ML13098A064
| ML13098A064 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 04/10/2013 |
| From: | Lyon C Plant Licensing Branch IV |
| To: | Division of Operating Reactor Licensing |
| Lyon C | |
| References | |
| TAC MF1381 | |
| Download: ML13098A064 (4) | |
Text
April 10, 2013 MEMORANDUM TO:
FILE FROM:
Carl F. Lyon, Project Manager /RA/
Plant Licensing Branch IV Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
COLUMBIA GENERATING STATION -
SUMMARY
OF TELEPHONE CONFERENCE RE: VERBAL AUTHORIZATION FOR RELIEF REQUEST ISI3-13 (TAC NO. MF1381)
This memorandum summarizes the telephone discussion on April 6, 2013, between the U.S. Nuclear Regulatory Commission (NRC) staff and Energy Northwest (EN, the licensee).
The discussion was in regard to the licensee=s request for relief ISI3-13 for Columbia Generating Station (CGS). Participants in the discussion included A. Javorik, D. Gregoire, L. Williams, et al. (EN), and T. Lupold, M. Markley, F. Lyon, et al. (NRC).
By letter dated April 5, 2013, as supplemented by letter dated April 6, 2013, EN submitted for NRC review and approval Relief Request ISI3-13. The licensee discovered a leak in the reactor water cleanup (RWCU) system piping between regenerative heat exchangers RWCU-HX-1A and RWCU-HX-1B. To perform a repair/replacement activity, IWA-4412 of the 2001 Edition of American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code,Section XI, with Addenda through 2003, requires that defect removal shall be accomplished in accordance with the requirements of IWA-4420. A code repair cannot be performed during plant operations since the RWCU system needs to be placed back in service prior to reactor water chemistry parameters exceeding limits that would necessitate a plant shutdown.
EN requested approval for the use of a temporary non-Code repair of ASME Class 3 piping to prevent a reactor shutdown at CGS due to a leak on the RWCU system. The licensee proposed to install a welded pad over the leak until refueling outage 21, which is scheduled to start on May 11, 2013.
The licensee stated that the temporary non-Code repair is a fillet welded patch, in accordance with ASME Post Construction Committee (PCC)-2, Repair of Pressure Equipment and Piping, Article 2.12. The patch is fabricated from ASTM International ASTM A234 GR WPB. The pad is sized to be a 3.5 x 5.25 x 0.5 thick patch. The licensee has analyzed the welded pad and determined that the pad will meet the structural requirements of the piping system. The NRC staff has reviewed the evaluation and concludes the repair will provide reasonable assurance of structural integrity and leak tightness of the system until a permanent repair can be completed during the next refueling outage. The licensee has agreed to perform a surface examination of the fillet weld attaching the pad to the existing piping system and also to conduct additional thickness measurements adjacent to the weld which leaked to ensure there are no other areas of thin wall on the weld. In order to make an ASME Code repair, the licensee would need to
shut down the plant, because the repair would require a long system outage, which would negatively impact primary chemistry parameters and require plant shutdown. Continued operation without the RWCU system in service would also require a plant shutdown due to degrading plant chemistry. This would impose an unnecessary burden on the licensee.
The additional extent of condition welds are not required to be conducted prior to the next scheduled refueling outage due to the near-term schedule of the refueling outage and amount of radiation dose that would potentially be received by the workers, were the examinations to be conducted during power operations. The licensee has agreed that the two additional welds in the system which had extensive repairs during original construction will be included in the extent of condition examinations.
The licensee made the following regulatory commitments in its letter dated April 6, 2013, which the NRC staff concludes are acceptable, since they address the extent of condition and non-destructive examination of the weld.
- 1.
The post-maintenance testing will include a VT-2 examination.
Scheduled completion: Prior to return of RWCU to service.
- 2.
Energy Northwest will perform an augmented inspection via UT
[ultrasonic testing] or RT [radiographic testing] to assess the overall degradation of the affected system. The inspection of at least 10 susceptible (and accessible) locations for high energy lines will be performed. Locations that were re-welded during initial fabrication of the RWCU regenerative heat exchanger skid will be included in this augmented inspection. Scheduled completion: Prior to startup from Refueling Outage 21 (June 2013).
- 3.
Energy Northwest will install a camera in the RWCU heat exchanger room to provide leak monitoring until the outage. Scheduled completion:
April 8, 2013
- 4.
The non-code repair will be replaced with an ASME Code repair.
Scheduled completion: Prior to startup from Refueling Outage 21 (June 2013)
- 5.
Energy Northwest will perform a surface examination of the fillet weld associated with the repair. Scheduled completion: Prior to return of RWCU to service.
- 6.
Energy Northwest will obtain additional wall thickness measurements along the circumference of the elbow downstream of the weld.
Scheduled completion: Prior to return of RWCU to service.
The NRC staff reviewed the licensees proposed alternative under the requirements of paragraph 50.55a(g)(6)(i) of Title 10 of the Code of Federal Regulations (10 CFR), since it is impractical for the licensee to comply with the ASME Code requirement without a plant shutdown, as discussed above. The staff also used the guidance of NRC Generic Letter 90-05,
Guidance for Performing Temporary Non-Code Repair of ASME Code Class 1, 2, and 3 Piping, dated June 15, 1990 (ADAMS Accession No. ML031140590). Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(6)(i). Therefore, on April 6, 2013, the Chief, Piping and NDE Branch, Division of Engineering, and the Chief, Plant Licensing Branch IV, Division of Operating Reactor Licensing, verbally authorized the use of Relief Request ISI3-13 at CGS until startup from refueling outage 21.
All other ASME Code,Section XI requirements for which relief has not been specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
The NRC's written final safety evaluation will follow as a matter of routine. The staff may ask clarification questions as it prepares the written safety evaluation. The licensee had no additional comments or questions.
Docket No. 50-397
ML031140590). Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(g)(6)(i). Therefore, on April 6, 2013, the Chief, Piping and NDE Branch, Division of Engineering, and the Chief, Plant Licensing Branch IV, Division of Operating Reactor Licensing, verbally authorized the use of Relief Request ISI3-13 at CGS until startup from refueling outage 21.
All other ASME Code,Section XI requirements for which relief has not been specifically requested and approved in this relief request remain applicable, including third-party review by the Authorized Nuclear Inservice Inspector.
The NRC's written final safety evaluation will follow as a matter of routine. The staff may ask clarification questions as it prepares the written safety evaluation. The licensee had no additional comments or questions.
Docket No. 50-397 DISTRIBUTION:
PUBLIC LPLIV Reading RidsNrrDeEpnb Resource RidsNrrDorlLpl4 Resource RidsNrrLAJBurkhardt Resource RidsNrrPMColumbia Resource RidsRgn4MailCenter Resource JTsao, NRR/DE/EPNB DAlley, NRR/DE/EPNB JGroom, RIV WWalker, RIV JDrake, RIV ADAMS Accession No. ML13098A064
- Previously concurred OFFICE NRR/DORL/LPL4/PM NRR/DORL/LPL4/LA NRR/DORL/LPL4/BC NRR/DORL/LPL4/PM NAME FLyon JBurkhardt*
MMarkley*
FLyon DATE 4/10/13 4/9/13 4/10/13 4/10/13