Персона: Апсэ, Владимир Александрович
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Институт ядерной физики и технологий
Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.
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Владимир Александрович
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- ПубликацияТолько метаданныеSafety of a fast reactor with a reflector containing a moderator with heavy atomic weight and weak neutron absorption БЕЗОПАСНОСТЬ БЫСТРОГО РЕАКТОРА С ОТРАЖАТЕЛЕМ, СОДЕРЖАЩИМ ЗАМЕДЛИТЕЛЬ С БОЛЬШИМ АТОМНЫМ ВЕСОМ И МАЛЫМ ПОГЛОЩЕНИЕМ НЕИТРОНОВ(2019) Kulikov, G. G.; Shmelev, A. N.; Apse, V. A.; Kulikov, E. G.; Куликов, Геннадий Генрихович; Апсэ, Владимир Александрович; Куликов, Евгений Геннадьевич© 2019 Obninsk Institute for Nuclear Power Engineering, National Research Nuclear University 'MEPhI'. All rights reserved.The purpose of the study is to justify the possibility of improving the safety of fast reactors by surrounding their cores with reflectors made of material with special neutron#physical properties. Such properties of the 208Pb lead isotope as heavy atomic weight, small absorption cross section, and high inelastic scattering threshold lead to some peculiarities in neutron kinetics of the fast reactor with a 208Pb reflector, which can significantly improve the reactor safety. The reflector will also make it possible to generate additional delayed neutrons, which are characterized by «dead» time. This will increase the resistibility of the fission chain reaction to reactivity jumps and exclude prompt supercriticality. Note that the additional delayed neutrons can be generated by the reactor designers. The relevance of the study is that the generation of additional delayed neutrons in the reflector will make it possible to reduce the consequences of a reactivity accident even if the reactivity introduced exceeds the effective fraction of delayed neutrons. At the same time, the role of the fraction of delayed neutrons as the maximum permissible reactivity for reactor safety is depreciated. The scientific novelty of the study is that the problem of the formation of additional neutrons, which in their properties are close to traditional delayed neutrons, has not been posed so far. The authors propose a new method for improving the safety of fast reactors by replenishing the fraction of delayed neutrons due to the time delay of prompt neutrons during their transfer in the reflector. To implement the considered advantages, the following combination is acceptable: lead enriched by 208Pb is used as a neutron reflector while natural lead or other material (sodium, etc.) is used as a coolant in the reactor core.
- ПубликацияТолько метаданныеProliferation-protected, ultra-high burn-up reactor fuel produced in the thorium blanket of a fusion neutron source(2020) Kulikov, G. G.; Shmelev, A. N.; Kulikov, E. G.; Apse, V. A.; Куликов, Геннадий Генрихович; Куликов, Евгений Геннадьевич; Апсэ, Владимир АлександровичCopyright © GLOBAL 2019 - International Nuclear Fuel Cycle Conference and TOP FUEL 2019 - Light Water Reactor Fuel Performance Conference.All rights reserved.This paper aims at finding solutions of so important problems of nuclear power as decreasing the scope and the number of technological operations, as well as enhancing the proliferation resistance of fissile materials in nuclear fuel cycle by means of minimal changes in the cycle. The method is including fusion neutron sources with thorium blanket into future nuclear power system. In addition to production of light uranium fraction consisting of 233U and 234U, high-energy 14-MeV neutrons emitted in the process of fusion (D,T)-reaction can generate 231Pa and 232U through (n,2n)- and (n,3n)reactions. It has been demonstrated that admixture of 231Pa into fresh fuel composition can stabilize its neutron-multiplying properties thanks to two well-fissile consecutive isotopes 232U and 233U, products of radiative neutron capture by 231Pa. Coupled system of two well-fissile isotopes can allow us to reach the following goals: the higher fuel burn-up and, as a consequence, the longer fuel lifetime; the shorter scope and the lower number of technological operations in nuclear fuel cycle; the better economic potential of nuclear power technologies.
- ПубликацияТолько метаданныеOn a significant deceleration of the kinetics of fast transient processes in a fast reactor О СУЩЕСТВЕННОМ ЗАМЕДЛЕНИИ КИНЕТИКИ БЫСТРЫХ ПЕРЕХОДНЫХ ПРОЦЕССОВ В ЯДЕРНОМ РЕАКТОРЕ НА БЫСТРЫХ НЕИТРОНАХ(2020) Kulikov, G. G.; Shmelev, A. N.; Apse, V. A.; Kulikov, E. G.; Апсэ, Владимир Александрович; Куликов, Евгений Геннадьевич© 2020 Obninsk Institute for Nuclear Power Engineering, National Research Nuclear University 'MEPhI'. All rights reserved.The kinetics of nuclear reactors is determined by the average neutron lifetime. When the inserted reactivity is more than the effective fraction of delayed neutrons, the reactor kinetics becomes very rapid. The fast reactor kinetics can be slowed down by increasing the neutron lifetime. The authors consider the possibility of using a lead isotope, 208Pb, as a neutron reflector with specific properties in the lead-cooled fast reactor. To analyze the emerging effects in a fast reactor, a point kinetics model was selected, which takes into account neutrons returning from the 208Pb reflector to the reactor core. Such specific properties of 208Pb as the high atomic weight and weak neutron absorption allow neutrons from the reactor core to penetrate deeply into 208Pb reflector, slow down in it, and have a noticeable probability to return to the reactor core and affect the chain fission reaction. The neutrons coming back from the 208Pb reflector have a long «dead-time» i.e., the sum of times when neutrons leave the reactor core entering the 208Pb reflector and then diffuse back into the reactor core. During the 'dead-time', these neutrons cannot affect the chain fission reaction. In terms of the delay time, the neutrons returning from the deep layers of the 208Pb reflector are close to the delayed neutrons. Moreover, the number of the neutrons coming back from the 208Pb reflector considerably exceeds the number of the delayed neutrons. As a result, the neutron lifetime formed by the prompt neutron lifetime and the «dead-time» of the neutrons from the 208Pb reflector can be substantially increased. This will lead to a longer reactor runaway period, which will mitigate the effects of prompt supercriticality. Thus, the use of 208Pb as a neutron reflector can significantly improve the safe fast reactor operation.
- ПубликацияТолько метаданныеAdvantages of a Fast Reactor Core Surrounded by a Physically Thick Neutron Reflector Made of Lead-208(2020) Shmelev, A. N.; Apse, V. A.; Kulikov, G. G.; Kulikov, E. G.; Апсэ, Владимир Александрович; Куликов, Геннадий Генрихович; Куликов, Евгений Геннадьевич© 2020, Pleiades Publishing, Ltd.Abstract: In the paper, the influence of replacement of natural lead with lead-208 as a coolant and fast reactor reflector on its neutron-physical parameters is considered. The possibility of significantly increasing the mean prompt neutron lifetime by using lead-208 is shown. It is proposed to place a layer containing a neutron absorber over the core in its reflector to control the reactor reactivity. It is shown that when using lead-208, the efficiency of this layer is noticeably higher, and the Doppler effect is enhanced than when using natural lead.
- ПубликацияТолько метаданныеFavorable Effects of an Inner Lead Cavity on Neutronic Physics of a Lead-Cooled Fast Reactor(2020) Shmelev, A. N.; Apse, V. A.; Kulikov, G. G.; Kulikov, E. G.; Апсэ, Владимир Александрович; Куликов, Геннадий Генрихович; Куликов, Евгений Геннадьевич© 2020, Pleiades Publishing, Ltd.Abstract: The paper considers the effects produced by arranging a lead cavity in the central part of a lead-cooled fast reactor core. It is shown that the most favorable effect from the presence of an inner lead cavity at the center of the core can be obtained when radiogenic lead with a dominant 208Pb isotope content is used as the material of the cavity, coolant, and neutron reflector. This is explained by the extremely low neutron absorption of 208Pb in a wide range of neutron energies. If the thickness of the 208Pb inner cavity is chosen properly, then a spectral region with the prevailing share of resonance, epithermal, and thermal neutrons is created in the cavity. This results in a sharp increase in the mean prompt neutron lifetime (by few orders of magnitude) and enhancement of the stabilizing Doppler effect. The neutron migration from the inner cavity to the reactor core is able to intensify the fission chain reaction (FCR) and contribute positively to reactor reactivity. In addition, the high flux of slowed neutrons in the inner 208Pb-cavity makes it possible to expect efficient transmutation of long-lived fission products.