BWR [boiling water reactor] reactor vessel in-service inspection requirements, programs, and examination results

The 1971 edition of Section XI of the ASME Boiler and Pressure Vessel Code provided inspection requirements for welds in nuclear reactor pressure vessels (RPVs). It was recognized in the foreword to that initial edition that some technological advances would have to be made before all the proposed inspections could be performed as required. When these requirements were incorporated in the Code of Federal Regulations 10 CFR 50.55a(g), there were also incorporated provisions 50.55a(g) paragraphs (5) and (6), whereby owners could under certain conditions obtain relief from the requirements. The design of the earlier RPVs of boiling water reactors (BWRs) was considered to be significantly less amenable to these inspection requirements than that of pressurized water reactors (PWRs). As the vessel design was improved, the required inspections were facilitated. Major design changes in BWR-RPVs are indicated by the type number of the plant, as BWR-1 through BWR-6. This report performs a preliminary analysis of in-service inspection programs and inspections for 35 BWR reactor vessels (Type 1 to Type 6) based on records in the NRC Public Document Room (PDR). The intent is: to determine the extent of the vessel inspections relative to the requirements of the applicable edition and addenda of Section XI of the ASME Boiler and Pressure Vessel Code; and to identify any specific areas that may need additional attention in the future. A database was developed using dBase III Plus. The database contains 2,153 records. There is a record for each BWR reactor vessel weld, nozzle, and integrally welded attachment that a utility listed in its program