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Journal Articles

Development of radiation resistant monitoring system in light water reactor

Takeuchi, Tomoaki; Otsuka, Noriaki; Nakano, Hiroko; Iida, Tatsuya*; Ozawa, Osamu*; Shibagaki, Taro*; Komanome, Hirohisa*; Tsuchiya, Kunihiko

QST-M-16; QST Takasaki Annual Report 2017, P. 67, 2019/03

no abstracts in English

Journal Articles

Development of radiation resistant monitoring camera system

Takeuchi, Tomoaki; Otsuka, Noriaki; Watanabe, Takashi*; Tanaka, Shigeo*; Ozawa, Osamu*; Komanome, Hirohisa*; Ueno, Shunji*; Tsuchiya, Kunihiko

Proceedings of 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2017) (Internet), 3 Pages, 2018/11

no abstracts in English

Journal Articles

Evaluation of in-water wireless transmission system under the conditions simulated the severe accident

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

Proceedings of 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC 2017) (Internet), 3 Pages, 2018/11

no abstracts in English

Journal Articles

Challenge of decommissioning of Fukushima I Nuclear Power Plant, 4; Development of radiation resistant image sensor

Watanabe, Takashi*; Ozawa, Osamu*; Takeuchi, Tomoaki

Denki Gakkai-Shi, 138(8), p.529 - 534, 2018/08

no abstracts in English

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

JAEA-Technology-2017-026.pdf:4.0MB

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

JAEA-Testing-2017-002.pdf:9.3MB

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

Image processing method for optical transmission system using 2-dimensional LED matrix array in spent fuel pool

Yatsuzuka, Junji*; Shibagaki, Taro*; Otsuka, Noriaki; Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Komanome, Hirohisa*

Bijon Gijutsu No Jitsuriyo Wakushoppu (ViEW 2017) Koen Yoshishu (USB Flash Drive), 6 Pages, 2017/12

no abstracts in English

Journal Articles

A New radiation hardened CMOS image sensor for nuclear plant

Watanabe, Takashi*; Takeuchi, Tomoaki; Ozawa, Osamu*; Komanome, Hirohisa*; Akahori, Tomoyuki*; Tsuchiya, Kunihiko

Proceedings of 2017 International Image Sensor Workshop (IISW 2017) (Internet), p.206 - 209, 2017/05

no abstracts in English

Journal Articles

Development of high-performance monitoring system under severe accident condition

Takeuchi, Tomoaki; Tsuchiya, Kunihiko; Komanome, Hirohisa*; Miura, Kuniaki*; Ishihara, Masahiro

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 6 Pages, 2017/04

After the accident at the Fukushima Dai-ichi (1F) Nuclear Power Plant (NPP), the Japanese Government referred to "Enhancement of instrumentation to identify the status of the reactors and PCVs", in the report of Japanese government to the IAEA ministerial conference in June 2011. In response to these provisions, a research and development of a monitoring system for NPPs situations during severe accidents started in November 2012. The objectives of the R&D are composed of radiation-resistant monitoring camera, radiation-resistant in-water transmission system, and heat-resistant signal cable. For all the three objectives, the elemental technologies have been already developed and now trial system are being fabricated and tested under simulated conditions of severe accidents. The results will enable us to determine the basic specifications of the systems and to provide the information about application limits for users.

Journal Articles

Degradation behavior of surface-mounted LED by $$gamma$$ irradiation

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

QST-M-2; QST Takasaki Annual Report 2015, P. 80, 2017/03

no abstracts in English

Journal Articles

Effect of dissolved gas on mechanical property of sheath material of mineral insulated cables under high temperature and pressure water

Takeuchi, Tomoaki; Nakano, Hiroko; Uehara, Toshiaki; Tsuchiya, Kunihiko

Nuclear Materials and Energy (Internet), 9, p.451 - 454, 2016/12

 Times Cited Count:1 Percentile:82.75(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Application of Cherenkov light observation to reactor measurements, 3; Evaluation of spent fuel elements of LWRs with Cherenkov light estimation system

Yamamoto, Keiichi; Takeuchi, Tomoaki; Hayashi, Takayasu*; Kosuge, Fumiaki*; Tsuchiya, Kunihiko

JAEA-Testing 2016-002, 25 Pages, 2016/11

JAEA-Testing-2016-002.pdf:4.97MB

Development of the reactor measurement system has been carried out to obtain the real-time in-core nuclear and thermal information, where the quantitative measurement of brightness of Cherenkov light was investigated. The system would be applied as a monitoring system in severe accidents and for the advanced operation management technology in existing LWRs. This report summarized the modification of Cherenkov light estimation system described JAEA-Testing 2015-001 and the result of the burn-up evaluation by Cherenkov light image emitted from spent fuel elements of LWRs with the modified system.

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:69.03(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

The Two-step nucleation of G-phase in ferrite

Matsukawa, Yoshitaka*; Takeuchi, Tomoaki; Kakubo, Yuta*; Suzudo, Tomoaki; Watanabe, Hideo*; Abe, Hiroaki*; Toyama, Takeshi*; Nagai, Yasuyoshi*

Acta Materialia, 116, p.104 - 113, 2016/09

 Times Cited Count:40 Percentile:3.92(Materials Science, Multidisciplinary)

Atom probe tomography (APT) and TEM were combined for identifying the stage at which solute clusters transform into compounds crystallographically distinct from the matrix, in the precipitation of the G-phase (Ni$$_{16}$$Si$$_{7}$$Mn$$_{6}$$) from ferrite solid solution subjected to isothermal annealing at 673 K. Based on a systematic analysis of solute clusters as a function of annealing time, the nucleation of the G-phase was found to occur via a two-step process. Moreover, the structural change was found to occur via another two-step process. There was a time lag between the end of cluster growth to become a critical size and the start of the structural change. During the incubation period solute enrichment occurred inside the clusters without further size growth, indicating that the nucleation of the G-phase occurs at the critical size with a critical composition. Judging from the results of APT, TEM and the simulation of electron diffraction patterns, the critical composition was estimated to be Ni$$_{16}$$Si$$_{3.5}$$(Fe,Cr)$$_{3.5}$$Mn$$_{6}$$.

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

Effect of dissolved gases on mechanical property of AISI 304 and 316 stainless steels under high temperature and pressure water

Takeuchi, Tomoaki; Nakano, Hiroko; Uehara, Toshiaki; Tsuchiya, Kunihiko

Proceedings of International Conference on Asia-Pacific Conference on Fracture and Strength 2016 (APCFS 2016) (USB Flash Drive), p.95 - 96, 2016/09

Monitoring system of the nuclear power plants during a severe accident has increased in importance after the accident at the Fukushima Dai-ichi Nuclear Power Plant. As part of the system, the development of mineral insulated (MI) cables available under the normal and severe environments was started. In this study, in order to investigate mechanical integrity of MI cables in reactor coolant condition, effects of dissolved oxygen on fracture properties of the sheath materials of the MI cables in high temperature and pressure pure water were evaluated. As the sheath materials, AISI 304 and 316 stainless steels were selected and slow strain rate testing was performed at 5$$times$$10$$^{-3}$$ mm/min in strain rate in pure water at 325$$^{circ}$$C and 15 MPa. In both the cases of the 304 and 316 steel, from 8500 to 50 ppb dissolved oxygen (DO), fully ductile fracture surfaces were observed and tensile strength and breaking elongation were almost the same values. However, at 10 and 1 ppb DO, brittle fracture surfaces were observed around the outer edge of the samples, and the tensile strength and breaking elongation decreased. The results indicated the existence of a threshold level of DO for brittle fracture of both the steels at lower than 100 ppb.

Journal Articles

Development of radiation-resistant in-water wireless transmission system

Takeuchi, Tomoaki; Otsuka, Noriaki; Shibagaki, Taro*; Komanome, Hirohisa*; Ueno, Shunji*; Tsuchiya, Kunihiko

Nippon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.379 - 386, 2016/07

no abstracts in English

Journal Articles

Gamma irradiation effects of image sensor for radiation-resistant camera

Takeuchi, Tomoaki; Otsuka, Noriaki; Tsuchiya, Kunihiko; Tanaka, Shigeo*; Ozawa, Osamu*; Komanome, Hirohisa*; Watanabe, Takashi*; Ueno, Shunji*

Nippon Hozen Gakkai Dai-13-Kai Gakujutsu Koenkai Yoshishu, p.391 - 394, 2016/07

no abstracts in English

114 (Records 1-20 displayed on this page)