05000370/LER-2005-007, Re Power Reduction Due to Entry Into LCO 3.0.3 Caused by Inoperable Control Room Area Cooling Water System
| ML053470329 | |
| Person / Time | |
|---|---|
| Site: | Mcguire |
| Issue date: | 12/01/2005 |
| From: | Gordon Peterson Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 05-007-00 | |
| Download: ML053470329 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3702005007R00 - NRC Website | |
text
PhDuke GARY R. PETERSON OrPowere Vice President McGuire Nuclear Station A Duke Energy Company Duke Power MG0I VP / 12700 Hagers Ferry Road Huntersville, NC 28078-9340 704 875 5333 704 875 4809 fax grpeters@duke-energy. corn December 1, 2005 U.S. Nuclear Regulatory Commission ATTENTION: Document Control Desk Washington, D.C.
20555
Subject:
McGuire Nuclear Station, Unit 2 Docket No. 50-370 Licensee Event Report 370/2005-07, Revision 0 Problem Investigation Process (PIP) M-05-04906 Pursuant to 10 CFR 50.73, Sections (a)(l) and (d), attached is Licensee Event Report (LER) 370/2005-07, Revision 0, concerning a power reduction on McGuire Unit 2 due to entry into Technical Specifications Limiting Condition for Operation (LCO) 3.0.3 caused by an inoperable Control Room Area Cooling Water System.
This report is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications (TS).
This event is determined to be of no significance to the health and safety of the public.
This LER contains a regulatory commitment for Duke Energy Corporation to submit a future license amendment request (LAR).
This LAR will address operability requirements for shared and unit designated equipment on a shutdown unit when this equipment is relied on to support an operating unit in Modes 1 thru 4. This situation is identified as a contributing cause to the occurrence of the event discussed in this LER.
Very truly yours, Gary R. Peterson Attachment www. duke-energy. corn
I U. S. Nuclear Regulatory Commission December 1, 2005 Page 2 of 2 cc:
W. D. Travers U. S. Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, GA 30303 J. F. Stang, Jr. (Addressee Only)
NRC Project Manager (McGuire)
U. S. Nuclear Regulatory Commission Mail Stop 8 H4A Washington, DC 20555-0001 J. B. Brady Senior Resident Inspector U. S. Nuclear Regulatory Commission McGuire Nuclear Site Beverly 0. Hall, Section Chief Radiation Protection Section 1645 Mail Service Center Raleigh, NC 27699-1645
Abstract
Unit Status:
At the time of the event, Unit 1 was in Mode 6 (Refueling) at 0% power and Unit 2 was in Mode 1 (Power Operation) at 100% power.
Event Description
On October 8, 2005, at 03:20, both trains of the Control Room Area Cooling Water System (CRACWS) were declared inoperable, a condition prohibited by Technical Specifications (TS).
Even though one CRACWS train was fully functional and provided cooling to the Control Room during this event, it was determined to be administratively inoperable.
A Unit 2 shutdown was initiated when the problems with the CRACWS could not be resolved in the time allowed by the TS.
This led to Duke Energy Corporation (Duke) requesting a Notice of Enforcement Discretion (NOED).
Following the approval of the NOED, shutdown of Unit 2 was discontinued.
This event was determined to be of no significance to the health and safety of the public.
Event Cause
The cause of this event is attributed to a defective oil pressure switch on the CRACWS "A" Chiller while the CRACWS "B" Chiller was administratively inoperable due to its reliance on shared and unit designated equipment aligned to the outage unit.
Corrective Action
A temporary modification was made to the "A" Chiller during the NOED period.
Permanent repairs were subsequently made by replacing the defective oil pressure switch.
NRC FORM 366 (6-2004)
(If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (if more space is required, use additional copies of NRC Form 366A) measures as described in plant Abnormal Procedures.
As a result, the loss of the CRACWS System, including the control room chillers, has been screened out of the McGuire PRA as either an initiating event or as a support system failure. Therefore, the CRACWS System has no impact on the calculated Core Damage Frequency (CDF) or Large Early Release Frequency (LERF) at McGuire.
During the period allowed by the NOED, the "BO Chiller was recorded as inoperable, but it was available and did perform its safety function of cooling the control room.
Based on the opportunity to mitigate the consequence of this event, and the fact that the "B" chiller was available to perform its intended safety function, the impact on the incremental conditional core damage probability (ICCDP) was expected to be much less than 5E-07 and the impact on the incremental conditional large early release probability (ICLERP) was expected to be much less than 5E-08.
This event was determined to be of no significance to the health and safety of the public.
ADDITIONAL INFORMATION A review of the McGuire corrective action database identified no previous LERs, within the past three years, caused by a CRACWS chiller failing to start due to a defective oil pressure switch.
Therefore, this is not considered a recurring event.