Embedded system using a radiation-hardened processor (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Okayama University*

JAEA-Review 2023-038, 48 Pages, 2024/03

JAEA-Review-2023-038.pdf:2.58MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2022, this report summarizes the research results of the "Embedded system using a radiation-hardened processor" conducted in FY2022. The present study aims to be developing a radiation-hardened optoelectronic processor with a 10 MGy total-ionizing-dose (TID) tolerance, a radiation-hardened processor without any optical component with a 4 MGy TID tolerance, a radiation-hardened memory with a 4 MGy TID tolerance, and a radiation-hardened power supply unit with a 1 MGy TID tolerance. Moreover, Japanese research group will support radiation- hardened field programmable gate arrays, power supply units, and radiation-hardened optical systems for radiation-hardened robot systems and radiation sensor systems developed by UK team.

Inelastic neutron scattering study of magnon excitation by ultrasound injection in yttrium iron garnet

Shamoto, Shinichi; Akatsu, Mitsuhiro*; Chang, L.-J.*; Nemoto, Yuichi*; Ieda, Junichi

Applied Physics Letters, 124(11), p.112402_1 - 112402_5, 2024/03

https://doi.org/10.1063/5.0189768

The magnon excitation by ultrasound injection in YFeO is studied by inelastic neutron scattering. Both longitudinal and transverse ultrasound injections enhanced the inelastic neutron scattering intensity.

Progress status and future issues of development of analysis and estimation technology for fuel debris characterization, 5; Progress status of development of Non-Destructive assay technologies for sorting and segregation of fuel debris and others

Kamada, Masaki*; Yoshida, Takuma*; Sugita, Tsukasa*; Okumura, Keisuke

Nihon Genshiryoku Gakkai-Shi ATOMO, 66(2), p.83 - 86, 2024/02

https://doi.org/10.3327/jaesjb.66.2_83

no abstracts in English

Development of rapid and sensitive radionuclide analysis method by simultaneous analysis of , , and X-rays (Contract research); FY2022 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Japan Chemical Analysis Center*

JAEA-Review 2023-022, 93 Pages, 2023/12

JAEA-Review-2023-022.pdf:4.7MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2022. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2020, this report summarizes the research results of the "Development of rapid and sensitive radionuclide analysis method by simultaneous analysis of , , and X-rays" conducted from FY2020 to FY2022. The present study aims to enable rapid analysis of radionuclides in fuel debris and waste, we have established the latest measurement system, such as the multiple -ray detection methods, and the Spectral Determination Method (hereinafter referred to as "SDM") was developed. In the research in 2022, we developed a code that handles measurement data of LSC, singles Ge, and 2D spectra (multiple ). In addition, to develop an integrated database, spectral data of 40 nuclides were obtained by actual measurements and simulation calculations.

Survey of air dose rate distribution inside and outside of wooden houses in Fukushima Prefecture; Actual condition of dose reduction factor

Kim, M.; Malins, A.*; Machida, Masahiko; Yoshimura, Kazuya; Saito, Kimiaki; Yoshida, Hiroko*

Nihon Genshiryoku Gakkai Wabun Rombunshi (Internet), 22(4), p.156 - 169, 2023/11

https://doi.org/10.3327/taesj.J23.001

Dose reduction factor of a Japanese house is important information in the external exposure estimation of returning residents. In 2019, a total of 19 wooden houses were surveyed in Iitate Village and Namie Town using a gamma plotter that can continuously measure the air dose rate. In addition, the characteristics of the reduction factor were investigated from the measured air dose rate. In the vicinity of houses, uncontaminated areas exist underneath houses and, the ratio of paved surfaces such as asphalt roads is relatively high; furthermore, the pavement has a tendency for the radiation source to decay quickly. Therefore, the air dose rate near the house showed a relatively low value in common at all sites. Air dose rates above unpaved surfaces showed higher values and larger variations than those above paved surfaces within a radius of 50 m form the center of a house. The reduction factor was widely distributed even for one house, if the ratio of every air dose rate observed inside and outside the house is considered. It is suggested that a realistic reduction factor may not be obtained when the reduction factor is obtained based on the measured values at a small number of points that do not have the representativeness of the radiation field to be measured.

Data report of ROSA/LSTF experiment TR-LF-15; Accident management actions during station blackout transient with pump seal LOCA

Takeda, Takeshi

JAEA-Data/Code 2023-012, 75 Pages, 2023/10

JAEA-Data-Code-2023-012.pdf:4.45MB

An experiment denoted as TR-LF-15 was conducted on June 11, 2014 using the Large Scale Test Facility (LSTF) in the Rig of Safety Assessment-V (ROSA-V) Program. The ROSA/LSTF experiment TR-LF-15 simulated accident management (AM) actions during a station blackout transient with TMLB' scenario with pump seal loss-of-coolant accident (LOCA) in a pressurized water reactor (PWR). This scenario is featured by loss of auxiliary feedwater functions. The pump seal LOCA was simulated by a 0.1% cold leg break. The test assumptions included total failure of both high pressure injection system and low pressure injection system of emergency core cooling system (ECCS). Also, it was presumed non-condensable gas (nitrogen gas) inflow to the primary system from accumulator (ACC) tanks of ECCS. When steam generator (SG) secondary-side collapsed liquid level dropped to a certain low liquid level, the primary pressure turned to rise. After the SG secondary-side became voided, the safety valve of a pressurizer cyclically opened which led to loss of primary coolant. Core uncovery thus took place owing to core boil-off at high pressure. When an increase of 10 K was confirmed in cladding surface temperature of simulated fuel rods, SG secondary-side depressurization was started as the first AM action. At that time, the safety valves in both SGs were fully opened. Primary depressurization was initiated by completely opening the pressurizer safety valve as the second AM action with some delay after the first AM action onset. When the SG secondary-side pressure lowered to 1.0 MPa following the first AM action, water was injected into the secondary-side of both SGs via feedwater lines with low-head pumps as the third AM action. A reduction in the primary pressure was accelerated because the heat removal from the SG secondary-side system resumed shortly after the third AM action initiation.

New market opened up by advanced nuclear reactors (Chapter 3, 4, 5, 7)

Kamide, Hideki; Kawasaki, Nobuchika; Hayafune, Hiroki; Kubo, Shigenobu; Chikazawa, Yoshitaka; Maeda, Seiichiro; Sagayama, Yutaka; Nishihara, Tetsuo; Sumita, Junya; Shibata, Taiju; et al.

Jisedai Genshiro Ga Hiraku Atarashii Shijo; NSA/Commentaries, No.28, p.14 - 36, 2023/10

Developments of next generation nuclear reactors, e.g., Fast Reactor, and High Temperature Gas cooled Reactor, are in progress. They can contribute to markets of electricity and industrial heat utilization in the world including Japan. Here, current status of reactor developments in Japan and also situation in the world are summarized, especially for activities of Generation IV International Forum (GIF), developments of Fast Reactor and High Temperature Gas cooled Reactor in Japan, and SMR movements in the world.

Soil dust and bioaerosols as potential sources for resuspended Cs occurring near the Fukushima Dai-ichi Nuclear Power Plant

Ota, Masakazu; Takahara, Shogo; Yoshimura, Kazuya; Nagakubo, Azusa; Hirouchi, Jun; Hayashi, Naho; Abe, Tomohisa; Funaki, Hironori; Nagai, Haruyasu

Journal of Environmental Radioactivity, 264, p.107198_1 - 107198_15, 2023/08

https://doi.org/10.1016/j.jenvrad.2023.107198

One of the current major radiation exposure pathways from the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident-fallout is inhalation of the re-suspended Cs occurring in air. While wind-induced soil particle resuspension has been recognized as a primary mechanism of Cs resuspension, studies following the FDNPP accident suggested that fungal spores can be a significant source of the atmospheric Cs particularly in the rural areas such as difficult-to-return zone (DRZ). To elucidate the relative importance of the two resuspension phenomena, we propose a model simulating resuspension of Cs as soil particles and fungal spores, and applied it to DRZ. Our model's calculation showed that soil particle resuspension was responsible for the surface-air Cs observed during winter-spring, but could not account for the higher Cs concentrations observed in summer-autumn. The higher concentrations in the summer-autumn were in general reproduced by implementing fungal spore Cs emission, that replenished low soil particle Cs resuspension in that period. According to our model's concept, Cs accumulation in fungal spores and high spore emission rate characterized by the rural environment were likely responsible for the abundance of spore Cs in the air. It was inferred that the influence of the fungal spores on the atmospheric Cs would last longer since un-decontaminated forests still exist in DRZ.

Oxygen potential of neodymium-doped UPuAmO uranium-plutonium-americium mixed oxides at 1573, 1773, and 1873 K

Vauchy, R.; Sunaoshi, Takeo*; Hirooka, Shun; Nakamichi, Shinya; Murakami, Tatsutoshi; Kato, Masato

Journal of Nuclear Materials, 580, p.154416_1 - 154416_11, 2023/07

https://doi.org/10.1016/j.jnucmat.2023.154416

Neutron total and capture cross-section measurements of Gd and Gd in the thermal energy region with the Li-glass detectors and NaI(Tl) spectrometer installed in J-PARCMLFANNRI

Kimura, Atsushi; Nakamura, Shoji; Endo, Shunsuke; Rovira Leveroni, G.; Iwamoto, Osamu; Iwamoto, Nobuyuki; Harada, Hideo; Katabuchi, Tatsuya*; Terada, Kazushi*; Hori, Junichi*; et al.

Journal of Nuclear Science and Technology, 60(6), p.678 - 696, 2023/06

https://doi.org/10.1080/00223131.2022.2134224