05000482/LER-2009-005, Regarding Loss of Both Diesel Generators with All Fuel in the Spent Fuel Pool

Regarding Loss of Both Diesel Generators with All Fuel in the Spent Fuel Pool

ML093640041
Person / Time
Site:	Wolf Creek
Issue date:	12/21/2009
From:	Matthew Sunseri Wolf Creek
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
WO 09-0048 LER 09-005-00
Download: ML093640041 (4)

LER-2009-005, Regarding Loss of Both Diesel Generators with All Fuel in the Spent Fuel Pool

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
4822009005R00 - NRC Website

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W LF CREEK NUCLEAR OPERATING CORPORATION Matthew W. Sunseri Vice President Operations and Plant Manager December 21, 2009 WO 09-0048 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555

Subject:

Docket No. 50-482: Licensee Event Report 2009-005-00, Loss of both Diesel Generators with all fuel in the Spent Fuel Pool Gentlemen, The enclosed Licensee Event Report (LER) 2009-005-00 is being submitted pursuant to 10 CFR 50.73(a)(2)(v). This is in regards to a Loss of both Diesel Generators with all fuel in the Spent Fuel Pool at the Wolf Creek Generating Station.

This letter contains no commitments. If you have any questions concerning this matter, please contact me at (620) 364-4008, or Mr. Richard D. Flannigan, Manager Regulatory Affairs at (620) 364-4117.

Sincerely, Matthew W. Sunseri MWS/rlt Enclosure cc:

E. E. Collins (NRC), w/e G. B. Miller (NRC), w/e B. K. Singal (NRC), w/e Senior Resident Inspector (NRC), w/e P.O. Box 411 / Burlington, KS 66839 / Phone: (620) 364-8831 An Equal Opportunity Employer M/F/HC/VET nIC4'

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 (9-2007)

, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.

13. PAGE WOLF CREEK GENERATING STATION 05000 482J 1 OF 3

4. TITLE Loss of both Diesel Generators with all fuel in the Spent Fuel Pool

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.

MONTH DAY YEAR 05000 FACILITY NAME DOCKET NUMBER 10 22 2009 2009

- 005 00 12 21 2009 05000

9. OPERATING MODE

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

El 20.2201(b)

El 20.2203(a)(3)(i)

El 50.73(a)(2)(i)(C)

-] 50.73(a)(2)(vii)

De-fueled El 20.2201(d)

[I 20.2203(a)(3)(ii)

El 50.73(a)(2)(ii)(A)

El 50.73(a)(2)(viii)(A)

El 20.2203(a)(1)

El 20.2203(a)(4)

El 50.73(a)(2)(ii)(B)

[I 50.73(a)(2)(viii)(B)

_ 20.2203(a)(2)(i)

El 50.36(c)(1)(i)(A)

El 50.73(a)(2)(iii)

El 50.73(a)(2)(ix)(A)

10. POWER LEVEL El 20.2203(a)(2)(ii)

[1 50.36(c)(1)(ii)(A)

El 50.73(a)(2)(iv)(A)

El 50.73(a)(2)(x)

[I 20.2203(a)(2)(iii)

[E 50.36(c)(2)

El 50.73(a)(2)(v)(A)

El 73.71(a)(4)

El 20.2203(a)(2)(iv)

El 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B)

El 73.71(a)(5) 000 El 20.2203(a)(2)(v)

El 50.73(a)(2)(i)(A)

.0 50.73(a)(2)(v)(C)

El OTHER El 20.2203(a)(2)(vi)

El 50.73(a)(2)(i)(B)

M 50.73(a)(2)(v)(D)

Specify in Abstract below or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (include Area Code)

Richard D. Flannigan, Manager Regulatory Affairs 1(620) 364-4117MAU EOTBEMN-RPOR

CAUSE

SYSTEM COMPONENT REPORTABLE

CAUSE

SYSTEM COMPONENT FACTURER TO EPIX FACTURER TO EPIX A

EK JX C470 Yes

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR SUBMISSION El YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 0 NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

At 1206 CDT on 10/22/2009, with Wolf Creek Generating Station in Refueling Outage 17, Control Room annunciators 20D and 20B for the "A" Diesel Generator (DG) actuated. At 1208 CDT the "A" DG was taken out of service for troubleshooting of abnormal alarm indications.

At 1739 CDT on 10/22/2009, a Notification of Unusual Event (NUE) was declared due to the loss of the "A" DG with the "B" DG out of service for refueling outage maintenance. At the time of the event, the reactor vessel was defueled with all fuel located in the Spent Fuel Pool. Povwer to the safety related busses was being supplied by offsite power.

The cause of the event was the speed switches on the "A" DG had actuated due to failure of the capacitor on the DC input feed to the annunciator power supply. The annunciator power supply and speed switch were replaced and the new switch calibrated.

The "A" DG was returned to service at 0738 CDT on 10/23/2009. The NUE was exited at 0740 CDT on 10/23/2009.

NRC FORM 366 (9-2007)U.S. NUCLEAR REGULATORY COMMISSION (9-2007)

LICENSEE EVENT REPORT (LER)

1. FACILITY NAME

2. DOCKET

6. LER NUMBER

3. PAGE SEQUENTIAL I

REV WOLF CREEK GENERATING STATION 05000 482 YEAR NUMBER NO.

2 OF 3

2009 005--

00 PLANT CONDITIONS PRIOR TO EVENT:

MODE - De-fueled Power- 000

EVENT DESCRIPTION

At 1206 CDT on 10/22/2009, with Wolf Creek Generating Station (WCGS) in Refueling Outage 17, Control Room annunciators 20D, DG NE01 Trouble, and 20B, DG NE01 UV or UF, for the "A" Diesel Generator (DG)

[EIIS Code: EK] actuated. At 1208 CDT the "A" DG was taken out of service for troubleshooting of abnormal alarm indications.

At 1739 CDT on 10/22/2009, a Notification of Unusual Event (NUE) was declared due to the loss of the "A" DG with the "B" DG out of service for refueling outage maintenance. The NUE was delayed due to the licensed operator failure to recognize that "All" Modes in the Emergency Action Level Classification scheme is effective at all times: The delay in the NUE has been entered into the WCGS corrective action program. At the time of the event, the reactor vessel was defueled with all fuel assemblies located in the Spent Fuel Pool. There are no Technical Specifications (TS) requirements for the DGs when defueled. The TS defines Mode as "A MODE shall correspond to any one inclusive combination of core reactivity condition, power level, average reactor coolant temperature, and reactor vessel head closure bolt tensioning specified in Table 1.1-1 with fuel in the reactor vessel."

Power to the safety related busses were being supplied by offsite power.

The cause of the event was the speed switches in the starting circuit of the A DG had actuated due to the failure of the capacitor on the DC input feed to the annunciator power supply. This allowed higher levels of AC noise to be applied to the DC feed to the speed switches. The high AC noise was more than the capacitors on the DC feed to the speed switches could filter out. The AC noise actuated the switches.

The source of electrical noise on the DC supply circuit was traced to the annunicator power supply within the emergency generator gauge board panel. The annunciator power supply and speed switch were replaced on the A DG and the new switch calibrated.

The "A" DG was returned to service at 0738 CDT on 10/23/2009. The NUE was exited at 0740 CDT on 10/23/2009.

BASIS FOR REPORTABILITY This event is reportable in accordance with 10 CFR 50.73(a)(2)(v)(B), (C) and (D) as an event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to: (B)

Remove residual heat; (C) Control the release of radioactive material; or (D) Mitigate the consequences of an accident. Specifically, the guidance in NUREG-1022, Rev. 2, states: "Both offsite electrical power (transmission lines) and onsite emergency power (usually diesel generators) are considered to be separate functions by GDC-

17. If either offsite power or onsite emergency power is unavailable to the plant, it is reportable regardless of whether the other system is available. GDC-17 defines the safety function of each system as providing sufficient capacity and capability, etc., assuming that the other system is not available."U.S. NUCLEAR REGULATORY COMMISSION (9-2007)

LICENSEE EVENT REPORT (LER)

1. FACILITY NAME

2. DOCKET

6. LER NUMBER

3. PAGE SEQUENTIAL I

REV WOLF CREEK GENERATING STATION 05000 482 YEAR NUMBER N

NO.

3 OF 3

2009 005 00 ROOT CAUSE:

The high AC noise affecting the speed switch was caused by the lack of a preventative maintenance (PM) activity to monitor ripple voltages on the annunciator power supply DC input. Monitoring of the AC noise will allow detection and actions to be taken prior to the AC noise reaching a level higher than the capacitor on the DC input feed to the speed switches can filter out.

CORRECTIVE ACTIONS

A PM activity was established to have the AC ripple voltage measured at the DC input to the annunciator power supply every three months. If the measured AC ripple voltage reaches a value of 500 milivolts, a work request will be generated to have the power supply replaced.

SAFETY SIGNIFICANCE

The Outage Control Center performed a shutdown risk assessment on 10/22/2009 after the loss of the DG. The shutdown safety risk condition for the plant was Risk condition 2. Risk condition 2 indicates a moderate risk.

There is a reduction in the equipment available for satisfying a shutdown safety function because of electrical power resources and decay heat removal.

The entire core was in the Spent Fuel Pool (SFP) and the SFP water inventory was full. The plant-operating mode was de-fueled. Switchyard activities were not in progress. Power was available from the offsite power sources. The SFP time to boil was 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />.

OPERATING EXPERIENCE/PREVIOUS EVENTS:

LER 2008-004-01 involves a loss of off-site power when the reactor was de-fueled. That event had one source of on-site power available, while this event had off-site power available.