Demonstration of crack growth by delayed hydrogen cracking in the rolled joints of Zr-2.5% Nb pressure tubes

Delayed hydrogen cracking in cold-worked Zr-2.5 wt% Nb pressure tubes has been examined in rolled-joint assemblies in tests closely simulating the power reactor conditions. The experiments were designed to demonstrate that the tube failures in Pickering were due to delayed hydrogen cracking. Most features of the failures in Pickering have been reproduced, and the growth of artificial defects occurred at stress intensity factors and crack velocities quite consistent with both laboratory experiments on small specimens and the experience at Pickering. (auth)