A STUDY ON PROBABILISTIC FRACTURE-MECHANICS FOR NUCLEAR PRESSURE-VESSELS AND PIPING

This paper describes some recent research activities on probabilistic fracture mechanics (PFM) for nuclear pressure vessels and piping (PV&P ) performed by the RC111 research committee of the Japan Society of Me chanical Engineers (JSME) under a subcontract of the Japan Atomic Ener gy Research Institute (JAERI). To establish standard procedures for ev aluating failure probabilities of nuclear PV&P, we have set up the fol lowing three kinds of PFM round-robin problems on: (a) primary piping under normal operating conditions, (b) aged reactor pressure vessel (R PV) under normal and upset operating conditions, and (c) aged RPV unde r pressurised thermal shock (PTS) events. The basic problems of the la st one are chosen from some US benchmark problems such as EPRI (Electr ic Power Research Institute) and US NRC (Nuclear Regulatory Commission ) joint PTS benchmark problems. For the above round-robin problems, va rious sensitivity analyses are performed to quantify effects of uncert ainty of data on failure probabilities. This paper summarizes some sen sitivity studies on the above three kinds of problems mainly varying m aterial properties such as flow stress, fracture toughness, fatigue cr ack growth rate, Cu content. Employed in this study are the PFM comput er codes developed in Japan and USA. Failure probabilities of nuclear PV&P are quantitatively discussed in detail. (C) 1997 Elsevier Science Ltd.