05000336/LER-1997-014-02, :on 970415,insufficient RBCCW Flow to HPSI Seal Coolers Was Identified.Cause of Condition Has Not Been Determined.Required Design Flow & Effect Deficient Flow Has on HPSI Pump Seal Coolers Performances Will Be Evaluated

:on 970415,insufficient RBCCW Flow to HPSI Seal Coolers Was Identified.Cause of Condition Has Not Been Determined.Required Design Flow & Effect Deficient Flow Has on HPSI Pump Seal Coolers Performances Will Be Evaluated

ML20141E238
Person / Time
Site:	Millstone
Issue date:	05/13/1997
From:	Joshi R NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20141E211	List: 05000336/LER-1997-014, Forwards LER 97-014-00 Which Documents an Event That Occurred on 970415.Commitments Made within Ltr,Submitted 05000336/LER-1997-014-02, :on 970415,insufficient RBCCW Flow to HPSI Seal Coolers Was Identified.Cause of Condition Has Not Been Determined.Required Design Flow & Effect Deficient Flow Has on HPSI Pump Seal Coolers Performances Will Be Evaluated
References
LER-97-014-02, LER-97-14-2, NUDOCS 9705200373
Download: ML20141E238 (3)

LER-1997-014, on 970415,insufficient RBCCW Flow to HPSI Seal Coolers Was Identified.Cause of Condition Has Not Been Determined.Required Design Flow & Effect Deficient Flow Has on HPSI Pump Seal Coolers Performances Will Be Evaluated

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(v), Loss of Safety Function
3361997014R02 - NRC Website

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e NRC FORM 366 U.s. NUCLEAR REGULATORY COMMisslON A.PPROVED BY OMB NO.3160-0104 e

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Millstone Nuclear Power Station Unit 2 05000336 1OF3

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TITLA 647 Insufficient RBCCW Flow to HPSI Seal Coolers EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILillES INv0LVED (8) sE U AL RE N

MONTH DAY YEAR YEAR MONTH DAY YEAR g

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04 15 97 97

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00 05 13 97 OPERATINo THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR 1: (Check one or more) f11)

MODE (9)

N 20.2201 (b) 20.2203(a)(2)(v) 50.73(a)(2)p)

So.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.22o3(al(3)(i) bo.73(a)(2)(ii)

So.73(a)(2)(x)

LEVEL (10) 000 20.2203(a)(2)(i) 20.2203(a)(3)(n) so.73(a)(2)(iii) 73.71 20.2203(a)(2)pi) 20.2203(a){4) 50.73(a)(2)0v)

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So.73(a)(2)(vii) i LICENSEE CONTACT FOR THis LER (12)

NAME TELEPHONE NUMBER pnclude Area Cocal R. G. Joshi, MP2 Nuclear Licensing (860) 440-2080 i

COMPLETE ONE LINE FOR EACH COMPCNENT FAILURE DESCRIBED IN THis REPORT (13)

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CAUSE

SYSTEM COMPONENT M ANUF ACTURER

CAUSE

SYSTEM COMPONENT MANUFACTURER TO N DS PRDS MONm DAY YEAR SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED SUBMisslON YEs NO DATE (15) 01 01 98 v^

(if yes. complete EXPECTED SUBMisslON DATE).

ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten knes) (16) 1 On April 15,1997 a report was made to the Nuclear Regulatory Commission in accordance with the requirements of 10 CFR 50.72(b)(2)(iii). This report documented that Reactor Building Closed Cooling Water (RBCCW) flow to the High Pressure Safety injection (HPSI) pump seal coolers for all three HPSI Pumps may not be adequate to ensure reliable operation of each pump shaft seal. Failure of a seal could result in Contamination of HPSI pump bearing oil and eventual pump failure.

The cause of this condition has not been conclusively determined and is pending the results of the ongoing evaluation.

The effect of any deficient flow on the HPSI pump seal coolers performance and mechanical seal integrity will be evaluated. A seal cooler flow adequacy evaluation will be completed as part of the ongoing reanalysis of the RBCCW System.

9705200373 970513 PDR ADOCK 05000336 S

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YEAR NUMBER NUMBER 2OF3 Millstone Nuclear Power Station Unit 2 05000336 014 00 97 TEXT (11more space is required. use additionalcopies of NRC Form 366A) (17)

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pgscriotion of Event On April 15,1997 a report was made to the Nuclear Regulatory Commission in accordance with the requirements I

. of 10 CFR 50.72(b)(2)(lii). This report documented that Reactor Building Closed Cooling Wate.r (RBCCW) [CC) flow to the High Pressure Safety injection (HPSI) [BQ) pump [P) seal [ SEAL) coolers [CLR) for all three HPSI i

Pumps may not be adequate to ensure reliable operation of each pump shaft seal. Failure of a seal could result in contamination of HPSI pump bearing oil and eventual pump failure. At the time of discovery of this condition,

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the unit was defueled.

An Inservice Test (IST) was performed to measure RBCCW system performance data for several system configurations. During the test, flow data was recorded for various components including the HPSI pump seal and bearing coolers (two each per pump) which are supplied by a common branch line from the RBCCW main

. header The results of the test, documented on January 28,1997, identified total cooling water flow to the pump l

I and bearing seal coolers to be below the design flow of 35 GPM. Actual flow rates were measured at approximately 18,25, and 29 gallons per minute (GPM) for HPSI pumps "A", "B", & "C", respectively. There are two HPSI coolers per pump providing heat removal for the two pump shaft seals. The RBCCW flow deficit to the coolers, as compared to design flow of 35 GPM, could result in HPSI pump seal failure and subsequent pump failure. The flow diagram and piping configuration reflect the original system design.

Th.s condition is being reported in accordance with 10 CFR 50.73(a)(2)(v)(D), any event or condition that alone t

i could have prevented the fulfillment of the safety function of structures or systems needed to mitigate the consequences of an accident.

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11. Cause of Event

The cause of this condition has not been conclusively determined and is pending the results of the ongoing evaluation.

ill. 6aalvsis of Event i

i The primary function of the HPS! pumps is to inject borated water into the reactor coolant system (RCS) [AB)if a large or small break occurs in the RCS pressure boundary. Following a Loss of Coolant Accident (LOCA), the pumps provide long term recirculation to maintain borated water cover over the core. HPSI pump seal cooling is provided by the circulation of a portion of borated water from the first stage through a seal cooler and then to the pump seal cavity. The RBCCW system supplies the pump see' :ooler with cooling water, providing heat removal to the ultimate heat sink via the service water system.

During the test, RBCCW System header flow was close to maximum flow which resulted in minimum flow on the i

branch line to the pump seal coolers. Further evaluation of the RBCCW System parameters is underway to determine system cooling capability, including calculated cooling water temperature and flow rate to the pump seal coolers.

The potential exists for the pump seat leakage to contaminate the bearing oil which, if uncorrected, could result in pump failure and a loss of HPSI flow.

Baccd on the above, this condition is considered to be potentially safety significant.

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4 IV.. Corrective Action The required design flow and the effect that any deficient flow has on the HPSI pump seal coolers performance and mechanical scal integrity will be evaluated. A seal cooler flow sdequacy evaluation will be completed as part of the ongoing reanalysis of the RBCCW System. Based on these results, RBCCW piping modifications and/or design document revisions will be implemented. These activities will be completed prior to entry into Mode 4 from the current outage.

l A supplemental LER will be issued to provide the results of the investigation including the cause of the event and resultant correctivo actions.

V.

Additional InformatiDD

Similar Events

No previous similar conditions involving pump seal deficiencies or HPSI Pump operability were identified.

Energy industry identification System (Ells) codes are identified in the text as [XX).

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