ML19353B184
| ML19353B184 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 12/04/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19353B182 | List: |
| References | |
| NUDOCS 8912120117 | |
| Download: ML19353B184 (4) | |
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION i
RELATED TO AMENDMENT NO. 29 TO FACILITY OPERATING LICENSE NO. NPF-51 AND AMENDMENT NO. 19 TO FACILITY OPERATING LICENSE NO. NPF-74 ARIZONA PUBLIC LERVICE COMPANY. ET AL.
PALO VERDE NUCLEAR GiNERATING STATION. UNITS 2 AND 3 DOCKET NOS. STN 50-529 AND STN 50-530
1.0 INTRODUCTION
By letter dated October 25, 1989 the Arizona Public Service Company (APS) on behalf of itself, the Salt River Project Agricultural Improvement and Power District, Southern California Edison Company, El Paso Electric Company, Public Service Company of New Mexico Los Angeles Department of Water and Power, and Southern California Public Power Authority (licensees),requestedchangestotheTechnicalSpecificationsforthe Palo Verde Nuclear Generating Station, Units 1, 2 and 3 (Appendix A to Facility Operating License Nos. NPF 41, NPF-51 and NPF-74, respectively).
The proposed amendments were requested on an emergency basis for Units 2 and 3 to preont unnecessary delays in return to power. The review of the proposed changes for Unit 1 is being performed separately.
The proposed changes would revise surveillance requirement 4.5.2.h to Technical Specification 3/4.5.2, " Emergency Core Cooling Systems," by I
specifying minimum flow requirements during simultaneous hot leg and cold l
1eg injection.
In addition, a maximum pump flowrate requirement would be specified to ensure pump protection against runout.
2.0 DISCUSSION AND EVALUATION l
Surveillance requirement 4.5.2.h of Technical Specification (TS) 3/4.5.2,
" Emergency Core Cooling Systerrs" currently specifies a flow rate require-ment of 545 t 20 gpm for high pressure safety injection (HPSI) pump simultaneous hot leg and cold leg injection flow balancing.
The intent of the TS was to ensure approximately balanced flow to the hot leg and I
cold legs during ~ post-LOCA recirculation, and to ensure that a maximum l
HPSI pu np design flowrate of 1130 gpm, as specified in the CESSAR FSAR, would not be exceeded.
On October 20, 1989, APS discovered that due to an error in the original installation of the flow measuring orifices in the "A" train HPSI pump hot leg injection lines, and the use of inappropriate flow calibration curves during system testing, the existing surveillance acceptance criteria could not be met.
8912120117 891204 PDR ADOCK 05000529 F'
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The orifices installed in the "A" train HPSI pump hot leg injection line for each of the three Palo Verde units were larger in diameter than specified in the instrument data sheets. This resulted in the HPSI hot leg injection flow indication reading less than the actual flow during the performance of the simultaneous hot leg and cold leg injection testing required by TS 4.5.2.h.
Since the test was perfonned with the hot leg flow indicators reading lower than actual flow, tie actual hot leg flows after correcting for the misinstalled orifices, were approximately 30 gpm higher than the indicated flow, thus exceeding the TS limit. These orifices only provide flow indication and do not provide a flow control function.
APS could reperform the surveillance test to readjust the flows to be within the TS allowables, but can only do so in Mode 5 with a reduced inventory, or in Mode 6.
This option was not considered viable by the licensees since Unit 2 was in Mode 3, and Unit 3 was in Mode 5, preparing for mode change.
The proposed surveillance requirements would maintain the current minimum flowraterequiredforhotlegandcoldleginjection(525gpm)butwould remove the upper limit on injection flowrate to the extent that total pump flowrate would not exceed 1200 gpm. This maximum total flow, to prevent pump runout, is based on the installed capabilities of the HPSI pumps rather than the design specification runout flow of 1130 gpm.
Based upon our review of the pump characteristic curves for the associated HPSI pumps and currently installed impe11ers, we conclude that the proposed TS changes are acceptable.
The proposed changes to the associated Bases, and the corrections to the typographical errors are also acceptable.
FINAL SIGNIFICANT HAZARDS CONSIDERATION DETERMINIATION In accordance with the requirements of 10 CFR 50.92, the licensee stated that the changes involved no significant hazards consideration and submitted the following analysis:
" Standard I - Involve a significant increase in the probability or consequences of an accident previously evaluated.
The proposed amendment increases the maximum allowable flow from the HPSI pump during simultaneous hot and cold leg injection.
The HPSI
)um) minimum runout flow was originally specified at 1130 gpm in
>ot1 the Combustion Engineering Standard Safety Analysis Report System 80(CESSAR)andtothepumpvendor,Ingersol~ SIC]-Rand.
Ingersol[ SIC]-Randhasverifiedthatthepumpsthatl SIC]arecapable of flows greater than 1200 gpm. This amendment utilizes the measured capability of the pump to increase the operational flexibility in the hot and cold leg simultaneous injection flow balancing.
The assumptions in the safety analysis are not affected as the minimum flow values to both the hot and cold legs are maintained. The increased maximum flow value will increase the margin of safety in the analysis by allowing increased flushing flow to the vessel while maintaining the HPSI pump below its runout flowrate."
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" Standard 2 - Create the possibility of a new or different kind of accident from any accident previously evaluated.
The proposed amendment to the Technical Specification Surveillance Requirements does not alter the plant configuration or operation.
Credit is taken for the actual installed capability of the HPSI pumps, increasing the maximum allowable flow beyond the minimum design specification of 1130 gpm can improve the plants [ SIC] performance during the long-term cooling phase of a loss of coolant accident.
The increased flow can provide a greater flushing action to prevent boron precipitation in the vessel and more water for decay heat removal during the long-term cooling phase of the accident."
'! Standard 3 - Involve a significant reduction in a margin of safety.
l As discussed in Standard 2, the proposed amendment can improve the t
margin of safety during the long-term cooling following a loss of coolant accident. The margin of safety during long-term cooling is determined by adequate flow to the vessel to match decay heat boiloff, prevent boron precipitation in the reactor vessel, and keep the HPSI pump flow below runout.
All three of these requirements will be i
satisfied by the proposed anendment. The increased allowable flow can provide more margin to the flow required to the vessel to match the boiloff due to decay heat an;i prevent boron precipitation. The higher maximum allowable flow will also be below the runout condition of the HPSI pump. The PVNGS Nuclear Engineering Department also performed a l
review of the net positive suction head (NPSH) requirements for the NPSI pump and the diesel generator loading during long-term cooling and found this change to be acceptable to both.
The proposed change does not match any of the examples, given ir. 51 FR 7751 of amenaments, that do not involve a significant hazards consideration. The proposed amendment is a change resulting from a review of the installed equipment capabilities versus the original specification, in this case the allowable flowrate value was provided by Combustion Engineering and Ingersol[ SIC]-Rand after a review of the HPSI pump performance. This review verified that the HPSI pump will perform in excess of the original minimum design specifications for runout and allows this proposed increase in operational flexibility during simultaneous hot and cold leg HPSI pump flow balancing "
The staff has reviewed the licensees' significant hazards consideration determination and concurs with the licensees that the changes do not involve a significant hazards consideration.
FINDING.ON EXISTENCE OF.EMERGEWCY. SITUATION In their submittal of October 25, 1989, the licensees explain that the misinstalled flow measuring orifices were discovered on October 20, 1989 while both Units 2 and 3 were making preparations to return to power (Unit 2 was in Mode 3 and Unit 3 was in Mode 5 with the reactor coolant system
. closed). Thus reperformance of the flow balancing surveillance woulo have significantly delayed plant startup.
The staff has reviewed the submittal and concludes that since the previous surveillance test demonstrated that the minimum flow requiraments for maximum hot leg injection flowrate (jection were met and that the actualin excess simultaneous hot leg and cold leg in not have resulted in the HPSI pump exceeding it capacity, failure to act in a timely manner would result in an unnecessary delay of plant startup.
Also, the licensee made a timely application for amendment af ter discovering the installation error. Accordingly, the Comission granted emergency authorization on October 26, 1989 and is issuing these amendments under the provisions of 10 CFR 50.91 (a)(5).
l 4.0 CON _ TACT WITH. STATE OFFICIAL The Arizona Radiation Regulatory Agency was advised on October 26, 1989, of the proposed issuance of the emendment. No conenents were received.
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5.0 ENVIRONMENTAL CONSIDERATION
i l-The anandments involve changes in the surveillance requirements of facility components located within the restricted area os defined in 10 CFR Part
- 20. The staff has determined that the amendments involve no significant increase in the amount, and no significant change in the type, of any effluent that may be released offsite and that there is no significant increase in individual or cumulative occupational radiation exposure.
Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need to be prepored in connection with the issuance of the amendments.
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6.0 CONCLUSION
The staff has concluded, baseo on the considerations aiscussed above, that (1) there is reosonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Comission's regulations, and (3) the issuance of the amendments will not be inimical to the comon defense and security or to the health and safety of the public. We, therefore, conclude that the charges are accept 6ble.
Principal contributor: T. Chan Dated: December 4,1989 l
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