NRC-15-0104, Notification of Revision to BWRVIP Core Plate Deviation Disposition
| ML15356A601 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 12/22/2015 |
| From: | Kaminskas V DTE Electric Company |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC-15-0104 | |
| Download: ML15356A601 (3) | |
Text
Vito A. Kaminskas Site Vice President DTE Energy Company 64001N. Dixie Highway, Newport, MI 48166 Tei: 734.586.6515 Fax: 734.586.4172 Emii kamnskav~denrgy~co December 22, 2015 NRC-15-0104 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-94NP, "BWR Vessel and Internals Project Program Implementation Guide," Revision 2, September 2011
- 4) DTE Energy Letter to the NRC, "Notification of Deviation from BWRVIP-25 Guidelines," NRC-11-0022, dated May 2, 2011
Subject:
Notification of Revision to BWRVIP Core Plate Deviation Disposition A deviation disposition from a guideline that is designated as "needed" by the BWR Vessel and Internals Project (BWRVIP) was signed by DTE Electric Company's (DTE) Fermi 2 Site Vice President-Nuclear Generation on November 11, 2015.
Reference 3 requires notifying the Nuclear Regulatory Commission (NRC) anytime a utility does not implement any portion of an applicable "mandatory" or "needed" 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.
The BWRVIP-25 inspection guidelines require that 50% of the core plate rim hold-down bolts of BWR/2-5 plants not equipped with repair wedges, such as Fermi 2, be examined by enhanced visual method (EVT-1) from below the core plate, or by
USNRC NRC-15-0104 Page 2 Ultrasonic method (UT) from above the core plate. However, it was determined by the BWRVIP that the bolts cannot be inspected by UT due to configuration issues and that an EVT-1 exam does not provide meaningful results. Accordingly, a technical justification for deviation from the BWRVIP-25 guidance was developed, and DTE previously reported to the NRC (Reference 4) of the need to deviate from the BWRVIP-25 inspection guidelines, with an anticipated deviation closure date of December 31, 2015.
The deviation disposition included 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 (SLC) system could be used to bring the reactor to a safe shutdown.
The BWRVIP is currently working on developing revised guidance for the inspection of core plate bolts; however, the BWRVIP recently informed the industry that revisions to the BWRVIP-25 inspection guidance will not be available in time to support NRC approval by December 31, 2015. Therefore, DTE has revised the deviation disposition due date and is providing this notification to the NRC that the deviation will remain in place until the revised BWRVIP-25 is approved by the NRC or until some other NRC approved solution is implemented. The technical bases behind the deviation disposition were not time limited and are not affected by this revision.
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.
Alan I. Hassoun of my staff at (734) 586-4287.
Sincerely,
)
Michel A. Philippon Director - Nuclear Production For Vito A. Kaminskas
USNRC NRC-15-0104 Page 3 cc:
NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III NRC BWRVIP Project Manager Michigan Public Service Commission Regulated Energy Division (kindschldmichigan.gov)
Vito A. Kaminskas Site Vice President DTE Energy Company 64001N. Dixie Highway, Newport, MI 48166 Tei: 734.586.6515 Fax: 734.586.4172 Emii kamnskav~denrgy~co December 22, 2015 NRC-15-0104 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-94NP, "BWR Vessel and Internals Project Program Implementation Guide," Revision 2, September 2011
- 4) DTE Energy Letter to the NRC, "Notification of Deviation from BWRVIP-25 Guidelines," NRC-11-0022, dated May 2, 2011
Subject:
Notification of Revision to BWRVIP Core Plate Deviation Disposition A deviation disposition from a guideline that is designated as "needed" by the BWR Vessel and Internals Project (BWRVIP) was signed by DTE Electric Company's (DTE) Fermi 2 Site Vice President-Nuclear Generation on November 11, 2015.
Reference 3 requires notifying the Nuclear Regulatory Commission (NRC) anytime a utility does not implement any portion of an applicable "mandatory" or "needed" 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.
The BWRVIP-25 inspection guidelines require that 50% of the core plate rim hold-down bolts of BWR/2-5 plants not equipped with repair wedges, such as Fermi 2, be examined by enhanced visual method (EVT-1) from below the core plate, or by
USNRC NRC-15-0104 Page 2 Ultrasonic method (UT) from above the core plate. However, it was determined by the BWRVIP that the bolts cannot be inspected by UT due to configuration issues and that an EVT-1 exam does not provide meaningful results. Accordingly, a technical justification for deviation from the BWRVIP-25 guidance was developed, and DTE previously reported to the NRC (Reference 4) of the need to deviate from the BWRVIP-25 inspection guidelines, with an anticipated deviation closure date of December 31, 2015.
The deviation disposition included 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 (SLC) system could be used to bring the reactor to a safe shutdown.
The BWRVIP is currently working on developing revised guidance for the inspection of core plate bolts; however, the BWRVIP recently informed the industry that revisions to the BWRVIP-25 inspection guidance will not be available in time to support NRC approval by December 31, 2015. Therefore, DTE has revised the deviation disposition due date and is providing this notification to the NRC that the deviation will remain in place until the revised BWRVIP-25 is approved by the NRC or until some other NRC approved solution is implemented. The technical bases behind the deviation disposition were not time limited and are not affected by this revision.
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.
Alan I. Hassoun of my staff at (734) 586-4287.
Sincerely,
)
Michel A. Philippon Director - Nuclear Production For Vito A. Kaminskas
USNRC NRC-15-0104 Page 3 cc:
NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 5, Region III Regional Administrator, Region III NRC BWRVIP Project Manager Michigan Public Service Commission Regulated Energy Division (kindschldmichigan.gov)