ML042870604
| ML042870604 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 10/08/2004 |
| From: | Baranowsky P NRC/RES/DRAA/OERAB |
| To: | Leach M, Marsh L NRC/NRR/DLPM, NRC/RGN-III |
| References | |
| IR-04-012 | |
| Download: ML042870604 (4) | |
Text
October 8, 2004 MEMORANDUM TO:
Ledyard B. Marsh, Director Division of Licensing Project Management Office of Nuclear Reactor Regulation FROM:
Patrick W. Baranowsky, Chief /RA/
Operating Experience Risk Analysis Branch Division of Risk Analysis and Applications Office of Nuclear Regulatory Research
SUBJECT:
TRANSMITTAL OF PRELIMINARY PALO VERDE UNITS 1, 2, AND 3 ASP ANALYSIS FOR EXTERNAL PEER REVIEW This memorandum provides a preliminary Accident Sequence Precursor (ASP) analysis of a loss of offsite power event which occurred at Palo Verde Units 1, 2, and 3 on June 14, 2004.
This event is documented in NRC Inspection Report 50-528/04-012, dated July 16, 2004, and Licensee Event Report (LER) 528/04-06, dated August 13, 2004. This analysis is being issued for simultaneous staff and licensee peer review.
NRC peer review requested. Please review the preliminary ASP analysis and provide us with any comments that you may have. We are requesting that DLPM coordinate reviews from SPSB, IIPB, and Region IV. In order to facilitate incorporation of licensee and staff comments and preparation of the final report in a timely manner, consistent with the NRR and RES agreement on peer review, please provide your comments to us within 60 calendar days from the date of this memorandum.
Licensee peer review requested. We are also requesting NRR/DLPM to send the preliminary ASP analysis to the licensee for peer review. Since each preliminary ASP analysis undergoes an in-house independent review before it is sent out by OERAB, peer review by NRR and the region can be performed concurrently with the licensees review. This process is also consistent with the NRR/RES peer review agreement. The analysis and a transmittal letter will be provided separately to the NRR ASP Program liaison (Roy Mathew). This letter reflects the modifications made by NRR/DLPM based on recent preliminary analyses sent to licensees, as well as the instruction added to the letter regarding the transmittal of comments by the licensee that may contain potentially sensitive information.
Event Summary: On June 14, 2004, at approximately 7:41 a.m. MST, a ground-fault occurred on Phase C of a 230 kV transmission line in northwest Phoenix, Arizona, between the West Wing and Liberty substations located approximately 47 miles from the Palo Verde Nuclear Generating Station (PVNGS). A failure in the protective relaying resulted in the ground fault not isolating from the local grid for approximately 38 seconds. This uninterrupted fault cascaded into the protective tripping of a number of 230 kV and 500 kV transmission lines, a nearly concurrent trip of all three PVNGS units and the loss of six additional generation units nearby within approximately 30 seconds of fault initiation.
2 Offsite power was restored to the East Switchyard Bus at 0813, 32 minutes after power was lost. Licensed operators declared the grid stable at 0830, and at 0838 and 0844, power was restored to the Startup Transformers X01 and X03 respectively. All three units were shutdown and stabilized under hot shutdown conditions. However, two complications were experienced during the event: (1) the Unit 2 emergency diesel generator (EDG) A failed to load and (2) two breakers failed to close during recovering offsite power to Units 1 and 3.
ASP analysis calculated the mean conditional core damage probability (CCDP) of 7x10-4 for Unit 2 and 4x10-5 for Units 1 and 3. The uncertainty range for Unit 2 is 3x10-5 (5% uncertainty bound) to 3x10-3 (95% uncertainty bound), and for Units 1 and 3 is 6x10-6 (5% uncertainty bound) and 1x10-4 (95% uncertainty bound). These results are consistent with the Augmented Inspection Team (AIT) results. Furthermore, the AIT used draft ASP results in their report.
The ASP analysis can be found at ML042590206. If you have any questions about the analysis, please contact Christopher Hunter (415-4127).
Sensitive information. The detailed ASP analyses are classified as SENSITIVE - NOT FOR PUBLIC DISCLOSURE. This classification is based on the guidance provided by the EDO in the memorandum to the Commission (dated April 4, 2002) concerning the release of information to the public that could provide significant assistance to support an act of terrorism. In particular, Criteria 1 was determined to apply to ASP analysis reports:
Plant-specific information, generated by NRC, our licensees, or our contractors, that would clearly aid in planning an assault on a facility. An example might be drawings depicting the location of certain safety equipment within plant buildings. Examples may include portions of Final Safety Analysis Reports (FSARs),
Individual Plant Examination (IPE) material, and other risk and facility vulnerability information.
This classification could change in the future based on revised Agency guidance and office (NRR and RES) procedures in response to the Staff Requirements Memorandum, Staff Requirements -
COMSECY-02-0015 - Withholding Sensitive Homeland Security Information From the Public, dated April 4, 2002. Future changes in the transmittal of ASP analyses will be coordinated with the NRR ASP Program liaison. The sensitive ASP analyses are referenced in Adams for NRC staff use only.
For questions concerning the transmittal letter or the ASP Program, please call Don Marksberry (415-6378).
2 Offsite power was restored to the East Switchyard Bus at 0813, 32 minutes after power was lost.
Licensed operators declared the grid stable at 0830, and at 0838 and 0844, power was restored to the Startup Transformers X01 and X03 respectively. All three units were shutdown and stabilized under hot shutdown conditions. However, two complications were experienced during the event: (1) the Unit 2 emergency diesel generator (EDG) A failed to load and (2) two breakers failed to close during recovering offsite power to Units 1 and 3.
ASP analysis calculated the mean conditional core damage probability (CCDP) of 7x10-4 for Unit 2 and 4x10-5 for Units 1 and 3. The uncertainty range for Unit 2 is 3x10-5 (5% uncertainty bound) to 3x10-3 (95% uncertainty bound), and for Units 1 and 3 is 6x10-6 (5% uncertainty bound) and 1x10-4 (95% uncertainty bound). These results are consistent with the Augmented Inspection Team (AIT) results. Furthermore, the AIT used draft ASP results in their report.
The ASP analysis can be found at ML042590206. If you have any questions about the analysis, please contact Christopher Hunter (415-4127).
Sensitive information. The detailed ASP analyses are classified as SENSITIVE - NOT FOR PUBLIC DISCLOSURE. This classification is based on the guidance provided by the EDO in the memorandum to the Commission (dated April 4, 2002) concerning the release of information to the public that could provide significant assistance to support an act of terrorism. In particular, Criteria 1 was determined to apply to ASP analysis reports:
Plant-specific information, generated by NRC, our licensees, or our contractors, that would clearly aid in planning an assault on a facility. An example might be drawings depicting the location of certain safety equipment within plant buildings. Examples may include portions of Final Safety Analysis Reports (FSARs),
Individual Plant Examination (IPE) material, and other risk and facility vulnerability information.
This classification could change in the future based on revised Agency guidance and office (NRR and RES) procedures in response to the Staff Requirements Memorandum, Staff Requirements -
COMSECY-02-0015 - Withholding Sensitive Homeland Security Information From the Public, dated April 4, 2002. Future changes in the transmittal of ASP analyses will be coordinated with the NRR ASP Program liaison. The sensitive ASP analyses are referenced in Adams for NRC staff use only.
For questions concerning the transmittal letter or the ASP Program, please call Don Marksberry (415-6378).
To receive a copy of this document, indicate in the box: C = Copy wo/encl E = Copy w/encl N = No copy e = e-mail copy OFFICE OERAB C
OERAB e
OERAB E
OERAB N
NAME CHunter DMarksberry MCheok PBaranowsky DATE 9/15/04 9/15/04 9/23/04 10/8/04 OFFICIAL RECORD COPY OAR in ADAMS? (Y or N)
Y Publicly Available? (Y or N)
N Template Number: RES-006 Accession Number: ML042870604 RES File Code: 2C-3
3 MEMORANDUM DATED: 10/8/04
SUBJECT:
TRANSMITTAL OF PRELIMINARY PALO VERDE UNITS 1, 2 AND 3 ASP ANALYSIS FOR INTERNAL AND LICENSEE PEER REVIEW Distribution:
OERAB RF WBeckner, NRR RBywater, RIV (SRA)
DRAA RF BBoger, NRR GWarnick, RIV (SRI)
File Center DCoe, NRR MSnodderly, ACRS RGibbs, NRR/IIPB JCraig/CPaperiello, RES RMathew, NRR CAder, RES MTschiltz, NRR FEltawila, RES SWong, NRR/IIPB MGamberoni, RES MCaruso, NRR GLanik, RES MFields, NRR (PM)
JDyer, NRR BMallett, RIV BSheron, NRR AHowell, RIV (DRP)
RBarrett, NRR DChamberlain, RIV (DRS)
HBerkow, NRR DLoveless, RIV (SRA)