ML20011E741

Application for Amend to License NPF-38,consisting of Change Request NPF-38-107,revising Tech Spec 4.5.2.f to Refine Min Acceptance Criteria for HPSI Pump Surveillance Requirements

ML20011E741
Person / Time
Site:	Waterford
Issue date:	02/12/1990
From:	Dewease J LOUISIANA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20011E742	List: ML20011E741 ML20011E743
References
W3P89-2128, NUDOCS 9002220356
Download: ML20011E741 (8)

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) Louisiana Power & Light Compa:iy  ;

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317 Baronne Street P. O. Box 60340 I

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February 12, 1990 l 1

l U.S. Nuclear Regulatory Commission ]

ATTN Document Control Desk Washington, D.C. 20555

Subject:

Waterford 3 SES .

l Docket No. 50-382 License No. NPF-38 Technical Specification Change Request NPF-38-107 Gentlemen Please find attached the proposal to amend Technical Specification 3.5.2 "ECCS Subsystems - Modes 1, 2 and 3". As discussed with members of your staff, the attached request became necessary when High Pressure Safety -

Injection Pump-(HPSI) B was tested during Refueling Outage 3 and a slight increase in pump performance was measured. Althcugh small, the increase in performance was sufficient to raise pump differential pressure under full flow conditions above the maximum differential pressure specified in the subject Technical Specification.

Since the performance of the HPSI B flow- test, LP&L has been working with Combustion Engineering to develop an analytical basis for the proposed technical specification change. As discussed with members of the NRC staff CE, in a letter dated November 17, 1989, assured LP&L that pump performance was_ acceptable with respect to the existing Safety Analyein.

Unfortunately, the necessary analyses to support a technical specification change were sufficiently detailed to delay immediate submittal of the change. Nonetheless, during the week of November 20, 1989, LP&L and members of the NRC staff discussed in detail the. test results and the on-going analyses. The attached request is consistent with these discussions and conclusions.

Should you have any questions or need additional information, please contact Larry Laughlin at (504) 464-3499.

Very truly yours, (L4 M.

G[LEL/pi g> Messrs. R.D. Martin, F.J. Hebdon D.L. Wigginton, E.L. Blake, W.M. Stevencon NRC Resident Inspectors Office F

Administrator Nuclear Energy Division (State of Louisiana)

American Nuclear Insurers i.

9002220356 900212 PDR 6Ib2 'f ADOCK 05000302 P pyu j j

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• W UNITED STATES OF AMERICA

' -* NUCLEAR REGULATORY COMMISSION 1

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In the matter of )

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- Louisiana Power & Light Company- ) Docket No. 50-382  :

Waterford 3 Steam Electric Si;ation )  ;

r AFFIDAVIT r

J.G. Devease, being duly sworn, hereby deposes and says that.he is Senior  !

Vice President - Nuclear Operations of Louisiana Power & Light Company; i that he is duly authorized to sign and iile with the Nuclear Regulatory Commission the attached Technical Specification Change Request NPF-38-107; t that he is fan.iliar with the content thereof g and that the matters set forth therein are true and correct to the beat of his knowledge,  ;

informatter. and belief. l t

K l f A & ck 2 0 -

.'G. Dhwcase  ;

/, Senior Vice President .

Nuclear Operations

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- STATE OF LOUISIANA ) -

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Land State above named thia /d ')K., day ofSubscribed and y ,sworn 1990.to before me, a Nota g >

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~ DESCRIPTION AND SAFETY AKALYSIS OF PROPOSED CEANGE NPF-38-107 I

b l L This is request to revise Surveillance Requirements 4.5.2.f and 4.5.2.h-of Technical Specification 3.5.2, Emergency Core Cooling System (ECCS)

Subsystems - Modes 1, 2, and 3. *

, i Existing Specifications f'

.See Attachment A l I- Proposed Specifications See Attachment B Deccription The proposed' change would revise Surveillance Requirements 4.5.2.f and 4.5.2.h of Technical Specification 3.5.2, ECCS Subsystems - Modes 1, 2, and ,

3 for the High Pressure Safety injection (HPSI) Pumps. The reason for this {

change is that the existing Technical Specification for maximum differential pressure under full flow cold leg injection conditions ,

precludes moderate increases in HPSI pump performance. Proposed  !

Specification 4.5.2.h establishes a single criterion based on Combustion Engineering (CE) analyses for required HPSI pump cold leg injection flow ,

and deletes the previous requirement for a aaximum acceptable differential ,

pressure. The proposed Specification 4'5.2.f establishes a single criterion for required HPSI pump head during the pump recirculation flow test.

The existing HPSI pump specification was derived in part from data obtained during preoperational testing of the HPSI pumps. This pump testing and the i subsequent' analysis resulted in individual Technical Specification limits for each HPS1 pump. The current Technical Specification limit on maximum .{

differential pressure under full flow conditions was included to limit the ,

maximum system resistance that had to be assumed in the safety analyses.  ;

This allowed a lower value for the minimum required flow under full flow: .

conditions, thus giving Waterford 3 an increased margin to the .

. Specification 4.5.2.h flow limit.

The, existing Technical Specifications provide separate criteria for minimum '

acceptable flow under full-flow conditions and for mir.imum pressure under pump recirculation conditions. These individual pump requirements are based on actual test data and safety analysis requirements. The maximum ,

differential pressure requirement was instituted to control any increases in system resistance. However, increased pump flow under full flow conditions, which is indicative of an improved HPSI pump,'results in increased differential pressures. As a consequence, the limit on maximum differential pressure of Section 4.5.2.h does not allow for moderate performance increases following pump maintenance, and is therefore unduly restrictive.

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l Pump flow capacity depends in part on rotating assembly clearances within i the pump. When a pump rotating assembly is replaced, dimensions of the new  !

L assembly may differ, within allowable tolerances, from those of the -

previously installed components. Actual pump performance may differ as a result of the clearances in the rebuilt pump.

In May 1989, while at power, LP&L replaced the B HPSI pump internals (a like-for-like replacement) to correct problems caused by an inboard bearing i housing misalignment. The pump was subsequently tested per Technical Specification 4.5.2.f and declared operable. At the next refueling outage.

LP&L performed a full flow test per Technical Specification 4.5.2.h on the B HPSI pump. The as found data was a differential pressure of 497.2 psid at 740 gpm. As a result of replacing the pump internals, the pump ,

performance curve improved, that is, the flow under full flow conditions .

, increased. The corresponding increase in pump differential  ;

l- pressure at full flow conditions, although relatively small, exceeded p, existing Technical Specification limits. Even though overall pump  :

performance improved, the B HPSI pump was declared INOPERABLE for exceeding the maximum differential pressure requirement of Technical Specification 4.5.2.h. '

LP&L has reviewed the Technical Specifications for HPSI pump surveillance .

requirements. Based on the new analysis described below, LP&L concluded 8 that Technical Specification 4.5.2.h and the associated Technical 7 Specification 4.5.2.f should be revised. The proposed changes include i deletion of the maximum differential pressure requirement of 4.5.2.h. As discussed below a surveillance requirement for maximum differential i pressure under full-flow conditions is not required. A minimum pump flow acceptance criterion alone will accomplish the same purpose. Deletion of t the maximum differential pressure requirement would also be consistent with  ;

the Standard Technical Specifications. A single value applicable to all three HPSI pumps is also proposed for the minimum acceptable HPSI pump flow s rate under maximum flow conditions and minimum pump head at pump recirculation conditions.

Combustion Engineering (CE) has performed analyses to establish a commun Technical Specification for Waterford 3 HPSI pumps. The proposed change >

does not include a maximum differential pressurir.ation requirement under ,

full flow conditions. Based on these analyses, the proposed acceptance criteria are 1429 paid for the minimum differential pressure under pump recirculation conditions and 675 gpm for the minimum acceptable flow under full flow cold leg injection conditions. This flow rate is the total flow for the four cold legs minus the highest cold leg flow rate, as required in the existing Technical Specifications. These criteria vill ensure that the i HPSI. pumps are capable of delivering a flow equal to or greater than that '

assumed in existing safety analyses. The basis for this proposed change is

k. described below. ,

The HPSI pump technical specifications for differential pressure under pump recirculation flow conditiens and for minimum flow under full flow conditions are interrelated. The technical specification for the pump recirculation differential pressure establishes the maximum degradation in

. pump perf ormance for which the pump perf ormance still meets saf ety analysis assumptions. The minimum flow under full flow conditions establishes the maximum system resistance, and thus the minimum required pump performance

.to meet safety analysea.

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' ., l; The basic approach to determining acceptable Technical Specification limits .

is to assume a minimum required flov and from this determine the required pump dif f erential pressure under pump renirculation conditions. The assumed minimum flow requirement must equal or exceed the assumed safety analysis flow to the Reactor Coolant System (RCS) under full flow conditions. The assumed minimum flow requirement is used in conjunction with the best pump performance curve (based on actual data) to determine the maximum acceptable system resistance. This system resistance is used to determine the minimum required pump performance based on safety analyses. A minimum recirculation pressuro is determined to assure that the pump performance exceeds the minimum required to support safety analyses.

The best pump performance curve is used to determine the system resistance, since this results in the maximum resistance. Otherwise the minimum flow requirement would be potentially nonconservative. For Waterford 3, the best pump performance curve is based upon the 1989 HPSI B test data. The maximum system resistance is used in constructing the minimum required pump performance curve to-support safety analyses.

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FSAR Table 6.3-7 lists the HPSI safety injection flow as a function of RCS pressure which is assumed in Waterford 3 safety analyses, including the small break LOCA analyses. Because the required safety injsction flow is specified based upon RCS preasure, the required pump performance curve is dependent upon the maximum system resistance. As the assumed system resistance is increased, the pump performance curve required for safety ,

analyses will also increase.

The Technical Specification 4.5.2.f requirement for minimum differential pressure under pump recirculation conditions (tested quarterly) is chosen to ensure that pump performance will equal or exceed the performance required to deliver acceptable safety analysis flow. To determine this minimum differential pressure, the safety analysis flow curve based on FSAR Table 6.3-7 was compared with the pump performance curve for the A/B HPSI pump from plant startup tests. The analysis _ conservatively used the startag data f rom the A/B pump- for comparison'with the safety analysis flow requirement, since the A/B HPSI pump has the lowest performance of the three Waterford 3 HPSI pumps. The performance of all three HPSI pumps has inproved since startup, that is, the HPSI A/B pump performance curve from startup tests bounds the current performance curves of all three HPSI pumps.

The Specification 4.5.2.h flow requirement is based on the sum of the f our injection line flow rates, excluding the highest flow rate. This will ensure that adequate safety injection flow is delivered to the RCS in the event of a Loss of. Coolant Accident.

Based on most recent 1989 data, all three'HPSI pumps have flows of at least 715 gpm under full flow conditions, which is adequate margin to the

proposed Specification 4.5.2.h minimum flow requirement of 675 gpm.

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_ Based on CE analysie, the 675 gpm limit proposed for Specification 4.5.2.h corresponds to a minimum total flow to all four cold legs of 895.gpm. -This is-acceptabic as it exceeds._the llPSI pump minimum delivered flow of'829 gpm- y P- listed in FSAR Table 6.3-7 which is used for the swall break LOCA analysis.-

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. The existing Specification 4.5.2.h includes a maximum differential pressure requirement which_the proposed Specification' deletes.> This differential

' ' pressure established additional limits on system resistance that allowed a lower minimum flow requirement under full. flow conditiono. This was done due to the small margin between actual and required pump performance when--

the existing ~ Technical Specification was written. Ilowever, while specifying a maximum differential pressure for full flow conditions allowed f a reduction in the minimum flow requi_rement it-also precluded moderate

-increases in pump performance. Greater pump flow results in a higher-

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differential pressure at full flow conditions. It has been concluded;that this differential pressure limit is not required ninee the minimum flow

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limit.at-full flow conditions fulfills the same purpose, i.e., ensuring that system resistance does not increase above that used to determine the minimum pump performance. required for safety. analyses.

Safety Analysis j The proposed change described above shall be deemed to invo.ve a significant hazards-consideration if there is a positive finding-in any of the following areast

1. Mill che operation of the fo.:llity in accordance with this proposed change involve a significant increase in-the probability or consequence of any accident previously evaluated?-

Response: -No The primary function of the HpSI pumps is to inject borated water _ into the RCS under accident conditions. The proposed change establishes common limits for all three HPSI pumps which will ensure the HPSI -;

pumps can deliver a flow equal to or greater than that assumed in the Waterford 3 safety analyaes. The proposed change is required because-the existing Technical S.ecification 1 resulted in the B HPSI pump

. :having to be declared INOP?RABLE due to an increase in performance after recent maintenance. Thus, the proposed change will allow g

improved HPSI system performance.. Because the proposed change will ensure that the HPSI pumps deliver a flow greater than or equal to-the flow assumed in existing safety analyses, there is no increase in the probability or consequence of any accident previously evaluated as a result of this change.

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cu lb /Will the_ operation of.the facility in accordance with the-proposed i, '

' change create the possibility of a new or different kind of accident-from any accident previously evaluated?

Responset No

-The proposed change refines the minimum acceptance criteria for HPSI pump surve111aace requirements. There'is no change in plant configuration or plant _ operation associated with this change. Because o the HPSI, pumps will perform as required for accident mitigation, the Lproposed change does not create'the possibility of/a new or different

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kind of accident.

3.- Will the operation of this facility in accordance with this proposed change involve a significant reduction in the margin of safety?

Responset No Safety margin is established through the Waterford 3 safety cualyses.

Since the proposed change preserves all assumptions and results for the safety analyses, there is no reduction in any margin of safety related to_the proposed change, e Safety and Significant Hazards Determination Based on the above Safety Analysis, it is concluded that: (1) the proposed change does not constitute a significant hazards consideration as defined by 10CFR50.92; and_(2) there is a reasonable assurance that the health and

. safety of the public will not be endangered by the proposed change; and (3) this action will not result in a condition which significantly alters the impact of _the_ station on the environment as described in the NRC Final Environmental Statement.

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NPF-38-107 ,

ATTACHMENT A-1-

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