ML17306A852
| ML17306A852 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 07/28/1992 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17306A851 | List: |
| References | |
| NUDOCS 9208030161 | |
| Download: ML17306A852 (9) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SUPPLEMENTAL SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION STATION BLACKOUT EVALUATION ARIZONA PUBLIC SERVICE COMPANY ET AL.
PALO VERDE NUCLEAR GENERATING STATION UNIT NOS.
1 2
AND 3 DOCKET NOS.
50-528 50-529 AND 50-530
- 1. 0 INTRODUCTION The NRC staff's Safety Evaluation (SE) pertaining to the licensee's initial responses to the Station Blackout (SBO) rule, 10 CFR 50.63, was transmitted to the licensee by letter dated February 11, 1992.
The staff found the licensee's proposed method of coping with an SBO to be acceptable contingent upon satisfactory resolution of the recommendations presented in the SE.
The licensee responded to the Staff's SE, and specifically to the recommendations, by letter from W. F.
Conway, Arizona Public Service
- Company, to the Document Control
- Desk, U. S. Nuclear Regulatory Commission, dated March 20, 1992.
The licensee also provided clarification of information contained in the Technical Evaluation Report appended to the SE.
2.0 EVALUATION The licensee's responses to each of the staff's recommendations are evaluated below:
- 2. 1 Station Blackout Duration SE Section
- 2. 1 SE Recommendation:
The licensee needs to have an analysis showing the EDG reliability statistics for the last 20, 50, and 100 demands in its SBO submittal supporting documentation.
Licensee Res onse:
The licensee indicated that Palo Verde Nuclear Generating Station (PVNGS) has calculated the emergency diesel generator (EDG) reliability in accordance with NUMARC 87-00, Revision 1, Appendix A.
The NUMARC 87-00 reliability program was designed to monitor and maintain current EDG reliability against the EDG target reliability on a plant unit basis.
Therefore, the NUMARC 87-00 program is based on the more recent demand history of the EDG system.
The PVNGS EDG reliability database was 9208030ibi 920728 PDR ADOCK 05000528 P
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brought current in February 1992 in response to a
NUMARC EDG reliability survey.
The PVNGS EDG reliability for the past 20, 50, and 100 demands reported to NUMARC in February 1992 is as follows:
UNIT FAILURES IN 20 DEMANDS FAILURES IN 50 DEMANDS FAILURES IN 100 DEMANDS The PVNGS EDG reliability database used for this analysis is documented in PVNGS Engineering Evaluation Request 92-DG-011.
Staff Evaluation:
The staff finds the above licensee's response acceptable and, therefore, considers this SE issue resolved.
2,2 Pro osed AC AAC Power Source SE Section 2.2.2 SE Recommendation:
The licensee needs to clarify its intent with respect to the 3-month testing requirement of the AAC power source.
Licensee Res onse:
The licensee stated that it will comply with NUMARC 87-00, Appendix B, Criterion B. 10 regarding periodic testing of the Alternate AC (AAC) power source.
The licensee will develop specific plant operating procedures in accordance with manufacturer recommendations containing the following elements:
1)
A periodic operability test will be performed on each of the two gas turbine generators on 3-month intervals.
This test will include starting and operating each unit unloaded for a sufficient period to achieve stable operating parameters (temperatures, pressures, voltages, etc.).
2)
On approximately an 18-month interval, periodic tests of each gas turbine generator will be performed to demonstrate AAC operability.
This test will include a timed start (within the one-hour time period specified for SBO) and operation of each unit in parallel with the offsite source (which is feeding the emergency buses),
at rated load, until stable operating parameters are achieved.
Staff Evaluation:
The staff finds the above licensee's response to be acceptable, except that the operability test at 3-month intervals should include the gas turbine generators being tested under load.
NUMARC 87-00, Item B. 10, states that the AAC source shall be started and brought to operating conditions that are consistent with its function as an AAC source.
The staff interprets this to mean that the AAC should be load tested to verify that it can meet its intended operability and reliability.
Technical specifications are being considered by the NRC for nonsafety related
I 1 y t
SBO equipment which may prescribe further requirements as necessary to verify the operability and reliability of the AAC power source per RG 1. 155, paragraph 3.3.5, item 5.
2.3 Com ressed Air SE Section 2.3.3 SE Recommendation:
The licensee should provide its plan for the implementation of nitrogen gas supply as a backup to the compressed air for the RCP seal bleed-off valves.
Licensee Res onse:
The licensee indicated that it has no plans to perform additional modifications to the reactor coolant pump (RCP) seal bleed-off valve compressed air backup system.
The RCP seal bleed-off valves receive compressed air from the plant instrument air (IA) system.
The plant IA system is currently configured with a backup nitrogen gas system with a nitrogen gas source from both a 3,082-gallon liquid nitrogen tank and a 65,300 standard cubic feet high-pressure cylinder bank at each unit, thus providing a
sufficient source of backup air for the one hour prior to the AAC source availability during an SBO
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Staff Evaluation:
The staff finds the above licensee's response acceptable and, therefore, considers this SE issue related to the compressed air system required to cope with an SBO event at the Palo Verde plant resolved.
2.4 Pro osed Hodifications SE Section 2.5 SE Recommendation:
The licensee should include a full description including the nature and objectives of the required modifications in the documentation that is to be maintained by the licensee in support of the SBO submittal.
Licensee Res onse:
The licensee stated that it will include a full description and the nature and objectives of each modification in the SBO design change packages.
This is in accordance with the Design Change Program.
The licensee further stated that the SBO-related design modifications and procedure changes are currently scheduled to be implemented during future refueling outages as follows:
Unit 1 in November 1993, Unit 3 in April 1994, and Unit 2 in November 1994.
Because the radio systems are to be entirely replaced, it is not desirable to install battery backup to the current radio consoles in support of the SBO schedule.
Therefore, the licensee requests the SBO commitment be modified and amended as follows:
The radio communication change will be installed for all units by the fifth cycle of Unit 1, which is scheduled to be completed in February 1995.
The licensee also indicated that it has no plan to perform additional modifications to the reactor coolant pump seal bleed-off valve compressed air backup system.
For justification, refer to Section 2.3.
The licensee further stated that the atmospheric dump valve (ADV) position transmitters which are located in the turbine-driven auxiliary feedwater (AFW) pump room, are not required to be moved or upgraded with the utilization of an AAC power source to cope with an SBO.
The licensee stated that the loss of ventilation analysis for the turbine-driven AFW pump room shows that the equipment operability limits are not exceeded in the one-hour coping period prior to the initiation of the AAC power source.
Therefore, the transmitters do not need to be moved or upgraded.
Staff Evaluation:
The staff finds the above licensee's response acceptable and, therefore, considers this SE issue related to the proposed modifications at the Palo Verde plant resolved.
2.5 ualit Assurance and Technical S ecifications SE section 2.6 SE Recommendation:
The licensee should confirm that the nonsafety related equipment required to cope with a SBO event will, as a minimum, meet the criteria of Appendix A of RG 1. 155.
Licensee Res onse The licensee stated that it has confirmed that the added (new) nonsafety related systems and equipment required to cope with an SBO event will be in compliance with Appendices A and B of Regulatory Guide (RG) 1.155.
Staff Evaluation:
The staff finds the above licensee's response acceptable and, therefore, considers this SE issue related to the quality assurance at the Palo Verde plant resolved.
2.6 EDG Reliabilit Pro ram SE Section 2.7 SE Recommendation:
The licensee should confirm that its EDG reliability program will meet, as a minimum, the guidelines of RG 1. 155.
Licensee Res onse:
The licensee stated that the PVNGS has a procedure for implementation of the EDG Reliability Program.
This procedure, 70PR-ODGOl, Emergency Diesel Generator Reliability Program, was developed in accordance with NUMARC 87-00 and became effective on March 13, 1992.
NUMARC 87-00 guidance is endorsed by RG 1. 155.
Staff Evaluation:
The staff finds the above licensee's response acceptable and, therefore, considers this SE issue related to the EDG Reliability Program at the Palo Verde plant resolved.
3.0
SUMMARY
AND CONCLUSION The NRC staff's Safety Evaluation (SE) pertaining to the licensee's initial response to the SBO Rule, 10 CFR 50.63, was transmitted to the licensee by letter dated February 11, 1992.
The staff found the licensee's proposed method of coping with an SBO to be acceptable contingent upon the satisfactory resolution of the recommendations presented in the SE.
The licensee's response to each of the staff's recommendations has been evaluated in this Supplemental Safety Evaluation (SSE) and found acceptable except for the 3-month testing of the AAC power source.
The clarification of informati'on contained in the Technical Evaluation Report (Enclosure 2 to the APS letter of March 20, 1992) was also reviewed and found acceptable.
Principal Contributors:
A. Pal D.
Shum Date:
Buly 28, 1992
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