Design of hydrogen vent line for the cryogenic hydrogen system in J-PARC

Tatsumoto, Hideki; Aso, Tomokazu ; Kato, Takashi; Otsu, Kiichi; Hasegawa, Shoichi   ; Maekawa, Fujio  ; Futakawa, Masatoshi  

As one of the main experimental facilities in J-PARC, an intense spallation neutron source (JSNS) driven by a 1-MW proton beam selected supercritical hydrogen at the temperature of 20 K and the pressure of 1.5 MPa as a moderator material. A cryogenic hydrogen system plays a role in cooling the moderators. For safety reasons, we have designed a hydrogen relief system that can release hydrogen to the outside safely, even if some off-normal events occur. The design of the hydrogen vent line should be considered to prevent the cryogenic hydrogen from freezing purge nitrogen gas in the vent line and freezing moisture in the stack placed in an outdoor location, and to inhibit the piping temperature drop at the building wall penetration. In this work, the temperature change behaviors in the hydrogen vent line were analyzed by using a CFD code, STAR-CD. We determined the required sizes of the vent line based on the analytical results and its layout in the building.