ML19263C176

RO-NP-09-78-01 on 781215:svc Water Sys Out Header Radiation Monitor Was Inoperable.Caused by Component Failure Due to Design Error.Personnel Informed of Environ Tech Specs

ML19263C176
Person / Time
Site:	Davis Besse
Issue date:	12/15/1978
From:	TOLEDO EDISON CO.
To:
Shared Package
ML19263C175	List: ML19263C174 ML19263C176
References
NUDOCS 7902080250
Download: ML19263C176 (2)

Text

• TOLEDO EDISON COMPANY

, DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE REPORTABLE OCCURRENCE NP-09-78-01 DATE OF EVENT: December 15, 1978 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: RE 8432, Service Water System Out Header Radiation Monitor, was inoperable.

Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) =

approximately 2550, and Load (Gross MWE) = approximately 833.

Description of Occurrence: During a routine review of the Shift Foreman's Log on December 15, 1978, at 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br /> it was discovered that the Service Water System Out Header Radiation Monitor, RE 8432 had been inoperable. In the course of per-formance of Surveillance Test ST 5032.01, " Monthly Functional Test of the Radia-tion Monitoring System", at 1230 hours0.0142 days <br />0.342 hours <br />0.00203 weeks <br />4.68015e-4 months <br /> on December 11, 1978, the computer alarm and low flow light for RE 8432 were inoperable. Through conversation with the Instrument and Control Coordinator, it was noted that previous failures had also occurred. In each instance, the inoperability was detected through performance of either Surveillance Test ST 5032.01 or ST 5032.02, " Radiation Monitoring System Channel Calibration". See table below.

Previous Inoperabilities ojf RE 8432 Date

• Reason For Inoperability November 13, 1978 Low flow light inoperable October 16, 1978 Low flow light inoperable May 29, 1978 Low flow alarm wouldn't clear May 9, 1978 Low flow alarm already present Janua ry 17, 1978 Low flow light on October 23, 1977 Low flow light inoperable October 6, 1977 Low flaw light inoperable August 4, 1977 Low flow light inoperable Exact dates and times for return to operability of RE 18432 cannot in every instance be determined due to lack of awareness of reportability requirements.

In each case, the unit was not in compliance with Environmental Technical Specifi-cation (ETS) Tab 1e 2.4.3.

No Action Statement was applicable.._

Designation of Apparent Cause of Occurrence: The apparent cause of the occurrences is canponent failure due to design error. There is not enough pressure differential to maintain correct sample flow in all modes of operation of the Service Water System.

The flow switch tenda to stick, and will not operate when there is insufficient flow to keep it flushed out.

7902080A50

TOYEDO EDISON C04PANY DAVIS-PESSE NUCLEAR POWER STATION UNIT ONE REPORTABLE OCCURRENCE NP-09-78-0] PAGE 2 The reason that previous occurrences had not been reported is due to improper inter-pretation of the Environmental Technical Specifications.

Analysis of Occurrence: There was no danger to the health and safety of the public or to unit parsonnel. RE 1412 and RE 1413 on Component Cooling Lines 1 and 2, res-pectively, are upstream f rom RE 8432 and would indicate activity if any were pre-sent. RE 1.412 and RE 1413, as well as weekly grab samples, have never indicated any leaks or activity.

Corrective Action: Although the exact dates and times far return to operability of the radiation monitors cannot in every instance be determined, the radiation monitor was repaired and returned to operability in each case. Facility Change Request (FCR)78-503 has been written suggesting two possible methods of corrective action.

A memo dated January 4, 1979, has been sent to various station personnel to make them more cognizant of the fact that the inoperability of RE 8432, as well as other RE's in the Environmental Technical Specifications, is a reportable occurrence. The Environmental Technical Specifications are currently in the process of revision.

Major Modifications to ST 5032.01 and ST 5032.02 have been submitted to emphasize the reportability requirements of those RE's in the Environmental Technical Speci-fications.

Major Modifications have been written on ST 5032.01 and ST 5032.02, respectively, stating'when RE 8432 is inoperable, that the occurrence is reportable.

Failure Data: There have been no previously reported occurrences of the failure of kE 8432.