05000305/LER-2005-012, Re Residual Heat Removal Pump Run-Out Upon Loss of Instrument Air While Aligned for Sump Recirculation

Re Residual Heat Removal Pump Run-Out Upon Loss of Instrument Air While Aligned for Sump Recirculation

ML052280237
Person / Time
Site:	Kewaunee
Issue date:	08/10/2005
From:	Gaffney M Dominion Energy Kewaunee
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
05-534 LER 05-012-00
Download: ML052280237 (6)

LER-2005-012, Re Residual Heat Removal Pump Run-Out Upon Loss of Instrument Air While Aligned for Sump Recirculation

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(B)
3052005012R00 - NRC Website

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Hasn" Dominions Dominion Energy Kewaunee, Inc.

N490 Highway 42, Kewaunee, WI 54216-9511 AUG 1 0 20005 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No.05-534 KPS/LIC/RB: RO Docket No.

50-305 License No. DPR-43 DOMINION ENERGY KEWAUNEE, INC.

KEWAUNEE POWER STATION LICENSEE EVENT REPORT LER 2005-012-00

Dear Sirs:

Pursuant to 10 CFR 50.73, Dominion Energy Kewaunee, Inc., hereby submits the following Licensee Event Report applicable to Kewaunee Power Station.

Report No. 50-305/LER 2005-012-00 This report has been reviewed by the Plant Operating Review Committee and will be forwarded to the Management Safety Review Committee for its review.

If you have any further questions, please contact Rachaelle Braenne at (920) 388-8839.

Very truly yours, Michael

. Gaff ey Site Vice Presid nf, Kewaunee Power Station Attachment Commitments made by this letter: NONE 1

4(

CW-1%

e-

Serial No.05-534 Page 2 of 2 cc:

Mr. J. L. Caldwell Administrator Region IlIl U.S. Nuclear Regulatory Commission 2443 Warrenville Road Suite 210 Lisle, IL 60532-4352 Mr. J. F. Stang Project Manager U.S. Nuclear Regulatory Commission Mail Stop 0-8-H-4a Washington, D. C. 20555 Mr. S. C. Burton NRC Senior Resident Inspector Kewaunee Power Station

NRC FORM 366 U.S. NUCLEAR REGULATORY APPROVED BY OMB NO. 3150-0104 EXPIRES 6-30-2007 COMMISSION (6.2004) digits/characters for each block) the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

FACILITY NAME (1)

DOCKET NUMBER (2)

PAGE (3)

Kewaunee Power Station 05000305 1 of 4

TITLE (4)

Residual Heat Removal Pump Run-out Upon Loss of Instrument Air While Aligned for Sump Recirculation EVENT DATE (5)

LER NUMIBER (6)

REPORT DATE (7)

OTHER FACILITIES INVOLVED (S)

REV FACILITY NAME DOCKET NUMBER MO DAY EAR YEAR NMER NO MO DY YEAR 06 10 2005 2005

-- 012 --

0 0800 FACILITY NAME DOCKET NUMBER OPERATING N

TIlS REPORT IS SUBMITTED PURSUANT TO TIlE REQUIREMENTS OF 10 CFR : (Check all that apply) (11)

MIODE (9) 20.2201 (b) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(B)

_ 50.73(a)(2)(ix)(A)

POWER 20.2201 (d) 20.2203(a)(4) 50.73(a)(2)(iii) 50.73(a)(2)(x)

LEVEL (10) 000 20.2203(a)(1) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 73.71 (a)(4) 20.2203(a)(2)(i) 50.36(c)(1)(ii)(A)

_ 50.73(a)(2)(v)(A)

_ 73.71(a)(5) 20.2203(a)(2)(ii) 50.36(c)(2) 50.73(a)(2)(v)(B)

OTHER 20.2203(a)(2)(iii) 50.46(a)(3)(ii) 50.73(a)(2)(v)(C)

Specify in Abstract below or in 20.2203(a)(2)(iv) 50.73(a)(2)(i)(A) 50.73(a)(2)(v)(D) 20.2203(a)(2)(v) 50.73(a)(2)(i)(B)

X 50.73(a)(2)(vii) 20.2203(a)(2)(vi) 50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A) 20.2203(a)(3)(i) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)

LICENSEE CONTACT FOR TIllS LER (12)

NAME TELEPHONE NUMBER (Include Area Code)

Rachaelle Braenne - Technical Specialist - I&C Maintenance (920) 388-8839 COMPLETE ONE LINE FOR EACII COMPONENT FAILURE DESCRIBED IN TIIS REPORT (13)

Ij MAN'U-REPORTABLE MANU.

REPORTABLE

CAUSE

SYSTEM COMPONENsT FACTURER TO EPIX

CAUSE

SYSTEM ICOMPONENT FACTURER TO EPIX SUPPLEMIENTAL REPORT EXPECTED (14)

EXPECTED MOlTI.

DAY YEAR SUBMISSION X lYES (If yes, complete EXPECTED SUBMISSION DATE).

No DATE (15) 10 10 2005 ABSTRACT On June 10, 2005 with the Kewaunee Power Station in refueling shutdown mode, a possible run-out condition of the Residual Heat Removal (RHR) pumps was identified. The possible run-out condition exists upon loss of Instrument Air (IA) to the RHR flow control valves (RHR-8A(B)). These flow control valves are fail-open air operated valves that are not supplied by a safety related IA source. This issue is a concern only if containment spray pump operation is required during the post Loss of Coolant Accident (LOCA) containment sump recirculation phase.

This is reportable in accordance with 10 CFR 50.73(a)(2)(vii) as a condition causing one independent train in multiple systems to become inoperable. The cause of this event is an inadequate original Safe Shutdown Analysis of certain loss of operating air scenarios during post LOCA alignment. Procedure revisions for appropriate operator actions and contingencies have been completed to eliminate the potential run-out condition for the RHR pumps. This report does not involve a safety system functional failure since containment spray is not needed during the post LOCA recirculation phase. The post LOCA containment sump recirculation phase is the phase of the event in which the concern for RHR pump runout exists, with runout occurring if a RHR pump is supplying the suction of a containment spray pump with the RHR pump flow control valves failed to the full open position.

NRC FORIM 366A U.S. NUCLEAR REGULATORY CONMMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NANIE (1)

DOCKET NUMBER (2)

LER NUMNIBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION l

Kewvaunee Power Station 05000305 NMBER NUMINSBER 2 of 4 2005 012

- a 0

TEXT (If more space is required, use additional copies ofNRC Form 366A) (17)

Event Description

On June 10, 2005 with the Kewaunee Power Station in refueling shutdown mode, a possible run-out condition of the Residual Heat Removal (RHR) pumps upon loss of Instrument Air (IA) to the RHR flow control valves (RHR-8A(B)) was identified. These valves are fail-open air operated valves that are not supplied by a safety related IA source. This issue is a concern only if the containment spray pump operation is required during the post Loss of Coolant Accident (LOCA) containment sump recirculation phase. The station operators are directed to throttle RHR flow to 1500 gpm using RHR-8A(B) for the operating train in accordance with operating procedure ES-1.3, Transfer to Containment Sump Recirculation following a LOCA. For the recirculation standby RHR train, if the flow control valve fails open while flow is being supplied to an ICS pump, there is a possibility of RHR pump run-out. If valve RHR-8A(B) fails open due to loss of IA pressure, the operators would not be able to control RHR pump flow rate.

RHR pump run-out is 2750 gpm, based on pump curve evaluation and calculation. Review of pre-operational testing procedure indicates that when aligned only to vessel injection, RHR pump design flow (2000 gpm) is maintained due to system resistance alone (i.e., all valves open). Pre-operational test data demonstrates that without the ability to limit low head safety injection flow from the RHR pump following a large break LOCA, a runout condition on the RHR pump might occur. This condition would only occur if the ability to throttle the injection flow were lost due to RHR-8A and -8B failing open due to loss of instrument air, and the RHR pumps were aligned to the suction of an operating ICS pump and supplying injection flow.

Procedures directed alignment of RHR pump discharge in series with an Internal Containment Spray (ICS) pump in the event that spray flow was required after alignment to sump recirculation. If a standby RHR train was not available, procedural guidance resulted in the operator aligning the running train of RHR through the associated ICS pump without starting the ICS pump (idle). This results in RHR flow through the vessel injection line and flow through the idle spray pump. This alignment was not tested in pre-operational testing procedures, and no other test or calculation has been located to determine the RHR pump flowrate in this alignment. Reviews of pre-operational test results and calculated piping friction loss results, along with assumptions for differential pressure across the idle spray pump, indicate that RHR pump flowrates in this alignment could reach or exceed run-out conditions.

In the event of a LOCA, with the loss of non safety related IA pressure, the RHR pump flowrate would not be controllable as directed in the emergency procedures. In the event that spray flow would be required to mitigate the accident after entering the sump recirculation phase, series (piggyback) alignment to ICS pump suction from RHR pump discharge could result in the RHR pump reaching run-out flow conditions and potentially damage the pump.

Event Analysis and Safety Significance:

This is reportable in accordance with 10 CFR 50.73(a)(2)(vii) as a condition causing one independent train in multiple systems to become inoperable.

NRC FOR.NI 366A U.S. NUCLEAR REGULATORY CONIMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUIBER(2)

LER NUMIBER (6)

PAGE (3)

YEAR' SEQUENTIAL REVISION Kcwaunee Power Station 05000305 I

NUMBER NUR 3 of 4 l

2005 012 0

TEXT (If&more space is required, use additional copies ofNRC Form 366A) (17)

RHR pump run-out would only be a concern if ICS is required as part of the containment sump recirculation actions. Current analysis does not credit this alignment during the post LOCA recirculation phase. Other system alignments allowed by procedure would be self-limiting with respect to RHR pump run-out flow conditions with RHR-8A(B) failed open. ICS would not be required following transfer to containment sump recirculation unless containment pressure conditions warranted continued ICS flow. A basic premise of safeguards system design, which is confirmed by Kewaunee USAR accident analysis, is that containment pressure will reach a peak pressure early in the accident and then steadily decrease. The USAR accident analysis does not credit ICS operation during the sump recirculation phase of the accident. Therefore, for any accident that is within the plant's design basis, ICS spray will not be required to relieve high containment pressure during the sump recirculation phase of accident response.

This report does not involve a safety system functional failure. The post LOCA containment sump recirculation procedure aligns one train of RHR for recirculation and the other redundant train of RHR in standby mode. Loss of IA to the RHR flow control valves would not affect the recirculation train, as ICS was not lined up to this train. ICS could then be aligned to the standby RHR train procedurally, with steps to close the RHR flow control valve to prevent a runout condition of the RHR pump.

Cause

The cause of this event is an inadequate analysis of certain loss of operating air scenarios during post LOCA alignment. Loss of air to RHR-8A(B) during post LOCA sump recirculation would prevent throttling of the valves for flow control, resulting in exceeding design flow and eventual RHR pump run-out. Investigation of the cause continues and will be included in the supplement to this LER.

Corrective Actions

1. Technical Specification TS 3.3.c.1.A.1.(ii) was changed (LAR216) to delete the words "and from the containment sump" from the last sentence. This removed the requirement that the ICS pumps must be capable of taking suction from the containment sump.

2. Station procedures were revised to:

a. Include contingency actions that can be taken from the control room to reduce/stop ICS flow, i.e., stopping the ICS pump, if RHR pump cavitation or run-out conditions are observed after establishing ICS flow, and b. Verify RHR-8A(B) are closed with a contingency action to not start ICS flow if RHR-8A(B) cannot be closed (due to a loss of IA) and to delete the contingency actions that open ICS pump Motor Operated Valves of the operating train.

3. An analytical system flow model for the ECCS is being developed.

NRC FORMl 366A U.S. NUCLEAR REGULATORY COMMI1SSION (1-2001)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUIBIER (2)

LER NUMBER (6)

PAGE (3)

YEAR SEQUENTIAL REVISION Kewaunee Power Station 05000305 NUMBER NUMBER 4 of 4 2005 012 0

TEXT (Ifmore space is required, use additional copies of NRC Form 366A) (17)

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