PSTEP: Project for solar-terrestrial environment prediction

Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.

Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12

https://doi.org/10.1186/s40623-021-01486-1

The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.

Isomer production ratio of the Cd()Cd reaction in an -process branching point

Hayakawa, Takehito*; Toh, Yosuke; Kimura, Atsushi; Nakamura, Shoji; Shizuma, Toshiyuki*; Iwamoto, Nobuyuki; Chiba, Satoshi*; Kajino, Toshitaka*

Physical Review C, 103(4), p.045801_1 - 045801_5, 2021/04

https://doi.org/10.1103/PhysRevC.103.045801

Summary of instructor training program in FY2014 aiming at Asian countries introducing nuclear technologies for peaceful use (Contract program)

Hidaka, Akihide; Nakano, Yoshihiro; Watanabe, Yoko; Arai, Nobuyoshi; Sawada, Makoto; Kanaizuka, Seiichi*; Katogi, Aki; Shimada, Mayuka*; Ishikawa, Tomomi*; Ebine, Masako*; et al.

JAEA-Review 2016-011, 208 Pages, 2016/07

JAEA-Review-2016-011-01.pdf:33.85MB
JAEA-Review-2016-011-02.pdf:27.68MB

JAEA has been conducting the Instructor Training Program (ITP) since 1996 under the auspices of MEXT to contribute to human resource development in currently 11 Asian countries in the field of radiation utilization for seeking peaceful use of nuclear energy. ITP consists of Instructor Training Course (ITC), Follow-up Training Course (FTC) and Nuclear Technology Seminars. In the ITP, trainings or seminars relating to technology for nuclear utilization are held in Japan by inviting nuclear related people from Asian countries to Japan and after that, the past trainees are supported during FTC by dispatching Japanese specialists to Asian countries. News Letter is also prepared to provide the broad range of information obtained through the trainings for local people near NPPs in Japan. The present report describes the activities of FY2014 ITP and future challenges for improving ITP more effectively.

Performance test of ex-core high temperature and high pressure water loop test equipment (Contract research)

Nakano, Hiroko; Uehara, Toshiaki; Takeuchi, Tomoaki; Shibata, Hiroshi; Nakamura, Jinichi; Matsui, Yoshinori; Tsuchiya, Kunihiko

JAEA-Technology 2015-049, 61 Pages, 2016/03

JAEA-Technology-2015-049.pdf:14.7MB

In Japan Atomic Energy Agency, we started a research and development so as to monitor the Nuclear Plant Facilities situations during a severe accident, such as a radiation-resistant monitoring camera under a severe accident, a radiation resistant in-water transmission system for conveying the information in-core and a heat-resistant signal cable. As part of advance in a heat-resistant signal cable, we maintained to ex-core high-temperature and pressure water loop test equipment which can be simulated conditions of BWRs and PWRs for evaluation reliability and property of construction sheath materials. This equipment consists of Autoclave, water conditioning tank, water pump, high-pressure metering pump, preheater, heat exchanger and pure water purification equipment. This report describes the basic design and the results of performance tests of construction machinery and tools of ex-core high-temperature and pressure water loop test equipment.

On-site training using JMTR and related facilities in FY2014

Eguchi, Shohei; Takemoto, Noriyuki; Tanimoto, Masataka; Kubo, Ayako; Ishitsuka, Etsuo; Nakamura, Jinichi; Ito, Haruhiko

JAEA-Review 2015-005, 38 Pages, 2015/06

JAEA-Review-2015-005.pdf:15.06MB

Since fiscal 2011, a practical training course using the JMTR and other research infrastructures has been provided by Neutron Irradiation Testing Reactor Center for foreign young researchers and engineers in Asian and other countries which are planning to introduce power reactors. The aim of this course is to contribute to the human resource development in nuclear research field and to increase the future use the JMTR. On the other hand, a training course for Japanese young researchers and engineers has been conducted since fiscal 2010. In fiscal 2014, these two separate courses were integrated into one and it was conducted for 3 weeks for young researchers and engineers at home as well as abroad. Nineteen persons from seven countries participated and they studied about the general outline of nuclear research, current status and R&D of nuclear energy, irradiation test facilities and technologies, nuclear characteristics of the reactor and safety and operation management of nuclear reactors. At the end of the course, we had an active discussion about the current status and future of energy mix. The content of this training course in fiscal 2014 are reported in this paper.

Supernova neutrino nucleosynthesis of the radioactive Nb observed in primitive meteorites

Hayakawa, Takehito; Nakamura, Ko*; Kajino, Toshitaka*; Chiba, Satoshi; Iwamoto, Nobuyuki; Cheoun, M. K.*; Mathews, G. J.*

Astrophysical Journal Letters, 779(1), p.L9_1 - L9_5, 2013/12

https://doi.org/10.1088/2041-8205/779/1/L9

Short-lived radioactivities are used as nuclearcosmochronometers for understanding the free decay time from the last nucleosynthesis episode until the time of solar system formation (SSF). Nb (half-life of 34.7 Myr) is one of a short-lived isotope existed at SSF. However, there is a controversy in that the inferred initial abundance ratios for Nb/Nb at the time of SSF cluster around two different values; one is near 10, while the other is near 10. Moreover, the astrophysical mechanism for the synthesis of Nb has remained an unsolved problem. Here we argue that conventional nucleosynthesis mechanisms cannot produce Nb and propose a new mechanism for the nucleosynthesis of this isotopebased upon neutrino induced reactions occurring during core-collapse supernova explosions.

Development of instrumentation systems for safety measure at LWR's severe accident

Takeuchi, Tomoaki; Shibata, Akira; Nagata, Hiroshi; Kimura, Nobuaki; Otsuka, Noriaki; Saito, Takashi; Nakamura, Jinichi; Matsui, Yoshinori; Tsuchiya, Kunihiko

Proceedings of 3rd Asian Symposium on Material Testing Reactors (ASMTR 2013), p.52 - 58, 2013/11

In-pile instrumentation systems in present LWR's are indispensable to monitor all situations during reactor operation and reactor shut down. However, those systems did not work sufficiently under the conditions like as the severe accident at the Fukushima Dai-Ichi Nuclear Power Station. Therefore, based on the irradiation measurement technique of experiences accumulated in JMTR, the developments of reactor instrumentation systems to prevent severe core damage accident in advance have been started. The development objects are four instrumentation systems, which are a solid electrolysis type hydrogen concentration sensor, a water gauge of thermocouple type equipped with the heater, a -ray detector of self-powered type SPGD, and an image analysis system of Cherenkov light for quantification of in-reactor information by CCD cameras. After the developments, the in-pile verification tests of four instrumentation systems are planned at the JMTR.

Assessment of residual stress due to overlay-welded cladding and structural integrity of a reactor pressure vessel

Katsuyama, Jinya; Nishikawa, Hiroyuki*; Udagawa, Makoto; Nakamura, Mitsuyuki*; Onizawa, Kunio

Journal of Pressure Vessel Technology, 135(5), p.051402_1 - 051402_9, 2013/10

https://doi.org/10.1115/1.4024617

The residual stresses generated within the weld-overlay cladding and base material of reactor pressure vessel (RPV) steel was evaluated for as-welded and post-welded heat-treated conditions using thermo-elastic plastic creep analyses considering phase transformation. By comparing the analytical results with the experimentally determined values, we found a good agreement for the residual stress distribution within the cladding and the base material. It was shown that considering phase transformation during welding was important for improving the accuracy of residual stress analysis. Using the calculated residual stress distribution, we performed fracture mechanics analyses for an RPV during pressurized thermal shock events. We evaluated the effect of the weld residual stress on the structural integrity of an RPV. The results indicated that consideration of residual stress produced by weld-overlay cladding and PWHT is important for assessing the structural integrity of RPV.

Development of instruments for improved safety measure for LWRs

Takeuchi, Tomoaki; Shibata, Akira; Nagata, Hiroshi; Miura, Kuniaki*; Sano, Tadafumi*; Kimura, Nobuaki; Otsuka, Noriaki; Saito, Takashi; Nakamura, Jinichi; Tsuchiya, Kunihiko

Proceedings of 5th International Symposium on Material Testing Reactors (ISMTR-5) (Internet), 8 Pages, 2012/10

http://www.murr.missouri.edu/ismtr/papercall/Papers/JAEA/Tsuchiya_ISMTR-5_instruments(Takeuchi).pdf

In-pile instrumentation systems in present LWR's are indispensable to monitor all situations during reactor operation and reactor shut down. However, those systems did not work sufficiently under the conditions of the severe accident at the Fukushima Dai-ichi (F1) Nuclear Power Plant. Based on instrumentation and irradiation experiences accumulated in JMTR, the developments of reactor instrumentation systems to prevent severe core damage accident in advance have been started. The development objects are water level gauge utilizing heating, self-powered -ray detector, hydrogen concentration gauge, and analysis system for imaging and quantification of in-reactor information using Cherenkov light.

Development of reactor water level sensor for extreme conditions

Miura, Kuniaki*; Shibata, Akira; Nakamura, Jinichi; Ogasawara, Toshihiko*; Saito, Takashi; Tsuchiya, Kunihiko

JAEA-Conf 2011-003, p.193 - 195, 2012/03

https://jopss.jaea.go.jp/pdfdata/JAEA-Conf-2011-003.pdf#page=203

In the Fukushima accident, measurement failure of water level was one of the most important factors which caused this serious situation. The differential pressure type water level indicators are widely used in various place of nuclear plant but after the accident of TMI-2, the need of other reliable method has been demanded. And the BICOTH type and the TRICOTH type water level indicator for light water power reactors had been developed for in-pile water level indicator but currently those are not adopted to a nuclear power plant. In this study, the development of new type water level indicator which composed of thermocouple and heater, and the demonstration test and characteristic evaluation of the water level indicator were described.