Conceptual structure design of high temperature isolation valve for high temperature gas cooled reactor

Takada, Shoji; Abe, Kenji; Inagaki, Yoshiyuki

The high temperature isolation valve (HTIV) is a key component to assure the safety of a HTGR connected with a hydrogen production system. The structure design of an angle type HTIV was carried out. A seat made of Hasteloy-XR is welded inside a valve box. Internal thermal insulation is employed. Inner diameter of the top of seat was 445 mm. Numerical analysis was carried out to estimate temperature and thermal stress of metallic components by 3-dimensional finite element method. Numerical results showed that the temperature of the seat was simply decreased from the top to the root, and the thermal stress locally increased at the root. Thermal stress was lowered below the allowable limit 120 MPa by optimizing the structure. The thermal stress increased at the top of the seat. A creep analysis showed that a creep damage factor was limited below allowable limit during the start-up and shut-down during normal operation, as well as during the depressurization accident.