A rapid, realistic and reliable in-service failure assessment system

Following the detection of a defect during inservice inspection or after an abnormal transient has occurred, plant operator has to decide whether he must repair or not and whether he can resume operation or not. Before taking this decision, structural analysis is to be performed with an appropriate 'tool'. Such a tool should be rapid (because of outage cost), realistic (because repair of operating components may do more harm than good) and reliable (because of consequences of an erroneous analysis). Different parts of the proposed analysis system are described: geometry data bank; 'stress book' which gives minimum and maximum principal stresses in each point and for each transient; material characteristic data; knowledge of actual transients through the bookkeeping procedure; different possibilities to estimate stress intensity factors; various criteria; easy-to-use computer program for stress and fracture mechanics analysis. As for abnormal transients, they are discussed with regard to the transient bookkeeping procedure and/or to their fast fracture significance. (orig.)