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Shibata, Akira; Ito, Masayasu; Takemoto, Noriyuki; Nakatsuka, Masafumi*; Ohara, Hiroshi*; Kodama, Mitsuhiro*; Tanimoto, Masataka; Tsuchiya, Kunihiko
JAEA-Technology 2011-034, 67 Pages, 2012/02
JAEA-Technology-2011-034.pdf:6.94MB
Reflector elements made from metal beryllium is widely used as neutron reflectors to increase neutron flux in test reactors. When beryllium reflector elements are irradiated by neutron, bending of reflector elements caused by swelling occurs, and beryllium reflector elements must be replaced in several years. In this report, investigation for non-destructive inspection method of metal Beryllium and experiments for Preliminary inspection to establish post irradiation examination method for research of characteristics of metal beryllium under neutron irradiation were reported.
Takemoto, Masafumi; Nakamura, Hideo; Owada, Akihiko; Osaki, Hideki
JAEA-Research 2006-009, 48 Pages, 2006/03
JAEA-Research-2006-009.pdf:3.8MB
Nitrogen (N
)gas used for the pressurization of accumulator (ACC) tanks may flow into the PWR primary system during LOCAs after the ACC coolant injection is completed. Since N gas may travel to and accumulates in reactor vessel top and U-tubes in steam generators (SGs), primary cooling and depressurization via SG secondary-side depressurization would become ineffective because of the degradation of condensation heat transfer in SG U-tubes. Quantitative measurement of gas accumulation is necessary to clarify the influences of gas onto such degradation in the heat transfer and thus the primary depressurization. However, direct measurement method of non-condensable gas concentration in steam has not been established. An apparatus to directly measure gas concentration in high-temperature steam was developed to measure gas concentration in vessel upper head and SG U-tubes during LOCA experiments using ROSA/LSFT. The developed apparatus is primarily composed of zirconia oxygen sensor and turbine meter, enabling to deal with small amount of steam-gas mixture at high temperature when air is used to pressurize ACC tanks instead of N gas. This report describes the developed apparatus and its operation method with several test results for the confirmation of oxygen gas measurement capability and applicability of the apparatus to the ROSA/LSTF experiments.