ML17312B554
| ML17312B554 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/14/1997 |
| From: | Thomas K NRC (Affiliation Not Assigned) |
| To: | James M. Levine ALABAMA PUBLIC SERVICE CO. |
| References | |
| TAC-M91817, TAC-M91818, TAC-M91819, NUDOCS 9707170032 | |
| Download: ML17312B554 (7) | |
Text
July 14, 1997 Mr. James M. Levine Executive Vice President, Nuclear
'Arizona Public Service Company Post Office Box 53999
- Phoenix, Arizona 85072-3999
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION REGARDING CHARGING SYSTEM COMMITMENTS FOR THE PALO VERDE NUCLEAR GENERATING STATION (TAC NOS.
- M91817, M91818 AND M91819)
Dear Mr. Levine:
The NRC staff has reviewed your letter dated March 9, 1995, which contained a
probabi listic argument to relinquish the charging system modification commitments.
To assist the staff in completing its evaluation of the conclusions reached in your letter, we request that you provide the additional information requested in the enclosure within 60 days of receipt of this letter.
If you have any questions, please contact me at (301) 415-1362.
Sincerely.
ORIGINAL SIGNED BY Kristine M. Thomas, Project Manager Project Directorate IV-2 Division of Reactor Projects
- III/IV Office of Nuclear Reactor Regulation Docket Nos.
STN 50-528, STN 50-529 and STN 50-530
Enclosure:
Request for Additional Information cc w/encl:
See next page DISTR]'BUTION:
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055$ 4001 Ouly 14, 1997 Hr. James H. Levine Executive Vice President, Nuclear Arizona Public Service Company Post Office Box 53999
- Phoenix, Arizona 85072-3999
SUBJECT:
REQUEST FOR ADDITIONAL INFORHATION REGARDING CHARGING SYSTEH COHHITHENTS FOR THE PALO VERDE NUCLEAR GENERATING STATION (TAC NOS.
- H91817, H91818 AND H91819)
Dear Hr. Levine:
The NRC staff has reviewed your letter dated Harch 9, 1995, which contained a
probabilistic argument to relinquish the charging system modification commitments.
To assist the staff in completing its evaluation of the conclusions reached in your letter, we request that you provide the additional information requested in the enclosure within 60 days of receipt of this letter.
If you have any questions, please contact me at (301) 415-1362.
Sincerely, Docket Nos.
STN 50-528, STN 50-529 and STN 50-530
Enclosure:
Request for Additional Information cc w/encl:
See next page
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Kristine H. Thomas, Project Manager Project Directorate IV-2 Division of Reactor Projects
- III/IV Office of Nuclear Reactor Regulation
Mr. James M. Levine cc w/encl:
Mr. Steve Olea Arizona Corporation Commission 1200 W. Washington Street Phoenix.
Arizona 85007 Douglas Kent Porter Senior Counsel
.Southern Cali fornia Edison Company Law Department, Generation Resources P.O.
Box 800 Rosemead.
California 91770 Senior Resi.dent Inspector USNRC P. 0.
Box 40 Buckeye. Arizona 85326 Regional Administrator, Region IV U. S. Nuclear Regulatory Commission Harris Tower & Pavillion 611 Ryan Plaza Drive. Suite 400 Arlington, Texas 76011-8064
- Chairman, Board of Supervisors ATTN:
Chairman 301 W. Jefferson, 10th Floor Phoenix.
Arizona 85003 Mr. Aubrey V. Godwin, Director Arizona Radiation Regulatory Agency 4814 South 40 Street Phoenix.
Arizona 85040 Ms. Angela K. Krainik, Manager Nuclear Licensing Arizona Public Service Company P.O.
Box 52034 Phoenix.
Arizona 85072-2034 Mr. John C. Horne, Vice President Power Supply Palo Verde Services 2025 N. Third Street, Suite 220 Phoenix.
Arizona 85004 Mr. Robert Burt Los Angeles Department of Water
& Power Southern California Public Power Authority 111 North Hope Street, Room 1255-B Los Angeles, California 90051 Mr. David Summers Public Service Company of New Mexico 414 Silver SW, f0604 Albuquerque, New Mexico 87102 Mr. Robert D. Bledsoe Southern California Edison Company 14300 Mesa Road.
Drop D41-SONGS San Clemente, California 92672 Mr. Robert Henry Salt River Project 6504 East Thomas Road Scottsdale, Arizona 85251 Terry Bassham, Esq.
General Counsel El Paso Electric Company 123 W. Mills El Paso, Texas 79901
ENCLOSURE PALO VERDE NUCLEAR GENERATING STATION CHARGING SYSTEM/AUXILIARYPRESSURIZER SPRAY SYSTEM COMMITMENTS RE VEST FOR ADDITIONAL INFORMATION DOCKET NOS.
STN 50-528 STN 50-529 AND STN 50-530 3.
4 5.
7.
Please explain any major differences between your cur rent PRA and the PRA used to support your IPE.
Among these differences, specifically identify differences related to loss of offsite power (LOOP) sequences and explain the differences
'and impact of LOOP risk.
Describe any review of the PRA that has been made to ensure that the current PRA represents the as-built, as-operated plant.
Discuss any changes made to the PRA due to such reviews, specifically with changes associated with the LOOP contributions.
Provide.the results of the Fussell-Vesely and Risk Achievement Worth Importance analyses for the APSS/Charging System.
Appendix A, page 7. of your submittal states that the probability of nonrecovery of offsite power was estimated at 6.0E-3 and 5.0E-4 at 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> and 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> respectively, and that these values were obtained from Figure A. 14 of'UREG-1032.
Please explain the applicabi lity of Figure A.14 (estimated frequency of losses of offsite power exceeding specified durations for Limerick) in modeling nonrecovery at your site.
Also, since NUREG-1032 was published in.1988.
how is the value of CDF given in Appendix A of yo'ur submittal (1.7E-7 core damage events/yr) affected by using more recent data on LOOP recovery?
Please explain how the LOOP initiating event frequency used in the scoping study of page 6 of 7 of Appendix A is calculated.
This value is also used in the IPE.
Had the initiating event frequency been updated to incorporate additional data attained on LOOP initiating event frequencies?
In the scoping study on page 6 of' of Appendix A, the analysis only includes depletion of the condensate storage tank (CST) as a failure mechanism for failure of auxiliary feedwater system (AFW) to perform decay-heat removal.
Please explain why other failure mechanisms of the AFW system were not included in the analysis.
In your IPE submittal, dated April 28, 1992, you state that the chemical and volume control system (CVCS)/APSS success criteria for steam generator tube rupture (SGTR) conditions is "at least one charging pump is supplying borated water from the RWT through one of the APSS valves for 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />."
- However, page 3 of the Engineering Evaluation of your March 9.
1995, submittal states that Supplement 9 to the PVNGS SER concluded that the APSS was not needed for mitigation of a design basis SGTR.
How is this consistent with your IPE SGTR success criteria?
Also, the scoping study on pages 6 and 7 of Appendix A only includes the change in CDF from LOOP initiating event.
Please explain how SGTR contributes to a decrease in CDF resulting from an increase in APSS.
rel iabi 1 ity.
On page 5-54 of your IPE, you state that the.,CVCS success criteria for ATWS conditions is one charging pump supplying 40 gpm of borated water for one hour.
The CVCS system includes both charging system and APSS.
The scoping study on pages 6 and 7 of Appendix A only includes the change in CDF from the LOOP initiating event.
Explain how improved APSS reliability contributes to a decrease in CDF resulting from AVOWS.
Also on page 5-54 of your IPE, you state that the success criteria to maintain reactor coolant system (RCS) integrity is seal injection or nuclear cooling water.
It is further stated that if loss of nuclear cooling water occurs.
the operator must secure the reactor coolant pumps (RCPs) within 10 minutes if seal, injection is available or within 5 minutes if seal injection is not available.
The success criteria for providing seal injection flow is one charging pump for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
Since the scoping study in Appendix A of your submittal only includes LOOP initiating event, please explain whether an increase in APSS reliability will decrease the contribution of loss of nuclear cooling water to CDF.
If there is an impact, please provide the quantitative CDF estimate for projected changes in APSS reliability given loss of nuclear cooling water In your PRA. what is the success criteria of the volume control tank (VCT) during a
LOOP?
What volume of inventory is requi red in the VCT during a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> LOOP?
What inventory is normally stored in the VCT?
Also, what are the setpoints for low VCT level alarm and for the closure of CHN-UV501, opening of CHN-UV514 and actuation of the BAM pumps, as shown on Figure 2 of your March 9.
1995, submittal?
What is the probability that the VCT will drain down within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> given a
LOOP?
The Engineering Evaluation of your March 9, 1995, submittal discussed the ability to recover from the charging pump gas binding event.
If a charging pump gas binding event does occur, how long will it take operators to recover from this event?
What is the, probability that the operators will recover the charging pumps from a gas binding event as a
function of time?
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