Oyama,-Sunao (Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)); Hamamoto,-Shimpei; Nemoto,-Takahiro; Sekita,-Kenji; Isozaki,-Minoru; Emori,-Kouichi; Ohta,-Yukimaru; Mizushima,-Toshihiko (Japan Atomic Energy Agency, Oarai Research and Development Center, Oarai, Ibaraki (Japan)); Kaneshiro,-Noriyuki; Ito,-Yoshiteru; Yamamoto,-Hideo (Kaji Technology Corp., Sakai, Osaka (Japan) High-Temperature engineering Test Reactor (HTTR) built by Japan Atomic Energy Agency (JAEA) has reciprocating compressor commonly used to extract and discharge helium gas into primary/secondary coolant helium loop from helium purification system. Piston rod seal of the compressor consist of several components to prevent coolant leak. However, rod seal system has weak reliability during long term operation due to repeated leakage of seal oil in operation. As a result of investigations, leakage's root is found in that seal were used in a range beyond limit sliding properties of seal material. For this reason, a lip of the seal was worn and transformed itself and was not able to sustain a seal function. Therefore, through tests using facility actual equipment for endurance of candidate materials, one seal material were chosen for long term operation.
