05000305/LER-2006-004, Regarding Incorrect Assumption Regarding De-Rating of EDGs During Loaded Operation

Regarding Incorrect Assumption Regarding De-Rating of EDGs During Loaded Operation

ML062050232
Person / Time
Site:	Kewaunee
Issue date:	07/14/2006
From:	Hartz L Dominion, Dominion Energy Kewaunee
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
06-610 LER 06-004-00
Download: ML062050232 (7)

LER-2006-004, Regarding Incorrect Assumption Regarding De-Rating of EDGs During Loaded Operation

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)
3052006004R00 - NRC Website

text

!i-ýVDominion Dominion Energy Kewaunee, Inc.

N490 Highway 42, Kewaunee, WI 54216-9511 JUL 1 4 2006 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Serial No.06-610 KPS/LIC/RS: RO Docket No.

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

KEWAUNEE POWER STATION LICENSEE EVENT REPORT 2006-04-00

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. 50-305/2006-004-00 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 Mr. Richard Sattler at (920) 388-8121.

Very truly yours, Leslie N. Hartz Site Vice President, Kewaunee Power Station Attachment Commitments made by this letter: NONE

Serial No.06-610 Page 2 of 2 cc: Regional Administrator, Region III U.S. Nuclear Regulatory Commission 2443 Warrenville Road Suite 210 Lisle, IL 60532-4352 Mr. D. H. Jaffe Project Manager U.S. Nuclear Regulatory Commission Mail Stop O-7-D-1 Washington, D. C. 20555 NRC Senior Resident Inspector Kewaunee Power Station

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 6-30-2007 (8-2o04)

Estimated burden per response to comply with this mandatory collection request 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />.

Reported lessons learned are incorporated into the licensing process and fed back to industry.

LICENSEE EVENT REPORT (LER)

Send comments regarding burden estimate to the Records and FOIA/Privacy Service Branch (T-5 F52), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by intemete-(See reverse for required number of mail to infocollects@nrc.gov, and to the Desk Officer, Office of Information and Regulatory (Segrveslharte roAffairs, NEOB-10202, (3150-0066), Office of Management and Budget, Washington, DC20503.

digits/characters for each block)

If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person Is not required to respond to, the Information collection.

FACILITY NAME (1)

KET NUMBER (2)

Kewaunee Power Station 050D0305 1

Of 5

TrLE (4)

Incorrect Assumption Regarding De-Rating of EDGs During Loaded Operation EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7)

OTHER FACILmES INVOLVED (8)

SSEOUENTIAL JREV FACILITY NAME DOCKET NUMBER MO DAY YEAR YEAR NUMBER NO MO DAY YEAR RVFACILITY NAME DOCKET NUMBER 05 19 2006 2006 004 00 07 14 2006 FACILITY NAME DOCKET NUMBER OPERATING N

THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR.: (Check all that apply) (11)

MODE (9) 1 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) 000 120.2203(a)(1) 50.36(c)(1)(i)(A) 50.73(a)(2)(iv)(A) 173.71(a)(4) 20.2203(a)(2)(I)

,50.36(c)(1)(ii)(A) 50.73(a)(2)(v)(A) 173.71 (a)(5) 20*2203(a)(2)(ii) 50.36(c)(2)

X 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)

X 50.73(a)(2)(i)(B) 50.73(a)(2)(vii) 20.2203(a)(2)(vl) 50.73(a)(2)(i)(C) 50.73(a)(2)(viii)(A) 20.2203(a)(3)(0) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(B)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER (Include Area Code)

Rich Sattler 1

(920) 388-8121 COMPLETE ONE MNE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 13)

MANU-REPORTABLE MANU-REPORTABLE

CAUSE

SYSTEM COMPONENT FACTURER TO EPIX

CAUSE

SYSTEM COMPONENT FA CTURER TO EPIX SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR X

YES (If yes, complete EXPECTED SUBMISSION DATE).

SUBMISSION 10 1

2006 DAT (15 10 1D00 ABSTRACT The Kewanee emergency diesel generators (EDGs) are required to carry loads in excess of their continuous rating (2600 kW) following a design basis accident. To support EDG operability under these conditions, combustion air temperatures should not exceed limits set by the vendor via de-rating curves.

At 21:54 on May 19, 2006, with the plant in HOT SHUTDOWN, it was discovered that an incorrect interpretation of the de-rating curves has resulted in the potential to operate the EDGs outside of the vendor recommended ratings during the initial diesel loading following a design basis accident.

Both EDGs have been operated within the vendor ratings for the last three years and successfully completed an elevated load test following an overhaul verifying that no degraded condition existed prior to the elevated load test. Therefore, with outside air temperature at 44 degrees F, an initial determination was made that both EDGs were operable. A review showed that seven times in the last three years, outdoor air temperatures exceeded the 87.1 degrees F limit for the A EDG which should have resulted in an inoperability determination for the A EDG. At no time were the other EDG temperature limits exceeded. A subsequent operability recommendation established compensatory measures that extend operability to outside air temperatures of 97.8 degrees F (for A EDG), and 100.9 degrees F (for B EDG).

This is considered a safety system functional failure.U.S. NUCLEAR REGULATORY COMMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

Kewaunee Power Station 05000305 UMBER I NUMBER 2 of 5 1 2006 004 00 TEXT (if mom space Is reqwmd, use adkitional copies of NRC Form 366A) (17)

Event Description

At Kewanee Power Station (KPS), both emergency diesel generators (EDGs) are required to exceed their continuous operating load limit (2600 kW) during a loss of coolant accident (LOCA) with loss of off-site power (LOOP). Operation outside this continuous operating limit is acceptable provided the duration of the loading and the maximum combustion air temperatures are not exceeded.

At the time of the event, the EDGs had the following vendor recommended ratings:

Allowable Maximum Duration load (kW)

Continuous 2600 2000 hrs/yr 2860 7 days/yr 2950 30 min/yr 3050 In 2000, KPS evaluated and implemented the EDG de-rating curves (which reduce the maximum allowed ratings in the table above as combustion air intake temperature increases).

At 21:54 on May 19, 2006, with the plant in HOT SHUTDOWN, KPS determined that the de-rating curves for the EDGs were incorrectly interpreted. This resulted in the potential to operate the EDGs outside of the vendor recommended ratings during the initial diesel loading (from 0 to 1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> per Kewanee Updated Safety Analysis Report Table 8.2-1) following a design basis document.

A correct interpretation of the de-rating curves results in the following temperature limits (using actual EDG loadings for the first hour and at the current 2000 hr/yr rating for the remainder of a LOCA with LOOP):

Max Combustion Max Outdoor EDG EDG Loading Air Temp (deg F)

Air Temp (deg F)

Actual for the first hour - 2884.8 kW 104.5 87.1 A

2000 hr/yr rating - 2864 kW 115.0 97.8 Actual for the first hour - 2838.4 kW 118.25 104.3 B

2000 hr/yr rating - 2864 kW 115.0 100.9 Temperatures in the above table are not corrected for instrument inaccuracy.

Outside air is mixed with the EDG room air prior to the combustion air intake. Thus, heat generated from equipment in the room and from the EDG itself, contributes to the overall combustion air intake temperature.

A review shows that seven times in the last three years, outdoor air temperatures exceeded the 87.1 deg F limit for the A EDG which should have resulted in an inoperability determination for the A EDG. At no time during those three years were the other EDG temperature limits exceeded.U.S. NUCLEAR REGULATORY COMMISSION (1-200)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER (6)

PAGE (3)

YEA I

SEQUENTIAL IREVISION I Kewaunee Power Station 05000305 NR NUMBER I NUMBER 3 of 5 I 2006 004 00 TEXT (If more space is required, use additional copies of NRC Form 3664) (17)

Event Analysis

This event is being reported in accordance with 10CFR50.73(a)(2)(i)(B), "Any operation or condition which was prohibited by the plant's Technical Specifications", and 10CFR50.73(a)(2)(v), "Any event or condition that could have prevented the fulfillment of the safety function of structures or systems."

A review of the 10 meter meterological tower historical data from 2003 to present determined the following instances where site temperature (corrected for instrument uncertainty), exceeded the A EDG limit:

Date & Time Date & Time Max temp above A EDG below A EDG Duration (hrs)

(deg F) during

Plant Conditions

Temp Limit Temp Limit event 08/21/2003 12:47 08/21/2003 14:50 2.06 88.20 100% power 06/24/2005 11:04 06/24/2005 18:05 7.01 91.76 0% power (507.9 deg F Tavg) 07/24/2005 10:32 07/24/2005 14:52 4.34 90.93 100% power 07/31/2005 13:45 07/31/2005 17:41 3.93 87.60 100% power 08/01/2005 12:43 08/01/2005 16:35 3.85 88.27 100% power 08/08/2005 11:51 08/08/2005 13:10 1.31 88.41 100% power 08/09/2005 10:23 08/09/2005 14:14 3.85 91.34 100% power At no time during the occurrences above was A EDG operating, so it was never operated when de-rating was required, and thus never operated outside the vendor recommended ratings.

Tech Spec LCO 3.7.b.2 states: "One diesel generator may be inoperable for a period not exceeding 7 days provided the other diesel is tested daily to ensure OPERABILITY and the engineered safety features associated with this diesel generator are OPERABLE."U.S. NUCLEAR REGULATORY COMMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2 LER NUMBER (6)

PAGE (3)

YEAR I SEQUENTIAL REVISION Kewaunee Power Station 05000305 YEAR NUMBER NUMBER 4 of 5 2006-004 00 TEXT (If more space Is required, use additional copies of NRC Fom 366W)

(17)

None of the above cases exceeded twenty four hours and B EDG was never concurrently inoperable.

However, on three occasions, the following Train B engineered safety features were concurrently inoperable (for the durations shown):

During the 6/24/05 event: turbine driven auxiliary feedwater pump [BA] (for 4.63 hrs), internal containment spray train B [BE] (for 1.33 hrs), component cooling train B [CC] (for 0.8 hrs), and residual heat removal (RHR) train B [BO] (for 1.02 hrs)

During the 8/8/05 event: reactor protection system logic train B [JC] (for 0.28 hrs) and B train RHR /

safety injection (SI) [BO/BQ] (for 1.31 hrs)

During the 8/9/05 event: B train RHR/SI (for 0.23 hrs) and engineered safety features train B logic channel [JE] (for 1.48 hrs)

The three occasions above (involving inoperable concurrent Train B engineered safety features), should have resulted in entry into Tech Spec LCO 3.0.c, which did not occur. Tech Spec LCO 3.0.c states:

When a LIMITING CONDITION FOR OPERATION is not met, and a plant shutdown is required except as provided in the associated ACTION requirements, within one hour action shall be initiated to place the unit in a MODE in which the specification does not apply by placing it, as applicable, in:

1. At least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />,

2. At least HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, and

3. At least COLD SHUTDOWN within the subsequent 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

Safety Significance

The safety significance of this event is considered very low.

Documentation from the EDG vendor indicates that operating outside of the ratings specified on the de-rating curves will not cause immediate catastrophic failure, but will result in accelerated wear of internal engine components and could ultimately result in the inability of the EDG to complete its mission time. The higher combustion air intake temperatures will not affect the ability of the EDGs to start and assume load.

The calculated total core damage frequency (CDF) for events that would actuate SI combined with a loss of offsite power and a failure of both EDGs to operate during occurrences of ambient temperature exceeding the A EDG temperature limit is 9.2E-8/yr.

This is considered a safety system functional failure because this was an event that could have prevented the fulfillment of the safety function of structures or systems that are needed to remove residual heat and mitigate the consequences of an accident.U.S. NUCLEAR REGULATORY COMMISSION (1-2001)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION FACILITY NAME (1)

DOCKET NUMBER (2)

LER NUMBER 16 PAGE (3)

Kewaunee Power Station I 05000305 YR SEQUENTIAL REVISION Kewune owr taton050005NUMBER NUMBER 5 of 5 12006

- 004 00 TEXT (if more space is requre4 use additonal copies of NRC Fom 36M4) (17)

Cause

The cause evaluation of this event is in progress. The final cause determination will be provided in a supplemental report. Any changes to the corrective actions, based on the results of the final cause evaluation, will also be included in the supplemental report.

Corrective Actions

Changes were made to reduce the LOCA with LOOP load requirement on the A EDG to within the 2000 hr/yr limit (2864 kW).

Compensatory actions with alarms and actions on increasing/decreasing ambient temperatures culminating with action to declare the affected EDG INOPERABLE at its temperature limit have been implemented.

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