ML082840702
| ML082840702 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/08/2008 |
| From: | West R Tennessee Valley Authority |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML082840702 (3) | |
Text
Tennessee Valley Authority, Post Office Box 2000, Decatur, Alabama 35609-2000 October 8, 2008 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop: OWFN, P1-35 Washington, D.C. 20555-0001
Dear Sir:
In the Matter of Tennessee Valley Authority
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Docket Nos. 50-296 BROWNS FERRY NUCLEAR PLANT (BFN) - UNIT 3 SPECIAL REPORT 296/2008-001 FOR INOPERABLE POST ACCIDENT MONITORING (PAM) INSTRUMENTATION In accordance with Technical Specification (TS) 5.6.6, PAM Report, this letter provides notification of PAM instrumentation that was not restored to OPERABLE status within 30 days as required by TS Limiting Condition of Operation (LCO) 3.3.3.1, Post Accident Monitoring (PAM) Instrumentation.
BACKGROUND INFORMATION:
On August 25, 2008, it was determined that the recorder for Primary Containment (Drywell) Area High Range Radiation Monitor (RM) 3-RM-90-272A, 3-RR-90-272, was reading low and had gone below the downscale reading. The monitor was declared inoperable, and the Actions of TS LCO 3.3.3.1 were entered.
With Unit 3 in Mode 1 or Mode 2, the number of required operable channels is two:
3-RM-90-272A, Division I Drywell Radiation Monitor, and 3-RM-90-273A, Division II Drywell Radiation Monitor. When one required channel is inoperable, the plant either restores the inoperable channel to OPERABLE status with 30 days or initiates action in accordance with TS 5.6.6.
U. S. Nuclear Regulatory Commission Page 2 October 8, 2008 Due to the recorder failure and the lack of a readily available replacement, the 30-day LCO time limit was exceeded on September 24, 2008.
The PAM function of these high range radiation monitors is to monitor for the potential of significant radiation releases and to provide release assessment for use by operators in determining the need to invoke site emergency plans.
Containment radiation levels are sensed via 3-RE-90-272A with a corresponding current signal sent to 3-RM-90-272A. The radiation monitor processes the current signal and provides outputs to the plant Integrated Computer System, radiation recorder 3-RR-90-272A, as well as high and downscale annunciator windows.
CAUSE OF THE INOPERABILITY:
Troubleshooting of the inoperable channel determined that the recorder, 3-RR-90-272, had failed and had to be replaced. At the time of the failure, Design Change Notice (DCN) 69236, Stage 11, was in progress to replace several obsolete Unit 3 Main Control Room recorders including recorder 3-RR-90-272. The DCN was issued on September 23, 2008 and includes replacement of the existing Yokogawa strip chart recorder with a Thermo Electron digital, paperless recorder. Upon completion of the installation of the new recorder, post modification testing (PMT) including re-performance of the applicable calibration, functional tests, and channel checks were performed.
PREPLANNED ALTERNATE MONITORING METHOD:
Division II Drywell Radiation Monitor 3-RM-90-273A also monitors primary containment area radiation (high range) and was available to function as the preplanned alternate method of post-accident high radiation monitoring (indication, recording, and alarm) until 3-RM-90-272A was returned to operable status.
Radiation monitor 3-RM-90-272A was returned to operable status on October 4, 2008 at 1625 Hours; therefore, a preplanned alternate method ofmonitoring is no longer required.
PLANS AND SCHEDULE FOR RESTORING THE INSTRUMENT CHANNEL:
On October 4, 2008, the recorder was declared operable, and the LCO exited.
U. S. Nuclear Regulatory Commission Page 3 October 8, 2008 There are no regulatory commitments contained in this letter. If you have any questions, please telephone D. Tony Langley at (256) 729-2636.
Sincerely,
.G.
es t Site Vice President cc: State Health Officer Alabama State Department of Public Health RSA Tower - Administration Suite 1552 P.O. Box 303017 Montgomery, Alabama 36130-3017 NRC Senior Resident Inspector Browns Ferry Nuclear Plant 10833 Shaw Road Athens, AL 35611-6970 Mr. Eugene F. Guthrie, Branch Chief U.S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth Street, SW, Suite 23T85 Atlanta, Georgia 30303-3415 Ms. Eva Brown, Project Manager U.S. Nuclear Regulatory Commission (MS 08G9)
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