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JAEA Reports

Verification of the tables for control rods calibration at NSRR

Motome, Yuiko; Agake, Toshiki; Yanagisawa, Hiroshi

JAEA-Technology 2024-015, 30 Pages, 2025/01

JAEA-Technology-2024-015.pdf:1.36MB

The tables for calibration of control rods were verified, which is used positive period method and improved rod drop method of periodic inspection at Nuclear Safety Research Reactor (NSRR). Those tables are "DOUBLING TIME-REACTIVITY" and "DECAY OF NEUTRON FLUX AFTER INSTANTANEOUS REDUCTION OF REACTIVITY". They are prepared around 1975. Since those tables do not clearly express source of values and records of data used in calculations, the authors verified those tables again. For the verification, the tables were reproduced as follows. For the positive period method, the relationship between the period and reactivity was analytically evaluated by using the inhour equation with NSRR's parameters. For the improved rod drop method, the ratios of neutron flux after the rod drop with parameters of negative reactivities was calculated using the EUREKA- 2 code. As a result, the values described in the tables well agree with those by the present evaluation because it is confirmed that standard deviations of the differences in the value by between the present evaluation and the tables are less than 0.035%. For this reason, it is verified that these tables are valid in the practical use for NSRR operations.

Journal Articles

Effect of extrusion ratio in hot-extrusion on kink deformation during compressive deformation in an Mg/LPSO dual-phase magnesium alloy monitored by neutron diffraction

Harjo, S.; Gong, W.; Aizawa, Kazuya; Kawasaki, Takuro; Yamasaki, Michiaki*; Mayama, Tsuyoshi*; Kawamura, Yoshihito*

Materials Transactions, 64(4), p.766 - 773, 2023/02

https://doi.org/10.2320/matertrans.MT-MD2022004

Times Cited Count：9 Percentile：57.18(Materials Science, Multidisciplinary)

Journal Articles

Periodic level measurements of Materials and Life science experimental Facility in J-PARC

Harada, Masahide; Sakai, Motonobu*; Kurosawa, Takashi*; Haga, Katsuhiro

JPS Conference Proceedings (Internet), 33, p.011098_1 - 011098_5, 2021/03

https://doi.org/10.7566/JPSCP.33.011098

Materials and Life science experimental Facility (MLF) in J-PARC has a high-intense spallation neutron source and a high-intense muon source induced by 3-GeV and 1MW proton beam. To reduce beam loss, components of proton, neutron and muon beam lines are precisely aligned. However, a settlement of MLF caused by a building construction, installation of heavy shields, earthquakes, consolidation of basement, instrument installation (weight increase), and so on, was assumed in the design stage. Therefore, periodic level measurements in MLF was started from the design stage. A few tens of level measuring points are installed inside and outside MLF. The level measurements were done once per month in the construction stage and per year after operation start. In the construction stage of MLF, it was found that the MLF building largely settled by construction of the building and installation of many shields. And it was also found that The Great East Japan Earthquake on March 11, 2011, caused large settlements of MLF attached buildings. Figure 1 shows fluctuations of measured levels at representative points in each area from December 2011. No critical deterioration (small changes within 1.0 mm) could be detected. However, a few local settlements are found in the MLF building. In the presentation, periodic level measurement results at MLF will be introduced.

JAEA Reports

Verification of alternative dew point hygrometer for CV-LRT in MONJU; Short- and long-term verification for capacitance-type dew point hygrometer (Translated document)

Ichikawa, Shoichi; Chiba, Yusuke; Ono, Fumiyasu; Hatori, Masakazu; Kobayashi, Takanori; Uekura, Ryoichi; Hashiri, Nobuo*; Inuzuka, Taisuke*; Kitano, Hiroshi*; Abe, Hisashi*

JAEA-Research 2017-001, 40 Pages, 2017/03

JAEA-Research-2017-001.pdf:5.19MB

In order to reduce the influence on a plant schedule of the MONJU by the maintenance of dew point hygrometers, The JAEA examined a capacitance type dew point hygrometer as an alternative dew point hygrometer for a lithium-chloride type dew point hygrometer which had been used at the CV-LRT in the MONJU. As a result of comparing a capacitance type dew point hygrometer with a lithium-chloride type dew point hygrometer at the CV-LRT (Atmosphere: nitrogen, Testing time: 24 hours), there weren't significant difference between a capacitance type dew point hygrometer and a lithium-chloride type dew point hygrometer. As a result of comparing a capacitance dew point hygrometer with a high-mirror-surface type dew point hygrometer for long term verification (Atmosphere: air, Testing time: 24 months), the JAEA confirmed that a capacitance type dew point hygrometer satisfied the instrument specification (2.04 $^{circ}$ C) required by the JEAC4203-2008.

Journal Articles

Development of a method of periodic safety review to cope with the aging degradation of hot laboratories

Tamaoki, Yuichi; Omori, Tsuyoshi; Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki

Proceedings of 53rd Annual Meeting of Hot Laboratories and Remote Handling Working Group (HOTLAB 2016) (Internet), 6 Pages, 2016/11

Post irradiation examinations are conducted in hot laboratories in Oarai Research and Development Center of the Japan Atomic Energy Agency in order to develop fuels and materials for fast reactors. These facilities, the majority of which were constructed in the 1970s, have accumulated operating experience over a period of more than 40 years. Continuous operational safety requires the maintenance of important equipment such as electronic devices, manipulators, in-cell cranes, as well as air conditioning and ventilation systems. A method for the periodic safety review for hot laboratories based on the periodic safety review method employed for preventive maintenance at commercialized power reactors in Japan has been developed. In this paper, the status of implementation of the periodic safety review for hot laboratories using the safety review method are introduced.

JAEA Reports

Preventive measures for the recurrence of control rod insertion failure in Japan Research Reactor No.4 (JRR-4)

JRR-4 Operation Division; Research Reactor Utilization Division

JAERI-Tech 2005-042, 58 Pages, 2005/07

JAERI-Tech-2005-042.pdf:5.4MB

Japan Research Reactor No.4 (JRR-4) was shut down manually, due to the control rod insertion failure occurred during the rated power (3,500kW) operation on June 10, 2005. It became evident by the investigation that a screw bolt at the control rod support got loose and blocked the control rod insertion. The failure was recovered through replacement with the new screw bolt. Considering the importance of this event, we decided to inspect all screw bolts over the core that may cause a control rod insertion failure. Furthermore, we decided to carry out periodical inspection about these screw bolts whether they were tightened enough or not. This report describes the result of inspection carried out as the preventive measures.

Journal Articles

Long periodic magnetic structure in CeBC

Oyama, Kenji*; Kaneko, Koji; Onimaru, Takahiro*; Tobo, Aya*; Ishimoto, Kenichi*; Onodera, Hideya*; Yamaguchi, Yasuo*

Journal of the Physical Society of Japan, 72(12), p.3303 - 3304, 2003/12

https://doi.org/10.1143/JPSJ.72.3303

Times Cited Count：6 Percentile：42.11(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Optical parametric oscillator with periodically poled KTiOPO $_{4}$ pumped by 100Hz Nd:YAG green laser

Oba, Masaki; Kato, Masaaki; Maruyama, Yoichiro

Japanese Journal of Applied Physics, Part 2, 41(8A), p.L881 - L883, 2002/08

https://doi.org/10.1143/JJAP.41.L881

Times Cited Count：0 Percentile：0.00(Physics, Applied)

Optical parametric oscillator using a periodically poled KTP as a gain medium pumped by a pulsed Nd:YAG green laser of which maximum pulse repetition frequency is 100 Hz is demonstrated. Output energy of 5.8 mJ at the pulse repetition frequency of 100 Hz with the conversion efficiency of about 40% is obtained by double-pass pumping scheme. Threshold pumping energy is 1.6 mJ of which peak power is as low as 18 MW/cm $^{2}$ . At the pulse repetition frequency between 10 Hz and 100 Hz, the conversion efficiency is almost constant and undesirable thermal effects are not observed.