Manufacture of substitutive assemblies for MONJU reactor decommissioning

Sakakibara, Hiroshi; Aoki, Nobuhiro; Muto, Masahiro; Otabe, Jun; Takahashi, Kenji*; Fujita, Naoyuki*; Hiyama, Kazuhiko*; Suzuki, Hirokazu*; Kamogawa, Toshiyuki*; Yokosuka, Toru*; et al.

JAEA-Technology 2020-020, 73 Pages, 2021/03

JAEA-Technology-2020-020.pdf:8.26MB

The decommissioning is currently in progress at the prototype fast breeder reactor Monju. Fuel assemblies will be taken out of its core for the first step of the great task. Fuel assemblies stand on their own spike plugged into a socket on the core support plate and support with adjacent assemblies through their housing pads each other, resulting in steady core structure. For this reason, some substitutive assemblies are necessary for the purpose of discharging the fuel assemblies of the core. Monju side commissioned, therefore, Plutonium Fuel Development Center to manufacture the substitutive assemblies and the Center accepted it. This report gives descriptions of design, manufacture, and shipment in regard to the substitutive assemblies.

Degradation prediction using displacement damage dose method for AlInGaP solar cells by changing displacement threshold energy under irradiation with low-energy electrons

Okuno, Yasuki*; Ishikawa, Norito; Akiyoshi, Masafumi*; Ando, Hirokazu*; Harumoto, Masaki*; Imaizumi, Mitsuru*

Japanese Journal of Applied Physics, 59(7), p.074001_1 - 074001_7, 2020/07

https://doi.org/10.35848/1347-4065/ab9713

Performance degradation prediction for space solar cells under irradiation with low-energy electrons is greatly affected by displacement threshold energy (Ed) when a displacement damage dose (DDD) model is used. According to recent studies, the Ed of P atoms is much lower than the conventional Ed value in InP-type solar cells irradiated with low-energy electrons. This indicates that the value of Ed typically used in DDD model leads to significant error in performance degradation prediction. In this study, degradation of AlInGaP solar cells is observed after irradiation with 60 keV electrons. The results suggest that the Ed of P atoms in AlInGaP solar cells is much smaller than the conventionally used Ed value. By using the DDD model with the Ed value obtained in this study, we demonstrated that the performance degradation predicted by the DDD model agrees well with the experimental results.

Development of minute test piece evaluation technique using positron annihilation lifetime spectroscopy

Ando, Hirokazu*; Yamawaki, Masato*; Hirade, Tetsuya; Akiyoshi, Masafumi*

no journal, , 

Positron annihilation lifetime spectroscopy (PALS) is very strong tool to investigate sab-nanometer scale defects in metals and semiconductors. PALS is based on the -ray measurement techniques and it is difficult to measure radioactive samples such as Neutron irradiated samples. Therefore we are creating a method by which you can measure PALS for one very small radioactive sample. It is needed to reject events that positrons annihilate at outside of the sample. We placed the sample at a small space between scintillators and used signals from the scintillators for the anti-coincidence method to reject the events. We succeeded to reject 20% of the events.

New method for high counting rate of positron annihilation age-momentum correlation (AMOC) measurement

Hirade, Tetsuya; Ando, Hirokazu*; Manabe, Kensuke*; Ueda, Daisuke*

no journal, , 

Although positron annihilation ray age-momentum correlation (AMOC) measurements can give information that cannot be obtained by other methods, it takes a long time to measure. The time resolution and the counting rate are in a trade-off relationship. We tried to improve the counting rate by increasing detectors. If the position of the detector deviates by 1 mm, it shifts 3 ps on the time axis. Even if multiple detectors are introduced, it is very difficult to match the time information obtained by each detector. Therefore, we have introduced each characteristic waveform to the signal from every detector. It was possible to identify a detector by use of a characteristic shape of waveforms, i.e. every spectrum for each detectors can be obtained. Afterward, every time shift for each spectrum can be calculated and then finally all of the events can be analyzed by correcting time shifts to construct one spectrum. Hence we succeeded to perform high count rate AMOC measurements.

Degradation by irradiation with low-energy electrons in AlInGaP solar cell

Okuno, Yasuki; Kitamura, Akane; Ishikawa, Norito; Akiyoshi, Masafumi*; Ando, Hirokazu*; Harumoto, Masaki*; Shibata, Yuichi*; Imaizumi, Mitsuru*; Yamaguchi, Masafumi*

no journal, , 

The displacement damage dose (DDD) for space solar cell is greatly affected by the displacement threshold energy (Ed) during degradation by irradiation with low-energy electrons. In the proposed study, the unpredictable degradation of AlInGaP solar cells in the present DDD model is observed. The findings suggest that the predicted degradation during exposure to low-energy electrons may differ from the actual value. However, it is clarified that if the Ed value is rederived, the nonionizing energy loss can indicate the induced-defect rates in the AlInGaP under irradiation with electrons with a wide range of energy.

陽電子消滅寿命測定装置、放射線計測器の調整方法、放射線計測器

平出 哲也; 安藤 太一; 真鍋 賢介; 上田 大介

not registered

JP, 2017-239693  Patent licensing information  Patent publication (In Japanese)

【課題】複数の放射線検出器を並列に用いた場合に、各放射線検出器を同時に用いて高精度の測定を行わせる。 【解決手段】スタート用検出器11Aからのパルス出力P0A、スタート用検出器11Bからのパルス出力P0Bと、ストップ用検出器からのパルス出力P1との間の時間差ΔTを測定し、ΔTのヒストグラムを生成する。パルス出力P1とパルス出力P0Bの時間間隔は、パルス出力P0Aを基準とした場合において、本来の時間間隔であるΔTBに加えて一様にシフト時間Tだけ広がるように設定される。測定されたΔTのヒストグラムである図2の(III)においては、ΔTBに対してTが一様に付加されたために、左側のピークの分布がΔTAのヒストグラムに対応し、右側のピークの分布がΔTBのヒストグラムに対応する。このΔTBのヒストグラムを横軸方向にシフトさせれば、ΔTAのヒストグラムと重複させることができる。