ML19256A801

Reportable Occurrence NP-09-78-01:on 781215,during Routine Review of Shift Foreman'S Log,Discovered Svc Water Sys Out Header Radiation Monitor RE8432 Had Been Inoperable.Caused Apparently by Design Error.Facility Change Request Prepared

ML19256A801
Person / Time
Site:	Davis Besse
Issue date:	01/12/1979
From:	TOLEDO EDISON CO.
To:
Shared Package
ML19256A799	List: ML19256A798 ML19256A801
References
NP-09-78-01, NP-9-78-1, NUDOCS 7901160168
Download: ML19256A801 (2)

Text

{{#Wiki_filter:* 6

• 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. , I _C_onditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = approximately 2550, and Load (Gross MWE) = appteximately 833.

                                                                                                          !

Description of Occurrence: During a routine review of the Shift Foreman's Log on December 15,1978, at 1200 hours 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 hours 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 f ailures 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 of 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 Maf 9, 1978 Low flow alarm already present January 17, 1978 Low flow light on October 23, 1977 Low flow light inoperable October 6, 1977 Low flow light inoperable August 4, 1977 Low flow light inoperable Exact dates and times for return to operabilitf of RE 18432 cannot in every instance be determined due to lack of awareness of reportability requirements.

In each case, the unit was net in compliance with Environmental Technical Specifi- ~ cation _(ETS) Table _2.4.3. _ , _No Action Statement was applicable.[][[ _^ _ _ _ _ , _ _ __ _

                                                                                                        '

~. -. - .. - . . - ....

                                          - - ._

Designation of Apparent Cause of Occurrence: The apparent cause of the occurrences is component failure due to des.gn 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 tends to stick, and will not operate when there is insufficient flow to keep it flushed out.

           ?S01160t68

. .

TOLEDO EDISON COMPANY DAVIS 'BESSE NUCLEAR POWER STATION UNIT ONE REPORTABLE OCCURRENCE NP-09-78-01 PAGE 2 The reason that previous occurrences had not been reported is due to improper inter-pretation of the Environmental Technical Specifications. Analysis of Occurrente: There was no danger to the health and safety of the public or to unit personnel. RE 1412 and RE 1413 on Component Cooling Lines 1 and 2, res-pectively, are upstream from RE 8432 and would indicate activity if any were pre-sent. RE 1412 and RE 1413, as well as weekly grab samples, have never indicated any leaks or activity. Corrective Action: Although the exact dates and times for 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. I 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 Technicdl Speci-fications.

                                                                                        '
                                                                                        ,

Major Modifi~.tions have been wr' a_ 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 RE 8432. I l

                                                                                        !

t}}