A Failure investigation of the beam collimator system in the J-PARC 3 GeV rapid cycling synchrotron

Okabe, Kota; Yamamoto, Kazami; Kamiya, Junichiro; Takayanagi, Tomohiro; Yamamoto, Masanobu; Yoshimoto, Masahiro; Takeda, Osamu*; Horino, Koki*; Ueno, Tomoaki*; Yanagibashi, Toru*; et al.

Proceedings of 14th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.853 - 857, 2017/12

http://www.pasj.jp/web_publish/pasj2017/proceedings/PDF/WEP0/WEP021.pdf

The most important issue is to reduce the uncontrolled beam loss in the high intensity hadron accelerator such as J-PARC proton accelerators. The J-PARC 3 GeV Synchrotron (RCS) has a collimator system which narrows a high intensity beam in the RCS. After startup of RCS in 2007, the collimator system of the RCS worked well. However, in April 2016, vacuum leakage at the collimator system occurred during the maintenance operation. To investigate a cause of the failure, we took apart iron shields of the collimator reducing exposed dose of operators. As a result of inspection, we succeeded to identify the cause of the vacuum leakage failure. In this presentation, we report the failure investigation of the beam collimator system in the RCS.

Characteristics of OSL dosimeter as individual monitoring for external radiation

Suzuki, Akifumi; Suzuki, Takehiko; Takahashi, Masa; Nakata, Toru; Murayama, Takashi; Tsunoda, Masahiko

JAEA-Technology 2014-049, 19 Pages, 2015/03

JAEA-Technology-2014-049.pdf:9.12MB

Optically Stimulated Luminescence, OSL, dosimeters have been used as individual dosimeters for external radiation in Nuclear Science Research Institute and so on since October, 2014 as successor of the RPL glass dosimeters. Characteristics of the OSL dosimeters such as dose linearity, energy response, angular dependence, fading characteristics and responses at mixed irradiation fields were examined prior to the start of use. As a result, it was found that the OSL dosimeters met the performances that the national standard (JIS Z 4339) determined. The characteristics of OSL dosimeters were comparable with those of the RPL glass dosimeters. In conclusion, it was confirmed the OSL dosimeters had sufficient performances for the practical use on individual monitoring. This report shows the testing methods and the results for the characteristics of OSL dosimeters.

Influences of long term aging and creep deformation on precipitation behavior in high-Cr steels (3) A study on the relationship between impact property and Laves phase precipitation based on quantitative analyses

Takahashi, Toru; Wakai, Takashi; Aoto, Kazumi

JNC TN9400 2005-013, 42 Pages, 2005/03

JNC-TN9400-2005-013.pdf:4.46MB

Considering the application of the high-chromium (Cr) steel for FBR pipes and components, it can be pointed out that there are some room for improvement especially in toughness. JNC proposed a provisional specification of high Cr steel for FBR pipes, focusing on tungsten (W) and molybdenum (Mo) contents. Both W and Mo form Laves phase during long term thermal aging. Laves phase is known as an inter-metallic compound which degrades ductility and toughness of the steel. In this study, quantitative analyses of the precipitated Laves phase are performed to clarify the relationship between and Laves phase precipitation behavior and toughness degradation with thermal aging. As a result, following conclusions are obtained: (1) A number of fine W-Laves phase are observed in aged W-rich high-Cr steel. (2) In the steels with W, precipitated Laves phase coheres and no new precipitation occurs after aging longer than 3,000h at 873K. In contrast, in the steel without W, Laves phase precipitates and coheres simultaneously. (3) It can be said that the impact property degrades with the increase of area fraction of Laves phase due to the increase of interface between matrices and Laves phases. (4) In order to explore the optimal specification of the high-Cr steel suitable for FBR pipes and components, W contents should be eliminated.

Influences of long term aging and creep deformation on precipitation behavior in high-Cr steels (1) Observations by optical and scanning electron microscopy and extracted residue analyses

Takahashi, Toru; Wakai, Takashi; Aoto, Kazumi

JNC TN9400 2003-114, 52 Pages, 2004/02

JNC-TN9400-2003-114.pdf:2.83MB

For the commercialization of the fast breeder reactors, it is investigated that the application of high chromium ferritic steels for the structural material to optimize the economic performance. Microstructures of a martensitic stainless steel SUS410J3 used in thermal power plants and a modified one are observed by optical and scanning electron microscopy. Some long term aged and/or creep ruptured materials are also examined to clarified the influence of aging and creep deformation on precipitation behavior. In addition, a series of extracted residue analyses of these steels are conducted. As a result, following conclusions are obtained ;(1) Obvious influence of heat treatment on the Laves phase precipitation behavior can not be found. (2) The Laves phase precipitation tends to saturate at the aging condition longer than 550C4,500h. (3) It is observed that precipitated Laves phase grows remarkably and that the number of precipitations decrease between the aging conditions of 550C4,500h and 600C3,000h.(4)iv).Under the creep condition of 550C160h and 550C4,500h, obvious acceleration of the Laves phase precipitation behavior can not be seen.

Integrity Test of Multi-Stage Design Packages of Radioactive Wastes for Sea Disposal

; ; ; ; Wadachi, Yoshiki; ; ; ; ; ; et al.

JAERI-M 9100, 6 Pages, 1980/09

JAERI-M-9100.pdf:0.33MB

no abstracts in English

Development of the electrolytic and thermochemical hybrid hydrogen production process for FBR, 8

Takahashi, Toru; Kato, Shoichi; Nakagiri, Toshio; Aoto, Kazumi

no journal, , 

no abstracts in English

Test results of CS insert for ITER; Test method

Isono, Takaaki; Kawano, Katsumi; Ozeki, Hidemasa; Saito, Toru; Nabara, Yoshihiro; Suwa, Tomone; Shimono, Mitsugu; Ebisawa, Noboru; Sato, Minoru; Uno, Yasuhiro; et al.

no journal, , 

JAEA is procuring conductors for ITER Central Solenoid (CS) and has evaluated its superconducting performance using CS Model Coil Test facility. We measured Tcs values during cyclic charge of 16,000 cycles and warm-up and cool-down cycle of 3 times. And we measured effect of coil deformation by electro-magnetic force on Tcs values and performed quench test. In this presentation, test method will be reported.