ML110740767
| ML110740767 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 03/15/2011 |
| From: | Tulon T Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 2011-0044, LER 10-002-00 | |
| Download: ML110740767 (2) | |
Text
Exel n Co pau. LLC wexo o o p cri Nuclear N t uenan Cb R aC
- bvroo, ho1 974 10 CFR 50.73 March 15, 2011 Byron Ltr: 2011-0044 FiIe# 1.10.0101 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 2 Facility Operating License No. NPF-66 NRC Docket No. STN 50-455
Subject:
Withdrawal of Licensee Event Report 455-20 1 0-002-00, Essential Service Water System Inoperable Due to Inadequate Seismic Restraint from Original Construction Error
Reference:
Letter from Daniel J. Enright (Exelon Generation Company, LLC) to U.S. NRC, Licensee Event Report 2010-002-00, Essential Service Water System Inoperable Due to Inadequate Seismic Restraint from Original Construction Error, dated August 3, 2010 The referenced Licensee Event Report (LER) involved the discovery of an inadequate seismic restraint of safety related Essential Service Water (SX) piping attached to the non-safety related Containment Ventilation chillers. The chillers were not welded to their support base plates as required by design. On June 4, 2010, Exelon Generation Company, LLC (EGC), completed an evaluation concluding that during a postulated Safe Shutdown Earthquake event, the SX piping could have failed. Consequently, at the time this condition was conservatively reported to the NRC in accordance with 10 CFR 50.73 (a)(2)(ii)(B), as a unanalyzed condition that significantly degraded plant safety. Additional engineering analysis was pursued in order to more accurately assess the safety significance of this condition and the conclusions were to be reported to the NRC in a supplement to the LER.
U. S. Nuclear Regulatory Commission March 11,2011 Page 2 The additional analysis was completed and concluded the SX piping, in this condition, would have been able to perform its design function for the worst case loading conditions and that the SX piping met operability criteria. Since this analysis demonstrates there was minimal safety significance to this condition, EGO has determined the reporting requirement of 10 CFR 50.73 (a)(2)(ii)(B) is no longer satisfied.
In addition, since past operability was demonstrated, ECG has also determined that 10 CFR 50.73 (a)(2)(i)(B), (i.e., operations or condition which was prohibited by the plants Technical Specifications) is not satisfied.
Therefore, the referenced LER is being withdrawn.
There are no regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact Mr. David Gudger, Regulatory Assurance Manager, at (815) 406-2800.
Respectfully, Ai I
Tithy J. Tulon Sle Vice President Byron Station TJT/DTG/J E L/cy