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P N Alekseev - One of the best experts on this subject based on the ideXlab platform.
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Analysis of changes in the Fuel component of the cost of electricity in the transition to a Closed Fuel Cycle in nuclear power system
Kerntechnik, 2017Co-Authors: A. V. Gurin, P N AlekseevAbstract:Abstract This paper presents a study of scenarios of transition to a Closed Fuel Cycle in the system of nuclear power, built basing on resource availability requirements at the stage of full life-Cycle reactors. Conventionally, there are three main scenarios for the development of nuclear energy: with VVER reactors operating in an open Fuel Cycle; with VVER reactors operating in a Closed Fuel Cycle; and co-operating VVER and BN, operating in a Closed Fuel Cycle. For the considered scenarios, a quantitative estimation of change in time of material balances were performed, including spent Fuel balance, balance of plutonium, reprocessed and depleted uranium, radioactive waste, and the analysis of the Fuel component of the cost of electricity.
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The basic features of a Closed Fuel Cycle without fast reactors
Journal of Physics: Conference Series, 2017Co-Authors: E A Bobrov, P N Alekseev, P S TeplovAbstract:In this paper the basic features of a Closed Fuel Cycle with thermal reactors are considered. The three variants of multiple Pu and U recycling in VVER reactors was investigated. The comparison of MOX and REMIX Fuel approaches for Closed Fuel Cycle with thermal reactors is presented. All variants make possible to reCycle several times the total amount of Pu and U obtained from spent Fuel. The reported study was funded by RFBR according to the research project № 16-38-00021
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Economical aspects of multiple plutonium and uranium recycling in VVER reactors
Kerntechnik, 2016Co-Authors: P N Alekseev, E A Bobrov, A A Dudnikov, P S TeplovAbstract:Abstract The basic strategy of Russian Nuclear Energy development is the formation of the Closed Fuel Cycle based on fast breeder and thermal reactors, as well as the solution of problems of spent nuclear Fuel accumulation and availability of resources. Three options of multiple Pu and U recycling in VVER reactors are considered in this work. Comparison of MOX and REMIX Fuel recycling approaches for the Closed Fuel Cycle involving thermal reactors is presented. REMIX Fuel is supposed to be fabricated from non-separated mixture of uranium and plutonium obtained in spent Fuel reprocessing with further makeup by enriched U. These options make it possible to reCycle several times the total amount of Pu and U obtained from spent Fuel. The main difference is the full or partial Fuel loading of the core by assemblies with reCycled Pu. The third option presents the concept of heterogeneous arrangement of Fuel pins made of enriched uranium and MOX in one Fuel assembly. It should be noted that fabrication of all fu...
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Multiple reCycle of REMIX Fuel at VVER-1000 operation in Closed Fuel Cycle
Physics of Atomic Nuclei, 2015Co-Authors: P N Alekseev, E A Bobrov, P S Teplov, A. V. Chibinyaev, A A DudnikovAbstract:The basic features of loading the VVER-1000 core with a new variant of REMIX Fuel (REgenerated MIXture of U–Pu oxides) are considered during its multiple reCycle in a Closed nuclear Fuel Cycle. The Fuel composition is produced on the basis of the uranium–plutonium regenerate extracted at processing the spent nuclear Fuel (SNF) from a VVER-1000, depleted uranium, and the fissionable material: ^235U as a part of highly enriched uranium (HEU) from warheads superfluous for defense purposes or ^233U accumulated in thorium blankets of fusion (electronuclear) neutron sources or fast reactors. Production of such a Fuel assumes no use of natural uranium in addition. When converting a part of the VVER-1000 reactors to the Closed Fuel Cycle based on the REMIX technology, the consumption of natural uranium decreases considerably, and there is no substantial degradation of the isotopic composition of plutonium or change in the reactor-safety characteristics at the passage from reCycle to reCycle.
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Prospects of subcritical molten salt reactor for minor actinides incineration in Closed Fuel Cycle
Kerntechnik, 2015Co-Authors: P N Alekseev, A A Dudnikov, A. L. Balanin, V. Yu. Blandinsky, P. A. Fomichenko, V. A. Nevinitsa, A. A. Frolov, A. S. Lubina, A. A. Sedov, A. S. SubbotinAbstract:Abstract A subcritical molten salt reactor is proposed for minor actinides (separated from spent Fuel VVER-1000 light water reactor) incineration and for 233U conversion from 232Th. Here the subcri...
A A Dudnikov - One of the best experts on this subject based on the ideXlab platform.
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Economical aspects of multiple plutonium and uranium recycling in VVER reactors
Kerntechnik, 2016Co-Authors: P N Alekseev, E A Bobrov, A A Dudnikov, P S TeplovAbstract:Abstract The basic strategy of Russian Nuclear Energy development is the formation of the Closed Fuel Cycle based on fast breeder and thermal reactors, as well as the solution of problems of spent nuclear Fuel accumulation and availability of resources. Three options of multiple Pu and U recycling in VVER reactors are considered in this work. Comparison of MOX and REMIX Fuel recycling approaches for the Closed Fuel Cycle involving thermal reactors is presented. REMIX Fuel is supposed to be fabricated from non-separated mixture of uranium and plutonium obtained in spent Fuel reprocessing with further makeup by enriched U. These options make it possible to reCycle several times the total amount of Pu and U obtained from spent Fuel. The main difference is the full or partial Fuel loading of the core by assemblies with reCycled Pu. The third option presents the concept of heterogeneous arrangement of Fuel pins made of enriched uranium and MOX in one Fuel assembly. It should be noted that fabrication of all fu...
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Multiple reCycle of REMIX Fuel at VVER-1000 operation in Closed Fuel Cycle
Physics of Atomic Nuclei, 2015Co-Authors: P N Alekseev, E A Bobrov, P S Teplov, A. V. Chibinyaev, A A DudnikovAbstract:The basic features of loading the VVER-1000 core with a new variant of REMIX Fuel (REgenerated MIXture of U–Pu oxides) are considered during its multiple reCycle in a Closed nuclear Fuel Cycle. The Fuel composition is produced on the basis of the uranium–plutonium regenerate extracted at processing the spent nuclear Fuel (SNF) from a VVER-1000, depleted uranium, and the fissionable material: ^235U as a part of highly enriched uranium (HEU) from warheads superfluous for defense purposes or ^233U accumulated in thorium blankets of fusion (electronuclear) neutron sources or fast reactors. Production of such a Fuel assumes no use of natural uranium in addition. When converting a part of the VVER-1000 reactors to the Closed Fuel Cycle based on the REMIX technology, the consumption of natural uranium decreases considerably, and there is no substantial degradation of the isotopic composition of plutonium or change in the reactor-safety characteristics at the passage from reCycle to reCycle.
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Prospects of subcritical molten salt reactor for minor actinides incineration in Closed Fuel Cycle
Kerntechnik, 2015Co-Authors: P N Alekseev, A A Dudnikov, A. L. Balanin, V. Yu. Blandinsky, P. A. Fomichenko, V. A. Nevinitsa, A. A. Frolov, A. S. Lubina, A. A. Sedov, A. S. SubbotinAbstract:Abstract A subcritical molten salt reactor is proposed for minor actinides (separated from spent Fuel VVER-1000 light water reactor) incineration and for 233U conversion from 232Th. Here the subcri...
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variants of the perspective Closed Fuel Cycle based on regenerated mixture technology combining use of thermal and fast reactors
Progress in Nuclear Energy, 2014Co-Authors: P N Alekseev, E A Bobrov, P S Teplov, A. V. Chibinyaev, A A DudnikovAbstract:Abstract In the traditional Closed Fuel Cycle, based on REMIX-technology ( RE generated MIX ture of U and Pu oxides) the Fuel composition is produced on the basis of a uranium and plutonium mixture from depleted Light Water Reactor (LWR) Fuel and additional natural uranium. In this case, there is some saving in the amount of natural uranium used. Here variants are considered of the perspective Closed Fuel Cycle in which fissile feed materials for Fuel manufacture is produced in the blankets of fast breeder reactors. The fissile material is 233 U or Pu. The raw material is depleted uranium from the stocks of enrichment factories, or thorium. Natural uranium is not used in this case. The minimum feed material required for the REMIX technology in a Closed Fuel Cycle was determined through calculations of different types of fissile and raw materials, with different Cycle lengths and Fuel-water ratios.
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Variants of the perspective Closed Fuel Cycle, based on Regenerated Mixture – Technology, combining use of thermal and fast reactors
Progress in Nuclear Energy, 2014Co-Authors: P N Alekseev, E A Bobrov, P S Teplov, A. V. Chibinyaev, A A DudnikovAbstract:Abstract In the traditional Closed Fuel Cycle, based on REMIX-technology ( RE generated MIX ture of U and Pu oxides) the Fuel composition is produced on the basis of a uranium and plutonium mixture from depleted Light Water Reactor (LWR) Fuel and additional natural uranium. In this case, there is some saving in the amount of natural uranium used. Here variants are considered of the perspective Closed Fuel Cycle in which fissile feed materials for Fuel manufacture is produced in the blankets of fast breeder reactors. The fissile material is 233 U or Pu. The raw material is depleted uranium from the stocks of enrichment factories, or thorium. Natural uranium is not used in this case. The minimum feed material required for the REMIX technology in a Closed Fuel Cycle was determined through calculations of different types of fissile and raw materials, with different Cycle lengths and Fuel-water ratios.
P S Teplov - One of the best experts on this subject based on the ideXlab platform.
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The basic features of a Closed Fuel Cycle without fast reactors
Journal of Physics: Conference Series, 2017Co-Authors: E A Bobrov, P N Alekseev, P S TeplovAbstract:In this paper the basic features of a Closed Fuel Cycle with thermal reactors are considered. The three variants of multiple Pu and U recycling in VVER reactors was investigated. The comparison of MOX and REMIX Fuel approaches for Closed Fuel Cycle with thermal reactors is presented. All variants make possible to reCycle several times the total amount of Pu and U obtained from spent Fuel. The reported study was funded by RFBR according to the research project № 16-38-00021
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The choice of the Fuel assembly for VVER-1000 in a Closed Fuel Cycle based on REMIX-technology
EPJ Nuclear Sciences & Technologies, 2016Co-Authors: Evgenii Bobrov, P S Teplov, P. A. Alekseev, A. V. Chibinyaev, Anatoliy DudnikovAbstract:This paper shows basic features of different Fuel assembly (FA) application for VVER-1000 in a Closed Fuel Cycle based on REMIX-technology. This investigation shows how the change in the water–Fuel ratio in the VVER FA affects on the Fuel characteristics produced by REMIX technology during multiple recycling.
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Economical aspects of multiple plutonium and uranium recycling in VVER reactors
Kerntechnik, 2016Co-Authors: P N Alekseev, E A Bobrov, A A Dudnikov, P S TeplovAbstract:Abstract The basic strategy of Russian Nuclear Energy development is the formation of the Closed Fuel Cycle based on fast breeder and thermal reactors, as well as the solution of problems of spent nuclear Fuel accumulation and availability of resources. Three options of multiple Pu and U recycling in VVER reactors are considered in this work. Comparison of MOX and REMIX Fuel recycling approaches for the Closed Fuel Cycle involving thermal reactors is presented. REMIX Fuel is supposed to be fabricated from non-separated mixture of uranium and plutonium obtained in spent Fuel reprocessing with further makeup by enriched U. These options make it possible to reCycle several times the total amount of Pu and U obtained from spent Fuel. The main difference is the full or partial Fuel loading of the core by assemblies with reCycled Pu. The third option presents the concept of heterogeneous arrangement of Fuel pins made of enriched uranium and MOX in one Fuel assembly. It should be noted that fabrication of all fu...
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Multiple reCycle of REMIX Fuel at VVER-1000 operation in Closed Fuel Cycle
Physics of Atomic Nuclei, 2015Co-Authors: P N Alekseev, E A Bobrov, P S Teplov, A. V. Chibinyaev, A A DudnikovAbstract:The basic features of loading the VVER-1000 core with a new variant of REMIX Fuel (REgenerated MIXture of U–Pu oxides) are considered during its multiple reCycle in a Closed nuclear Fuel Cycle. The Fuel composition is produced on the basis of the uranium–plutonium regenerate extracted at processing the spent nuclear Fuel (SNF) from a VVER-1000, depleted uranium, and the fissionable material: ^235U as a part of highly enriched uranium (HEU) from warheads superfluous for defense purposes or ^233U accumulated in thorium blankets of fusion (electronuclear) neutron sources or fast reactors. Production of such a Fuel assumes no use of natural uranium in addition. When converting a part of the VVER-1000 reactors to the Closed Fuel Cycle based on the REMIX technology, the consumption of natural uranium decreases considerably, and there is no substantial degradation of the isotopic composition of plutonium or change in the reactor-safety characteristics at the passage from reCycle to reCycle.
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Variants of the Perspective Closed Fuel Cycle, Based on REMIX-Technology
Volume 1: Plant Operations Maintenance Engineering Modifications Life Cycle and Balance of Plant; Nuclear Fuel and Materials; Plant Systems Structures, 2014Co-Authors: E A Bobrov, P S Teplov, P. A. Alekseev, A. V. Chibinyaev, Anatoliy DudnikoxAbstract:In the traditional Closed Fuel Cycle, based on REMIX-technology (REgenerated MIXture of U and Pu oxides) the Fuel composition is produced on the basis of a uranium and plutonium mixture from spent Light Water Reactor (LWR) Fuel and additional natural uranium. In this case, there is some saving in the amount of natural uranium used.The basic features of the WWER-1000 Fuel loadings with a new variant REMIX-Fuel during multiple reCycle in the Closed nuclear Fuel Cycle are described in this paper. Such Fuel compositions are produced on a basis of a uranium and plutonium mixture allocated at processing the spent Fuel after irradiation in the WWER-1000 core, depleted uranium and fission material such as: 235U as a part of high-enriched uranium from the warheads superfluous for defense.Also here variants are considered of the perspective Closed Fuel Cycle in which fissile feed materials for Fuel manufacture is produced in the blankets of fast breeder reactors. The fissile material is 233U or Pu. The raw material is depleted uranium from the stocks of enrichment factories, or thorium. Natural uranium is not used in this case. The minimum feed material required for the REMIX technology in a Closed Fuel Cycle was determined through calculations of different types of fissile and raw materials, with different Cycle lengths and Fuel-water ratios.Copyright © 2014 by ASME
E A Bobrov - One of the best experts on this subject based on the ideXlab platform.
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The basic features of a Closed Fuel Cycle without fast reactors
Journal of Physics: Conference Series, 2017Co-Authors: E A Bobrov, P N Alekseev, P S TeplovAbstract:In this paper the basic features of a Closed Fuel Cycle with thermal reactors are considered. The three variants of multiple Pu and U recycling in VVER reactors was investigated. The comparison of MOX and REMIX Fuel approaches for Closed Fuel Cycle with thermal reactors is presented. All variants make possible to reCycle several times the total amount of Pu and U obtained from spent Fuel. The reported study was funded by RFBR according to the research project № 16-38-00021
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Economical aspects of multiple plutonium and uranium recycling in VVER reactors
Kerntechnik, 2016Co-Authors: P N Alekseev, E A Bobrov, A A Dudnikov, P S TeplovAbstract:Abstract The basic strategy of Russian Nuclear Energy development is the formation of the Closed Fuel Cycle based on fast breeder and thermal reactors, as well as the solution of problems of spent nuclear Fuel accumulation and availability of resources. Three options of multiple Pu and U recycling in VVER reactors are considered in this work. Comparison of MOX and REMIX Fuel recycling approaches for the Closed Fuel Cycle involving thermal reactors is presented. REMIX Fuel is supposed to be fabricated from non-separated mixture of uranium and plutonium obtained in spent Fuel reprocessing with further makeup by enriched U. These options make it possible to reCycle several times the total amount of Pu and U obtained from spent Fuel. The main difference is the full or partial Fuel loading of the core by assemblies with reCycled Pu. The third option presents the concept of heterogeneous arrangement of Fuel pins made of enriched uranium and MOX in one Fuel assembly. It should be noted that fabrication of all fu...
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Multiple reCycle of REMIX Fuel at VVER-1000 operation in Closed Fuel Cycle
Physics of Atomic Nuclei, 2015Co-Authors: P N Alekseev, E A Bobrov, P S Teplov, A. V. Chibinyaev, A A DudnikovAbstract:The basic features of loading the VVER-1000 core with a new variant of REMIX Fuel (REgenerated MIXture of U–Pu oxides) are considered during its multiple reCycle in a Closed nuclear Fuel Cycle. The Fuel composition is produced on the basis of the uranium–plutonium regenerate extracted at processing the spent nuclear Fuel (SNF) from a VVER-1000, depleted uranium, and the fissionable material: ^235U as a part of highly enriched uranium (HEU) from warheads superfluous for defense purposes or ^233U accumulated in thorium blankets of fusion (electronuclear) neutron sources or fast reactors. Production of such a Fuel assumes no use of natural uranium in addition. When converting a part of the VVER-1000 reactors to the Closed Fuel Cycle based on the REMIX technology, the consumption of natural uranium decreases considerably, and there is no substantial degradation of the isotopic composition of plutonium or change in the reactor-safety characteristics at the passage from reCycle to reCycle.
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Variants of the Perspective Closed Fuel Cycle, Based on REMIX-Technology
Volume 1: Plant Operations Maintenance Engineering Modifications Life Cycle and Balance of Plant; Nuclear Fuel and Materials; Plant Systems Structures, 2014Co-Authors: E A Bobrov, P S Teplov, P. A. Alekseev, A. V. Chibinyaev, Anatoliy DudnikoxAbstract:In the traditional Closed Fuel Cycle, based on REMIX-technology (REgenerated MIXture of U and Pu oxides) the Fuel composition is produced on the basis of a uranium and plutonium mixture from spent Light Water Reactor (LWR) Fuel and additional natural uranium. In this case, there is some saving in the amount of natural uranium used.The basic features of the WWER-1000 Fuel loadings with a new variant REMIX-Fuel during multiple reCycle in the Closed nuclear Fuel Cycle are described in this paper. Such Fuel compositions are produced on a basis of a uranium and plutonium mixture allocated at processing the spent Fuel after irradiation in the WWER-1000 core, depleted uranium and fission material such as: 235U as a part of high-enriched uranium from the warheads superfluous for defense.Also here variants are considered of the perspective Closed Fuel Cycle in which fissile feed materials for Fuel manufacture is produced in the blankets of fast breeder reactors. The fissile material is 233U or Pu. The raw material is depleted uranium from the stocks of enrichment factories, or thorium. Natural uranium is not used in this case. The minimum feed material required for the REMIX technology in a Closed Fuel Cycle was determined through calculations of different types of fissile and raw materials, with different Cycle lengths and Fuel-water ratios.Copyright © 2014 by ASME
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variants of the perspective Closed Fuel Cycle based on regenerated mixture technology combining use of thermal and fast reactors
Progress in Nuclear Energy, 2014Co-Authors: P N Alekseev, E A Bobrov, P S Teplov, A. V. Chibinyaev, A A DudnikovAbstract:Abstract In the traditional Closed Fuel Cycle, based on REMIX-technology ( RE generated MIX ture of U and Pu oxides) the Fuel composition is produced on the basis of a uranium and plutonium mixture from depleted Light Water Reactor (LWR) Fuel and additional natural uranium. In this case, there is some saving in the amount of natural uranium used. Here variants are considered of the perspective Closed Fuel Cycle in which fissile feed materials for Fuel manufacture is produced in the blankets of fast breeder reactors. The fissile material is 233 U or Pu. The raw material is depleted uranium from the stocks of enrichment factories, or thorium. Natural uranium is not used in this case. The minimum feed material required for the REMIX technology in a Closed Fuel Cycle was determined through calculations of different types of fissile and raw materials, with different Cycle lengths and Fuel-water ratios.
Konstantin Mikityuk - One of the best experts on this subject based on the ideXlab platform.
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core neutronics characterization of the gfr2400 gas cooled fast reactor
Progress in Nuclear Energy, 2015Co-Authors: Zoltan Perko, Konstantin Mikityuk, Sandro Pelloni, Jiri Křepel, Mate Szieberth, Girardin Gaetan, Branislav Vrban, Jakub Luley, Stefan Cerba, Mate HalaszAbstract:The Generation IV initiative was launched with the goal of developing nuclear reactors which surpass current designs in safety, sustainability, economics and non-proliferation. From the six most promising concepts the Gas Cooled Fast Reactor (GFR) represents a challenging and innovative idea that is prominent in the sustainability aspect with the ability to have a Closed Fuel Cycle and the potential to burn minor actinides (MAs). The European FP7 GoFastR project was one of the latest steps in the development and further optimization of GFRs. This paper presents a comprehensive overview of the neutronic performance of GFR2400 which was considered as a conceptual design for a large scale GFR within the collaboration. This reactor is the newest on the evolutionary path of fully ceramic GFRs featuring ceramic Fuel and structural materials allowing high temperatures and efficiency using helium coolant. An important innovation of the current design is the application of refractory metallic liners to enhance the fission product retention of the cladding, resulting in a significant neutronic penalty during normal operation, at the same time being advantageous under transient conditions involving spectrum softening. Using the ERANOS and SCALE code systems several parameters were determined for beginning of life (BOL) conditions, including excess reactivity, various reactivity effects such as depressurization, Doppler or thermal expansion effects, as well as kinetic parameters. An extensive sensitivity and uncertainty analysis of these parameters was also done with the 15 group BOLNA and 44 group SCALE covariance libraries. Open and Closed Fuel Cycle operations were investigated and the transmutational capabilities were studied with the GFR connected to traditional light water reactors in a symbiotic system. The presented analysis shows that the GFR2400 design is a major improvement compared to previous concepts. All preliminary constraints are respected resulting in a manageable initial Pu inventory of 10 t/GWel at 45% plant efficiency, a low MA mass fraction of 1% by self-recycling and a near zero breeding gain without the use of fertile blankets. At the same time the reactor has acceptable safety features precluding super-prompt-criticality in depressurized conditions at BOL and in open Cycle equilibrium. Either of the two planned control devices is sufficient to shut down the reactor independently of the other and the refractory liners introduce significant negative reactivity in case of water ingress. However the occurrence of hot spots when all control rods are inserted needs further analysis. The design also shows promising Closed Fuel Cycle and transmutational performance. However as is the case in other fast reactors the Fuel Cycle closure causes safety related parameters to degrade, most importantly the depressurization reactivity effect to exceed the effective delayed neutron fraction in the current design. To assess the acceptability of this deterioration further analysis is needed. Finally, it can be concluded that current commercial codes are satisfactory for such analysis; however there is a need for better covariance data. Several parameters exceed their target uncertainty value, most notably the k-effective by a factor of 6, the main source of the uncertainty being the inelastic scattering of U-238. (C) 2014 Elsevier Ltd. All rights reserved.
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coupled 3 d neutronics thermal hydraulics optimization study for improving the response of a 3600 mw thermal sfr core to an unprotected loss of flow accident
Nuclear Technology, 2013Co-Authors: Kaichao Sun, Aurélia Chenu, Jiri Krepel, Konstantin Mikityuk, Rakesh ChawlaAbstract:The sodium-cooled fast reactor (SFR), as a fast neutron spectrum system, is characterized by several performance advantages. In particular, the long-term operation of an SFR core in a Closed Fuel Cycle will lead to an equilibrium state, where both reactivity and Fuel mass flow stabilize. However, the SFR has one dominating neutronics drawback, namely, there is generally a positive reactivity effect when there is voiding of the sodium coolant in the core. Furthermore, this effect becomes even stronger in the equilibrium Closed Fuel Cycle. Considering that in a hypothetical SFR unprotected loss-of-flow (ULOF) accident scenario, i.e., flow rundown without SCRAM, sodium boiling can be anticipated to occur, it is crucial to assess the corresponding impact of the positive sodium void effect. An optimization study for improving the safety characteristics of a large [3600-MW(thermal)] SFR has currently been conducted in the above context. The dynamic core response to a reference ULOF scenario is investigated with the use of a coupled three-dimensional neutronics/thermal-hydraulics PARCS/TRACE model. The starting point of the study is the reference core design considered in the framework of the Collaborative Project on the European Sodium Fast Reactor (CP-ESFR). To reduce the sodium void effect, the core has been modified by introducing an upper sodium plenum, along with a boron layer above it. Furthermore, the original core height-to-diameter ratio is reduced. In comparison to the reference ESFR core behavior, certain improvements are achieved, thanks to the static neutronics optimization carried out. However, these changes are found, in themselves, to be insufficient as regards the prevention of cladding and Fuel melting during the considered ULOF event. Thermal-hydraulics optimization has thus been considered necessary, in order to (a) prevent sodium flow blockage in the Fuel channel and (b) avoid boiling instabilities caused by the vaporization/condensation process in the upper sodium plenum. The corresponding measures taken are (a) the introduction of an innovative wrapper design, which features small openings in each side surface of the Fuel assembly, and (b) replacement of the original upper sodium plenum by an extended fission gas plenum. Following implementation of these thermal-hydraulics-related design changes, one arrives at a final configuration of the SFR core, in which, for the selected accident scenario, a new "steady state" involving stable sodium boiling is found to be achievable, with melting of neither cladding nor Fuel. Such a satisfactory behavior has been confirmed not only for the beginning-of-life state of the core but also for the equilibrium Closed Fuel Cycle.
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Coupled 3-D Neutronics/Thermal-Hydraulics Optimization Study For Improving The Response Of A 3600 Mw(Thermal) Sfr Core To An Unprotected Loss-Of-Flow Accident
Nuclear Technology, 2013Co-Authors: Kaichao Sun, Aurélia Chenu, Jiri Krepel, Konstantin Mikityuk, Rakesh ChawlaAbstract:The sodium-cooled fast reactor (SFR), as a fast neutron spectrum system, is characterized by several performance advantages. In particular, the long-term operation of an SFR core in a Closed Fuel Cycle will lead to an equilibrium state, where both reactivity and Fuel mass flow stabilize. However, the SFR has one dominating neutronics drawback, namely, there is generally a positive reactivity effect when there is voiding of the sodium coolant in the core. Furthermore, this effect becomes even stronger in the equilibrium Closed Fuel Cycle. Considering that in a hypothetical SFR unprotected loss-of-flow (ULOF) accident scenario, i.e., flow rundown without SCRAM, sodium boiling can be anticipated to occur, it is crucial to assess the corresponding impact of the positive sodium void effect. An optimization study for improving the safety characteristics of a large [3600-MW(thermal)] SFR has currently been conducted in the above context. The dynamic core response to a reference ULOF scenario is investigated with the use of a coupled three-dimensional neutronics/thermal-hydraulics PARCS/TRACE model. The starting point of the study is the reference core design considered in the framework of the Collaborative Project on the European Sodium Fast Reactor (CP-ESFR). To reduce the sodium void effect, the core has been modified by introducing an upper sodium plenum, along with a boron layer above it. Furthermore, the original core height-to-diameter ratio is reduced. In comparison to the reference ESFR core behavior, certain improvements are achieved, thanks to the static neutronics optimization carried out. However, these changes are found, in themselves, to be insufficient as regards the prevention of cladding and Fuel melting during the considered ULOF event. Thermal-hydraulics optimization has thus been considered necessary, in order to (a) prevent sodium flow blockage in the Fuel channel and (b) avoid boiling instabilities caused by the vaporization/condensation process in the upper sodium plenum. The corresponding measures taken are (a) the introduction of an innovative wrapper design, which features small openings in each side surface of the Fuel assembly, and (b) replacement of the original upper sodium plenum by an extended fission gas plenum. Following implementation of these thermal-hydraulics-related design changes, one arrives at a final configuration of the SFR core, in which, for the selected accident scenario, a new "steady state" involving stable sodium boiling is found to be achievable, with melting of neither cladding nor Fuel. Such a satisfactory behavior has been confirmed not only for the beginning-of-life state of the core but also for the equilibrium Closed Fuel Cycle.
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Comparison of open and Closed U–Pu equilibrium Fuel Cycles for Generation-IV fast reactors with the EQL3D procedure
Nuclear Engineering and Design, 2012Co-Authors: Jiri Krepel, Sandro Pelloni, Konstantin MikityukAbstract:Abstract The advanced fast reactors of the fourth generation should enable an indirect burning of poorly fissile 238 U through 239 Pu breeding and recycling of the actinides from their own spent Fuel. The recycling or actually the Fuel Cycle closure can significantly reduce the amount of long-lived radioactive waste and the 238 U burning can multiply the sustainability of the uranium Fueled reactors. Regular periodic operation with the Fuel recycling converges to an equilibrium Cycle. To enable its simulation a numerical tool named equilibrium Fuel Cycle procedure for fast reactors (EQL3D) was developed in the FAST group of LRS at Paul Scherrer Institut. The procedure is based on the ERANOS code and can be used to yield the description of two basic situations: the equilibrium of an open Fuel Cycle and the equilibrium of a Closed Fuel Cycle. The goals of the present study are (i) to apply EQL3D to the Gas-cooled Fast Reactor (GFR), Sodium-cooled Fast Reactor (SFR), and Lead-cooled Fast Reactor (LFR), (ii) to simulate and confirm the GFR, SFR, and LFR neutronics capability for Closed Fuel Cycle, and (iii) to evaluate and compare the equilibrium Cycle safety and performance parameters. The EQL3D capability enables to characterize the equilibrium Cycle for complex reloading patterns within a multi-batch scheme. Therefore, a specific ring-wise reloading pattern within a multi-batch Cycle was developed for each core. The convergence path to equilibrium differs between the cores. It is determined mainly by the initial Fuel composition. However, the capability for Closed Fuel Cycle was proved for all three systems. It was also found that the equilibrium 239 Pu/ 238 U mass ratio, even though it depends on the feed and spectrum, is similar for all compared fast reactors. In spite of this similarity, the equilibrium safety-related parameters differ between the cores. Nevertheless, the degradation caused by the Fuel Cycle closure is comparable with the degradation between initial core state and open Cycle equilibrium. From neutronics point of view all three cores could serve after prospective optimization as a sustainable and clean energy source.
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GFR equilibrium Cycle analysis with the EQL3D procedure
Nuclear Engineering and Design, 2010Co-Authors: Jiri Krepel, Konstantin Mikityuk, Sandro Pelloni, Paul CoddingtonAbstract:Abstract Advanced fast reactors of the fourth generation should be capable to breed their own Fuel from 238 U feed and to reCycle the actinides from their own spent Fuel. This recycling or virtually the closure of Fuel Cycle can converge to an equilibrium Fuel Cycle and has impact on the safety-related parameters. The goals of this study are: (i) to apply an equilibrium Cycle procedure EQL3D to the Gas cooled Fast Reactor (GFR), (ii) to simulate and confirm the GFR neutronics capability for Closed Fuel Cycle, and (iii) to evaluate the safety-related parameters of the equilibrium Cycle. Equilibrium Cycle method for considering the homogeneous recycling of actinides is a known approach. However, in EQL3D the equilibrium method is newly applied for hexagonal-z 3D core geometry and 33 energy-groups neutron-flux calculation. This geometry enables to characterize the equilibrium Cycle for complex reloading patterns within a multi-batch Cycle. Two GFR geometries were studied, the first based on an international neutronics benchmark with a simple set-up and the second based on more advanced core design. For the advanced design, three reloading patterns within a multi-batch Cycle with four different feeds were compared. The GFR neutronics capability for Closed Cycle was proved. The negative impact of the Fuel Cycle closure on safety-related parameters was confirmed and quantified. The GFR core with Closed Fuel Cycle could serve after prospective optimization as a sustainable and clean energy source.