PNO-IV-97-014, on 970306,Unit 3 Spent Fuel Pool Trouble Alarm Actuated at Setpoint Level of 137 Feet 6 Inches.No Increased Radiation Levels Detected as Result of Level Decrease.Work Completed & Instrument Air Sys Returned to Svc
| ML17312B407 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/06/1997 |
| From: | Johnston K, Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| References | |
| PNO-IV-97-014, PNO-IV-97-14, NUDOCS 9705060068 | |
| Download: ML17312B407 (6) | |
CATEGORY 1 REGULATOr INFORMATION DISTRIBUTION TEM (RIDS)
ACCESSION"NOR:9705060068 DOC.DATE: 97/03/06 NOTARIZED:
NO FACIL:STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi AUTH.NAME AUTHOR AFFILIATION KIRSCH,D.
Region 4 (Post 820201)
JOHNSTON,K.
Region 4 (Post 820201)
RECIP.NAME RECIPIENT AFFILIATION DOCKET I 05000530
SUBJECT:
PNO-IV-97-. 014:on 970306,Unit 3 spent fuel pool trouble alarm actuated at setpoint level of 137 feet 6 inches.No increased radiation levels detected as result of level decrease.
Work completed
& instrument air sys returned to svc.
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TITLE: 59 Docket a Vendors PNO/Non-Routine Event/Safeguards Event (PN)
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6
3 March 6, 1997
~>!'P'>> j (J' Q
j J ~'i'l 'll ~ Q PNO-IV-97-014 This preliminary notification constitute'5>AFtC74BC8 (PWents of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by Region IV staff in Arlington, Texas on this date.
ERQRY Arizona Public Service Co.
Palo Verde 3 Wintersburg,Arizona Dockets: 50-530 X Notification of Unusual Event Alert Site Area Emergency General Emergency Not Applicable
Subject:
DECLARATIONOF UNUSUALEVENT DUE TO PARTIALDRAINDOWNOF UNIT 3 SPENT FUEL POOL EVENT NUMBER: 31902 On March 6, 1997, at 6:25 a.m. (MST), the Unit 3 spent fuel pool (SFP) trouble alarm actuated at the setpoint level of 137 feet 6 inches.
The Technical Specification low level limit is 137 feet 0 inches (23 feet above the top of fuel). Operators responded in accordance with the abnormal operating procedures for the alarm.
Makeup water to the SFP was initiated, but level continued to drop.
Operators observed water leaking from the inflatable seal between the spent fuel pool and transfer canal and noted that air pressure to the seal had dropped from its normal pressure of about 30 psi to approximately 5 psi.
The operators took action,to increase the air pressure.
Air pressure reached approximately 30 psi at about 7:15 a.m., and operators observed that the leak at the seal between the SFP and transfer canal stopped.
SFP water level was restored to 138 feet 0 inches.
SFP water level reached 137 feet 0 inches at its lowest point, so SFP level was never below the Technical Specification allowable level during the event.
No increased radiation levels were detected as a result of the level decrease.
SFP cooling was never lost and SFP temperature remained the same during the event.
During the event, as part of the actions required in the abnormal operating procedures, the operators isolated the normal Fuel Handling Building Ventilation (FHBV) system and transferred to the Essential FHBV system, which is a filtered system.
During the transfer, one damper did not automatically respond and had to be manually realigned.
The licensee is investigating this, as well as the cause of the initial SFP leak.
The licensee entered and exited the Unusual Event at 7:15 a.m. (MST), after determining that the event had met the entry condition for an Unusual Event.
I The licensee's preliminary investigation of this event indicates that work had been performed on the instrument air system, which is the normal supply to the SFP seal, on the evening preceding the event.
Instrument air to the SFP seal was isolated in accordance with procedures as part of the work process.
The work was completed, and the instrument air system was returned to service.
However, instrument air was not Ci.i00gg
'P705060068
'770306 PDR TS.E PNO-IV-'P7-014 PDR
PNO-IV-97-014 realigned to the SFP seal.
Subsequently, as the backup nitrogen supply dissipated, the SFP seal pressure decreased.
This resulted in the leak and loss of SFP level.
Region IV received notification of this occurrence by telephone call from the licensee on March 6, 1997.
Region IV has informed the EDO, NRR, and PA. The state of Arizona will be informed.
Additionally, the licensee has notified the Arizona Department of Environmental Quality, the Arizona Corporation Commission, and the US Environmental Protection Agency. The licensee issued a press release.
This information has been discussed with the licensee and is current as of March 6, 1997, at 10:30 a.m. (PST).
4 Contacts:
D. Kirsch r'. Johnston (510) 975-0290 (602) 386-3638