Stress corrosion cracking of low alloy steels under BWR conditions; Assessment of crack growth rate algorithms

The stress corrosion cracking (SCC) behaviour of low-alloy, pressure-vessel steels in oxygenated, high-temperature water and its possible relevance to BWR operation has been a subject of controversial discussion for many years. The present paper briefly reviews some of the reasons for this and attempts to define current understanding on the basis of both mechanistic knowledge and more recent experimental data of improved quality. The derivation is given for an interim crack growth rate algorithm (V = 2 x 10(-8) mm/s for K <55 MPa<root>m) which may be used for the assessment of possible component SCC behavior under defined boundary conditions (plane-strain, constant-load conditions; high-temperature water with corrosion potential <+200 mV(she) and conductivity <0.3 muS/cm). An indication is given of possible ways to treat deviations from these conditions (mechanical/chemical transients) on the basis of engineering judgment.