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Hamamoto, Shimpei; Watanabe, Shuji; Oyama, Sunao*; Ota, Yukimaru; Tochio, Daisuke; Fujimoto, Nozomu
JAERI-Tech 2005-035, 35 Pages, 2005/07
JAERI-Tech-2005-035.pdf:2.54MB
The Vessel Cooling System (VCS) is one of the safety engineered features of the HTTR. The VCS removes the decay heat of the reactor core when the forced circulation can not be maintained due to pipe rupture accidents, etc. VCS cools the core by water cooling panels surrounding the reactor pressure vessel. The VCS also keeps the temperature of the concrete of the primary shielding under the design limit during the operation. The temperature of cooling water of the VCS has recently tended to rise gradually, though the amount of heat removal of VCS has been constant. Accompanying with the increase of the cooling water temperature, the temperature of the shielding concrete is also possible to rise and exceed the limit. The heat exchange performance of the VCS cooler was evaluated and the deterioration of the cooler was verified. Therefore, the cleaning of heat transfer tubes was carried out to recover the heat exchange performance. The cleaning recovered the performance of the VCS cooler drastically and the cooling water temperature of the VCS could be reduced sufficiently.
Fujimoto, Nozomu; Tachibana, Yukio; Saikusa, Akio*; Shinozaki, Masayuki; Isozaki, Minoru; Iyoku, Tatsuo
Nuclear Engineering and Design, 233(1-3), p.273 - 281, 2004/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)From a viewpoint of heat leakage, there were two incidents during HTTR power-rise-tests. One was a temperature rise of the primary upper shielding, and the other was a temperature rise of the core support plate. Causes of the both incidents were small amount of helium flow in structures. For the temperature rise of the primary upper shielding, countermeasures to reduce the small amount of helium flow, enhancement of heat release and installation of thermal insulator were taken. For the temperature rise of the core support plate, temperature evaluations were carried out again considering the small amount of helium flow and design temperature of the core support plate was revised. By these countermeasures, the both temperatures were kept below their limits.
