Hydrogen concentration behavior in the IHTS of Monju

Ito, Kazuhiro ; Tanabe, Hiromi; Kaneko, Yoshihisa; Kagota, Eiichi; Takahashi, Yasuo

The Monju is equipped with two types of hydrogen-meters to detect water leakage in steam generators. Since they are so highly-sensitive as to detect minor water leak from a steam generator tube, they sometimes detect hydrogen concentration increases at plant operational condition changes such as start-up without any water leak. No water leak was experienced during one year operation of the Startup Test up to 40% in 1995, although hydrogen concentration sometimes increased at plant operational condition changes. The H behavior of Monju IHTS during the previous Startup Test was examined and the following knowledge was obtained: The in-sodium H behaves in parallel with the IHTS sodium temperature. In-cover-gas H behavior is more complicated and sensitive to plant operational condition changes such as plant load changes than the in-sodium one. Both types of H-meters underwent a certain degree of zero level drift during one year operation.