Baffle bolt failures—a B&W Owners Group approach

The natural aging of austenitic stainless steels irradiated with fast neutrons

“…The issue of void swelling for example, long known to the fast reactor community [12] and first predicted to seriously affect LWRs in 1993 [13,14], can take years to decades to occur. Void swelling continues to degrade material properties, especially those under stress, from baffle bolt heads [15] popping off in LWRs [16] to complete embrittlement of fast reactor fuel assembly boxes [17]. Other longterm radiation aging and embrittlement mechanisms, from Cu precipitate formation in LWR pressure vessels [18] to radiationaccelerated spinodal decomposition of stainless steel welds [19] to radiation-induced segregation (RIS) leading to irradiationassisted stress corrosion cracking (IASCC) [20], all take years or decades to nucleate.…”