PNO-IV-97-014A, on 970306,declaration of Unusual Event Due to Partial Draindown of Unit 3 Spent Fuel Pool Update Made. Region IV Plans to Initiate Special Insp to Followup on Event During Wk of 970310
| ML17312B408 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/07/1997 |
| From: | Johnston K, Kirsch D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| References | |
| PNO-IV-97-014A, PNO-IV-97-14A, NUDOCS 9705060082 | |
| Download: ML17312B408 (6) | |
CATEGORY REGULAT INFORMATION DISTRIBUTION STEM (RIDS)
ACCESSION NBR:9705060082 DOC.DATE: 97/03/07 NOTARIZED:
NO FACIL:STN '50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi AUTH.NAME AUTHOR AFFILIATION
'IRSCH,D.
Region 4 (Post 820201)
JOHNSTON,K.
Region 4 (Post 820201)
RECIP.NAME RECIPIENT AFFILIATION DOCKET ¹ 05000530
SUBJECT:
PNO-IV-97-014A:on 970306,declaration of unusual event due to partial draindown of Unit 3 spent fuel pool update made.
Region IV plans to initiate special insp to followup on event during wk of 970310.
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March 7, 1997 I ',I Ii,H f2 PI) l: 56 PUBLIC DOCUH"-HT ROOI'I PNO-IV-97-014A This preliminary notification constitutes EARLY notice of events 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.
Eacility.
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 UNUSUAL EVENT DUE TO PARTIALDRAINDOWNOF UNIT 3 SPENT FUEL POOL EVENT NUMBER: 31902:
UPDATE This updates information provided in PNO-IV-97-014, dated March 6, 1997, which discussed an event involving the partial draindown of the Palo Verde Nuclear Generating Station, Unit 3 spent fuel pool (SFP). Unit 3 was shutdown for refueling on February 22, 1997, and a full core off-load to the SFP was completed on March 1, 1997.
The fuel transfer tube gate valve was then closed and the reactor cavity drained to a midloop condition to facilitate steam generator eddy current testing.
The licensee's management review team met on March 6, 1997, to determine actions necessary prior to beginning work in the Unit 3 SFP following the subject event.
These actions include: (1) flood up the transfer canal to equalize level between the SFP and the transfer canal to prevent loss of SFP inventory in the event of transfer canal gate seal failure; (2) take transfer canal gate seal pressure readings twice per shift during operator rounds: (3) replace depleted nitrogen bottles on the backup seal pressurization system and set aside one full bottle as a spare; and (4) revise procedures to provide for the installation of the backup nitrogen bottles by operations or maintenance personnel.
In addition, personnel involved with SFP activities will be briefed prior to beginning work. These actions were completed during the morning of March 7, 1997.
The Plant Review Board will consider today whether additional measures are necessary for the Units 1 and 2 SFPs.
When the transfer canal gate seal began leaking on March 6, 1997, one fuel assembly was in t"'pent fuel rack reconstitution location. This location has a spacer at the bottom of the channel such that the fuel assembly extends about 2 feet higher than the top of the rack. The top of the rack is at 113 feet, 10 inches elevation.
The end cap of the fuel assembly being reconstituted was removed, with the result that the top of the fuel pins was exactly 2 inches above the top of the rack, at elevation 114 feet.
The Technical Specification required minimum SFP level of 137 feet, or 23 feet above the top of fuel in the reconstitution position, was reached but not exceeded during the event.
The top of a fuel assembly in the normal storage position is approximately 2 feet lower.
9705060082 970307 PDR XOE PNQ-EV-97-Oi4A PDR
P NO-IV-97-014A Because the transfer tube gate valve was already shut at the start of the event, the licensee determined that SFP level could have only decreased a maximum of 4 feet from its normal level of approximately 138 feet as a result of water equalizing between the SFP and the transfer canal.
This corresponds to a level of 134 feet, which is approximately 20 feet above the fuel assembly in the reconstitution rack.
Region IV plans to initiate a special inspection to followup on this event during the week of March 10, 1997.
This information has been discussed with the licensee and is current as of March 7, 1997, at 10:30 a.m. (PST).
Contact:
D. Kirsch K. Johnston (510) 975-0290 (602) 386-3638
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