05000305/LER-2006-009

LER-2006-009,

Docket Number
Event date:	08-17-2006
Report date:	04-16-2007
3052006009R01 - NRC Website

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) Kewaunee Power Station 05000305 YEAR

EVENT DESCRIPTION

At 17:35 on 8/17/06, after approximately 10 minutes of operation during a planned surveillance test on the train A emergency diesel generator (EDG) [DG], a previously identified minor fuel oil leak increased and required an unplanned engine shutdown. The EDG had been declared inoperable at the start of the surveillance test and remained so following the leak. At its maximum, the leakrate was estimated at between 0.12 and 0.25 gpm. The leak did not atomize.

By 05:53 on 8/18/06, the leak had been repaired, the surveillance test completed, and the EDG restored to OPERABLE.

The fuel oil leak (approximately 1 drop/minute) was initially identified on a copper tubing Swagelock fitting (downstream of the engine-driven fuel oil pump [P] and the fuel priming pump), on 6/28/06 and a Work Order was written to repair it. Between initial discovery on 6/28/06 and the engine shutdown on 8/17/06, the EDG had been operated four times with a cumulative run time of approximately 3.9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />.

On 10/26/06, the leak failure mechanism was determined to be an approximately 350 degree circumferential crack in the copper tubing of the fuel supply line inside a 3/8" fitting to a pressure gauge. On 12/15/06, the cracked tubing was tested on a similar diesel generator. The tubing fully severed after approximately one hour of diesel generator operation at rated load. Thus it is concluded that the EDG was not capable of meeting its design basis between the originally identified leak on 6/28/06 and its return to operability on 8/18/06.

EVENT ANALYSIS

This event is being reported under 10 CFR 50.73(a)(2)(v)(B) and (D) as a condition 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.

This event is also being reported under 10 CFR 50.73(a)(2)(i)(B) as an operation which was prohibited by the plant's Technical Specifications.

The following train B safety equipment was also inoperable between 6/28/06 at 16:48 and 8/18/06 @ 05:53:

Equip Inoperable Operable Duration (hrs) Total (hrs) EDG B 6/29/06 @ 9:27 6/30/06 @ 00:56 15.48 EDG B 7/27/06 @ 7:00 7/27/06 @ 15:49 8.82 29.97 EDG B 8/13/06 @ 8:54 8/13/06 @ 14:34 5.67 SW [BI] Train B 7/23/06 @ 12:30 7/23/06 @ 22:00 9.50 SW Train B 7/26/06 @ 3:47 7/27/06 @ 4:35 24.80 39.77 SW Train B 8/9/06 @ 7:46 8/9/06 @ 11:49 4.05 SW Train B 8/13/06 @ 8:55 8/13/06 @ 10:20 1.42 FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) Equip Inoperable Operable Duration (hrs) Total (hrs) RHR [BP] Pmp B 7/13/06 @ 8:43 7/14/06 @ 00:41 15.97 RHR Pump B 7/12/06 @ 15:51 7/12/06 @ 16:33 0.70 RHR Pump B 7/27/06 @ 13:35 7/27/06 @ 16:31 2.93 20.52 RHR Train B 7/12/06 @ 14:54 7/12/06 @ 15:25 0.52 RHR Train B 8/13/06 @ 13:12 8/13/06 @ 13:36 0.4 ICS [BE] Pump B 7/12/06 @ 14:46 7/12/06 @ 15:37 0.85 0.85 SI [BQ] Pump B 7/14/06 @ 1:03 7/14/06 @ 1:04 0.02 1.42 SI Train B 8/10/06 @ 9:41 8/10/06 @ 11:05 1.4 Chg [CB] Pump B 7/11/06 @ 7:04 7/11/06 @ 15:58 8.9 19.3 Chg Pump B 8/8/06 @ 7:09 8/8/06 @ 17:35 10.4 CC [CC] Pump B 7/02/06 @ 10:15 7/02/06 @ 10:30 0.25 CC Pump B 7/28/06 @ 23:40 7/28/06 @ 23:45 0.08 CC Train B 7/30/06 @ 21:39 7/30/06 @ 23:30 1.85 3.98 CC Train B 8/13/06 @ 00:04 8/13/06 @ 00:10 0.10 CC Train B 8/13/06 @ 10:21 8/13/06 @ 12:03 1.7 TDAFW [BA] Pmp 7/3/06 @ 8:58 7/3/06@ 9:07 0.15 TDAFW Pump 7/10/06 @ 9:18 7/10/06 @ 9:26 0.13 0.65 TDAFW Pump 8/3/06 @ 12:32 8/3/06 @ 12:45 0.22 TDAFW Pump 8/7/06 @ 10:24 8/7/06 @ 10:33 0.15 AFW [BA] Pmp B 7/10/06 @ 8:49 7/10/06 @ 8:56 0.12 AFW Train B 7/27/06 @ 10:15 7/27/06 @ 10:45 0.5 2.16 AFW Pump B 8/7/06 @ 10:00 8/7/06 @ 10:07 0.12 AFW Pump 8/13/06 @ 8:55 8/13/06 @ 10:20 1.42 Sfgds [JE] Train B 7/11/06 @ 9:18 7/11/06 @ 11:11 1.88 5.43 Sfgds Train B 8/8/06 @ 9:29 8/8/06 @ 13:02 3.55 With train A EDG inoperable, the plant should have entered Tech Spec LCO 3.7.b.2, which 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." During this event, train A EDG was inoperable in exceess of 7 days and train B EDG was never tested for operability under this LCO.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) Kewaunee Power Station 05000305 YEAR Exceeding the 7 day LCO for train A EDG, and each of the occasions above involving concurrently inoperable 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 overall incremental core damage probability (IDCP) for the time period in question is 2.2E-5, which is categorized in the NRC Significance Determination Process as Substantial safety significance.

CAUSE

The direct cause of the leak was determined to be circumferential cracking due to vibration induced fatigue.

The root cause for the event was that critical information was not known by decision makers - as evidenced by the following:

• Failure to initiate a CAP for the initial leak on 6/28/06 (missed opportunity for equipment operability evaluation)

• Training does not cover common industry-known tubing failure mechanisms.

• Managers and supervisors were not knowledgeable of OE from this type of failure event.

• The work request screen team did not walk down the equipment deficiency or recognize the need to do so, and did not communicate the proper sense of urgency to the rest of the organization.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) Kewaunee Power Station 05000305 YEAR

CORRECTIVE ACTIONS

For the direct cause, the leak was repaired, an operability test was performed, and the EDG was restored to OPERABLE status.

For the root cause, critical information will be made available to decision makers via the following changes:

• New software, (MAXIMO and CRS), will be implemented to ensure equipment issues are always captured within the corrective action system.

0 Until CRS and MAXIMO are implemented, the following interim corrective actions have been taken:

• On a daily basis, Outage and Planning reviews all new work requests to ensure CAPs are written when required.

• If a CAP was not generated, the work request initiator is contacted to write a CAP and include the CAP number on the work request.

• The CAP & Work Order process has been reiterated several times in the following:

• A plant standdown

• D-15 publications

• The daily Plan Of the Day meetings

• Material will be added to Lesson Plans to assure workers are aware of failure mechanisms of tubing compression fittings, signs of failure and interpretation of those signs.

• Supervisors and managers will receive training on this event.

• Work request screen team members will receive training on this event.

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