ML19270F315

LER 79-007/03L-0 on 790110:during Performance of Surveillance Test,Channel 2 of Containment Hydrogen Analyzer Was Found Inoperable.Caused by Defective Zener Diode in Millivolt Converter

ML19270F315
Person / Time
Site:	Davis Besse
Issue date:	01/31/1979
From:	Hitchens D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19270F313	List: ML19270F312 ML19270F315
References
LER-79-007-03L, LER-79-7-3L, NUDOCS 7902060242
Download: ML19270F315 (3)

Text

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U. S. NUCLEAR REGUL A

.RC F ORM 366 7 77)

LICENSEE EVENT REPORT (PLE ASE PRINT OR TYPE ALL REQUIREO INFORMATION) {

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REFCRT D ATE N 61 conET uvaEa u s oa EVENT DESCRIPTION AND PROS ABLE CCNSECUENCES h it was determined that Channell

,o 2 l On 1/10/79, during perforcance of surveillance testine, This occurrence placed the unik g7g ]2 of the containment hydrogen analyzer was inoperable.

There was no danger to the  !

o a in the Action Statements of T.S. 3.3.3.6 and 3.6.4.1.

health and safety of the public or unit personnel. Containment Hydrogen Analyzer i

o s Channel 2 was inoperable. In addition, j o 6 l Channel 1 was operable during the period that l

l o l 7 l l the containnent hydrogen analyzers are used caly during long term cooling af ter a has occurred. (!P-33-79-10) o 9 l loss of coolant accident VALVE 7 8 9 C A';5E CoVP.

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lJJB lgl34 Zl@ lJsC l@ l l@ a/ 43 43 42 44 CAUSE DESCHlPTION AND CORRECTIVE ACTICNS h i o lThe cause of the failure was found to be a defective zener diode in the millfenft c o, .J 1

The defective zener diode was replaced. Also an analyzer output lead was g j y rter.

discovered to have its insulation split very near the terminal lug and was repaired.

j , , ,, , g was recoved from the Action Statements of both Technical Specifications l g,9,; lThe unit 1979 at 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br /> when surveillance testing was j

, 4 [3.3.3.6 and 3.6.4.1 on Januarv 12, completed.

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR PO'.lER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-10 DATE OF EVENT: January 10, 1979 FACILITY: Davis-Besse Unit 1 ipENTIFICATION OF OCCURRENCE: Containment Hydrogen Analyzer Channel 2 inoperabic Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 2162, and Lond (Gross MWE) = 707.

pescription of Occurrence: On January 10, 1979, at 1750 hours0.0203 days <br />0.486 hours <br />0.00289 weeks <br />6.65875e-4 months <br />, during performance of ST 5065.01, "Containmu,t Hydrogen Vessel Atmosphere Hydrogen Analy.mr Calibra-tion Procedure", it was determined that Channel 2 (AIT-5028) was inoperabic. The hydrogen analyzer would not indiente any concentration of hydrogen when the span gas was introduced. This occurrence placed the unit.in the Action Statement of Technical Specifications 3.3.3.6 in Modes 1, 2, and 3, and 3.6.4.1 in Modes 1 and 2, which require the operability of both containment hydrogen analyzers. Both of these Action Statements require that the inoperable channel be restored to operabic status within 30 days.

Channel 1 of the containment hydrogen analyzer was operable throughout the inopera-bility of Channel 2.

Designation of Apparent Cause of Occurrence: The cause of the failure om the con-tainment hydrogen analyzer was found to be a defective zener diode in the milli-vo?t converter which converts the analyzer output into a usable signal for display on the recorder.

Analysis of Occurrence: There was no danger to the health and safety of the public or to unit personnel. Containment Hydrogen Analyzer Channel 1 was operable during the period that Channel 2 was inoperable. In addition, the containment hydrogen analyzers are used only af ter a loss of coolant accident has occurred.

Corrective _ Action: The defective zener diode was replaced under Instrument and Control Work Order 129-79, and Containment Hydrogen Analyzer Channel 2 returned to service on January 12, 1979. During re-installation of the millivolt converter, an analyzer output lead was discovered to have its insulation split very near the terminal lug. This was also repaired under Work order 129-79, but did t cause the failure of the zener diode, or the inoperability of the analyzer.

LER //79-007 9

e TOLEDO EDISON COMPA'iY DAVIS-BESSE NUCLEAR P0;ER STATION UNIT ONE SUPPLE'!EhTAL INFORMATION FOR LER NP-33-79-10 PAGE 2 The unit was removed from the Action Statements of both Technical Specifications 3.3.3.6 and 3.6.4.1 on January 12, 1979 at 2300 hours0.0266 days <br />0.639 hours <br />0.0038 weeks <br />8.7515e-4 months <br /> when ST 5065.01, "Contain-ment Vessel Atmosphere llydrogen Analyzer Calibration Procedure" was successfully coruple t ed .

Failure Data: There have been no previously reported f ailures of the containment hydrogen analyzers.

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LER #79-007 l.

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