Experimental results on fracture behaviors of type 304 stainless steel pipes with artificial part-through cracks in the circumferential direction are presented. The experiments are preformed in the BWR environment in terms of pressure, temperature and water chemistry under the cyclic tension loading with a high compliance test apparatus. Based on the test results, the break condition for pipes is found to be well represented by the net section stress approach. The leak before break condition is also studied by comparison of critical crack lengths for break and for detectable leak. From this evaluation, it is found that the former is considerably larger than the latter under the design stress condition and that the margin for the leak before break becomes bigger with the smaller compliance or the larger pipe diameter.
