ML20235Z502

Application for Amends to Licenses NPF-68 & NPF-79,revising Tech Spec 4.5.2.h.1(b) by Raising Max Flow Rate from 550 to 555 Gpm

ML20235Z502
Person / Time
Site:	Vogtle
Issue date:	03/06/1989
From:	Mcdonald R GEORGIA POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20235Z506	List: ML20235Z502 ML20235Z508
References
SLV-00325, SLV-325, NUDOCS 8903150488
Download: ML20235Z502 (10)

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Georgia Power Company f' .

333 Piedmont Avenue

' Atlant1 Georgia 30308 Telephone 404 526-3848 Mailing Address:

40 inverners Center Parkway Rast Office Box 1295 Birrningham, Mabama 35201 Telephone 205 868-5540 the southern ekttnc system R. P. Mcdonald Executive Vice President

""** P"'*" "S ELV-00325 1055D March 6, 1989 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555 PLANT V0GTLE - UNITS 1 AND 2 NRC DCCKETS 50-424, 50-425 OPERATING LICENSES NPF-68, NPF-79 REVISION TO TECHNICAL SPECIFICATION 4.5.2.h.1)b)

Gentlemen:

In accordance with the provisions of 10 CFR 50.91(a)(5) and 10 CFR 50.59, Georgia Power Company (GPC) hereby proposes to amend the Vogtle Electric Generating Plant (VEGP) Units 1 and 2 Combined Technical Specifications, Appendix A to Operating Licenses NPF-68 and NPF-79.

This Technical Specification change is necessary because it was discovered that the maximum total pump flow rate for the centrifugal charging pump lines, with a single pump running, is set to be greater than the 550 gpm allowed by Specification 4.5.2.h.1)b). During the pre-operational test program, the flow rate through the ECCS throttle valves (1204-U4-022, 023, 024, 025) was set based on the pump performance curve providec: by the manufacturer. This resulted in a maximum pump flow rate in excess of the Technical Specification limit. The error was discovered during a review of the pre-operatica.'.1 test data for the purpose of translation to surveillance test equivalence.

The review was performed because it was the first time that Unit 2 would be entering into Mode 4 and surveillance 4.5.2.h.1)b) was one of the surveillance identified as a Mode change restraint. This situation could not be avoided because the need for this Technical Specification change request was not identified until March 2, 1989, when the error was discovered. The flow through valves 1204-U4-022, 023, 024, 025 cannot be readjusted and the surveillance re-performed unless the Unit is in fiode 6, with the reactor vessel head removed. This would create a major unnecessary l delay on our startup schedule . Currently one pump is considered operable  ;

since its flow is 550 gpm. This meets Mode 4 requirements. 1 i

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ELV-00325 Page 2 Our projected date for entry into Mode 3 (where both pumps are required to meet the surveillance requirements) is March 8, 1989, therefore we are requesting this Technical Specification change on an emergency basis as outlined in 10 CFR 50.91(a)(5).

Enclosure 1 provides a detailed description of the proposed change, and the circumstances necessitating the change request.

Enclosure 2 provides the basis for a determination that the proposed change does not involve significant hazards considerations.

Enclosure 3 provides instructions for incorporating the proposed change into the Technical Specifications. The proposed revised page for the combined VEGP Units 1 and 2 Technical Specifications is included with Enclosure 3.

Pursuant to the requirements of 10 CFR 50.91, the designated state official will be sent a copy of this letter and all applicable enclosures.

Mr. R. P. Mcdonald states that he is an Executive Vice President of Georgia Power Company, and is authorized to execute this oath on behalf of Georgia Power Company and that to the best of his knowledge and belief, the facts set forth in this letter and enclosures are true.

GEORGIA POWER COMPANY By: , ,j [

' R. P. Mcdonald Sworn to and Subscribed before me this 6th day of March, 1989.

f 71cw Notary P0 blic e-RPM /HWM/ijb

Enclosures:

xc w/ enclosures: (see next page)

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1 Georgia Power L ELV-00325 Page-3 xc: Georgia Power-Company Mr. P. D. Rice Mr. C.'K. McCoy-Mr. G. Bockhold, Jr.

.Mr. J. P. Kane Mr. J. A. Bailey U.S. Nuclear Regulatory Commission Mr. S. Ebneter. . Regional Administrator Mr.-J. B. Hopkins, Licensing Project Manager, NRR (2 copies)

Mr.-J. F. Rogge, Senior Resident Inspector - Operations, Vogtle State of Georgia Mr..J. L. Ledbetter, Commissioner, Department.of Natural Resources I

ENCLOSURE 1 PLANT V0GTLE - UNITS 1 AND 2 NRC 00CKETS 50-424, 50-425 OPERATING LICENSES NPF-68, NPF-79 REVISION TO TECHNICAL SPECIFICATION 4.5.2.h.1)b)

BASIS FOR THE CHANGE This proposed change will raise the maximum flow rate for the VEGP Unit 2 Technical Specifications Surveillance Requirement 4.5.2.h.1)b) from 550 ,

gpm to 555 gpm. i During the pre-operational test program on VEGP Unit 2, ECCS throttle valves 1204 U4-022, 023, 024, 025 were set such that the maximum flow r;te was slightly in excess of the value stated in the surveillance requirement.

This error was discovered on March 2, 1989, prior to initial entry into Mode

4. The pre-operational test data indicated that one of the pumps had a maximum flow rate of 550.43 gpm which is 550 gpm when rounded to the three significant figures provided in the Technical Specifications. Therefore, Unit 2 can be operated in Mode 4, since only one train of ECCS is required.

The other pump flow was 553 gpm. Since re-adjustment of the ECCS throttle valves would result in significant delay in the startup of VEGP Unit 2, this Technical Specification Change is being requested on an emergency basis. As discussed in Enclosure 2, the effects of a 5 gpm increase in the pump flow rate have been evaluated and determined to be acceptable. These evaluations are applicable to both VEGP Units 1 and 2, however, this Technical Specification change is only being requested for Unit 2 on an emergency basis in order to avoid delay in the startup of VEGP Unit 2. An additional revision to this Technical Specification limit for both units will be requested in the' future on a non-emergency basis.

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ENCLOSURE 2 PLANT V0GTLE - UNITS 1 AND 2

. NRC DOCKETS 50-424, 50-425

[ OPERATING LICENSES NPF-68, NPF-79 REVISION T0 TECHNICAL SPECIFICATION 4.5.2.h.1)b) 10 CFR 50.92 EVALUATION In accordance with 10 CFR 50.92, the attached proposed amendment to,the VEGP L Units 1 and 2 Technical Specifications has been evaluated and it has been determined that operating the facility in accordance with the proposed amendment would not involve significant hazards considerations. The basis for this determination follows:

BACKGROUND During the pre-operational test program on VEGP Unit 2, the flow rate.for one Centrifugal Charging Pump (CCP) was set at 553 gallons per minute (gpm). Technical Specification (TS) 4.5.2.h.1)b) defines a maximum limit of 550 gpm for CCP flew. This evaluation addresses the effect on the safety analyses and safety related component performance in response to a Technical

. Specification change from 550 gpm to 555 gpm.

ANALYSIS An evaluation of the effect of a 5 gpm increase in CCP flow is provided below:

ECCS PERFORMANCE EVALUATION l The Vogtle ECCS is designed to cool the reactor core and to provide additional shutdown capability following initiation of the following accident conditions:

Loss of Coolant Accident (LOCA), including a pipe break or a spurious ,

relief or safety valve opening in the Reactor Coolant System (RCS) '

which would result in a discharge larger than that which could be made l

up by the normal makeup system.

Loss of Secondary Coolant Accident, including a pipe break or spurious !

relief or safety valve opening in the steam system which would result in an uncontrolled steam release, or a pipe break in the secondary feedwater system.

A Steam Generator Tube Rupture Accident.

The ECCS consists of the Centrifugal Charging Pumps, Safety Injection (SI) pumps, Residual Heat Removal (RHR) pumps, accumulators, residual heat exchangers, Refueling Vater Storage Tank (RWST), and the associated piping, valves, instrumentation, and other related equipment, j In the event of an accident, the Centrifugal Charging Pumps are automatically started on receipt of an SI signal and aligned to take suction from the RWST during the injection phase. These high-head pumps deliver flow to the RCS at the prevailing RCS pressure.

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ENCLOSURE 2 (Continued)

This evaluation addresses the safety impact of a 5 gpm increase in the total l ECCS charging pump flowrate, from 550 to 555 gpm. Westinghouse has reviewed this proposed modification and evaluated its effect on the Centrifugal i Charging Pump operability and the maximum safety injection flowrate.

Vogtle pre-operational test data indicates that the minimum injection flow requirement specified in the Technical Specifications (284 gpm) would l continue to be satisfied with the higher charging pump runout flow of 553 gpm. Thus, the safety injection flowrates previously generated for use in the accident analyses, remain valid.

The impact of an increased charging pump runout on maximum safeguards flow also needs to be addressed. Maximum Safety Injection (SI) flow is utilized in the large break LOCA, tube rupture and inadvertent safety injection analyses. To maximize the flow delivered to the RCS, the SI flowrates used in these accident analyses were calculated assuming an extremely high pump head in conjunction with a very low resistance. For example, the system resistance was based on a pump head of 1200 feet at a flowrate of 550 gpm.

However, the actual pump curve used for the analyses had a developed head of 2580 feet. A range between 1500 and 1750 feet at runout is indicated by the manufacturer's curve. Thus, the maximum safeguards flow provided for the safety analyses is highly conservative. The Vogtle charging pumps will deliver less flow than the maximum safeguards flows that are assumed in the accident analyses, j Based on the above discussion, the maximum safeguards flows provided for the safety analyses continue to be highly conservative for a total ECCS charging pump flowrate of 555 gpm. j Thus, due to available equipment and analyses margins, the increase in the total ECCS charging pump flowrate from 550 gpm to 555 gpm, is acceptable.

This change will not create any new scenario that would exceed the bounds of the analyses of record.

CCP COMPONENT PERFORMANCE EVALUATION The Combined Vogtle Units 1 & 2 Technical Specifications require that each centrifugal charging pump, operating alone, satisfy the following criteria, with the reactor coolant system (RCS) fully depressurized:

1. The sum of the three lowest branch injection line flow rates must be greater than or equal to 284 gpm.

2. The total pump flow rate must be less than or equal to 550 gpm.

Pre-operational test data for Vogtle Unit 2 indicates that the minimum injection flow requirement of 284 gpm is satisfied, but that the total pump flow of 553 gpm exceeds the 550 gpm limitation.

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ENCLOSURE 2 (Continued)

L The fact that the minimum injection requirement of 284 gpm is satisfied with ,

the pump at a higher runout condition demonstrates that the safety injection I flowrates generated for use in the accident analysis remain valid. The slight increase in aump runout can therefore be attributed to the fact that the pump-developed lead, at runout, is slightly higher than predicted.  !

Consequently, the concern to be addressed is to demonstrate that the pump runout condition is not detrimental to proper pump operation.

The Vogtle Units 1 & 2 Centrifugal Charging Pumps are Pacific Pump serial  ;

numbers 52233, 52234, 52235, and 52236. The vendor performance test curves for these pumps are Pacific Pump test curve numbers 38033A, 38033B, 38034A and 38034B respectively. The Pacific Pump outline drawing No. 300-B50033 l recommends a maximum pump runout flowrate of 550 gpm. It has been identified that the Vogtle pumps may have to operate at up to 555 gpm. The two considerations that must be evaluated for this increased runout '

limitation are the horsepower capability of the motor and the margin between the available and required net positive suction head (NPSH). The considerations are addressed as follows:

The pump performance curves indicate that the operation of the Vogtle charging pumps at 555 gpm will require a maximum brake horsepower of 680 HP. The charging pump motors are rated at 600 HP with a service factor of 1.15, thus the maximum horsepower for which the motor is designed is 690 HP. Therefore, the motor is capable of providing the horsepower required for pump operation at 555 gpm. The motor qualified life is based on continuous operation at 690 HP, therefore, this operation does not reduce the motor qualified life. j

- The charging pump performance curves provide NPSH requirements to a maximum flow rate of 555 gpm for aump #52233 and to approximately 550 gpm for the other three pumps. T1ese performance curves show that the NPSH required at 550 gpm is approximately 22 feet for the most limiting pump. Pacific Pumps has performed additional testing of this model pump which has demonstrated that the NPSH requirements remain stable through flow rates as high as 555 gpm.  !

1 By extrapolation of the performance curves, the required NPSH at 555 gpm will not exceed 22 feet. The available NPSH at 555 gpm has been ,

calculated to be in excess of 83 feet. Therefore, there is substantial l NPSH margin and pump operation at 555 gpm is acceptable. l Based on the evaluation of the charging pump motor horsepower capabilities and the substantial NPSH margin which is available, it is concluded that the centrifugal charging pumps are capable of operating at 555 gpm with no I damage to the pumps or degradation of pump performance. No special l operating precautions or maintenance requirements are necessary to support l operation of the pumps at 555 gpm.

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i ENCLOSURE 2 (Continued)

Based on this evaluation, operation of the VEGP centrifugal charging pumps at 555 gpm does not adversely affect pump performance.

STEAM GENERATOR TUBE RUPTURE EVALUATION The small increase to CCP flow is more than compensated for in the amount of conservatism used in the Fluid Systems calculations to determine charging pump flow used in the tube rupture analysis. Based on this conservative CCP flow calculation, it is determined that the 5 gpm increase in CCP flow will not change the results of the tube rupture analysis. The CCP flows used in I the tube rupture analysis remain conservative and therefore this TS change does not adversely affect the steam generator tube rupture analysis results.

LOCA AND LOCA-RELATED EVALUATION The following LOCA-related accidents do not consider the maximum runout flow of the charging pump. Since the minimum injection requirement is still satisfied, there is no adverse affect on these accidents:

small break LOCA LOCA hydraulic forcing functions rod ejection mass releases _

aost-LOCA long term cooling lot leg recirculation switchover to prevent boron precipitation Since the maximum ECCS safeguards large break LOCA analysis for the Vogtle units is limiting, an evaluation has been performed for the large break LOCA analysis for an increase of the charging pump runout flow by 5 gpm. For two charging pumps delivering during the maximum safeguards ECCS LOCA analysis, a total increase of 10 gpm would be seen. The evaluation demonstrated i approximately a 2 0F increase in the peak cladding temperature (PCT) for the large break LOCA analysis. The current PCT for the Vogtle units is i 1995.8 0F. Based on this evaluation, there is sufficient margin to the j 10 CFR 50.46 PCT limit of 2200 0F to offset the PCT increase due to the increased runout flow of the charging pumps at VEGP. Therefore, there is no l adverse affect on tne LOCA and LOCA-related accidents as a result of this i Technical Specification change NON-LOCA EVALUATION i Maximum safety injection flow is conservatively assumed for only one non-LOCA transient; Inadvertent Operation of the Emergency Core Cooling System During Power Operation (FSAR Section 15.5.1). For all other non-LOCA transients which model safety injection, a minimum flowrate is conservative. The current VEGP analysis for Inadvertent ECCS operation assumes that two charging pumps are injecting RWST water in the RCS. The pump data used in the analysis is very conservative and bounds the increase to 555 gpm. It is therefore concluded that this Technical Specification change does not adversely affect the non-LOCA safety analysis.

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1 ENCLOSURE 2 (Continued)

CONTAINMENT MASS AND ENERGY ANALYSIS The sr'all increase in CCP flow results in an insignificant increase in the LOCA mass and energy releases when compared with the total mass of fluid released to containment following a LOCA. The resulting effect on the containment response is correspondingly insignificant. It is therefore concluded that this Technical Specification change does not adversely affect the containment analysis results presented in the FSAR.

CONCLUSION It has been determined that both system and component performance will not be adversely affected by the increase in flow. Therefore, the probability of previously analyzed accidents has not been increased. Additionally, since no new failure mode or new limiting single failure has been identified, the possibility of a different accident being created does not exist and the probability of a malfunction of safety related equipment has not been increased.

The increased CCP flow has been determined to have no impact or an insignificant effect on the safety analysis results. Therefore, the consequences of an accident previously evaluated in the FSAR has not been increased and the consequences of a malfunction of equipment has not become more severe. Therefore, the increase in the CCP flow from 550 gpm to 555 gpm does not result in any increase in radioactive releases as a result of normal operation or as a result of evaluated accidents.

As indicated in the above evaluations, the acceptance criteria for each of the safety analyses has not been exceeded. Therefore, there is no reduction in the margin of safety between the safety analysis assumptions and the Technical Specification values as defined in the basis to the Technical Specification.

It can therefore be concluded that the Technical Specification change, increasing the CCP flow maximum limit from 550 gpm to 555 gpm, is supported by the current plant licensing basis and safety analyses of record, and will not involve significant hazards considerations as defined in 10 CFR 50.92(c).

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' ENCLOSURE 3  !

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~ PLANT V0GTLE - UNITS 1 AND 2 NRC DOCKETS 50-424, 50-425 OPERATING LICENSES NPF-68, NPF-79' REVISION TO TECHNICAL SPECIFICATION 4.5.2.h.1)b) ,

INSTRUCTIONS FOR INCORPORATION The'. proposed amendment to the Technical Specifications (Appendix A to

'.0perating License NPF-68 and NPF-79) would be incorporated as follows: ;

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