ML20217N472
| ML20217N472 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 02/27/1998 |
| From: | Wessman R NRC (Affiliation Not Assigned) |
| To: | Thomas C NRC (Affiliation Not Assigned) |
| Shared Package | |
| ML20217N453 | List: |
| References | |
| TAC-MA0106, TAC-MA106, NUDOCS 9804090107 | |
| Download: ML20217N472 (1) | |
Text
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wasumoton, s.c. mass enes February 27, 1998 MEMORANDUM TO: Cecil O. Thomas, Jr., Director Project Directorate I-3 Division of Reactor Projects Ull FROM:
O Richard H. Wessman, Chief
[VMechanical Engineering Branch Division of Engineering
SUBJECT:
CRACKING OF EDG LUBE OIL PIPING AT VERMONT YANKEE (TAC No. MA0106)
By letter dated November 10,1997. Region I requested NRR's assistance in reviewing the structural integrity of the skid-mounted piping associated with the emergency diesel generators (EDGs) at Vermont Yankee (VY). VY recently completed an operability determination for the EDG in order to address a degraded condition in the skid mounted support piping associated with the EDGs. The welds in the skid mounted piping were found to be less than full-penetration welds as assumed in the original design basis. The EDGs are required to remain operable during a design basis earthquake.
Several plants, including Crystal River, Millstone, and Vermont Yankee, have experienced problems with degradation of these welds during normal operation. Subsequent evaluebon showed significant lack of penetration and general lack of quality in the welds. In the VY case, the licensee has replaced a section of lube oil piping, added some additional supports, and performed metallurgical examination and destructive load testing of sample welds removed from the system. ' Based on the examination and testing of the piping, the licensee completed an operability determination which concluded that the EDGs remain operable for both normal operational loads and seismic loads that would be experienced in a design basis earthquake.
The Mechanical Engineering Branch and the Materials and Chemical Engineering Branch have completed a res aw of the licensee's submittals. Based on its review, the staff finds that there are no immediate safety concems regarding the near-term operability of the EDGs. However, the staff has identified a number of concoms in the structural analyses and metallurgical examinations performed by the licensee. Pending resolution of these concerns, and further actions by the licensee to demonstrate long-term operability, the staff is recommending augmented inspection of the EDGs during testing. Our evaluation is attached.
Attachment:
As stated CONTACT: J. Rajan, NRR/EMEB 415-2788 9804090107 980310 Attachment DR ADOCK 050002 1