Introduction (pressure vessel and heavy section)

Pressure vessel integrity receives much attention because the pressure vessel serves as the primary containment for the reactor core. In recognition of this function, the vessel is fabricated and qualified against a higher level of workmanship than are similar vessels used in other applications. The governing code is the ASME Boiler and Pressure Code Section III, Nuclear Vessels. Radiography is the NDE method used to verify that an acceptable level of workmanship has been achieved. Once the vessel is set in the field, jurisdiction for inspection changes to the ASME Boiler and Pressure Vessel Code Section XI, Rules for In-service Inspection of the Nuclear Power Plant Components. The primary NDE technique used to meet this requirement for periodic inspection is ultrasonic testing. Furthermore, if flaws are found, the code states how fracture mechanics analysis can be used to evaluate their engineering significance. Thus, a situation exists where fabrication quality is judged using one NDE technique, and operational (performance) integrity is verified by a different NDE technique. The overall goal of projects undertaken in this section is to develop and demonstrate a level of inspection technology that meets all operational and regulatory requirements. Specific goals are improved detection probability, improved flaw characterization ability, and fabrication of pressure vessel mockups for NDE equipment performance demonstration and personnel training