ML17306B256

Special Rept 1-SR-92-007:on 921227,CB Atmosphere RM Inoperable for Period Greater than 72 H Due to High Flow Conditions.Temporary Mod Installed on Subj RM to Remove Monitor from Dedicated Rms Grounding Sys

ML17306B256
Person / Time
Site:	Palo Verde
Issue date:	01/24/1993
From:	James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1-SR-92-007, 1-SR-92-7, 192-00824-JML-T, 192-824-JML-T, NUDOCS 9302010163
Download: ML17306B256 (5)

Text

ACCEI ERAT DOCUMENT DISTRI TION SYSTEM REGULATORMINFORMATION DISTRIBUTION ~TEM (RIDS)

ACCESSION NBR:9302010163 DOC.DATE: 93/01/24 NOTARIZED: NO DOCKET FACIL:6TN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 AUTH. NAME LEVINE,J.M.

RECIP.NAME

'rizona AUTHOR AFFILIATION Public Service,Co. (formerly Arizona Nuclear Power

,RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special'ept 1-SR-92-'007:on 921227,Containment Bldg.

Atmosphere Radiation Monitor declared inopeable due to high flow conditions. Caused by change in construction of Teledyne D Hastings Mass Flow Transducer.T-Mod installed on monitor.

DISTRIBUTION CODE: IE22D COPIES RECEIVED'LTR 2 TITLE:'50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

ENCL I SIZE:

/

NOTES:STANDARDIZED PLANT 05000528 P

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PD5 LA 1 1 PD5 PD 1 1 TRAMMELLFC 1 1 D INTERNAL: ACNW 2 2 ACRS 2 2 S

AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 2 NRR/DET/EMEB 7E .1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SICB8H3 1 1 NRR/DST/SELB 8D N /~l~DPLBSDI REG FILE 02 11 1

1 1

1 NRR/DST/SRXB 8E RES/DSIR/EIB 1

1 1

1 RGN5 FILE 01 1 1 EXTERNAL: EG6rG BRYCEFJ.H 2 2 L ST LOBBY,WARD 1 1 NRC PDR 1 1 NSIC MURPHYFG.A 1 1 NSIC POOREFW. 1 1 NUDOCS FULL TXT 1 1 D

D NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM PI-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 31 ENCL 31

Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O. BOX 52034 ~ PHOENIX, ARIZONA85072-2034 JAMES M LEVINE 192-00824-JML/TRB/RJR VICE PRESIDENT January 24, 1993 NUCLEAR PRODUCTION U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Unit 1 Docket No. STN 50-528 (License No. NPF-41)

Special Report 1-SR-92-007 Flic: 93-020-404 Enclosed please find Special Report 1-SR-92-007 prepared and submitted pursuant to Technical Specifications 3.3.3.1 ACTlON 27 and 6.9.2. This report discusses the Containment Building Atmosphere Radiation Monitor being inoperable for a period greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

If you have any questions, please contact Thomas R. Bradish at (602) 393-5421.

Sincerely,

~ipse'~l~ ~r4.>

JML/TRB/RR/pmm Enclosure cc: W. F. Conway (all w/enclosure)

J. B. Martin J. A. Sloan INPO Records Center 9302010163 930124 AgP' PDR ADOCK 05000528 8 PDR I

ENCLOSURE PALO VERDE NUCLEAR GENERATING STATION UNIT 1 Radiation Monitor Inoperable License No. NPF-41 Docket No. 50-528 Special Report 1-SR-92-007

PALO VERDE NUCLEAR GENERATING STATION UNIT 1 Radiation Nlonltor Inoperable ucense No. NPFA1 Docket No. 50-528 Special'Report 1-SR-92407 Initial Conditions:

On December 30, 1992, Palo Verde Unit 1 was in Mode 1 (POWER OPERATION) at approximately 100 percent power.

Descri tion of Event This special report is being submitted pursuant to Technical Specification 3.3.3.1 ACTION 27 and Technical Specification 6.9.2 to report an event in which the Containment Building Atmosphere Radiation Monitor (RU-1) was inoperable for a period greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

The 72-hour period for returning the monitor to service was exceeded at approximately 1600 MST on December 30, 1992.

On December 27, 1992, at approximately 1600 MST, the Containment Building Atmosphere Radiation Monitor (RU-1) was declared inoperable because of high flow conditions. Troubleshooting was conducted and identified=an inadequate ground connection on the Radiation Monitoring System (RMS) grounding system. The ground connection was repaired and the flow element recalibrated. RU-1 was returned to service and declared OPERABLE on December 30, 1992, at approximately 1503 MST after successful performance of the required surveillance testing. Three hours later, at approximately 1830 MST, on December 30, 1992, RU-1 was again declared inoperable due to high flow. A meeting was called by Unit 1 management to determine the operating status of RU-1. Based on the similarity of the December 30, 1992, high flow condition to the previous high flow condition, it was decided that RU-1 had been inoperable since December 27, 1992.

RU-1 continuously monitors the containment atmosphere for particulate and gaseous activity to provide a qualitative indication of an increase in primary coolant system leakage. A portable radiation monitor was installed to continuously sample containment air and grab sampling in accordance with Technical SpecNcation 3.3.3.1 ACTION 23 each time RU-1 was declared inoperable and at no time was the requirement of Technical 1of2

Specification 3.4.5.3 ACTION a exceeded. RU-1 was declared OPERABLE on January 18, 1993, at approximately 1715 MST after installation of the temporary modification described in the corrective action section and completion of required surveillance testing.

Cause of Event; The cause of the event was a change in the construction of the TeIedyne-Hastings Mass Flow Transducer used to monitor sample flowrate. The change consisted of internally grounding the thermocouples used to measure the degree of cooling associated with the mass flow measurement technique. This resulted in a normal bias between the plant grounding, system and the dedicated RMS grounding system being presented as a change in flow rate.

Bench tests confirmed that the erroneous readings would result from an electrical potential difference-between the transducer and the display module. Additional field testing confirmed that the bias error was removed when the transducer ground path was opened. Field testing with both the transducer and display module connected to the plant grounding system resolved the erroneous indication.

Corrective Action:

A Temporary Modification (T-Mod) was installed on the subject radiation monitor to remove the monitor from the dedicated RMS grounding system and connected it to plant grounding system. The purpose of the T-Mod is to evaluate the use of the plant grounding system as a means of eliminating the indication errors associated with sample flow measurement. If no further indication errors are noted by the end of March 1993, Systems Engineering is planning to implement a permanent change to the equipment to leave the monitor on the plant grounding system or modify the transducer to remove the ground path. It should be noted that the operation of the radiation monitor itself is adequate in either grounding configuration.

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