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Journal Articles

Progress of target system operation at the pulsed spallation neutron source in J-PARC

Takada, Hiroshi; Naoe, Takashi; Kai, Tetsuya; Kogawa, Hiroyuki; Haga, Katsuhiro

Proceedings of 12th International Topical Meeting on Nuclear Applications of Accelerators (AccApp '15), p.297 - 304, 2016/00

In J-PARC, we have continuously been making efforts to operate a mercury target of a pulsed spallation neutron source with rated power of 1-MW. One of technical progresses is to mitigate cavitation damages at the target vessel front induced by the 3-GeV proton beam injection at 25 Hz. We have improved the performance of a gas micro-bubbles injection into the mercury target, resulting that no significant cavitation damages was observed on the inner surface of target vessel after operation for 2050 MWh with the 300-kW proton beam. Another progress is to suppress the release of gaseous radioactive isotopes, especially tritium, during the target vessel replacement. We have introduced a procedure to evacuate the target system by an off-gas processing apparatus when it is opened during the replacement operation, achieving to suppress the tritium release through the stack. For example, the amount of released tritium was 12.5 GBq, only 5.4% of the estimated amount, after the 2050 MWh operation. After these progresses, the operating beam power for the pulsed spallation neutron source was ramped up to 500-kW in April, 2015.

JAEA Reports

Structural integrity assessment of helium component during safety demonstration test using HTTR, 1 (Contract Research)

Sakaba, Nariaki; Nakagawa, Shigeaki; Furusawa, Takayuki; Tachibana, Yukio

JAERI-Tech 2004-045, 67 Pages, 2004/04

JAERI-Tech-2004-045.pdf:4.74MB

Safety demonstration tests using the HTTR are now underway in order to verify the inherent safety features and to improve the safety design and evaluation technologies for HTGRs, as well as to contribute to research and development for the VHTR, which is one of the Generation IV reactors. In the safety demonstration tests, the coolant flow reduction test by tripping one or two out of three gas circulators is being performed between FY2002 and FY 2005 and by tripping all the three gas circulators will be conducted after FY2006. This paper describes the structural integrity assessment of the primary pressurised water cooler after one and two gas circulators run down. Also, the possibility of natural convection in the primary coolant after all the three gas circulator stopped was evaluated by the operation data of the reactor-scram test performed during the rise-to-power tests.

Journal Articles

Application of electron beam for the reduction of PCDD/F emission from Municipal solid waste incinerators

Hirota, Koichi; Hakoda, Teruyuki; Taguchi, Mitsumasa; Takigami, Machiko; Kim, H.; Kojima, Takuji

Environmental Science & Technology, 37(14), p.3164 - 3170, 2003/07

https://doi.org/10.1021/es021076t

Times Cited Count：43 Percentile：65.39(Engineering, Environmental)

The electron-beam technology was applied to reduce polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in flue gases from the municipal solid waste incinerator (MSWI) at a temperature of 200 $^{circ}$ C. More than 90% of PCDD/Fs in a flue gas of 1000 m $^{3}$ N/h was decomposed at a dose of 14 kGy. The decomposition of PCDD/Fs was probably initiated through reactions with OH radicals, followed by the dissociation of ether bond (-C-O-C-), the cleavage of aromatic rings, and dichlorination. The dechlorination of the higher dechlorinated PCDF homologues produced the lower chlorinated ones, which led to lower decomposition efficiency of PCDF than that of PCDD.

Journal Articles

Study on voloxidation process for tritium control in reprocessing

Uchiyama, Gunzo; ; ; ; Sugikawa, Susumu; Maeda, Mitsuru; Tsujino, Takeshi

Radioact. Waste Manage. Nucl. Fuel Cycle, 17(1), p.63 - 79, 1992/00

no abstracts in English

Journal Articles

Reduction of the operating gas pressure in a cesium-seeded large multicusp H $^{-}$ ion source

Okumura, Yoshikazu; Hanada, Masaya; Inoue, Takashi; Mizuno, Makoto; Ohara, Yoshihiro; Pamela, J.*; Suzuki, Yasuo*; Tanaka, Hideki*; Watanabe, Kazuhiro

Production and Application of Light Negative Ions, p.35 - 40, 1991/00

no abstracts in English

JAEA Reports