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Journal Articles

Current post irradiation examination techniques at the JMTR Hot laboratory

Shibata, Akira; Kato, Yoshiaki; Oishi, Makoto; Taguchi, Taketoshi; Ito, Masayasu; Yonekawa, Minoru; Kawamata, Kazuo

KAERI/GP-418/2015, p.151 - 165, 2015/05

The JMTR stopped its operation in 2006 for refurbishment. The reactor facilities have been refurbished from 2007. After refurbishment, JMTR Hot laboratory is expected to perform various post irradiation examinations. In this report, installations of experimental apparatuses and recent experimental method are introduced. (1) A nano-indenter with radius spherical indenter. Inverse analysis using FEM could presume material constants from load-depth curve of indentation. Mechanical properties of oxide layer of zirconium alloy and irradiated stainless steel will be analyzed. (2) Transmission Electron Microscope (TEM). TEM is capable of imaging at a significantly higher resolution than light microscopes or normal SEM. JAEA installed a TEM apparatus (JEOL JEM-2800) in JMTR Hot laboratory. The maximum magnification is 150,000,000 times. It can be operated from a remote location using a computer network. This contributes to the convenience of remote researchers and reducing the amount of exposure.

Journal Articles

Development of radiation detectors for in-pile measurement

Takeuchi, Tomoaki; Otsuka, Noriaki; Shibata, Hiroshi; Nagata, Hiroshi; Endo, Yasuichi; Matsui, Yoshinori; Tsuchiya, Kunihiko

KAERI/GP-418/2015, p.110 - 112, 2015/00

$$gamma$$ irradiation experiments with a $$^{60}$$Co source were carried out for developing Self-Powered Gamma Detectors (SPGDs) with lead (Pb) emitter and Self-Powered Neutron Detectors (SPNDs) with Pt-40%Rh emitter prior to in-core irradiation experiments. The results showed the output currents of the SPGDs were proportional to the $$gamma$$ dose rate in the range from about 200-6000 Gy/h with about 10% accuracy. In the case of SPNDs, the output currents flowed in inverse direction and were an order of magnitude lower compared with that of the SPGDs. These different behaviors of the output currents are considered to be caused by the difference in the emitter sizes and the current component originated at the MI cables.

Oral presentation

Improvement of JMTR core management system

Imaizumi, Tomomi; Ide, Hiroshi; Yamaura, Takayuki

no journal, , 

In the JMTR, neutronic calculations for core properties such as the shutdown margin, the maximum reactivity, the neutron flux and so on are implemented before each operation cycle. These calculations had been carried out using the SRAC on the JAEA's mainframe. However, the mainframe was abolished in 2012. Additionally, the SRAC used in the JMTR is not available on the computer with the UNIX operating system unlike the SRAC95 and the latest version of SRAC2006. PIJ, CITATION and COREBN are mainly used in neutronic calculations of JMTR. Therefore, these codes were improved to be available on PC-Linux. Furthermore, the new JMTR core management system was also improved by adding a graphical user interface (GUI). By using the new system, the cell and core calculation model can be confirmed visually. In addition, the GUI operation was able to simplify the input operation and the processing of the output result in comparison with the command operations of the past.

Oral presentation

Safety assessments of JMTR facilities for the new regulation

Hanakawa, Hiroki; Watahiki, Shunsuke; Ide, Hiroshi; Kitagishi, Shigeru; Imaizumi, Tomomi; Araki, Daisuke; Tobita, Masahiro; Yamaura, Takayuki; Kaminaga, Masanori

no journal, , 

On 18th December 2013, the new regulatory requirements for Japanese research reactor were enforced by the Nuclear Regulation Authority in Japan. This new regulatory requirements are also applied to any research reactor in Japan, even if licensed research reactor. Thus the verification of conformity in the JMTR facilities to the new regulatory requirements was carried out. In this reports, the safety assessment against the beyond design basis accident will be described. At first, events tree analyses were carried out to select beyond design basis accidents. From these analyses, it was confirmed that 8 events can be representative cases. These events were analyzed from the viewpoints of public dose exposer. As the result of analysis, it was confirmed that 3 events out of 8 has a possibility to give the considerable public dose exposer so that the counter measerments were taken account to reduce the dose exposer to acceptable limit.

Oral presentation

Current status of JRR-3

Kurumada, Osamu

no journal, , 

JRR-3 at Tokai site of JAEA was in its regular maintenance period, when the Great East Japan Earthquake took place on 11th March 2011. The reactor building with the solid foundations and the equipment important to safety survived the earthquake without serious damage, and no radioactive leakage has been occurred. Recovery work, check and test of the integrity for all components have been carried out. In response to the accident at Fukushima Daiichi NPS, the Reactor Regulation Act was revised in June 2012, for the purpose of introducing new regulations based on the latest technical analysis. The revision introduces the "backfit system" under which the existing nuclear facilities are also required to conform to new regulatory requirements. Now, we confirmed that JRR-3 conforms to new regulations on research and test reactor facilities which came into force on 18th December 2013. Therefore, we have applied for permission for changes in reactor installment license on 26th September 2014. We will present the current state of JRR-3 and future plan.

Oral presentation

Establishment of irradiation facility for LWR water environment simulation tests

Kitagishi, Shigeru; Endo, Yasuichi; Okada, Yuji; Hanawa, Hiroshi; Matsui, Yoshinori; Tsuchiya, Kunihiko; Yamaura, Takayuki

no journal, , 

no abstracts in English

Oral presentation

Current status toward the reoperation of JMTR

Kaminaga, Masanori; Kusunoki, Tsuyoshi; Araki, Masanori

no journal, , 

The Japan Materials Testing Reactor (JMTR) is a light water cooled and moderated tank type research reactor with 50MW thermal power. From its first criticality in March 1968, the JMTR has been utilized for the fuel/material irradiation examinations of the LWRs, the HTGR and nuclear fusion research as well as for the RI productions. The JMTR operation was once stopped in order to have a check & review in August 2006, and the refurbishment and restart of the JMTR was finally determined after the national discussion. The refurbishment was started from JFY 2007, and was finished in March 2011. However, at the end of the JFY 2010, the Great East Japan Earthquake occurred, and the functional tests before the JMTR restart were delayed. On the other hand, based on the safety assessments considering the Great East Japan Earthquake in 2011, new regulatory requirements for research and test reactors have been established on Dec.18, 2013 by the NRA (Nuclear Regulation Authority). The new regulatory requirements include the satisfaction of integrities for the updated earthquake forces, Tsunami, the consideration of natural phenomena, the provision of manuals for full evacuation, and the management of consideration in the Beyond Design Basis Accidents to protect fuel damage and to mitigate impact of the accidents. Above analyses have intensively been performed, and an application to the NRA was submitted on March 27, 2015. In this presentation, the recent activities for the new regulatory requirements and a training course for foreign young researchers and engineers are introduced.

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