ML17305B744

Special Rept 1-SR-91-002,on 910914:steam Generator Econimizer Valve SGN-FV-1112 Fully Opened Causing Level in Steam Generator 1 to Rapidly Increase.Caused by Malfunction of Lower Gripper High Voltage on Slipped Part Length CEA

ML17305B744
Person / Time
Site:	Palo Verde
Issue date:	09/18/1991
From:	James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1-SR-91-002, 1-SR-91-2, 192-00741-JML-T, 192-741-JML-T, NUDOCS 9109250050
Download: ML17305B744 (7)

Text

l ACCELERATED DISTRIBUTION DEMONSTRATION SYSTEM REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS) i ACCESSION NBR:9109250050 DOC.DATE: 91/09/18 NOTARIZED: NO DOCKET g FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 AUTH. NAME AUTHOR AFFILIATION LEVINE,J.M. Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk) R

SUBJECT:

Special rept:on 910914,power reduction recpxired by Tech Spec complicated by reactor trip & main stream isolation signal resulting from high steam generator level. D DISTRIBUTION CODE: IE22D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), ncident Rpt, etc. S NOTES:STANDARDIZED PLANT 05000528 /

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PD5 LA 1 1 PD5 PD 1 1 TRAMMELL,C 1 '

THOMPSON,M 1 1 D

INTERNAL: ACNW 2 2 ACRS 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DS P 2 2 NRR/DET/ECMB 9H 1 1 NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 '1 NRR/DREP/PRPBll 2 2 NRR/DST/SELB SD 1 1 NRR/DST/SICB8H3 1 1 SPLBSD1 1 1 NRR/DST/SRXB SE 1 1 REG F 02 1 1 RES/DSIR/EIB 1 1 FILE 01 1 1 EXTERNAL: EG&G BRYCE,J.H 3 3 L ST LOBBY WARD 1 1 NRC PDR 1 1 NSIC MURPHY,G.A 1 1 NSIC POORE,W. 1 1 NUDOCS FULL TXT 1 1 R

NOTES:

D A

D D

NOTE TO ALL "RIDS" RECIPIENTS:

S' PLEASE HELP US TO REDUCE i'i'ASTE! CONTACT THE DOCUMENT CONTROL DESK, ROON! PI-37 (EXT. %079) TO El.lib!INATE YOUR NAME FROiVI DISTRIBUTION I ISTS FOR DOCUiXIENTS YOU DON'T NEED!

TOTAL NUMBER OF COPIES REQUIRED: LTTR 35 ENCL 35

Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O. BOX 52034 ~ PHOENIX. ARIZONA85072-2034 192-00741-JML/TRB/tttHD JAMES M. LEVINE VICE PRESIDENT September 18, 1991 NUCLEAR PRDDUCTIDN U. S. Nuclear Regulatory Commission Attention: Document Control Desk Mail Station Pl-37 Washington, D.C. 20555

Dear Sirs:

Subj ect: Palo Verde Nuclear Generating Station (PVNGS)

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

Special Report 1-SR-91-002 File'1-020-404 Attached please find Special Report 1-SR-91-002 prepared and submitted pursuant to Emergency Plan Implementing Procedure (EPIP-03). This report discusses a condition requiring the declaration of a NOTIFICATION OF UNUSUAL EVENT due to a power reduction required by Technical Specification complicated by a reactor trip and a Main Steam Isolation Signal resulting from high steam generator level.

If you have any questions, please contact T. R. Bradish, Compliance Manager at (602) 393-2521.

Very truly yours, JML/TRB/WHD/nk Attachment cc: W. F. Conway (all with attachment)

J. B. Martin D. H. Coe

, ) ) 0c).gw00%0 P f Qo 1 u F'DR AEIOCI, 050')0,. 2": ',I L/

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r' PALO VERDE NUCLEAR GENERATING STATION Notification Of Unusual Event License No. NPF-41 Docket No. 50-528 Special Report 1-SR-91-002 ia Co d o s'n September 14, 1991, Palo Verde Unit 1 was in Mode 1 (POWER OPERATION) at approximately 100 percent power.

ve t'his Special Report is being submitted pursuant to Emergency Plan Implementing Procedure (EPIP-03), "Notification of Unusual Event Implementing Actions" to report a condition which required the declaration of an Unusual Event for Palo Verde Unit 1 at 1730 MST on September 14, 1991. The Unusual Event was terminated at 0401 MST on September 15, 1991.

On September 14, 1991, at approximately 1501 MST, Palo Verde Unit 1 was operating at approximately 100 percent power in Mode 1 (POWER OPERATION). Scheduled Control Element Assembly (CEA) testing was in progress when a Part Length CEA slipped from approximately 145 inches to 95 inches withdrawn. A downpower to 80 percent was commenced to comply with Limiting Condition for Operation (LCO) 3.1.3.1, "CEA deviation greater than 6.6 inches."

Attempts to raise the CEA were, unsuccessful and the Control Room Operator began to insert the remaining Part Length CEA's in order to align them with CEA No. 48 as required by LCO 3.1.3.1. Since the Part Length CEA's would be inserted beyond the transient insertion limit of Technical Specification 3.1.3.7, "Part Length CEA insertion limits," the decision was made to continue to downpower to less than 50 percent power to comply with LCO 3.1'.3.7.

The subgroup containing the slipped CEA was placed on the hold bus to allow troubleshooting of the coil traces for the CEA's. It was determined that the lower gripper high voltage on the slipped part length CEA was malfunctioning.

While continuing the downpower to less than 50 percent power, the No. 1 Steam Generator Economizer Valve (SGN-FV-1112) fully opened causing the level in the No. 1 Steam Generator to rapidly increase. The Control Room Operator took manual control of the economizer valve and attempted to clbse it prior to steam generator levels exceeding the Main Steam Isolation Signal (MSIS) Engineered Safety Features Actuation System (ESFAS) trip setpoint. Steam Generator level continued to increase and the Control Room Supervisor directed that the reactor be tripped manually. Before the manual trip could be initiated, steam generator level exceeded the MSIS trip setpoints resulting in automatic closure of the main steam isolation valves and an automatic reactor trip at approximately 1722 MST.

All components responded as designed to the MSIS and reactor trip.

A notification of unusual event (NUE) was declared at 1730 MST due to the power reduction required by Technical Specifications complicated by a reactor trip and MSIS. By 1739 MST, on September 14, 1991, the appropriate state and local agencies were notified. At approximately 1810 MST on September 14, 1991, the Nuclear Regulatory Commission (NRC) Operations Center was notified. At approximately 0401 MST on September 15,1991, the NUE was terminated in accordance with approved procedures. The plant was in Mode .3 (HOT STANDBY) and stable conditions had been achieved. By 0410 MST on September 15, 1991, the appropriate state and local agencies and the NRC Operations Center were notified-of the termination of the NUE.

Further investigation into the circumstances surrounding this event is being performed in accordance with the PVNGS Incident Investigation Program.

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