Prediction of the Shift in the Brittle-Ductile Transition Temperature of Light-Water Reactor (LWR) Pressure Vessel Materials

Abstract This report presents the results of an investigation undertaken by The Metal Properties Council Subcommittee 6 on Nuclear Materials and ASTM Subcommittee E10.02 on Behavior and Use of Metallic Materials in Nuclear Systems to determine the feasibility of establishing standard design curves for the purpose of predicting changes in the toughness properties of reactor pressure vessel materials as a result of exposure to neutron irradiation. It is based on a statistical treatment of irradiation data available as of November 1977. Since the conclusion of the analytical phase of the MPC-ASTM effort, more data have been published (particularly from commercial surveillance programs) that would statistically enhance various ranges within the present analysis. Some of the recently acquired data suggest a saturation effect and nickel contribution on radiated material behavior. For these and other reasons, the expressions presented in this report should be re-evaluated on a periodic basis as new data become available. One of the important products of the MPC-ASTM effort is the computer data bank. It has been carefully scrutinized by members of the MPC and ASTM and its applicability for the present study was unmatched. The periodic updating and expanding the data bank should be considered for future analyses involving revisions to the present study or in conjunction with studies aimed at determining the response of the Charpy upper shelf energy to neutron radiation exposure or both. This report represents the opinion of MPC Subcommittee 6 concerning the predictability of the shift in the brittle-ductile transition temperature based on data available as of November 1977. The data are presented as three sets of curves: total data base, experimental data, and surveillance data. The selection of the appropriate set of curves for a given application is left to the discretion of the user. Similarly, the use of the family of mean curves versus the family of bounding curves is also left to the discretion of the user. The MPC Subcommittee 6 has recommended that this report together with its Appendix be evaluated by ASTM Subcommittee E10.02 with respect to development of a Standard Practice. Furthermore, the Subcommittee has also recommended that the ASTM Standard Practice should clearly state that the Standard Practice be used until surveillance data from a specific plant become available, at which time, the specific plant surveillance information should be controlling.