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JAEA Reports

Design and production of the valve used in Radioactive Liquid Disposal Facility

Nishimura, Arashi; Okada, Yuji; Sugaya, Naoto; Sonobe, Hiroshi; Kimura, Nobuaki; Kimura, Akihiro; Hanawa, Yoshio; Nemoto, Hiroyoshi

JAEA-Technology 2021-003, 51 Pages, 2021/05

JAEA-Technology-2021-003.pdf:5.55MB

In the Japan Materials Testing Reactor (JMTR), the leakage accidents of radioactive waste liquid were occurred from the tanks and pipes of the liquid waste disposal facility in the JMTR tank-yard building in JFY2014. In order to respond to the accident, obtain the approval of the JAEA to the design and construction method from JFY2016, the tanks and pipes were replaced from JFY2016 to 2019. In the replaced, the production of the tanks and pipes of the liquid waste disposal facility applied Japanese technical standards correspondingly. On the other hand, the valve did not fall under the category of Japanese technical standards. The manufacturing specifications when replacing the valve were decided based on the including the selecting the standards of production and inspection for valves, Fluid properties, experience in JMTR. The production proceeded while carrying out the decided inspection. The valves that passed all the inspections were installed together with the tanks and pipes of the liquid waste, and the finished inspection was performed as a systems. The construction was completed with those inspection passed. This report is summarized valve Design, production and installation.

Journal Articles

Feasibility study on tritium recoil barrier for neutron reflectors of research and test reactors

Kenzhina, I.*; Ishitsuka, Etsuo; Ho, H. Q.; Sakamoto, Naoki*; Okumura, Keisuke; Takemoto, Noriyuki; Chikhray, Y.*

Fusion Engineering and Design, 164, p.112181_1 - 112181_5, 2021/03

Tritium release into the primary coolant during operation of the JMTR (Japan Materials Testing Reactor) and the JRR-3M (Japan Research Reactor-3M) had been studied. It is found that the recoil release by $$^{6}$$Li(n$$_{t}$$,$$alpha$$)$$^{3}$$H reaction, which comes from a chain reaction of beryllium neutron reflectors, is dominant. To prevent tritium recoil release, the surface area of beryllium neutron reflectors needs to be minimum in the core design and/or be shielded with other material. In this paper, as the feasibility study of the tritium recoil barrier for the beryllium neutron reflectors, various materials such as Al, Ti, V, Ni, and Zr were evaluated from the viewpoint of the thickness of barriers, activities after long-term operations, and effects on the reactivities. From the results of evaluations, Al would be a suitable candidate as the tritium recoil barrier for the beryllium neutron reflectors.

JAEA Reports

Feasibility study on dismantling and removal of hydraulic rabbit No.1 irradiation facility

Magome, Hirokatsu; Iimura, Koichi; Matsui, Yoshinori

JAEA-Testing 2020-008, 52 Pages, 2021/02

JAEA-Testing-2020-008.pdf:5.46MB

As to the removal of the hydraulic rabbit No.1 irradiation facility related to the decommissioning of JMTR, points to be noted for considering a removal plan and maintenance methods after the removal were studied based on the past experiences of removing the hydraulic rabbit No.2 irradiation facility. As results, it became clear that it was necessary to (1) add a shutoff valve and a closing flange to piping for preventing cooling water leakage, (2) prepare a drawing jig for inner tube, and (3) shorten the remaining piping to withstand earthquakes. In addition, regarding the management of equipment to be maintained after removal, the necessary management items for the removal methods of the three patterns of ground equipments were listed.

Journal Articles

Decommissioning of JMTR and study for construction of a new material testing reactor

Kaminaga, Masanori; Kusunoki, Tsuyoshi; Tsuchiya, Kunihiko; Hori, Naohiko; Naka, Michihiro

IAEA-TECDOC-1943, p.45 - 56, 2021/02

The JMTR operation was once stopped in order to have a check & review in August 2006, and the refurbishment and restart of JMTR was finally determined by the national discussion. The refurbishment was started from FY2007, and was finished in March 2011. However, at the end of the FY2010, the Great-Eastern-Japan-Earthquake occurred, and functional tests before the JMTR restart were delayed. On the other hand, based on the safety assessments considering the 2011 earthquake new regulatory requirements have established on Decmber18, 2013 by the NRA. The new regulatory requirements include the satisfaction of integrities for the updated earthquake forces, Tsunami, the consideration of natural phenomena, and the management of consideration in the Beyond Design Basis Accidents (BDBA) to protect fuel damage and to mitigate impact of the accidents. Analyses related to the new regulatory requirements have intensively been performed timely, and an application to the NRA had been submitted in March 27, 2015. After submission of application, seismic resistance assessment of JMTR reactor building was carried out by assuming the standard earthquake ground motion of 810 ga. As the results, it was found that seismic reinforcement work for reactor building and reactor pool wall were required. As a result, it became clear that at least 7 years of reinforcement work period and cost of about 40 billion yen are required for seismic reinforcement and to meet new regulatory standards. At the same time, it was made clear that high availability such as 8 operation cycles per year as originally planned cannot be expected due to aiging problem. For this reason, JAEA positioned JMTR as a decommissioning facility in the mid- and long-term plan of JAEA announced in April 2017. On the other hand, JAEA started to study the construction of a new material testing reactor. The examination results will be compiled by the end of FY2019. In this paper, outline of JMTR decommissioning plan is described.

Journal Articles

Evaluation of tritium release into primary coolant for research and testing reactors

Kenzhina, I.*; Ishitsuka, Etsuo; Okumura, Keisuke; Ho, H. Q.; Takemoto, Noriyuki; Chikhray, Y.*

Journal of Nuclear Science and Technology, 58(1), p.1 - 8, 2021/01

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The sources and mechanisms for the tritium release into the primary coolant in the JMTR and the JRR-3M containing beryllium reflectors are evaluated. It is found that the recoil release from chain reaction of $$^{9}$$Be is dominant and its calculation results agree well with trends derived from the measured variation of tritium concentration in the primary coolant. It also indicates that the simple calculation method used in this study for the tritium recoil release from the beryllium reflectors can be utilized for an estimation of the tritium release into the primary coolant for a research and testing reactors containing beryllium reflectors.

Journal Articles

Voltage drop analysis and leakage suppression design for mineral-insulated cables

Hirota, Noriaki; Shibata, Hiroshi; Takeuchi, Tomoaki; Otsuka, Noriaki; Tsuchiya, Kunihiko

Journal of Nuclear Science and Technology, 57(12), p.1276 - 1286, 2020/12

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The influence of materials of mineral-insulated (MI) cables on their electrical characteristics upon exposure to high-temperature conditions was examined via a transmission test, in the objective of achieving the stability of the potential distribution along the cable length. Occurrence of a voltage drop along the cable was confirmed for aluminum oxide (Al$$_{2}$$O$$_{3}$$) and magnesium oxide (MgO), as insulating materials of the MI cable. A finite-element method (FEM)-based analysis was performed to evaluate the leakage in the potentials, which was found at the terminal end. Voltage drop yields by the transmission test and the analysis were in good agreement for the MI cable of Al$$_{2}$$O$$_{3}$$ and MgO materials, which suggests the reproducibility of the magnitude relationship of the experimental results via the FEM analysis. To suppress the voltage drop, the same FEM analysis was conducted, the diameter of the core wires ($$d$$) and the distance between them ($$l$$) were varied. Considering the variation of $$d$$, the potential distribution in the MI cable produced a minimum voltage drop corresponding to a ratio $$d/D$$ of 0.35, obtained by dividing $$d$$ with that of the insulating material ($$D$$). In case of varying $$l$$, a minimum voltage drop was l/$$D$$ of 0.5.

JAEA Reports

Soundness survey of cooling tower of Utility Cooling Loop (UCL Cooling Tower) in JMTR

Oto, Tsutomu; Asano, Norikazu; Kawamata, Takanori; Yanai, Tomohiro; Nishimura, Arashi; Araki, Daisuke; Otsuka, Kaoru; Takabe, Yugo; Otsuka, Noriaki; Kojima, Keidai; et al.

JAEA-Review 2020-018, 66 Pages, 2020/11

JAEA-Review-2020-018.pdf:8.87MB

A collapse event of the cooling tower of secondary cooling system in the JMTR (Japan Materials Testing Reactor) was caused by the strong wind of Typhoon No.15 on September 9, 2019. The cause of the collapse of the cooling tower was investigated and analyzed. As the result, it was identified that four causes occurred in combination. Thus, the soundness of the cooling tower of Utility Cooling Loop (UCL cooling tower), which is a wooden cooling tower installed at the same period as the cooling tower of secondary cooling system, was investigated. The items of soundness survey are to grasp the operation conditions of the UCL cooling tower, to confirm the degradation of structural materials, the inspection items and inspection status of the UCL cooling tower, and to investigate the past meteorological data. As the results of soundness survey of the UCL cooling tower, the improvement of inspection items of the UCL cooling tower was carried out and the replacement and repair of the structural materials of the UCL cooling tower were planned for safe maintenance and management of this facility. And the renewal plan of new cooling tower was created to replace the existing UCL cooling tower. This report is summarized the soundness survey of the UCL cooling tower.

JAEA Reports

Validation of repairing method for concrete wall of the JMTR tank-yard building

Sugaya, Naoto; Okada, Yuji; Nishimura, Arashi; Sonobe, Hiroshi; Kimura, Nobuaki; Kimura, Akihiro; Hanawa, Yoshio; Nemoto, Hiroyoshi

JAEA-Testing 2020-004, 67 Pages, 2020/08

JAEA-Testing-2020-004.pdf:8.17MB

In the Japan Materials Testing Reactor (JMTR), the leakage accidents of radioactive waste liquid were occurred from the tanks and pipes of the liquid waste disposal facility in the JMTR tank-yard building in JFY2014. In order to respond to the accident, the tanks and pipes were replaced from JFY2016 to 2019. On the other hand, a lot of cracks were occurred on the concreate wall of the tank-yard building when the frame structure supports were fixed to the concrete wall in the replacement work. Thus, it is necessary to repair the concreate wall of the tank-yard building. Especially, some cracks with swelling (cone-shaped fracture) were raised around some anchor bolts (the post-installed chemical anchor bolts) fixed the frame structure supports. The repairing method for the cone-shaped fracture of the concrete wall is standardized, but there was no reference value of tensile strength for the validation of the post-installed chemical anchor bolts after the repairing method. In this report, the repairing method was selected for the cone-shaped fracture on the concreate wall and the reference value of tensile strength for the validation of the post-installed chemical anchor bolts by this repairing method. The mock-ups for repairing cone-shaped fracture were fabricated by the selected repairing method and the tensile tests of the post-installed chemical anchor bolts were performed. From the results, the validation of the repairing method was obtained in this test and it was obvious the repairing of cone-shaped fracture is preferable method for the concreate wall of the JMTR tank-yard building.

Journal Articles

Feasibility study of tritium recoil barrier for neutron reflectors

Ishitsuka, Etsuo; Sakamoto, Naoki*

Physical Sciences and Technology, 6(2), p.60 - 63, 2019/12

Tritium release into the primary coolant of the research and test reactors during operation had been studied, and it is found that the recoil release from chain reaction of $$^{9}$$Be is dominant. To reduce tritium concentration of the primary coolant, feasibility study of the tritium recoil barrier for the beryllium neutron reflectors was carried out, and the tritium recoils of various materials were calculated by PHITS. From these calculation results, it is clear that the thickness of tritium recoil barrier depends on the material and 20$$sim$$40 $$mu$$m is required for three orders reduction.

JAEA Reports

On-site training using JMTR and related facilities in FY2018

Eguchi, Shohei; Nakano, Hiroko; Otsuka, Noriaki; Nishikata, Kaori; Nagata, Hiroshi; Ide, Hiroshi; Kusunoki, Tsuyoshi

JAEA-Review 2019-012, 22 Pages, 2019/10

JAEA-Review-2019-012.pdf:3.37MB

A practical training course using the JMTR and other research infrastructures was held from July 31st to August 7th in 2018 for Asian young researchers and engineers. This course was adopted as Japan-Asia Youth Exchange Program in Science (SAKURA Exchange Program in Science) which is the project of the Japan Science and Technology Agency, and this course aims to enlarge the number of high-level nuclear researchers/engineers in Asian countries which are planning to introduce a nuclear power plant, and to promote the use of facilities in future. In this year, 11 young researchers and engineers joined the course from 6 countries. This course consists of lectures, which are related to irradiation test research, safety management of nuclear reactors, nuclear characteristics of the nuclear reactors, etc., practical training such as practice of research reactor operation using simulator and technical tour of nuclear facilities on nuclear energy. The content of this course in FY 2018 is reported in this paper.

Journal Articles

Susceptibility to neutron irradiation embrittlement of heat-affected zone of reactor pressure vessel steels

Takamizawa, Hisashi; Katsuyama, Jinya; Ha, Yoosung; Tobita, Toru; Nishiyama, Yutaka; Onizawa, Kunio

Proceedings of 2019 ASME Pressure Vessels and Piping Conference (PVP 2019) (Internet), 8 Pages, 2019/07

no abstracts in English

Journal Articles

Status of JMTR decommissioning plan formulation, 2

Otsuka, Kaoru; Ide, Hiroshi; Nagata, Hiroshi; Omori, Takazumi; Seki, Misaki; Hanakawa, Hiroki; Nemoto, Hiroyoshi; Watanabe, Masao; Iimura, Koichi; Tsuchiya, Kunihiko; et al.

UTNL-R-0499, p.12_1 - 12_8, 2019/03

no abstracts in English

Journal Articles

Preliminary analysis for demolition of secondary cooling system and pool canal cycling system secondary piping

Hanakawa, Hiroki; Kawamata, Takanori; Ogasawara, Yasushi; Otsuka, Kaoru; Omori, Takazumi; Ide, Hiroshi; Tsuchiya, Kunihiko

UTNL-R-0499, p.11_1 - 11_7, 2019/03

no abstracts in English

JAEA Reports

Setting of EAL in JMTR

Kawamata, Takanori; Onuma, Yuichi; Hanakawa, Hiroki

JAEA-Review 2018-031, 33 Pages, 2019/02

JAEA-Review-2018-031.pdf:1.62MB

As "Regulations on events to be reported by nuclear disaster prevention manager based on act on special measures concerning nuclear emergency preparedness" was revised and enfored in 2017, Nuclear operator emergency action plan at Oarai Research and Development Institute was reconsidered, and Emergency Action Level (EAL) in JMTR was newly set. In setting the EAL, characteristics of the JMTR and EAL in nuclear power reactors were considerd because the characteristics of research reactors are different in reactor types. This report shows the basic policy and the selection result of the EAL setting in the JMTR.

Journal Articles

Calculation of tritium release from driver fuels into primary coolant of research reactors

Ho, H. Q.; Ishitsuka, Etsuo

Physical Sciences and Technology, 5(2), p.53 - 56, 2019/00

Increasing of tritium concentration in the primary coolant of the research and test reactors during operation had been reported. To check the source for tritium release into the primary coolant during operation of the JMTR and the JRR-3M, the tritium release from the driver fuels was calculated by MCNP6 and PHITS. It is clear that the calculated values of tritium release from fuels are as about 10$$^{7}$$ and 10$$^{6}$$ Bq for the JMTR and JRR-3M, respectively, and that calculated values are about 4 order of magnitude smaller than that of the measured values. These results show that the tritium release from fuels is negligible for both the reactors.

JAEA Reports

Calculations of Tritium Recoil Release from Li and U Impurities in Neutron Reflectors (Joint research)

Ishitsuka, Etsuo; Kenzhina, I.*; Okumura, Keisuke; Ho, H. Q.; Takemoto, Noriyuki; Chikhray, Y.*

JAEA-Technology 2018-010, 33 Pages, 2018/11

JAEA-Technology-2018-010.pdf:2.58MB

As a part of study on the mechanism of tritium release to the primary coolant in research and testing reactors, tritium recoil release rate from Li and U impurities in the neutron reflector made by beryllium, aluminum and graphite were calculated by PHITS code. On the other hand, the tritium production from Li and U impurities in beryllium neutron reflectors for JMTR and JRR-3M were calculated by MCNP6 and ORIGEN2 code. By using both results, the amount of recoiled tritium from beryllium neutron reflectors were estimated. It is clear that the amount of recoiled tritium from Li and U impurities in beryllium neutron reflectors are negligible, and 2 and 5 orders smaller than that from beryllium itself, respectively.

JAEA Reports

Mechanical properties database of reactor pressure vessel steels related to fracture toughness evaluation

Tobita, Toru; Nishiyama, Yutaka; Onizawa, Kunio

JAEA-Data/Code 2018-013, 60 Pages, 2018/11

JAEA-Data-Code-2018-013.pdf:1.67MB

Mechanical properties of materials including fracture toughness are extremely important for evaluating the structural integrity of reactor pressure vessels (RPVs). In this report, the published data of mechanical properties of nuclear RPVs steels, including neutron irradiated materials, acquired by the Japan Atomic Energy Agency (JAEA), specifically tensile test data, Charpy impact test data, drop-weight test data, and fracture toughness test data, are summarized. There are five types of RPVs steels with different toughness levels equivalent to JIS SQV2A (ASTM A533B Class 1) containing impurities in the range corresponding to the early plant to the latest plant. In addition to the base material of RPVs, the mechanical property data of the two types of stainless overlay cladding materials used as the lining of the RPV are summarized as well. These mechanical property data are organized graphically for each material and listed in tabular form to facilitate easy utilization of data.

Journal Articles

Evaluation of tritium release curve in primary coolant of research reactors

Ishitsuka, Etsuo; Kenzhina, I. E.*

Physical Sciences and Technology, 4(1), p.27 - 33, 2018/06

Increase of tritium concentration in the primary coolant for the research and testing reactors during reactor operation had been reported. To clarify the tritium sources, a curve of the tritium release rate into the primary coolant for the JMTR and the JRR-3M are evaluated. It is also observed that the amount of released tritium is lower in the case of new beryllium components installation, and increases with the reactor operating cycle. These results show the beryllium components in core strongly affect to the tritium release into the primary coolant. As a result, the tritium release rate is related with produced $$^{6}$$Li by (n,$$alpha$$) reaction from $$^{9}$$Be, and evaluation results of tritium release curve are shown as the dominant source of tritium release into the primary coolant for the JMTR and the JRR-3M are beryllium components. Scattering of the tritium release rate with irradiation time were observed, and this phenomena in the JMTR occurred in earlier time than that of the JRR-3M.

Journal Articles

Status of JMTR decommissioning plan formulation

Otsuka, kaoru; Hanakawa, Hiroki; Nagata, Hiroshi; Omori, Takazumi; Takeuchi, Tomoaki; Tsuchiya, Kunihiko

UTNL-R-0496, p.13_1 - 13_11, 2018/03

no abstracts in English

JAEA Reports

On-site training using JMTR and related facilities in FY2017

Eguchi, Shohei; Shibata, Hiroshi; Imaizumi, Tomomi; Nagata, Hiroshi; Tanimoto, Masataka; Kusunoki, Tsuyoshi

JAEA-Review 2017-032, 26 Pages, 2018/02

JAEA-Review-2017-032.pdf:2.44MB

A practical training course using the JMTR and other research infrastructures was held from July 24th to August 4th in 2017 for Asian young researchers and engineers. This course was adopted as Japan-Asia Youth Exchange Program in Science (SAKURA Exchange Program in Science) which is the project of the Japan Science and Technology Agency, and this course aims to enlarge the number of high-level nuclear researchers/engineers in Asian countries which are planning to introduce a nuclear power plant, and to promote the use of facilities in future. In this year, 10 young researchers and engineers joined the course from 6 countries. This course consists of lectures, which are related to irradiation test research, safety management of nuclear reactors, nuclear characteristics of the nuclear reactors, etc., practical training such as practice of research reactor operation using simulator and technical tour of nuclear facilities on nuclear energy. The content of this course in FY 2017 is reported in this paper.

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