NRC-11-0022, Notification of Deviation from BWRVIP-25 Guidelines
| ML111240520 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 05/02/2011 |
| From: | Plona J DTE Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC-11-0022 | |
| Download: ML111240520 (3) | |
Text
Joseph H. Plona Site Vice President 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.5910 Fax: 734,586.4172 May 2, 2011 NRC-11-0022 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555-0001
References:
- 1) Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43
- 2) BWRVIP-25, "BWR Vessel and Internals Project, BWR Core Plate Inspection and Flaw Evaluation Guidelines," EPRI Report TR-107284, December 1996
- 3) BWRVIP-94, "BWR Vessel and Internals Project Program Implementation Guide," Revision 1, December 2005
Subject:
Notification of Deviation from BWRVIP-25 Guidelines Reference 3 requires notifying the Nuclear Regulatory Commission (NRC) anytime a utility does not implement any portion of an applicable "mandatory" or "needed" BWR Vessel and Internals Project (BWRVIP) guideline that has been approved by the BWRVIP Executive Committee and transmitted to the NRC. Reference 3 further states that the notification shall be sent to the NRC within 45 days of the utility executive concurrence with the deviation disposition.
A deviation disposition was signed by Detroit Edison's Fermi 2 Site Vice President-Nuclear Generation on March 30, 2011. The deviation is from a guideline that is designated as "needed" by the BWRVIP. The guidance requires that 50 percent of the core plate rim hold-down bolts of BWR/2-5 plants without core plate wedges be examined by enhanced visual inspection (EVT-1) from below the core plate or by ultrasonic testing (UT) from above the core plate once the technique has been developed. However, it was later determined by the BWRVIP that the bolts cannot be inspected by UT due to configuration issues.
USNRC NRC-11-0022 Page 2 Additionally, it has recently been concluded by the BWRVIP that meaningful EVT-1 examinations cannot be performed. Accordingly, a Deviation Disposition for deviation from the BWRVIP guidance was developed as required by Reference 3 and NEI 03-08, Guideline for the Management of Material Issues.
The Deviation Disposition includes analysis that concluded that the bolting has a relatively low susceptibility to cracking and a very high flaw tolerance. The 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. Furthermore, even with the extremely conservative assumptions of failures of both the bolting and the redundant hardware, the Standby Liquid Control system could be used to bring the reactor to a safe shutdown.
The BWRVIP is currently working on developing revised guidance for the Core Plate bolts and plans to submit the revised guidance for NRC review and approval. The BWRVIP schedule calls for providing approved revised guidance by December 31, 2015. Given the low likelihood of bolting failure and that the function of the core plate will not likely be compromised even if bolting failure were to occur, there is minimal risk in postponing inspections of the bolts until such time as the BWRVIP approved revised guidance becomes available.
This letter is being transmitted for NRC information only, based on the requirement in Reference 3. No regulatory action is being requested.
No regulatory commitments are included in this letter.
Should you have any questions or require additional information, please contact Mr.
Rodney W. Johnson of my staff at (734) 586-5076.
Sincerely,
USNRC NRC-11-0022 Page 3 cc:
NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 4, Region III Regional Administrator, Region III Matthew A. Mitchell, Chief, Vessels and Internals Integrity Branch Supervisor, Electric Operators, Michigan Public Service Commission