ML19323F310

LER 80-042/01T-0:on 800509,Westinghouse Informed Util That Following Secondary Side High Energy Line Rupture,Potential Exists for Charging Pumps to Be Damaged.Calculation Assessment Being Performed

ML19323F310
Person / Time
Site:	North Anna
Issue date:	05/22/1980
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19323F297	List: ML19323F294 ML19323F310
References
LER-80-042-01T, LER-80-42-1T, NUDOCS 8005280752
Download: ML19323F310 (3)

Text

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8 61 74 75 REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 1012l l Westinghouse has detemined that following a secondary side high enerov line rupture, a l I

lo 13 I potential exists for the charging pumps to be damaged before SI termination criteria are l l

lo l 41 atisfied and pump operation is terminated. This could occur if the pressurizer power l l

lo I s I pperated relief valves become inoperable and system pressure reaches the setpoint of the l l

0 l6 l pressurizer safety valves (fN 2485 psig). Under these conditions, the charging pumps woul;l oj7l possibly be operating at shutoff conditions without the minimum flow required by pump [

l aggi posign. The public health and safety were not affected. Reportable nursuant to T.S.6.9.lp81

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44 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 1 l0lIDamace to the charcing numos could result if RCS pressure reaches 2485 psic following a l 1 lii lsecondary side high enercy line rupture because the pump recirculation line isolation l i l 71 l valves automatically close on an SI signal and with such a high back pressure present, l 13l lthe charging pumps may not be able to supply enough flow to preclude pump damage. A cal-l il4l lculational assessment of the situation is being performed to determine if a plant specifjlc d , e, y Concern exists. METHODOP ST A tUS  % PCWER OTHER STATUS DISCOVERY DISCOVERv OESCRIPTION i15l b h i1IoIolhlu 12 MA 44 I ( ,,p,,,j@l 45 4e Notification from NSSS 80 I

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Virginia Electric and Power Company North Anna Power Station, Unit #1

Attachment:

Page 1 of 2 Docket No. 50-338 Report No. LER 80-42/01T-0 Description of Event A review of the Westinghouse Safety Injection Termination Criteria following a secondary side high energy line rupture (feedline or steamline rupture at high initial power levels) has revealed a potential for consequential damage of one or more centrifugal charging pumps before the SI termination criteria are satisfied and pump operation is terminated.

This concern exists for plants which utilize the charging pumps as Emergency Core Cooling System pumps, where the charging pumps are automa-tically started, and where the pump miniflow isolation valves are automa-tically isolated upon safety injection initiation.

I Probable Consequences of Occurrence With a potential for the charging pumps to be damaged prior to termination of Safety Injection, it is possible that the pumps could be prevented from performing their intended function during an accident condition. Such consequential damage may adversely impact long-term recovery operations for the initiating event and is not permitted by design criteria. Since there are three charging pumps, there is sufficient redunancy designed into the system to handle the possible loss of a charging pump and still ensure that the ECCS performs its intended function. The health and safety of the general public have not been affected by this potential problem. Unit 2 has an identical design and is similarly affected.

Cause of Event Following a secondary side high energy line rupture and subsequent safety injection initiation, the charging pump recirculation (miniflow) line isolation valves automatically close. If the pressurizer power operated relief valves (PORV's) were not operable due to loss of offsite power, adverse environment inside containment, PORV in manual mode, or the PORV block valve in a closed position due to PORV leakage, the RCS pressure would increase because of injection flow and core decay heat generation until it reached the setpcint of the pressurizer code safety valves (~ 2485 psig). At this high a back pressure, the charging pumps may not be able to supply sufficient flow to prevent damaging the pumps.

Immediate Corrective Action To assess this concern with respect to North Anna, a calculational plant specific evaluation in accordance with Wertinghouse recommendations is presently being performed. As soon as the results of this evaluation l are available, the results will be forwarded in another report. Westing-l house submitted a report to the NRC under 10CFR Part 21 concerning this problem.

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Attachment:

Page 2 of 2 Scheduled Corrective Action If a plant specific concern is identified, the necessary hardware and/or procedure changes will be made as required to ensure that the charging pumps remain adequately protected.

Actions Taken to Prevent Recurrence No further actions are required.

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