Study on chemical form of tritium in coolant helium of high temperature gas-cooled reactor with tritium production device

Hamamoto, Shimpei  ; Ishitsuka, Etsuo   ; Nakagawa, Shigeaki  ; Goto, Minoru  ; Matsuura, Hideaki*; Katayama, Kazunari*; Otsuka, Teppei*; Tobita, Kenji*

Impurity concentrations of hydrogen and hydride in the coolant were investigated in detail for the HTTR, a block type high-temperature gas reactor owned by Japan. As a result, it was found that CH was 1/10 of H concentration, which was under the conventional detection limit. If the ratio of H to CH in the coolant is the same as the ratio of HT to CHT, the CHT has a larger dose conversion factor, and this compositional ratio is an important finding for the optimal dose evaluation. Further investigation of the origin of CH suggested that CH was produced as a result of a thermal equilibrium reaction rather than being released as an impurity from the core.