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Np and 
Am by accelerator-driven system at Kyoto University Critical AssemblyPyeon, C. H.*; Yamanaka, Masao*; Oizumi, Akito; Fukushima, Masahiro; Chiba, Go*; Watanabe, Kenichi*; Endo, Tomohiro*; Van Rooijen, W. G.*; Hashimoto, Kengo*; Sakon, Atsushi*; et al.
Journal of Nuclear Science and Technology, 56(8), p.684 - 689, 2019/08
Times Cited Count：12 Percentile：80.27(Nuclear Science & Technology)This study demonstrates, for the first time, the principle of nuclear transmutation of minor actinide (MA) by the accelerator-driven system (ADS) through the injection of high-energy neutrons into the subcritical core at the Kyoto University Critical Assembly. The main objective of the experiments is to confirm fission reactions of neptunium-237 (Np) and americium-241 (Am), and capture reactions of Np. Subcritical irradiation of Np and Am foils is conducted in a hard spectrum core with the use of the back-to-back fission chamber that obtains simultaneously two signals from specially installed test (Np or Am) and reference (uranium-235) foils. The first nuclear transmutation of Np and Am by ADS soundly implemented by combining the subcritical core and the 100 MeV proton accelerator, and the use of a lead-bismuth target, is conclusively demonstrated through the experimental results of fission and capture reaction events.
Aizawa, Kosuke; Fujita, Kaoru; Kamide, Hideki; Kasahara, Naoto*
Nuclear Technology, 189(2), p.111 - 121, 2015/02
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Selector-valve mechanism is adopted in the design of JSFR for its failed-fuel detection and location (FFDL) system. JSFR has only two FFDL units for 562 core fuel subassemblies to reduce construction cost by decreasing the reactor vessel diameter. Consequently, one SV-FFDL unit must handle about 300 subassemblies. In addition, JSFR adopts an upper internal structure (UIS) with a slit above the core. Sampling performance for the subassemblies under the UIS slit has been evaluated to be lower than those under the normal UIS position in the previous water experiments and numerical simulation. In this paper, the outline of FFDL system is shown, which can be applied to so large number of fuel subassemblies in a compact reactor vessel. Detection capability of the FFDL system was studied to achieve the design conditions. Operation modes and procedure of the FFDL system also investigated.
Aizawa, Kosuke; Fujita, Kaoru; Hirata, Shingo*; Kasahara, Naoto*
Nuclear Technology, 183(1), p.1 - 12, 2013/07
In the design of Japan Sodium-cooled Fast Reactor (JSFR), a selector-valve mechanism is adopted for its failed-fuel detection and location (FFDL) system. Since JSFR has only two FFDL units for about 600 fuel subassemblies, one FFDL unit must handle much larger number of subassemblies than in previous designs. In addition, during long plant life of 60 years, the wear length of the selector-valve will become longer than those of past reactors. Therefore, the endurance of the selector-valve becomes important. To demonstrate the manufacturability and endurance of the selector-valve, a full size mock-up was manufactured, and an endurance experiment of the mock-up model under high-temperature sodium were conducted. The cross-section observation, hardness measurement, and chemical assay results after the endurance experiment showed that the coating layer on the sliding surface still remains. Thus, the endurance of the JSFR selector-valve was demonstrated.
Aizawa, Kosuke; Oshima, Jun*; Kamide, Hideki; Kasahara, Naoto
Journal of Nuclear Science and Technology, 49(1), p.47 - 60, 2012/01
Times Cited Count：2 Percentile：17.8(Nuclear Science & Technology)A selector-valve type failed fuel detection and location (FFDL) system is applied to the JSFR design that has an upper internal structure (UIS) with a slit above the core and several sampling nozzles for the FFDL are set in the UIS around the slit to detect the fission product (FP) from the subassemblies below the slit. Therefore, mixing process in the UIS should be known and appropriate arrangement of the sampling nozzles in the UIS is needed. A water experiment using a 1/5-scle model was carried out. Experimental results showed that the sampling nozzles set in the UIS detected the FP simulant concentration within the criteria of FFDL signal detection. In addition, identification of the failed fuel subassembly under the UIS slit was achieved by means of comparing concentration profiles in the UIS. A numerical simulation using a CFD code was carried out. The simulation results showed that the simulation predicts the FP concentration distributions.
Aizawa, Kosuke; Oshima, Jun*; Kamide, Hideki; Kasahara, Naoto
Proceedings of International Conference on Fast Reactors and Related Fuel Cycles (FR 2009) (CD-ROM), 11 Pages, 2012/00
JSFR adopts a Selector-Valve mechanism for the failed fuel detection and location (FFDL) system. The Selector-Valve FFDL system identifies failed fuel subassemblies by sampling sodium from each fuel subassembly outlet and detecting fission product or delayed neutron. One of the JSFR design features is employing an upper internal structure (UIS) with a radial slit, in which an arm of fuel handling machine can move and access the fuel assemblies under the UIS. Thus, JSFR cannot place sampling nozzles right above the fuel subassemblies located under the slit. To overcome above diffculties, we have developed the sampling method for indentifying the failed fuel subassemblies located under the slit by numerical simulations and water experiments.
Aizawa, Kosuke; Fujita, Kaoru; Kamide, Hideki; Kasahara, Naoto
Proceedings of 2011 International Congress on Advances in Nuclear Power Plants (ICAPP '11) (CD-ROM), p.605 - 613, 2011/05
A conceptual design study of an advanced large-sized (1,500 MWe class) sodium-cooled fast reactor, JSFR, is in progress in the FaCT project in Japan. JSFR has adopted a selector-valve mechanism for a failed-fuel detection and location (FFDL) system. The selector-valve FFDL system identifies a failed fuel subassembly by sampling sodium from each fuel subassembly outlet and detecting fission product gas or delayed neutron precursors of fission products. One of the technologies which JSFR has adopted is an upper internal structure (UIS) with a radial slit. Because sampling nozzles cannot be set in the UIS slit, several sampling nozzles are installed around the slit so as to sample sodium from the failed fuel subassemblies under the UIS slit. In this study, a signal and noise detected by the delayed neutron detector have been calculated. On the basis of these results, appropriate operation patterns of the selector-valve FFDL system for JSFR have been constructed.
Aizawa, Kosuke; Fujita, Kaoru; Kamide, Hideki; Kasahara, Naoto
Nihon Kikai Gakkai Rombunshu, B, 77(776), p.982 - 986, 2011/04
A conceptual design study of Japan Sodium-cooled Fast Reactor (JSFR) is in progress as an issue of the "Fast Reactor Cycle Technology Development (FaCT)" project in Japan. JSFR adopts a Selector-Valve mechanism for a failed fuel detection and location (FFDL) system. The Selector-Valve FFDL system identifies failed fuel subassemblies by sampling sodium from each fuel subassembly outlet and detecting fission product. One of the JSFR design features is employing an upper internal structure (UIS) with a radial slit, in which an arm of fuel handling machine can move and access the fuel assemblies under the UIS. Thus, JSFR cannot place sampling nozzles right above the fuel subassemblies located under the slit. In this study, appropriate sampling method for indentifying under-slit failed fuel subassemblies has been developed by water experiments.
Kamide, Hideki; Aizawa, Kosuke; Oshima, Jun*; Nakayama, Okatsu*; Kasahara, Naoto
Journal of Nuclear Science and Technology, 47(9), p.810 - 819, 2010/09
Times Cited Count：3 Percentile：24.08(Nuclear Science & Technology)Development of advanced loop type sodium cooled fast reactor is under going. An upper internal structure (UIS) has a radial slit to reduce the reactor vessel diameter. This UIS slit allows a high velocity from the core fuel subassemblies and influences the gas entrainment in the reactor vessel and also the delayed neutron precursor sampling for a failed fuel detection and location system. Then flow visualization and velocity measurements were carried out in an 1/10 scale water test model. The velocity measurement using particle image velocimetry showed that velocity in the slit region was accelerated at the heights of the UIS horizontal plates and kept higher value at the middle height of the upper plenum. Numerical simulation using a commercial CFD code was also carried out for this complex geometry of UIS to know adequate simulation method. The comparisons of velocity profiles in the UIS between the experiment and analysis showed good agreements.
Aizawa, Kosuke; Fujita, Kaoru; Kamide, Hideki; Kasahara, Naoto
Dai-15-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.229 - 230, 2010/06
A conceptual design study of Japan Sodium-cooled Fast Reactor (JSFR) is in progress as an issue of the "Fast Reactor Cycle Technology Development (FaCT)" project in Japan. JSFR adopts a selector-valve mechanism for the Failed Fuel Detection and Location (FFDL) system. The selector-valve FFDL system identifies failed fuel subassemblies by sampling sodium from each fuel subassembly outlet and detecting fission product. One of the JSFR design features is employing an Upper Internal Structure (UIS) with a radial slit, in which an arm of fuel handling machine can move and access the fuel assemblies under the UIS. Thus, JSFR cannot place sampling nozzles right above the fuel subassemblies located under the slit. In this study, the sampling method for identifying under-slit failed fuel subassemblies has been demonstrated by water experiments.
Aizawa, Kosuke; Fujita, Kaoru; Hirata, Shingo; Kasahara, Naoto
Proceedings of 2010 International Congress on Advances in Nuclear Power Plants (ICAPP '10) (CD-ROM), p.645 - 652, 2010/06
A conceptual design study of an advanced large-sized (1500MWe class) sodium-cooled fast reactor (named JSFR) has progressed in the FaCT project in Japan. JSFR adopts a selector-valve mechanism for the failed fuel detection and location (FFDL) system. The drive shaft rotates and moves vertically in order to select the channel. And, the drive shaft is in contact with the selector-valve drum by spring load. Thus, a mechanical wear could occur between the drive shaft and the drum of the selector-valve FFDL system. There is concern about manufacturing capability and endurance of the JSFR selector-valve. To demonstrate manufacturing capability and endurance of the JSFR selector-valve, a mock-up was manufactured and an endurance experiment under high temperature sodium has been conducted.
Kamide, Hideki; Aizawa, Kosuke; Oshima, Jun*; Nakayama, Okatsu*; Kasahara, Naoto
Proceedings of 6th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-6) (USB Flash Drive), 8 Pages, 2008/11
Development of advanced loop type sodium cooled fast reactor is under going. An upper internal structure (UIS) has a radial slit to reduce the reactor vessel diameter. This UIS slit allows a high velocity from the core fuel subassemblies and influences the gas entrainment in the reactor vessel and also the delayed neutron precursor sampling for a failed fuel detection and location system. Then flow visualization and velocity measurements were carried out in an 1/10 scale water test model. The velocity measurement using particle image velocimetry showed that velocity in the slit region was accelerated at the heights of the UIS horizontal plates and kept higher value at the middle height of the upper plenum. Numerical simulation using a commercial CFD code was also carried out for this complex geometry of UIS to know adequate simulation method. The comparisons of velocity profiles in the UIS between the experiment and analysis showed good agreements.
Nakajima, Kenji; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kajimoto, Ryoichi; Wakimoto, Shuichi; Osakabe, Toyotaka; Metoki, Naoto; Ito, Shinichi*; Sato, Taku*; Kakurai, Kazuhisa; et al.
no journal, ,
no abstracts in English
Aizawa, Kosuke; Oshima, Jun*; Kasahara, Naoto
no journal, ,
no abstracts in English
Nakajima, Kenji; Kajimoto, Ryoichi; Inamura, Yasuhiro; Takahashi, Nobuaki; Osakabe, Toyotaka; Wakimoto, Shuichi; Nakamura, Mitsutaka; Ito, Shinichi*; Aizawa, Kazuya; Suzuya, Kentaro; et al.
no journal, ,
A cold-neutron disk-chopper spectrometer AMATERAS is under construction in Materials and Life Science Facility in J-PARC. AMATERAS is dedicated to inelastic and quisielastic neutron scattering experiments in the range of cold thermal neutron region with high-efficiency and high-resolution. The spectrometer is expected to be ready in the beginning of 2009. In this presentation, we will show current status of construction of AMATERAS and expected scientific results from the spectrometer.
Nakajima, Kenji; Kawamura, Seiko; Kajimoto, Ryoichi; Inamura, Yasuhiro; Takahashi, Nobuaki; Osakabe, Toyotaka; Wakimoto, Shuichi; Nakamura, Mitsutaka; Ito, Shinichi*; Aizawa, Kazuya; et al.
no journal, ,
no abstracts in English
Nakajima, Kenji; Kawamura, Seiko; Nakamura, Mitsutaka; Kajimoto, Ryoichi; Inamura, Yasuhiro; Takahashi, Nobuaki; Osakabe, Toyotaka; Wakimoto, Shuichi; Aizawa, Kazuya; Suzuya, Kentaro; et al.
no journal, ,
AMATERAS is a cold-neutron disk-chopper spectrometer newly installed at MLF, J-PARC. The spectrometer has pulse shaping chopper which can cat the source pulse shape as it is required by the experiments. By using newly developed high-speed disk-choppers, the spectrometer realizes both high energy resolution and high intensity with high flexibility in the cold and thermal neutron energy region. The construction of the spectrometer has been completed in spring of 2009. After the commissioning works, now the spectrometer is open to users. In this presentation, we will show the evaluated performances which were obtained in commissioning works.
Aizawa, Kosuke; Fujimura, Ken; Hirata, Shingo; Kasahara, Naoto
no journal, ,
no abstracts in English
Nakajima, Kenji; Kawamura, Seiko; Nakamura, Mitsutaka; Kajimoto, Ryoichi; Inamura, Yasuhiro; Takahashi, Nobuaki; Osakabe, Toyotaka; Wakimoto, Shuichi; Aizawa, Kazuya; Suzuya, Kentaro; et al.
no journal, ,
no abstracts in English
Aizawa, Kosuke; Fujita, Kaoru; Hirata, Shingo; Kasahara, Naoto
no journal, ,
To demonstrate endurance of the JSFR selector-valve, an endurance experiment under high temperature sodium has been conducted. From the results of the endurance under-sodium experiment using the mock-up of JSFR selector-valve, the endurance of the sampling pad can be ensured completely by setting the manufactured coating layer to 50
m.
Aizawa, Kosuke; Oshima, Jun*; Kamide, Hideki; Kasahara, Naoto
no journal, ,
JSFR adopts a Selector-valve method for the failed fuel detection and location (FFDL) system. A Selector-valve FFDL system identifies the failed fuel subassembly by sampling outlet sodium of each fuel subassembly. One of the JSFR design features is an upper internal structure (UIS) with a radial slit, in which an arm of fuel handling machine can move and access the fuel assemblies under the UIS. This UIS can simplify a fuel handling system, and can downscale the reactor vessel diameter. Thus, JSFR cannot place the sampling ports right above the fuel subassemblies located under the slit. So, it is necessary that the sampling ports will be set around the UIS slit so as to catch the sodium flow from the fuel subassemblies located under the slit. To demonstrate sampling performance of under-slit subassemblies, water experiments and numerical analyses have been conducted.
