasing the NPP share in the production structure of the electric power industry up to 2050 is substantiated on the basis of model calculations. An assessment is made of the consequences of active development of NPP for the country’s economy.

Modern Nuclear Energetics (NE) based on Thermal Reactors (TR) with Uranium fuel in Open Nuclear Fuel Cycle (ONFC) has systemic problems that limit its further development: low utilization efficiency of extracted U, absence of ecologically suitable solution for long-lived high-level radioactive waste treatment and nonproliferation. Besides that one of the most serious barriers for modern NE development is the problem of competitiveness that is closely related to safety problem. Attempts to solve the safety problem by development of additional active means of safety protection led to the decrease of competitive ability of NE compared to organic power industry. Fast Reactors with inherent safety as the basis for the New Technological Platform (NTP) are to overcome the current development barriers. The near future transfer towards the two-component NE structure with Fast and Thermal Reactors and CNFC is the key direction of the nuclear energy development strategy. Reprocessing of spent fuel (SF) and recycling of accumulated Pu and unburned U in Fast Reactors fuels cycle allows to cut the need in natural U in 100 times and in 10 times the mass of heavy nuclei in long-lived high-level radioactive waste, which is one of the key means of ensuring ecological safety of NTP. This article presents the goals and means of achieving technological and ecological safety, political neutrality, resource stability and competitive ability of the New Technological Platform. Introduction

The status of development work on fuel pins with fast-reactor nitride fuel and a liquid-metal sublayer, which is being considered in Project Breakthrough (Project Proryv) together with fuel pins with a helium sub-layer, is presented. Such fuel pins are shown to have the potential to improve the core characteristics of the advanced high-power reactors BR-1200 and BN-1200. The basic results for the development and fabrication of experimental nitride-fuel pins with different variants of the lead sublayer and the results of their tests in the BOR-60 reactor and post-reactor studies are presented. The problems of fabricating fuel pins with a lead sublayer are noted, possible solutions are discussed, and the required additional studies are indicated.

Проблема оптимального выделения америция из ОЯТ БРЕСТ-ОД-300 на трансмутацию для обеспечения радиационной эквивалентности РАО и природного урана Иванов В.К. 1,2,3, Адамов Е.О. 3 , Спирин Е.В. 3 , Соломатин В.М. 3 , Чекин С.Ю. 1,2, Меняйло А.Н.1,2 1 МРНЦ им.А.Ф.Цыба -филиал «НМИЦ радиологии» Минздрава России, Обнинск; 2 ООО «НПК «Мединфо», Обнинск; 3 АО «Прорыв», Москва Замкнутый топливный цикл с применением быстрых реакторов позволяет решать проблему сокращения радиоактивных отходов (РАО) более эффективно, чем традиционный открытый цикл с тепловыми реакторами.Количественные параметры выделения радионуклидов из облучённого ядерного топлива (ОЯТ) определяются принципом радиологической эквивалентности (РЭ) образующихся РАО и исходной массы природного урана, использовавшегося для изготовления ядерного топлива.Время достижения такой РЭ не должно превышать 300 лет, что может быть достигнуто выделением Am из ОЯТ и его сжиганием в быстром реакторе.С увеличением содержания Am в РАО расходы на переработку ОЯТ уменьшаются, но увеличивается время достижения РЭ и, соответственно, растут расходы на контролируемое хранение РАО.Поэтому суммарные расходы на переработку ОЯТ и дальнейшее контролируемое хранение РАО могут иметь минимум при определённом содержании Am в РАО.В данной работе показана принципиальная возможность определения оптимального содержания Am в РАО, при котором сумма расходов на очистку ОЯТ от Am и на дальнейшее контролируемое хранение РАО достигает минимума.Оптимальное содержание Am в РАО зависит от способа оценки времени достижения РЭ, соотношения расходов на очистку ОЯТ и хранение РАО, а также от процедуры дисконтирования расходов на хранение РАО.При определении времени достижения РЭ РАО и природного урана по равенству соответствующих пожизненных атрибутивных рисков (LAR) оптимальный остаток Am в РАО оказывается существенно больше, чем при использовании для этого ожидаемых эффективных доз (ОЭД), а суммарные расходы на очистку ОЯТ и хранение РАО -меньше.В рассмотренных примерах оптимальный остаток Am в РАО составил 1-2% при использовании величины LAR для определения РЭ, против 0,5% Am при использовании ОЭД.Минимальные суммарные расходы в первом случае были в 1,5 раза меньше.Для уточнения этих оценок требуются дальнейшие ис

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.

Nuclear power is effective and safe source of electricity. Meanwhile, uranium reserves in the earth's crust will run out in 100 years with the development of traditional nuclear reactors. The Rosatom “Proryv” project implementation will allow multiplying fuel sources for the new genera-tion nuclear power through the closing fuel cycle. Radiation safety of the new nuclear powers should be based on the state of the art Russian national and international regulations, as well as on predicted radiation doses, estimates of potential radiation risks and radiation detriment of the public. Developed methods for computational analysis of possible doses of estimates of radia-tion risks and population-based detriment, associated with atmospheric fallouts of radioactive substances from the BREST-OD-300 reactor, corresponds to the currently recognized approach-es to evaluating safety of nuclear energy facilities. Developed method for radiation detriment es-timating is in accordance with ICRP recommendations. It allows making assessment of radiation-associated health effects for Russian population with account of patients’ quality of life provided by the current health care system. The analysis of possible radiation doses and potential radia-tion risks shows that the upper 95% confidence bound of radiation detriment for the critical group of population in the town of Seversk (girls of 5 years of age) even in the event of beyond design basis accident at the reactor equals 1.1610-5 year-1, and does not exceed the radiation risk limit of 510-5 years-1, established by Russian national radiation safety regulations NRB-99/2009 for the population during normal operation of ionizing radiation sources. In the event of an accidental situation on the Brest-OD-300 reactor, the average estimates of radiation risks for the population living within the 30-km zone around the JSC “Siberian Chemical Combine” will generally remain in the range of negligible risk and will not exceed the level of 10-6 year-1.