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Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*
JAERI-Tech 2003-041, 106 Pages, 2003/03
JAERI-Tech-2003-041.pdf:6.58MB
In the second stage of the research and development for a high-temperature helium-leak detection system, the temperature sensor using optical fibres was studied. The sensor detects the helium leakage by the temperature inclease surrounded opitical fibre with or without heat insulator. Moreover, the applicability of high temperature equipments as the HTTR system was studied. With the sensor we detected 5.0-20.0 cm
/s helium leakages within 60 minutes. Also it was possible to detect earlier when the leakage level is at 20.0 cm/s.
Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*
JAERI-Review 2002-041, 86 Pages, 2003/03
JAERI-Review-2002-041.pdf:3.21MB
In High Temperature Gas-cooled Reactors (HTGR), the detection of leakage of helium at an early stage is very important for the safety and stability of operations. Since helium is a colourless gas, it is generally difficult to identify the location and the amount of leakage when very little leakage has occurred. The purpose of this R&D is to develop a helium-leak detection system for the high temperature environment appropriate to the HTTR. This system can shorten the time of detection to several hours from about one week in the current detection time. In addition, it can also identify easily the leak location using the optical fibre network. As the first step in the development, this paper describes the result of surveying leakage events at nuclear facilities inside and outside Japan and current gas leakage detection technology to adapt optical fibre detection technology to HTGRs.
Sakaba, Nariaki; Nakazawa, Toshio; Kawasaki, Kozo; Urakami, Masao*; Saishu, Sadanori*
JAERI-Research 2003-006, 65 Pages, 2003/03
JAERI-Research-2003-006.pdf:2.89MB
In the final third stage of the research and development for a high-temperature helium-leak detection system, the radiation sensor was developed in order to detect very small helium leakage. Applying the radiation sensor, we proposed not only the direct detection method which uses the detection of FP gas in helium, but also the active method which uses the difference in the radiation absorption between helium and air. From obtained data it was found that we can detect 0.2 cm/s leakage within 10 minutes by the active method.
Sumita, Junya; Sawa, Kazuhiro; Tsuchie, Yasuo*; Urakami, Masao*; Kunitomi, Kazuhiko
JAERI-Tech 2002-104, 23 Pages, 2003/02
JAERI-Tech-2002-104.pdf:1.15MB
This report describes the result of study on disposal method of graphite blocks in future block-type reactor. Present study was carried out within a framework of joint research, "Research of Modular High Temperature Gas-cooled Reactors (No. 3)", between Japan Atomic Energy Research Institute (JAERI) and the Japan Atomic Power Company (JAPCO), in 2000. In this study, activities in fuel and reflector graphite blocks were evaluated and were compared with the disposal limits defined as low-level of radioactive waste. As a result, it was found that the activity for only C-14 was higher than disposal limits for the low-level of radioactive waste and that the amount of air in the graphite is important to evaluate precisely of C-14 activity. In addition, spent fuels can be stored in air-cooled condition at least after two years cooling in the storage pool.
Yamagishi, Hideshi; Soyama, Kazuhiko; Kakuta, Tsunemi; Ochiai, Masaaki; Iwamura, Takamichi; Saishu, Sadanori*; Urakami, Masao*; Masuda, Naohiro*; Yamauchi, Yuki*; Otani, Junichi*; et al.
JAERI-Tech 2001-053, 19 Pages, 2001/08
JAERI-Tech-2001-053.pdf:2.48MB
no abstracts in English
Kakuta, Tsunemi; Yamagishi, Hideshi; Tabata, Hiroaki*; Urakami, Masao*
Dai-7-Kai Doryoku Enerugi Gijutsu Shimpojiumu Koen Rombunshu (00-11), p.254 - 257, 2000/11
no abstracts in English
Yamagishi, Hideshi; Ikeda, Yujiro; Ito, Hiroshi; Kakuta, Tsunemi; Nakakawa, Masayuki; Iwamura, Takamichi; Tabata, Hiroaki*; Urakami, Masao*
JAERI-Tech 2000-037, p.12 - 0, 2000/03
JAERI-Tech-2000-037.pdf:1.12MB
no abstracts in English