View Rule

The NRC staff is preparing a regulatory basis for a proposed rule that would amend the Commission's regulations in part 50, appendix G to provide a risk-informed option for determining the fracture toughness requirements for ferritic materials of the pressure-retaining components of the reactor coolant pressure boundary. The proposed rule would also modify those requirements for pressure-temperature limits that are related to the metal temperature of the reactor pressure vessel closure head flange and vessel flange areas. Also, the proposed rule would amend footnotes 2 and 6 to table 1 of appendix G, and simplify restructuring of the table. The proposed rule would also modify part 50, appendix H, which contains reactor vessel material surveillance program requirements to monitor changes in the fracture toughness properties of the reactor vessel beltline due to neutron irradiation. This rule will also resolve issues raised in PRM-50-69. The appendix G and H rulemaking was bifurcated in August 2014, the Commission directed the staff to move forward on the appendix H rulemaking independent of the completion date or conclusions of appendix G technical basis development activities.