05000346/LER-1979-027-03, /03L-0 on 790216:absolute Position Indication Amplifer for Rod 9 of Group 5 Was Inoperable.Caused by Failure of Integrated Circuit Chip in Amplifier.Integrated Circuit Chip Replaced

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/03L-0 on 790216:absolute Position Indication Amplifer for Rod 9 of Group 5 Was Inoperable.Caused by Failure of Integrated Circuit Chip in Amplifier.Integrated Circuit Chip Replaced
ML19308A322
Person / Time
Site: Davis Besse 
Issue date: 03/15/1979
From: Hitchens D
TOLEDO EDISON CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19308A319 List:
References
LER-79-027-03L, LER-79-27-3L, NUDOCS 7903200366
Download: ML19308A322 (2)
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LER-1979-027, /03L-0 on 790216:absolute Position Indication Amplifer for Rod 9 of Group 5 Was Inoperable.Caused by Failure of Integrated Circuit Chip in Amplifier.Integrated Circuit Chip Replaced
Event date:
Report date:
3461979027R03 - NRC Website
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U. S. NUCLEAR REGULATORY COMMISSION NRC F ORM 36G 0411 LICENSEE EVENT REPORT

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8 60 61 DOCKET NUYBER 68 63 EVENT DATE I4 15 REPORT C ATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h At 2233 hours0.0258 days <br />0.62 hours <br />0.00369 weeks <br />8.496565e-4 months <br /> on 2/15/79, an asymmetry alarm was received on all rods in Group 5.

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The absolute and relative position indications indicated all rods 100% withdrawn. At ;

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l of the public or unit personnel. The control rod was verified aligned with the group l by zone reference location and API-the relative indication was operable. (NP-33-79-3 )

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Jo 31 40 41 42 43 44 47 cAUSE DESCRIPTION AND CORRECTIVE AFilONS l Upon investination, technicians found that an integrated circuit chip in the API *.am-l i

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i i plifier for Rod 9 of Group 5 had failed. The integrated circuit chip was replaced, J

l i 1,1 l returning operability to the API for Rod 9 of Group 5.

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NAME OF PREPARER

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-31 DATE OF EVENT:

February 16, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: The Absolute Position Indication (API) for Control Rod 9 of Group 5 was inoperable.

Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 2440, and Load (Gross MC) = 805.

Description of Occurrence: At 2233 hours0.0258 days <br />0.62 hours <br />0.00369 weeks <br />8.496565e-4 months <br /> on February 15, 1979, an asymmetry alarm was received on all rods in Group 5.

However, all rods indicated 100% withdrawn both on the absolute and relative position indications. At 2252 hours0.0261 days <br />0.626 hours <br />0.00372 weeks <br />8.56886e-4 months <br />, the API for each rod in Group 5 was placed in BYPASS, as it appeared that the asymmetric rod fault circuitry for Group 5 was inoperable. At 0230 hours0.00266 days <br />0.0639 hours <br />3.80291e-4 weeks <br />8.7515e-5 months <br /> and 0630 hours0.00729 days <br />0.175 hours <br />0.00104 weeks <br />2.39715e-4 months <br /> on Febru-ary 16,1979, all rods in Group 5 were verified as being 100% withdrawn on the absolute position indication, the relative position indication, and the 100% zone reference indication. At 0730 hours0.00845 days <br />0.203 hours <br />0.00121 weeks <br />2.77765e-4 months <br /> on February 16, 1979, the Instrument and Control technicians found the API amplifier for Rod 9 of Group 5 to be inoperable.

This placed the unit in Action Statement (a) of Technical Specification 3.1.3.3, which permits continued operation provided all relative position indication is operable.

Designation of Apparent Cause of Occurrence: Upon investigation, Instrument and Control technicians found that an integrated circuit chip in the API amplifier f or Rod 9 of Group 5 had f ailed high. This caused the group average amplifier to go high and this in turn caused asymmetry alarms on all rods (Rod 9 looked high, and all other rods in Group 5 looked low). The failure of this component caused the API for Rod 9 of Group 5 to be inoperable.

Analysis of Occurrence: There was no danger to the health and safety of the public cr to unit personnel. The control rod was actually aligned with the group, and the relative indication was operable. The control rod was operating properly.

Corrective Action

On February 16, 1979, the integrated circuit chip was replaced, returning operability to the API for Rod 9 of Group 5.

At 0930 hours0.0108 days <br />0.258 hours <br />0.00154 weeks <br />3.53865e-4 months <br /> on February 16, 1979, all of Group 5 API amplifiers were returned to normal status, which removed the unit from Action Statement (a) of Technical Specification 3.1.3.3.

Failure Data: There have been no previous API failures caused by API amplifier failures.

LER #79-027

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