Task 4: Validation of Irradiation and Aged Materials

The purpose of this task is to validate the assessment of the effects of neutron irradiation on the fracture-toughness properties of typical RPV materials obtained in the previous HSSI (L1098) Program, tasks 2 and 3 of this program, and retired RPVs. This is accomplished through the examination of the effects of neutron irradiation on the fracture toughness (ductile and brittle) of the HAZ of welds and of typical plate materials used in RPVs. The irradiated materials from retired RPVs will be machined and tested in the Irradiated Materials Examination and Testing (IMET) hot cells. The feasibility of reconstitution for CVN and 0.5T C(T) and aging of stainless steel welds will also be explored in this task. Other issues to be address include foreign interactions and technical assistance to the NRC.

A specially procured, computer-numerically-controlled (CNC) milling machine, the so-called prototyping mill, is being used in an unirradiated environment to develop and test the computer programs that subsequently control the sequence of operations used to machine Charpy specimens. Using Japan Power Demonstration Reactor (JPDR) material specimens on a nearly identical machine in the hot cell, CVN specimens were machined and tested with minimal problems.