Calculation of the conditions of crack initiation and arrest during a pressurized thermal shock in the material of the WWER-440 reactor pressure vessel

The initiation and arrest of a semi-elliptical surface crack in the WWER-440 reactor pressure vessel was treated. The stress from the pressurized thermal shock was determined by finite element calculations. The code was written in the C computer language. No arrest of the initiated crack was achieved for the various crack axis ratios and transient temperatures applied; there are two apparent reasons for this, viz., that the thermal shock failed to be strong enough, and that there is a rather large difference between fracture toughness KIC and KIA, the fracture toughness characterizing the material resistance against a running crack. (P.A.). 2 figs., 5 refs