PLA-6712, Deviation from BWRVIP-25 Inspection Requirements
| ML111170437 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 04/26/2011 |
| From: | Rausch T Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-6712 | |
| Download: ML111170437 (2) | |
Text
Timothy S. Rausch Sr. Vice President & Chief Nuclear Officer APR Z 6 2011 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station OP 1 - 17 Washington, DC 20555 PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3445 Fax 570.542.1504 tsrausch@pplweb.com SUSQUEHANNA STEAM ELECTRIC STATION DEVIATION PROM BWRVIP-25 INSPECTION REQUIREMENTS PLA-6712 Docket Nos. 50-387 and 50-388
Reference:
B WR Vessel and Internals Project, B Core Plate Inspection and Flaw Evaluation Guidelines (BWRVIP-25), EPRI Report TR-107284, December 1996.
BWRVIP-25 requires that 50% of the core plate rim hold-down bolts of BWRl2-5 plants without repair wedges be examined by enhanced visual methods (EVT-1) from below the core plate or by ultrasonic technique (UT) from above core plate once the technique is developed. However, it was determined that the bolts cannot be inspected by UT due to configuration issues and it has recently been concluded that an EVT-1 exam does not provide meaningful results. Accordingly, a technical justification for deviation from the BWRVIP guidance was developed.
The technical justification included an analysis that found that the bolting has a relatively low susceptibility to cracking and a very high flaw tolerance, and that postulated flaws would not grow to a size that significantly reduces the bolt preload over the life of the plant. Even if significant cracking did occur in the bolting, redundant structural components will prevent adverse displacement of the core plate.
The BWRVIP is currently working on developing revised guidance for the Core Plate bolts and expects to complete that work, including gaining NRC approval of the revised guidance, by 20 15. The deviation from BWRVIP-25 guidance will remain in affect until the guidance is revised and implemented in accordance with our current commitments to the BWRVIP Program. Given the low likelihood that the function of the core plate will be compromised by bolting failures, there is little risk in postponing inspections of the bolts until the BWRVIP develops revised guidance.
This letter is being transmitted for information only and PPL Susquehanna, LLC is not requesting any action from the NRC staff.
Document Control Desk PLA-67 12 Should you have any questions, please contact Cornelius T. Coddington at (6 10) 774-40 19.
Sincerely,
- v.
S Rausch Copy: NRC Regional I Mr. P. W. Finney, NRC Sr. Resident Inspector Mr. R. R. Janati, DEPIBRP Mr. B. K. Vaidya, NRC Project Manager