Safety design of the cryogenic hydrogen system at J-PARC

Kato, Takashi; Aso, Tomokazu ; Tatsumoto, Hideki; Hasegawa, Shoichi   ; Otsu, Kiichi

JAEA has been constructing the J-PRAC in collaboration with the KEK. The materials and life science experimental facility (MLF) has been constructed as one of the experimental science facilities at J-PARC. A spallation neutron source that produces neutrons through nuclear spallation reaction using high-energy proton beam injection and provides neutron beams for experimental users has been installed at the MLF. Hydrogen nuclei are used as a neutron moderating material (moderator) to reduce the neutron energy from MeV to meV order. Therefore, a cryogenic hydrogen system should be installed at the spallation neutron source to provide supercritical hydrogen to moderators. This paper describes the safety design of the cryogenic hydrogen system. Especially, the system is subject to high-pressure gas safety laws, and refrigeration safety regulations are applied to the system for the first time. We also discuss the technical contents that were argued through this application.