ML16300A266
| ML16300A266 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 10/21/2016 |
| From: | David Alley Piping and NDE Branch |
| To: | Robert Pascarelli Plant Licensing Branch IV |
| Rezai A | |
| Shared Package | |
| ML16300A178 | List: |
| References | |
| CAC MF8308 | |
| Download: ML16300A266 (1) | |
Text
ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION RELIEF REQUEST I3R-13 REGARDING WELD EXAMINATION COVERAGE WOLF CREEK NUCLEAR OPERATING CORPORATION WOLF CREEK GENERATING STATION DOCKET NUMBER 50-482 By letter dated August 23, 2016 (Accession Number ML16243A039), Wolf Creek Nuclear Operating Corporation (the licensee) requested relief from the requirements of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code) specifically related to ASME Code Case N-460 Alternative Examination Coverage for Class 1 and Class 2 Welds,Section XI, Division 1. Relief request I3R-13 pertains to the examination coverage of the Class 1 and 2 piping welds at the Wolf Creek Generating Station (Wolf Creek).
To complete its review, the U.S. Nuclear Regulatory Commission (NRC) staff requests the following additional information.
- 1. Given the susceptibility to thermal fatigue and the reduced coverage obtained, and for assurance of structural integrity of unexamined volume of the weld, provide cumulative fatigue usage factor for each weld.
- 2. The NRC staff notes that the refracted longitudinal waves have shown to have better penetration capability in the cast austenitic stainless steel and austenitic stainless steel materials, and they could be used as an extra effort to scan the far-side of examination volume (Best Effort examination). The NRC staff also notes that the Best Effort examination is not a requirement. Given the reduced inspection coverage of the weld under consideration:
- a. Discuss whether the license performed the Best Effort examination as an extra effort to interrogate the required downstream examination volume (far-side),
particularly the root of the weld and the heat affected zone of the base materials typically susceptible to high stresses and potential degradation, If not, explain;
- b. Provide percentage of coverage obtained from the Best Effort examination if this examination was performed.