ML19270G111

LER 78-022/01T-0 on 780404:Fischer & Porter 10B2496 Transmitters for Coolant Low Flow Monitoring Had High Output Deviation During Seismic Test.Caused by Vibration of Mounting Plate.Design Change Initiated

ML19270G111
Person / Time
Site:	Salem
Issue date:	04/17/1978
From:	Spencer T Public Service Enterprise Group
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19270G108	List: ML19270G107 ML19270G111
References
LER-78-022-01T, LER-78-22-1T, NUDOCS 7906040277
Download: ML19270G111 (3)

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Report Number: 78-22/0lT Report Date: h/17/78 Occurrence Date: 4/4/78 Facility: Salem Generating Station Public Service Electric & Gas Company Hancocks Bridge, New Jersey 08038 IDENTIFICATION OF OCCURRENCE:

Reactor Coolant Low Flow Protection seismic Qualification Deficiency CONDITIONS PRIOR TO OCCURRENCE:

N/A DESCRIPTION OF OCCURRENCE:

During a review of seismic test data for NEMA 12 panel enclosures, it was found that a transmitter manufactured by Fischer and Porter, Model No. 10B2496, was used in a NEMA 12 enclosure for monitoring reactor coolant flow. This transmitter had a high output deviation during the seismic test which exceeded acceptable tolerances. This transmitter in the noted application provides a low flow signal to the soiid state protection system for reactor trip. The transmitters' high output deviation during a seismic event could prevent it from performing its required function. This is only applicable if the reactor coolant low flow condition occurs in coincidence with a seismic event. Test reports indicate that the transmitter output returns to normal following the seismic disturbance.

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE:

The Fischer and Porter 10B2496 transmitter experienced the high out-put deviation during the seismic test due to vibratory motion of the instrument mounting plate within the NEMA 12 enclosure. The sub-panel mounting plate was not stiff enough to adequately support the heavy 10B2496 transmitter. As a result, this transmitter was subjected to high vibration levels which caused its output to be offset in the upscale direction during the test. Subsequent inspection and cali-bration checks showed no damage or significant shift in transmitter accuracy.

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ANALYSIS OF OCCURRENCE:

Sufficient diversity exists for protection against loss of reactor coolant flow transients to overcome the failure of one protection system parameter. However, if the cause of a loss in reactor coolant flow is not electrical in nature, the reactor coolant low flow transmitters are especially important. With the

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previously described condition existing, the low reactor coolant flow reactor trip may not have been initiated during a seismic event if needed within the time limitations imposed by the Technical Specifications. Eventually, the overtemperature AT reactor trip and/or the low reactor coolant flow reactor trip (when the seismic disturbance had subsided) would be initiated.

CORRECTIVE ACTION:

The installation of a unistrut to stiffen the sub-panel mounting plate in the NEMA 12 panel and enlarging the instrument mounting bracket will correct the output deviation of the transmitter to within acceptable tolerances during a seismic event. Confirmatory seismic tests have been performed demonstrating this design. This change will be incorporated in accordance with DCR ED-0357. Panel modifications will be completed prior to the unit returning to service from the present outage. ,

FAILURE _ DATA:

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Prepared by T. L. Spencer / ,

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Manager Salem Generating Statior SORC Meeting No. 22-78 2237 249

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LICENSEE EVENT REPORT

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,; l levels. Desian change ED-357 has been initiated to a unistrut succort I i, 2 ito stiffen the sub-canel mountinc clate. Installation will be comolete I ii. l prior to returninc unit to service. I 7 8 9 80 A  % PCWER CTNER STATUS 01 Q RY OtSCCVERY CE3CRIPTION iis l G @ l0 l O l 0 l@l N/A l l A l@l Seismic results review l A vtTY C TENT CPRELEASE AMOUNT CF ACTIVITY LCCATION CP RELEASE 1 6 RELEASE Izl @D lzi l N/A l l N/A l 7 8 9 10 11 44 45 80

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NAME OF PREPARER T. L. SOenCer PHCN E:

(6091365-7000 Sale, M .!

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