Document: NUREG-0800
Document ID: 4a46b35d-2e81-4517-9716-154b19f57049
Document Type: srp
Title: REACTOR COOLANT PRESSURE BOUNDARY MATERIALS
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0631/ML063190006.pdf
Revision Date: 2023-06
Chapter: 5
Section ID: 5.2.3
CFR Part: 
CFR Title: 

Content:
low alloy steels can be increased significantly by proper controls. In particular, the propensity for cold cracks or reheat cracks to form in areas under the bead and in heat-affected zones (HAZ) can be minimized by maintaining proper preheat temperatures of the base metal concurrent with controls on other welding variables. The 5.2.3-3 Revision 3 - March 2007 minimum preheat temperature and the maximum interpass temperatures are reviewed. (2) The quality of electroslag welds in low alloy steel components can be increased by maintaining a weld solidification pattern that possesses a strong intergranular bond in the center of the weld. The welding variables, which have a significant effect on the weld solidification pattern, must be controlled. The welding variables, solidification patterns, macro etch tests, and Charpy V-notch impact tests of electroslag welds are reviewed. It should be noted that electroslag welds characteristically exhibit a low degree of fusion between the base metal and such welds. Electroslag welds, where used in the RCPB, are reviewed with respect to regulatory guidance describing acceptable controls for the electroslag weld process. (3) Experience shows that a welder qualified to weld low-alloy steel or carbon steel components under normal fabricating conditions may not produce acceptable welds if the accessibility to the weld area is restricted. Limited accessibility can occur when component parts are joined in the final assembly or at the plant site, where other adjacent components or structures prevent the welder from assuming an advantageous position during the welding operation. The adequacy of accessibility during the welding of ferritic components is reviewed. (4) Controls can be exercised to limit the occurrence of underclad cracking in low-alloy steel components clad with stainless steel. Welding processes that generate excessive heating and promote base metal coarsening cause underclad cracking of certain steels. These variables