The Huge Missing Factor in LBB Analysis - How A Circumferential Through-Wall-Crack in A Pipe System Changes the Flexibility and Reduces the Applied Moments

Abstract In typical leak-before-break (LBB) analyses in the nuclear industry, uncracked piping normal operating forces and moments are applied a cracked-pipe analytical procedure to determine leakage, combined under condition safe shutdown earthquake seismic loading used fracture analysis predict margins on "failure". The International Piping Integrity Research Program (IPIRG) performed 1990 1998 provided some insights LBB behaviors where pipe system tests were conducted with simulated loadings. test results showed large margin which was also recognized 2011 when Argentinian Atucha II plant analyzed using robust full FE model. It found that circumferential through-wall cracks put highest stressed locations, moment dropped for both N+SSE as crack length increased. size causing double ended guillotine break (DEGB) greater than 90%-percent of circumference. Similar petrochemical thermal expansion stresses much higher primary stresses. Even very low toughness materials, critical leading DEGB 80% implication this work is pragmatically there failure operation, efforts would be better focused potential small-break loss-of-coolant accident (SB-LOCA).