ML17252B499

LER 78-034/03L-0 and LER 78-038/03L-0 for Dresden, Unit 2 Re Main Steam Line Temperature Isolation Switch 2-261-1BA Initiated a Group I Isolation Signal on Channel a

ML17252B499
Person / Time
Site:	Dresden
Issue date:	08/01/1978
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
BBS LTR 78-1132 LER 78-034/03L-0, LER 78-038/03L-0
Download: ML17252B499 (3)

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,9 Commonwe~Edison Dresden Nuclea;wer Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920

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James G. Keppler, Regional Director Director of Regulatory Operations - Region III U.S. Nucle~r: Regulatory Cormnission 799 Roosevelt Road Glen Eilyn, IL 60137

.occurrence Reports #78-034/03L-0 and 78-038/03L-0, Docket ere or.iginally evaluated as reguiring submittal to your office ccordance with Dresden Nuclear Power Station Technical Specification 6.6.B.2.(b), conditions leading to operation in a degraded mode permitted by a limiting condition for operation or pla~t shutdown required by a limiting condit*ion for op.e:i;::attd:o.n. After further discussion on July 21, 1978, with our Region III NRC inspect6'I!r,,":t:fr. J. Barker, the events have been reclass:i,fied as non-repor.trable because no limiting. condition for ope~ation was approached and the instrument switch failures were conservative.

We request that the reports previously mentioned be J:"emoved from the Licensee Event Report File. Copies of the reports are attached.

ens on Station Sup~rintendent Dresden Nuclear Power Station

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BBS/deb Enclosure cc: Director of Inspection & Enforcement Director of Management Information & Program Control File/NRC 71978

NRC FORM 366 u. s. NucLeAit R~GuLA'roilv~tsii.~1Jn!;~10~

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• 61 DOCKET NUMBER 68 69 EVENT DATE  ;, 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES@

• ~ I During normal plant operation Main Steam Line (MSL) temperature isolation switch

. @TI] 2-261-18A initiated a Group I Isolation signal on Channel "A". Plant operation conti11ued

[ill] as permitted by .-Technical Specification 3. 2.A. This type of event* last occurred on

[ill] 9/08/77 report number 77-034. Plant safety:was not degraded because the switch failu~e

[ill] was in t*he conservative direction.

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I Control room instrumentation indicated no abnormal temperature existed in the MSL Tunnel area. A visual inspection revealed no steam leaks and that the area coolers we~e functioning properly. The 2~261-18A switch, which is (1) of (16) installed SW. 's, was!

[JJJ::l jumpered to clear* the isolation signal and will* be calibrated at the earliest possible rr:m 7 8 9 date.

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I ATTACHMENT TO LICENSEE EVENT REPORT 78-034/031-0 COMMONWEALTH EDISON COMPANY (CWE)

DRESDEN UNIT-2 (ILDRS-2)

DOCKET II 050-237 During normal plant operation the Main Steam Line (MSL) Tunnel high temperature alarm annunciated in the control room and a half Group I Isolation resulted (Channel A). Control room instrumentation indicated that the MSL Tunnel area temperature was normal (approximately 1250F).

A visual inspection of the MSL Tunnel area revealed no steam leaks which would cause the temperature to reach the 180°F high temperature

• alarm or exceed the Technical Specification Limit (Table 3.2.1) of 200°F.

The MSL Tunnel area coolers were als.o functioning normally. A MSL Tunnel area temperature switch 2-261-18A was jumpered in order to remove the half Group I Isolation. The te.mperature switch is a United Electric coil bulb type F7 Model 76B. Work request was initiated to calibrate' the temperature switch at the earliest possible date. There is no degradation of plant saf~ty since the remaining redundant switches were operable in Channel "A" to perform the Group I Isolation function as required by the Technical Specifications.