Resolution of Generic Safety Issues: Issue 190: Fatigue Evaluation of Metal Components for 60-Year Plant Life (Rev. 2) ( NUREG-0933, Main Report with Supplements 1–34 )
DESCRIPTION
The risk of failure from fatigue of various reactor coolant system components was studied under Issue 78 and later integrated into the NRR Fatigue Action Plan which was completed and documented in SECY-95-245.547 The staff concluded that the risk from fatigue failure of the primary coolant pressure boundary components is very small; this conclusion was based on a plant life of 40 years. The impact of a license renewal period of 20 years on fatigue of metal components was to be considered in the resolution of Issue 166,1564 but Issue 190 was established to address this subject separately.928
CONCLUSION
Based on the existence of an ongoing action plan928 to address the safety concern and the NRR decision1517 to pursue its resolution, the issue was considered nearly-resolved in August 1996. It was later given a high priority ranking in SECY-98-166.1718
In resolving the issue, the staff performed probabilistic analyses which showed low core damage frequencies resulting from fatigue failure of metal components. However, the nature of age-related degradation indicated the potential for an increase in the frequency of pipe leaks as plants continue to operate. Consistent with 10 CFR 54.21, "Requirements for Renewal of Operating Licenses for Nuclear Power Plants: Contents of Application - Technical Information," licensees will have to address the effects of the reactor coolant system environment on component fatigue life, as aging management programs are formulated in support of license renewal. Thus, the issue was RESOLVED with no new or revised requirements.1764
