PNO-III-05-009, Technical Specification Required Shutdown of Prairie Island Unit 2 for Greater than 72 Hours

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PNO-III-05-009, Technical Specification Required Shutdown of Prairie Island Unit 2 for Greater than 72 Hours
ML051100183
Person / Time
Site: Prairie Island  Xcel Energy icon.png
Issue date: 04/20/2005
From:
NRC/RGN-III
To:
References
PNO-III-05-009
Download: ML051100183 (2)


April 20, 2005 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE -- PNO-III-05-009 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region III staff on this date.

Facility Licensee Emergency Classification Prairie Island Notification of Unusual Event Nuclear Management Company Alert Hudson, Wisconsin Site Area Emergency Docket: 50-282; 50-306 General Emergency License: DPR-42; DPR-60 x Not Applicable

SUBJECT:

TECHNICAL SPECIFICATION REQUIRED SHUTDOWN OF PRAIRIE ISLAND UNIT 2 FOR GREATER THAN 72 HOURS On April 16, 2005, Prairie Island Unit 2 shut down to repair emergency diesel generator (EDG)

D5 (Reference Event No. 41606). Prairie Island has two originally installed safety-related EDGs. In 1992, the licensee added two additional safety-related EDGs (D5 and D6) to make a total of four EDGs available to power safety-related equipment. The newer EDGs were manufactured by Soc,t, Alsacienne de Constructions M,chaniques de Mullhouse (SACM) and are configured with two diesel engines driving a single generator. Each of these newer EDGs are rated at 5400 kW.

While testing EDG D5 on April 11, 2005, the licensee observed elevated crankcase pressure and subsequently identified minor damage on 2 of 16 cylinders in Engine No. 2. After consultations with the vendor and an independent laboratory, the utility decided to replace all the liners and pistons on both engines of the EDG. However, the licensee determined that the repairs could not be completed within the 7-day outage time allowed by Technical Specifications, and opted to shut down the Unit with approximately 2-days remaining in the allowed outage time. The Unit is currently in Mode 5 (Cold Shutdown).

In early 2001, a high crankcase pressure condition was also identified on EDG D6, due to blow-by of the piston rings from incompatible lubricating and fuel oils. The licensee replaced all of the cylinder and piston assemblies on the D6 EDG and replaced the lubricating and fuel oils on both the D5 and D6 EDGs with a compatible mixture. Because the D5 EDG had significantly less run time and showed no evidence of damage, the cylinder and piston assemblies were not replaced at that time.

The cause of the high crankcase pressure identified on D5 EDG is currently under investigation.

Region III and Headquarters personnel will continue to follow the licensee's root cause investigation and monitor its recovery actions.

The information in this preliminary notification has been reviewed with licensee management.

The licensee notified the NRC Operations Center of the shutdown at 10:33 p.m. on April 15, 2005. This information is current as of 8:00 a.m. CDT on April 20, 2005.

CONTACT: David G. Passehl, 630-829-9872