ML20199F650

Special Rept:On 971031,one High Range Primary Containment Radiation Monitor Declared Inoperable for More than Seven Days.Caused by Component/Equipment Failure Inside Drywell. Will Repair or Replace Detector or Associated Cable

ML20199F650
Person / Time
Site:	Browns Ferry
Issue date:	11/14/1997
From:	Abney T TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9711240287
Download: ML20199F650 (3)

Text

6 s nn w usavc., e .a, wno m eo m n.ar., eu m m 3 November 14, 1997 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555

Dear Sir:

In the Matter ot ) Docket No. 50-260 Tennessee Valley Authority )

BROWNS FERRY NUCLEAR PLANT (BFN) - SPECIAL REPORT ON INOPERABLE HIGH RANGE PRIMARY CONTAINMEN4 RADIATION MONITOR This Special Report is being submitted in accordance with Technical Specification (TS) 3. 2 . F, Table 3.2.F, Note (7) and TS 6.9.2. This report informs NRC that a Unit 2 High Range Primary Containment Radiation Monitor (HRPCRM) has been inopetable for more than seven (7) days. The containment high-range radiation monitors were installed in response to NUREG-0737, Clarification of TMI Action Plan Requirements, Item II . F.1. 3. The purpose of these monitors is to detect gross fuel failures after an accident.

There are two HRPCRMs (2-90-272C and 2-90-273C) in the drywell on elevation 582. On October 31, 1997, one of the HRPCRMs

!. 2-90-27 2 C ) was declared inoperable due to a downscale indication. A downscale indication is the rcsult of a failed monitor or the monitor is not sensitive enough. At this time, HRPCRM (2-90-273C) is operable and capable of detecting gross fuel failures after an accident. The Post-Accident Sampling System (PASS) also provides a redundant method for detecting .

gross fuel failures, through both the sampling of primary 3/'

system coolant and the containment atmosphere. -jf I

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U.S. Nuclear Regulatory Commission Page 2 November 14,1997 The'immediate corrective actions taken for HRPCRM 2-90-272C (1) changed out the monitcr chassis,- (2) : tested -

-include:

coaxial cable from the monitor chassis to-the detector using a Time Domain Reflectometer, (3) repaired. rear connector of the monitor chassis, and (4) took continuity measurements-of the cable from its shielding to ground an'd-from the center

~

conductor to shield / ground using an electrometer and a digita]

multimeter. Based on these corrective actions, the root cause of the inoperable HRPCRM continues to be indeterminate.-

However, the most probable cause is a component / cable' failure inside the drywell. During power operations, the.drywell atmosphere is required to be inerted. Hence, additional troubleshooting within the drywell is not possible at this time.

TVA plans to repair / replace the detector or its associated cable the next time BFN has a forced Unit 2 outcge of sufficient duration in which ti.e drywell is entered, or the l next Unit 2 refueling outage, whichever comes first.

If you have any questions regarding this report, please contact me at (205) 729-2635, 4 Spacelely, O

W T. E. ey _

Manager Lic sing .

and Ind stry Affairs  !

P - -

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U.S. Nuclear-Regulatory Commission Page 3 November 14, 1997 cc:' Mr. Mark S.-Lesser, Branch Chief ~

- U.S. Nuclear Regulatory Commission

- Region II 61 Forsyth Street S.W.

Suite 23T05 Atlanta, Georgia 30303 NRC Resident Inspector ,

Browns Ferry Nuclear Plant- -

10833 Shaw Road .

Athens, Alabama 35611 Mr. Luis A. Reyes Regional Administrator U.S. Nuclear Regulatory Commission Atlanta Federal Center 61 Forsyth Street S.W.

Suite 23T85 Atlanta,-Georgia 30303 Mr. J. F. Williams, Project Manager U.S. Nuclear Regulatory Commission One White Flint, North 11555 Rockville Pike Rockville, Maryland 20852 a

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