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JAEA Reports

Investigation on soundness of JMTR Facility piping by ultrasonic thickness measurement

Omori, Takazumi; Otsuka, Kaoru; Endo, Yasuichi; Takeuchi, Tomoaki; Ide, Hiroshi

JAEA-Review 2021-015, 57 Pages, 2021/11


The JMTR reactor facility was selected as a decommissioning one in the Medium/Long-Term Management Plan of JAEA Facilities formulated on April 1, 2017. Therefore, the decommissioning plan was submitted to Nuclear Regulation Authority on September 18, 2019, and the approval was obtained on March 17, 2021 after two amendments. Currently, preparations for decommissioning are underway. The JMTR reactor facility has been aged for more than 50 years since the first criticality in March 1968. However, some of the water piping systems has not been updated since its construction, and there is a possibility of pipe wall thinning due to corrosion, etc. Therefore, the integrity of the water piping was investigated for the facilities that circulate cooling water and pump radioactive liquid waste. In this investigation, the main circulation system of the reactor primary cooling system, the pool canal circulation system, the CF pool circulation system, the drainage system of the liquid waste disposal system, and the hydraulic rabbit irradiation system of the main experimental facility were measured for the pipe wall thickness using the Ultrasonic Thickness Measurement (UTM) method. These values satisfied the technical standards for research and test reactor facilities. No loss of integrity is expected to occur during the upcoming decommissioning period. In the future, we will periodically confirm that there is no wall thinning in the piping of the cooling water circulation and the water transmission system during the decommissioning period by using this result as basic data.

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.

Journal Articles

Development of the treatment method for difficult wastes aimed at decommissioning of JMTR; Structural materials of reactor and used ion-exchange resins

Seki, Misaki; Nakano, Hiroko; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Takeuchi, Tomoaki; Ide, Hiroshi; Tsuchiya, Kunihiko

Dekomisshoningu Giho, (62), p.9 - 19, 2020/09

Japan Materials Testing Reactor (JMTR) has been contributing to various research and development activities such as the fundamental research of nuclear materials/fuels, safety research and development of power reactors, and radioisotope production since the beginning of the operation in 1968. JMTR, however, was decided as a one of decommission facilities in April 2017 and it is taken an inspection of a plan concerning decommissioning because the performance of JMTR does not confirm with the stipulated earthquake resistance. As aluminum and beryllium are used for the core structural materials in JMTR, it is necessary to establish treatment methods of these materials for the fabrication of stable wastes. In addition, a treatment method for the accumulated spent ion-exchange resins needs to be examined. This report describes the overview of these examination situations.

Journal Articles

Spallation and fragmentation cross sections for 168 MeV/nucleon $$^{136}$$Xe ions on proton, deuteron, and carbon targets

Sun, X. H.*; Wang, H.*; Otsu, Hideaki*; Sakurai, Hiroyoshi*; Ahn, D. S.*; Aikawa, Masayuki*; Fukuda, Naoki*; Isobe, Tadaaki*; Kawakami, Shunsuke*; Koyama, Shumpei*; et al.

Physical Review C, 101(6), p.064623_1 - 064623_12, 2020/06

 Times Cited Count:2 Percentile:35.83(Physics, Nuclear)

The spallation and fragmentation reactions of $$^{136}$$Xe induced by proton, deuteron and carbon at 168 MeV/nucleon were studied at RIKEN Radioactive Isotope Beam Factory via the inverse kinematics technique. The cross sections of the lighter products are larger in the carbon-induced reactions due to the higher total kinetic energy of carbon. The energy dependence was investigated by comparing the newly obtained data with previous results obtained at higher reaction energies. The experimental data were compared with the results of SPACS, EPAX, PHITS and DEURACS calculations. These data serve as benchmarks for the model calculations.

Journal Articles

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.

Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07

 Times Cited Count:5 Percentile:62.37(Physics, Multidisciplinary)

Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for $$^{107}$$Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.

Journal Articles

Development of evaluation method for variability of groundwater flow conditions associated with long-term topographic change and climate perturbations

Onoe, Hironori; Kosaka, Hiroshi*; Matsuoka, Toshiyuki; Komatsu, Tetsuya; Takeuchi, Ryuji; Iwatsuki, Teruki; Yasue, Kenichi

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.3 - 14, 2019/06

In this study, it is focused on topographic changes due to uplift and denudation, also climate perturbations, a method which is able to assess the long-term variability of groundwater flow conditions using the coefficient variation based on some steady-state groundwater flow simulation results was developed. Spatial distribution of long residence time area which is not much influenced due to long-term topographic change and recharge rate change during the past one million years was able to estimate through the case study of the Tono area, Central Japan. By applying this evaluation method, it is possible to identify the local area that has low variability of groundwater flow conditions due to topographic changes and climate perturbations from the regional area quantitatively and spatially.

Journal Articles

High-temperature oxidation of sheath materials using mineral-insulated cables for a simulated severe accident

Nakano, Hiroko; Hirota, Noriaki; Shibata, Hiroshi; Takeuchi, Tomoaki; Tsuchiya, Kunihiko

Mechanical Engineering Journal (Internet), 5(2), p.17-00594_1 - 17-00594_12, 2018/04

no abstracts in English

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

Degradation behavior of optical components by gamma irradiation (Contract research)

Takeuchi, Tomoaki; Shibata, Hiroshi; Hanakawa, Hiroki; Uehara, Toshiaki*; Ueno, Shunji*; Tsuchiya, Kunihiko; Kumahara, Hajime*; Shibagaki, Taro*; Komanome, Hirohisa*

JAEA-Technology 2017-026, 26 Pages, 2018/02


Under severe accidents, high-integrity transmission techniques are necessary so as to monitor the situation of the nuclear power plant. In this study, effects of gamma irradiation up to 10$$^{6}$$Gy on properties of optical devices were evaluated toward the development of a radiation-resistant in-water wireless transmission system using visible light. After the irradiation, for the LEDs, the total luminous flux decreased and the browning of resin lenses occurred. Meanwhile, the current-voltage characteristics hardly changed. For the PDs, the light sensitivity decreased and the browning of resin window occurred. The dark currents of PDs did not become large enough to adversely affect transmission. These results indicated that both the decreases of the total luminous flux of the LEDs and the light sensitivity of the PDs were mainly caused by not the degradation of the semiconductor parts but the browning of the resin parts by the irradiation. In addition, basic decrease behaviors of light transmission of several different types of glasses by gamma irradiation were also obtained so as to select the suitable optical windows and filters for the developing radiation-resistant in-water wireless transmission system.

JAEA Reports

Establishment of experimental equipments in irradiation technology development building, 2

Shibata, Hiroshi; Nakano, Hiroko; Suzuki, Yoshitaka; Otsuka, Noriaki; Nishikata, Kaori; Takeuchi, Tomoaki; Hirota, Noriaki; Tsuchiya, Kunihiko

JAEA-Testing 2017-002, 138 Pages, 2017/12


From the viewpoints of utilization improvement of the Japan Materials Testing Reactor (JMTR), the experimental devices have been established for the out-pile tests in the irradiation technology development building. The devices for the irradiation capsule assembly, material tests and inspections were established at first and experimental data were accumulated before the neutron irradiation tests. On the other hand, after the Great East Japan Earthquake, the repairs and earthquake-resistant measures of the existing devices were carried out. New devices and equipments were also established for the R&D program for power plant safety enhancement of the Agency for Natural Resources and Energy, Ministry of Economy, Trade and Industry (METI) and $$^{99}$$Mo/$$^{99m}$$Tc production development under the Tsukuba International Strategic Zone. This report describes the outline and basic operation manuals of the devices established from 2011 to 2016 and the management points for the safety works in the irradiation technology development building.

Journal Articles

Effect of surface treatment on adsorption and desorption behavior of impregnated adsorbent for extraction chromatography

Nagoshi, Kohei*; Arai, Tsuyoshi*; Watanabe, So; Sano, Yuichi; Takeuchi, Masayuki; Sato, Mutsumi*; Oikawa, Hiroshi*

Nihon Ion Kokan Gakkai-Shi, 28(1), p.11 - 18, 2017/01

no abstracts in English

Journal Articles

Development of radiation-resistant in-water wireless transmission system using light emitting diodes and photo diodes

Takeuchi, Tomoaki; Shibata, Hiroshi; Otsuka, Noriaki; Uehara, Toshiaki; Tsuchiya, Kunihiko; Shibagaki, Taro*; Komanome, Hirohisa*

IEEE Transactions on Nuclear Science, 63(5), p.2698 - 2702, 2016/10

 Times Cited Count:2 Percentile:25.63(Engineering, Electrical & Electronic)

In response to the lesson of the accident at the Fukushima Dai-ichi Nuclear Power Plant, we started a development of a radiation-resistant in-water wireless transmission system. In this study, capability of light emitting diodes (LED) and photo diodes (PD) as light emitting and receiving devices was researched. Results of irradiation tests of LEDs and PDs up to 1 MGy indicated a main cause of the degradation of the optical performances of the diodes was not the radiation damage at the semiconductor parts but the coloring of the resin parts. Assuming that the use of the candidate LED and PD, the PD's output current generated by the emission light of the LED at five meters away in water was estimated to be detectable intensity even considering the effects of the absorption of the light by water and the increased dark current by 1 MGy irradiation. Therefore, a radiation resistant in-water transmission system can be constructed using LEDs and PDs in principle.

Journal Articles

Corrosion property of sheath materials using MI cables at conditions simulated severe accident

Nakano, Hiroko; Shibata, Hiroshi; Takeuchi, Tomoaki; Matsui, Yoshinori; Tsuchiya, Kunihiko

Proceedings of International Conference on Asia-Pacific Conference on Fracture and Strength 2016 (APCFS 2016) (USB Flash Drive), p.283 - 284, 2016/09

no abstracts in English

Journal Articles

R&D of high-temperature resistance type mineral insulated cable for sever accident

Miura, Kuniaki*; Shibata, Hiroshi; Onizawa, Tatsuya*; Nakano, Hiroko; Takeno, Naofumi*; Takeuchi, Tomoaki; Tsuchiya, Kunihiko

Nihon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.387 - 390, 2016/07

no abstracts in English

Journal Articles

Evaluation of radiation resistant in-water transmission system using LED and camera

Otsuka, Noriaki; Takeuchi, Tomoaki; Shibagaki, Taro*; Komanome, Hiroshi*; Tsuchiya, Kunihiko

Proceedings of Decommissioning and Remote Systems 2016 (D&RS 2016) (CD-ROM), p.277 - 278, 2016/07

no abstracts in English

Journal Articles

Technical estimation for mass production of highly-concentrated $$^{rm 99m}$$Tc solution from $$^{99}$$Mo to be obtained by ($$n,gamma$$) reaction; A Preliminary study using inactive Re instead of $$^{rm 99m}$$Tc

Tanase, Masakazu*; Fujisaki, Saburo*; Ota, Akio*; Shiina, Takayuki*; Yamabayashi, Hisamichi*; Takeuchi, Nobuhiro*; Tsuchiya, Kunihiko; Kimura, Akihiro; Suzuki, Yoshitaka; Ishida, Takuya; et al.

Radioisotopes, 65(5), p.237 - 245, 2016/05

no abstracts in English

JAEA Reports

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


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.

Journal Articles

Degradation behavior of LED by $$gamma$$ irradiation

Takeuchi, Tomoaki; Shibata, Hiroshi; Otsuka, Noriaki; Uehara, Toshiaki; Kumahara, Hajime*; Tsuchiya, Kunihiko

JAEA-Review 2015-022, JAEA Takasaki Annual Report 2014, P. 29, 2016/02

$$gamma$$ irradiation effects on LEDs which were fabricated by different two fabricators and had relatively large amount of light were evaluated toward the development of a radiation-resistant in-water wireless transmission system using visible light. The current-voltage characteristics and total luminous flux of the LEDs were measured before and after the irradiation. After the irradiation, the total luminous flux decreased and the resin lenses turned oxblood. Meanwhile, the current-voltage characteristics hardly changed. These results indicated that the decreases of the total luminous flux of the LEDs were mainly caused by not the degradation of the semiconductor parts but the coloring of the resin parts by the irradiation. On the other hand, the decrease rates of the total lumious fluxes with $$gamma$$ absorbed dose of the LEDs fabricated one fabricator were smaller than the others. Therefore, they are possible candidates for the light emitting devices of the developing in-water transmission system.

JAEA Reports

Study of hydrogeology in the Mizunami Underground Research Laboratory Project; Hydrogeological modeling at site scale in Phase II

Onoe, Hironori; Kosaka, Hiroshi*; Takeuchi, Ryuji; Saegusa, Hiromitsu

JAEA-Research 2015-008, 146 Pages, 2015/08


Mizunami Underground Research Laboratory (MIU) Project is being carried out by Japan Atomic Energy Agency (JAEA) in the Cretaceous Toki granite in the Tono area, central Japan. The MIU Project has three overlapping phases: Surface-based Investigation (Phase I), Construction (Phase II) and Operation (Phase III). In this study, calibration of hydrogeological model and groundwater flow simulation using the data obtained by the Phase I and Phase II were carried out in order to develop the methodology for construction and update of hydrogeological model on Site Scale. As a result, hydrogeological model on Site Scale, which is able to simulate comprehensively the obtained data regarding groundwater pressure distribution before excavation of the MIU facilities, hydraulic responses and inflow volume during excavation of the MIU facilities, was constructed.

Journal Articles

Development of in-reactor observation system using Cherenkov light(VI)

Takeuchi, Tomoaki; Yamamoto, Keiichi; Otsuka, Noriaki; Shibata, Hiroshi; Shibata, Akira; Takemoto, Noriyuki; Tsuchiya, Kunihiko; Sano, Tadafumi*; Unesaki, Hironobu*; Fujihara, Yasuyuki*; et al.

KURRI Progress Report 2014, P. 108, 2015/07

Investigation of a relation between output power and brightness of Cherenkov light of a specific fuel element at KUR by a CCD camera was performed due to a development of a real-time in-core measurement technique using Cherenkov light. The results indicate that the inhomogeneous distribution of output power and the shadow of the control-rod guide tubes and the other irradiation equipment have significant effects on the brightness of the Cherenkov light. These effects could be suppressed by using a number of cameras located at various positions.

218 (Records 1-20 displayed on this page)