ML19309A873

LER 80-010/03L-0:on 800224,during Surveillance Testing, Control Element Assemblies 31 & 34 Dropped Into Core.Caused by Fault in Timer Module.Module Replaced

ML19309A873
Person / Time
Site:	Calvert Cliffs
Issue date:	03/24/1980
From:	Bauer E, Lagiewski J BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19309A868	List: ML19309A867 ML19309A873
References
LER-80-010-03L-01, LER-80-10-3L-1, NUDOCS 8004010448
Download: ML19309A873 (2)

Text

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61 DOCKET NUMBER 60 69 EVENT DATg 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h e lDuring the perfonnance of surveillance testing, control element assembly (CEA) 31 1 0 3 l dropped into the core at 0932. Similarly at 1112 CEA 34 also drooned into the 'l 1014 l Icore. Per the requirements of T.S. 3.1.3.1.f reactor power was reduced to < 70% 1 10 : s 1 lat 1007. At 1036, CEA 31 was restored to alionment with its aroup and at 1224 I 10 is I ICEA 34 was restored to alionment. LER's 80-12 (U-1) and 80-9 (U-2) describe I l o l 7 I Isimilar events. I 10181 l I

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35 M 37 40 41 42 43 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h i

l i 10 l lDurina CEA current trace surveillance, CEA 31 develooed d fault in its timer module. I Ii Ii 1TI he module was replaced and the CEA returned to service. It is sumited that durinn I li i 21 Ithe current trace on CEA 34. channel 6 of the visicordor. connected tn the i Ii i a I lenable sional of the timer. was loadino down that circuit. After renoval of the l tii4i Ivisicorder, CEA 34 operated satisfactorily. I STA  % POWER OTHER STATUS 015 O RY DISCOVERY DESCRIPTION NA li i s I [E_J@ l' 110 l 0 l@l" "

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NAME OF PREPARER J. S. Laciewski/E. R. Bauer psons: (301 )269-4747/4728 2, ,

LER [10. 80-10/3L DOCKET NO. 50-318 EVENT DATE 02/24/80 REPORT DATE 03/24/80 ATTACHMENT CAUSE DESCRIpTIO!1 Afl0 CORRECTIVE ACTIONS: (CONTIllUED)

The input impedance of the visicorder, channel 6, was subsequently checked and found to be very high due to the isolation amplifier, but it may have added some noise to the CEA's timer enable signal. Since using the visi-corder in this manner (i.e., to check the continued presence of the enable signal) was not procedural but troubleshooting, it has been decided to use an oscilloscope for this purpose and use the visicorder solely for current tracing.

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