05000369/LER-2007-003, Re Inoperable Source Range Neutron Flux Monitors During Mode 6 and Core Alterations
| ML071800312 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 06/14/2007 |
| From: | Gordon Peterson Duke Energy Corp, Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 07-003-00 | |
| Download: ML071800312 (9) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3692007003R00 - NRC Website | |
text
P Duke GARY R. PETERSON
- r Power Vice President McGuire Nuclear Station A Duke Energy Company Duke Power MG01 VP / 12700 Hagers Ferry Rd.
Huntersville, NC 28078-9340 704 875 5333 704 875 4809 fax grpeters@duke-energy. corn June 14, 2007 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555
Subject:
McGuire Nuclear Station, Unit 1 Docket No. 50-369 Licensee Event Report 369/2007-03, Revision 0 Problem Investigation Process (PIP) M-07-02486 Pursuant to 10 CFR 50.73, Sections (a)(1) and (d), attached is Licensee Event Report (LER) 369/2007-03, Revision 0.
On April 15, 2007, while McGuire Nuclear Station Unit 1 was in Mode 6, core alterations occurred with only one of the two required source range neutron flux monitors operable. Operators were unaware that only one of the source range neutron flux monitors was able to generate an audible high flux at shutdown alarm.
The requirement for two source range neutron flux monitors to provide visual count rate indication was met during this period. This report is being submitted in accordance with 10 CFR 50.73 (a)(2)(i)(B) as a condition prohibited by Technical Specifications.
This event was determined to be of no significance to the health and safety of the public. There are no regulatory commitments contained in the LER.
G. R. Peterson Attachment www. dukepower. com 1'J of (
U. S. Nuclear Regulatory Commission June 14, 2007 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 08H4A Washington, D.C. 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 in Mode 1 (Power Operation) at 100% power.
Event Description
On April 15, 2007, while Unit 1 was in Mode 6, core alterations occurred with only one of the two required source range neutron flux monitors operable.
Operators were unaware that only one of the source range neutron flux monitors was able to generate an audible high flux at shutdown alarm.
The requirement for two source range neutron flux monitors to provide visual count rate indication was met during this period.
This event, which constitutes an operation prohibited by Technical Specifications, was determined to be of no significance to the health and safety of the public.
Event Cause
The cause of this event was the failure to ensure that the operability requirements of the Gamma-Metrics shutdown monitors were adequately captured in the applicable surveillances and operating procedures when these monitors were credited in Technical Specifications as redundant monitors.
Corrective Actions
Revise applicable procedures with the appropriate operability requirements including the function of the Gamma-Metrics shutdown monitor alarm switch, and place a warning label near each Gamma-Metrics shutdown monitor alarm switch on both Units.
NRC FORM 366 (6-2004)
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- 1. LER 369/2005-05 (PIP M-05-04437)
On September 21, 2005, while Unit 1 was in Mode 6, all source range neutron monitors became inoperable when annunciator alarm circuitry failed.
Subsequently, on September 22, 2005 core alteration activities commenced with these monitors inoperable.
The inability of the required source range monitors to generate an audible high flux at shutdown alarm was not discovered until September 23, 2005.
All other Control room source range neutron flux indications were functioning properly during this period.
This activity represented an operation prohibited by McGuire's Technical Specifications.
The causes of this event were attributed to an inadequate Operator Aid Computer (OAC) alarm response procedure, and the common alarm circuitry of the high flux at shutdown alarm.