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

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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.

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U.S. Nuclear Regulatory Commission Page 2 November 14,1997 The'immediate corrective actions taken for HRPCRM 2-90-272C

-include:

(1) changed out the monitcr chassis,- (2) : tested -

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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