Thermal stress analysis for a transfer line of hydrogen moderator in J-PARC

Tatsumoto, Hideki; Teshigawara, Makoto   ; Aso, Tomokazu ; Otsu, Kiichi; Maekawa, Fujio  ; Kato, Takashi

In JSNS, cryogenic hydrogen at supercritical pressure is selected as a moderator material. Three kinds of hydrogen moderator are installed to provide higher neutronic performance. The transfer lines around the moderators should be changed every 6 years due to its radiation damage. The detachment of the transfer line will be only performed by a hands-on. Therefore, minimum pipe size and elbow-type bend sections are installed to reduce the radiation dose by the radiation streaming. Some spacers are installed so as to avoid touching the hydrogen pipe to the outer vacuum pipe due to thermal shrinkage. In the design, we should consider mechanical stress concentration, deformation, and, touching between the pipes due to the thermal shrinkage at the cryogenic hydrogen temperature. The appropriate locations of spacers to keep the thermal stress below an allowable stress and to avoid touching between the pipes were determined.