ML033570331
| ML033570331 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 12/19/2003 |
| From: | Shukla G NRC/NRR/DLPM/LPD4 |
| To: | Rueger G Pacific Gas & Electric Co |
| Shukla G, NRR/DLPM/LPDIV-2/415-8439 | |
| References | |
| TAC MB9969 | |
| Download: ML033570331 (5) | |
Text
December 19, 2003 Mr. Gregory M. Rueger Senior Vice President, Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Nuclear Power Plant P. O. Box 3 Avila Beach, CA 93424
SUBJECT:
REVIEW OF DIABLO CANYON NUCLEAR POWER PLANT, UNIT NO. 2 -
2003 REFUELING OUTAGE 11 STEAM GENERATOR INSPECTIONS 90-DAY REPORT (TAC NO. MB9969)
Dear Mr. Rueger:
By letter dated June 23, 2003, and supplemental letters dated September 30 and October 31, 2003, Pacific Gas and Electric Company submitted a report summarizing the steam generator tube inspections performed during the 2003 Diablo Canyon Power Plant Unit 2 eleventh refueling outage (2R11).
As discussed in the enclosed safety evaluation, the staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff did not identify any technical issues that warranted follow-up action at this time.
Sincerely,
/RA/
Girija S. Shukla, Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-323
Enclosure:
Safety Evaluation cc w/encl: See next page
December 19, 2003 Mr. Gregory M. Rueger Senior Vice President, Generation and Chief Nuclear Officer Pacific Gas and Electric Company Diablo Canyon Nuclear Power Plant P. O. Box 3 Avila Beach, CA 93424
SUBJECT:
REVIEW OF DIABLO CANYON NUCLEAR POWER PLANT, UNIT NO. 2 -
2003 REFUELING OUTAGE 11 STEAM GENERATOR INSPECTIONS 90-DAY REPORT (TAC NO. MB9969)
Dear Mr. Rueger:
By letter dated June 23, 2003, and supplemental letters dated September 30 and October 31, 2003, Pacific Gas and Electric Company submitted a report summarizing the steam generator tube inspections performed during the 2003 Diablo Canyon Power Plant Unit 2 eleventh refueling outage (2R11).
As discussed in the enclosed safety evaluation, the staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff did not identify any technical issues that warranted follow-up action at this time.
Sincerely,
/RA/
Girija S. Shukla, Project Manager, Section 2 Project Directorate IV Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket No. 50-323 DISTRIBUTION:
PUBLIC
Enclosure:
Safety Evaluation PDIV-2 Reading RidsNrrDlpmLpdiv (HBerkow) cc w/encl: See next page RidsNrrPMGShukla RidsNrrLAEPeyton RidsAcrsAcnwMailCenter RidsOgcRp RidsRgn4MailCenter (BJones)
LLund KKarwoski
- Memo dated Accession No: ML033570331 NRR-106 OFFICE PDIV-2/PM PDIV-2/LA EMCB/SC*
PDIV-2/SC NAME GShukla EPeyton LLund SDembek DATE 12/18/03 12/18/03 12/4/03 12/19/03 OFFICIAL RECORD COPY C:\\ORPCheckout\\FileNET\\ML033570331.wpd
Diablo Canyon Power Plant, Unit 2 cc:
NRC Resident Inspector Diablo Canyon Power Plant c/o U.S. Nuclear Regulatory Commission P.O. Box 369 Avila Beach, CA 93424 Sierra Club California 2650 Maple Avenue Morro Bay, California 93442 Ms. Nancy Culver San Luis Obispo Mothers for Peace P.O. Box 164 Pismo Beach, CA 93448 Chairman San Luis Obispo County Board of Supervisors Room 370 County Government Center San Luis Obispo, CA 93408 Mr. Truman Burns Mr. Robert Kinosian California Public Utilities Commission 505 Van Ness, Room 4102 San Francisco, CA 94102 Diablo Canyon Independent Safety Committee ATTN: Robert R. Wellington, Esq.
Legal Counsel 857 Cass Street, Suite D Monterey, CA 93940 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 Richard F. Locke, Esq.
Pacific Gas & Electric Company P.O. Box 7442 San Francisco, CA 94120 Mr. David H. Oatley, Vice President and General Manager Diablo Canyon Power Plant P.O. Box 56 Avila Beach, CA 93424 City Editor The Tribune 3825 South Higuera Street P.O. Box 112 San Luis Obispo, CA 93406-0112 Mr. Ed Bailey, Radiation Program Director Radiologic Health Branch State Department of Health Services P.O. Box 942732 (MS 178)
Sacramento, CA 94234-7320 Mr. James D. Boyd, Commissioner California Energy Commission 1516 Ninth Street (MS 31)
Sacramento, CA 95814 Mr. James R. Becker, Vice President Diablo Canyon Operations and Station Director Diablo Canyon Power Plant P.O. Box 3 Avila Beach, CA 93424
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION OF THE STEAM GENERATOR 90-DAY REPORT PACIFIC GAS AND ELECTRIC COMPANY DIABLO CANYON UNIT 2 DOCKET NO. 50-323
1.0 INTRODUCTION
By letter dated June 23, 2003, and supplemental letters dated September 30 and October 31, 2003, Pacific Gas and Electric Company (PG&E or licensee) submitted a report summarizing the steam generator tube inspections performed during the 2003 Diablo Canyon Power Plant Unit 2 eleventh refueling outage (2R11).
2.0 STAFF EVALUATION The scope and results of the licensees inspections are contained in the documents referenced above. Based on a review of the above documents, the staff concludes that the licensee provided the information required by their technical specifications. In addition, the staff did not identify any technical issues that warranted follow-up action at this time. However, the staff's observations regarding the licensees inspection and assessments are given below:
1.
The staff made several observations following its review of the Unit 1 2002 inspection summary reports, which are documented in an NRC letter dated November 20, 2003 (ADAMS Accession No. ML33250133). These observations are also applicable to Unit 2 and, therefore, not repeated here.
2.
In response to question 3 of the staffs requests for additional information (RAI) on the W* alternate repair criteria (ARC), the licensee provided a rationale for why no adjustment for crack growth is required in the flexible W* criterion for unflawed tubes. In their response, the licensee indicated that new indications are not anticipated to have sufficient through-wall depth to significantly decrease the contact pressure between the tube and tubesheet hole. The licensee, however, did not provide any data supporting their assertion that these newly initiated flaws (either axial or circumferential) do not significantly decrease the contact pressure. In future condition monitoring assessments, the licensee should consider providing the supporting data which confirms that the depths representative of newly initiated flaws in the W* region do not significantly decrease the contact pressure. This issue is more important as the potential for flaws below the W* region increases since any degradation below the W* region when combined with the newly initiated degradation in the W* region may result in a longer length of tubing being required to reduce the potential for tube pullout.
3.
In response to questions 5 and 6 of the staffs RAI on the W* ARC, the licensee discussed laboratory test data supporting a conclusion that a higher differential pressure across a tube wall will result in increased leakage for indications in the tubesheet region (which would result in conservative estimates of the leakage). In their response, however, the licensee did not discuss whether the existing leakage models also exhibited a similar trend. In approving the W* repair criteria, the NRC safety evaluation discussed some limitations in the leakage model. Nevertheless, the staff concluded the leakage model was acceptable for several cycles, in part, because the number of steam generator tubes affected by primary water stress corrosion cracking should remain low for the period of time for which the ARC was approved. Assuming that it may be desirable to use the W* ARC for longer period of times (i.e., beyond the period it is currently approved for), it appears that this issue would need to be addressed in a future technical specification amendment request. In addition, the effect of temperature changes during the postulated accident conditions may also need to be addressed in future amendment requests.
Principal Contributor: Ken Karwoski Date: December 19, 2003