The Results obtained from the 20 years of "Monju" plant data, 5; Effect of natural convection prevention plate in primary sodium pump

Morioka, Tatsuya; Sawazaki, Hiromasa; Uchida, Takenobu; Sato, Takeshi; Nakamura, Yoshihide; Shiotani, Hiroki; Kunogi, Kosuke

Thermal natural convection occurred in Ar gas region between the inner and outer casing of the sodium pump in the past, which induces asymmetric circumferential temperature distribution on the casings. This thermal effect causes the contact of the pump shaft with the lower hydrostatic bearing, which places the bearing at risk for damage. This phenomenon strongly appears in long size pumps of sodium fast reactors. To prevent this risk for Monju primary sodium pump, convection prevention plates are installed between the inner and outer casing of the pump. Monju plant data indicates the plates decrease the circumferential temperature difference, and then no contact arose between the pump shaft and the bearing.