ML023110401

Response to Request for Information Regarding High Pressure Coolant Injection System

ML023110401
Person / Time
Site:	Dresden
Issue date:	10/31/2002
From:	Hovey R Exelon Generation Co
To:	Region 3 Administrator
References
RHLTR #02-0082 IR-01-021
Download: ML023110401 (2)

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Exelon Generation www.exeloncorp.com Exelon.

Dresden Generating Station Nuclear 6500 North Dresden Road Morris, IL 60450-9765 Tel 815-942 2920 RHLTR #02-0082 October 31, 2002 U. S. Nuclear Regulatory Commission, Region III ATTN: Regional Administrator 801 Warrenville Road Lisle, IL 60532-4351 Dresden Nuclear Power Station, Unit 3 Facility Operating License No. DPR-25 NRC Docket No. 50-249

Subject:

Response to Request for Information Regarding High Pressure Coolant Injection System

References:

(1) Letter from U. S. NRC to 0. D. Kingsley (Exelon Generation Company, LLC), "Dresden Nuclear Power Station Units 2 and 3 NRC Inspection Report 50-237/01-21 (DRS); 50-249/01-21 (DRS)," dated November 16, 2001 (2) Letter from U. S. NRC, Region III, to J. L. Skolds (Exelon' Generation Company, LLC), dated June 26, 2002 In Reference 1, the NRC provided an inspection report to Exelon Generation Company (Exelon), LLC which transmitted several potential violations characterized as Unresolved Items pending completion of an evaluation of the operability of the High Pressure Coolant Injection (HPCI) System at Dresden Nuclear Power Station, (DNPS), Unit 3. This system was in a degraded condition during the period following discovery of a damaged pipe support on July 5, 2001, until the support was repaired on September 30, 2001. The purpose of this letter is to summarize our conclusions regarding the operability of the HPCI system during this period.

On July 5, 2001, the DNPS, Unit 3 HPCI system automatically initiated during a reactor scram.

On July 19, 2001, DNPS personnel identified a partially damaged pipe support on the HPCI injection line. We have concluded that the pipe support was damaged as a result of a hydraulic transient that occurred during the July 5 initiation. On September 30, 2001, the damaged pipe support anchors were repaired.

As a result of the conditions described above, we performed an evaluation and determined the system would have been able to perform its safety function given an automatic initiation. This evaluation was provided to the NRC, and Reference 2 transmitted the NRC's questions concerning this evaluation. These questions were discussed in a meeting on July 25, 2002, and in subsequent teleconferences between members of Exelon and Mr. J. Gavula of the NRC. In response to these questions, we performed additional evaluations.

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October 31, 2002 U. S. Nuclear Regulatory Commission Page 2 For the period following the initiation on July 5, 2001, until September 30, 2001, when the pipe support was in a degraded condition, we have been unable to demonstrate through analysis that the Unit.3 HPCI piping and supports would have met the operability evaluation acceptance criteria stated in DNPS procedures following an additional automatic initiation. Thus, we have determined that the Unit 3 HPCI system was inoperable during this period.

In order to prevent recurrence of similar events, we performed a root cause evaluation of the factors related to this event and have taken corrective actions based on this evaluation.

Should you have any questions concerning his letter, please contact Mr. J. Hansen at (815) 416-2800.

Respectfully, Robert J. Hovey Site Vice President Dresden Nuclear Power Station Attachment (none) cc: NRC Senior Resident Inspector - Dresden Nuclear Power Station NRC Document Control Desk