ML17300B239

Special Rept 2-SR-89-004,Suppl 1:on 890330 & 0406,PASS Inoperable for More than 7 Days.Caused by Planned Isolation of Demineralized Water Supply to Pass.On 890331,temporary Mod Approved to Isolate Demineralized Water Sys

ML17300B239
Person / Time
Site:	Palo Verde
Issue date:	12/28/1989
From:	James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
2-SR-89-004, 2-SR-89-4, NUDOCS 9001080075
Download: ML17300B239 (8)

Text

ACCELERATED QI~)TPJBUTION DEMON+ATION SYSTEM REGULATORY INFORMATION DXSTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:9001080075 DOC-DATE: 89/12/28 NOTARIZED: NO DOCKET g FACIL:STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 AUTH. NAME AUTHOR AFFILIATION LEVXNE,J.M. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Special Rept 2-SR-89-004,Suppl 1:on 890406,PASS greater than 7 days.

inoperable'or DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR TITLE: 50.73/50.9 Licensee Event Report (LER),

ENCL L nciden&Rpt, etc.

SIZE:

NOTES:Standardized plant. 5000529 RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD5 LA 1 1 PD5 PD 1 1 CHAN,T 1 1 DAVIS,M. 1 1 XNTERNAL: ACRS MICHELSON 1 1 ACRS MOELLER 2 2 ACRS WYLIE 1 1 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP 2 '

2 DEDRO 1 1 NRR/DET/ECMB 9H 1 NRR/DET/EMEB9H3 1 1 NRR/DET/ESGB 8D 1 1 NRR/DLPQ/LHFB11 1 1 NRR/DLPQ/LPEB10 1 '1 NRR/DOEA/OEAB11 1 1 NRR/DREP/PRPB11 2 '2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB 7E 1 ,'1 NRR/DST/SPLB8D1 1 1 N~/DSZ/~ XB 8E 1 '1 NUDOCS-ABSTRACT 1 1 G 1 1 RES/DSIR/EIB 1 1 RGN5 FILE 01 1 1 EXTERNAL: EG&G WILLIAMS,S 4 4 L ST LOBBY WARD 1 '1 LPDR 1 1 NRC PDR 1 1 NSIC MAYS,G 1 1 NSIC MURPHY,G.A 1 1 NUDOCS FULL TXT 1 1 NOTES: 1 1 NOTE TO ALL "RIDS" RECIPIENTS; PLEASE HELP US TO REDUCE WAS%I CONTACT THE. DOCUMENT CONTROL DISK, ROOM Pl-37 (EXT. 20079) TO ELIMINATEYOUR NAME FROM DISBUBUTION TOTAL NUMBER OF COPIES REQUXRED: LTTR 40 ENCL 40

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PALO VERDE NUCLEAR GENERATING STATION PASS Inoperable for Greater Than 7 Days License No. NPF-51 Docket No. 50-529 Special Report 2-SR-89-004-01 This Special Report is being submitted in accordance with Technical Specifications 3.3.3. 1 ACTION 28-2 and 6.9.2 to report an event in which the Post Accident Sampling System (PASS) was inoperable for a period greater than 7 days. The 7 day limit for inoperability was exceeded at approximately 0800 HST on April 6, 1989.

At approximately 0800 HST on March 30, 1989, Palo Verde Unit 2 was in Mode 3 (HOT STANDBY) at approximately 565 degrees F Reactor Coolant System (RCS) temperature and approximately 2255 psia pressurizer pressure when PASS was declared inoperable due to the planned isolation of the demineralized water supply to PASS. In accordance with Technical Specification 3.3.3. 1 ACTION 28-1 the Preplanned Alternate Sampling Program (PASP) was initiated at 1924 HST on April 3, 1989.

Prior to the event, at approximately 1630 HST on Harch 27, 1989, Palo Verde Unit 1 Chemistry personnel identified that a portion of the Demineralized Water System (DW) was contaminated. Subsequent investigation in Unit 1 identified backflow from the Reactor Coolant System Hot Leg Loop 1 sample line backwards through two (2) check valves and one (1) normally closed solenoid valve into the DW system. The DW system is connected into the RCS sample line to provide flush water for sample lines routed to the sample sink in the Chemistry Hot Laboratory. Flushing of the sample lines is to maintain radiation exposure As Low As Reasonably Achievable (ALARA) in th'e event that PASP is utilized for PASS.

On March 30, 1989, Unit 1 Operations personnel informed Units 2 and 3 personnel of the contamination of the Unit 1 DW lines. Unit 3 personnel investigated, but did not identify any contamination of the DW system. Unit 2 personnel investigated and identified contamination in the Unit 2 DW system.

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At approximately 0800 HST on March 30, 1989, Unit 2 personnel isolated the contaminated portion of the DW system by shutting isolation valve DWN-V-122.

Shutting DWN-V-122 isolated several DW service lines including the DW supply to PASS and the DW supply to the RCS Hot Leg sample line that is used when PASP is being utilized. Unit 2 personnel determined that the valves in the DW supply line to PASP had leaked contaminated RCS back to the DW header . These valves were SSN-.UV-564 (solenoid valve), SSN-V-856 (check valve), and SSN-V-857 (check valve). The DW supply line to PASS is required for

.operability of PASS, therefore, PASS was declared inoperable when DWN-V-122 was shut at approximately 0800 MST on Harch 30, 1989.

As an interim corrective action a Temporary Modification Request was approved on March 31, 1989. This modification isolates the DW system from the RCS Hot Leg sample line. This is accomplished by removing a section of the DW line

l'i Special Report 2-SR-89-004-01 Page 2 between the first check valve and the tee into the RCS sample line and then capping the two open ends of the line. The modification was completed in Unit 2 on April 9, 1989. After successful completion of Surveillance Test 74ST-2SS04 (PASS Functional Test) PASS was declared operable at 1140 MST on April ll, 1989. The modification was completed in Unit 1 on April 7, 1989 and in Unit 3 on May 7, 1989.

Additional sampling and analysis of the DW systems have been performed in Units 1, 2, and 3 since the modification was completed. No further radioactive contamination has been identified in the DW systems.

An engineering evaluation has determined the root cause of the event to be inadequate design. A Plant Change Request has been submitted to redesign the Nuclear Sampling system.

Additionally, an investigation is being performed to review other similar connections between contaminated systems and "clean" flushing water systems.

This investigation will be conducted to determine if additional controls are required to preclude other situations of cross-contamination.

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