No abstract

No abstract

No abstract

There is a lack of pressurized water reactor (PWR) surveillance program transition temperature shift and upper shelf toughness decrease data due to neutron irradiation exposure especially at high fluences indicative of 60 to 80 years of plant operation. The Electric Power Research Institute (EPRI) has funded the development of a supplemental reactor pressure vessel (RPV) surveillance program to allow testing of additionally irradiated specimens in two new capsules being installed in two different commercial reactor surveillance capsule positions. The previously irradiated materials were strategically selected and will be further irradiated to give final fluence levels equal to or above those for PWRs operating up to 80 years. This paper describes the final design of the capsules and selection of the key previously irradiated RPV materials reconstituted into new Charpy-size specimens being irradiated in the two PWR Supplemental Surveillance Program (PSSP) capsules.

Nuclear Reactor Pressure Vessel (RPV) integrity is a major issue concerning plant safety and this component is one of the few within a Pressurized Water Reactor (PWR) whose replacement is not considered as feasible. To ensure that adequate margins against failure are maintained throughout the vessel service life, research engineers have developed and applied computational tools to study and assess the probability of pressure vessel failure during operating and postulated loads. The Materials Ageing Institute (MAI) sponsored a benchmark study to compare the results from software developed in France, Japan and the United States to compute the probability of flaw initiation in reactor pressure vessels. This benchmark study was performed to assess the similarities and differences in the software and to identify the sources of any differences that were found. Participants in this work included researchers from EDF in France, CRIEPI in Japan and EPRI in the United States, with each organization using the probabilistic software tool that had been developed in their country. An incremental approach, beginning with deterministic comparisons and ending by assessing Conditional Probability of crack Initiation (CPI), provided confirmation of the good agreement between the results obtained from the software used in this benchmark study. This conclusion strengthens the confidence in these probabilistic fracture mechanics tools and improves understanding of the fundamental computational procedures and algorithms.