ML17229A539

LER 97-010-00:on 971027,inadvertant Core Alteration Prohibited by TS Occurred.Caused by CEA Failure to Detach from Ugs.Safety Evaluation Was Performed & Procedural Rev Made to Continue Upper Guide Structure move.W/971126 Ltr

ML17229A539
Person / Time
Site:	Saint Lucie
Issue date:	11/26/1997
From:	Revell J, Stall J FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-97-297, LER-97-010, LER-97-10, NUDOCS 9712030199
Download: ML17229A539 (6)

Text

CATEGORY 1 S

REGULATE Y INFORMATION DISTRIBUTION STEM (RIDS)

ACCESSION NBR:9712030199 , DOC.DATE: 97/11/26 NOTARIZED: NO DOCKET ¹ FACXL:50-335 St. Lucie Plant, Unit 1, Florida Power & Light Co. 05000335 AUTH. NAME AUTHOR AFFILIATION REVELL,J. Florida Power & Light Co.

STALL,J.A. Florida Power & Light Co.

RECIP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 97-010-00:on 971027,inadvertant core alteration prohibited by TS occurred. Caused by CEA failure to detach from UGS.Safety evaluation was performed & procedural rev made to continue UGS move.W/971126 ltr.

DISTRIBUTION CODE: IE22T COPIES RECEIVED:LTR i ENCL TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

SIZE: l5 E

NOTES:

RECIPIENT COPIES RECIPIENT COPIES 0 ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD2-3 PD 1 1 WIENS,L. 1 1 INTERNAL: ACRS 1 1 2 2 AEOD/SPD/RRAB 1 1 ILE CENT 1 1 NRR/DE/ECGB 1 1 NRR 1 1 NRR/DE/EMEB 1 1 NRR/DRCH/HHFB 1 1 NRR/DRCH/HICB 1 1 NRR/DRCH/HOLB 1 1 NRR/DRCH/HQMB 1 1 NRR/DRPM/PECB 1 1 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 RES/DET/EIB 1 1 RGN2 FXLE 01 '1 1 D EXTERNAL: L ST LOBBY WARD 1 1 LITCO BRYCE,J H 1 1 NOAC POORE,W. 1 1 NOAC QUEENER,DS 0

1 1 NRC PDR 1 1 NUDOCS FULL TXT 1 1 U

NOTE TO ALL "RIDS" RECZPZENTS PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT LISTS THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 25 ENCL 25

Florida Power & Light Company, 650t South Ocean Drive, Jensen Beach, FL 34957 November 26, 1997 L-97-297 FPL 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re: St. Lucie Unit 1 Docket No. 50-335 Reportable Event: 97-010 Date of Event: October 27, 1997 Inadvertant Core Alteration Prohibited by Technical Specifications Due to Stuck Control Element Assembl CEA The attached Licensee Event Report is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.

Very truly yours, J. A. Stall Vice President St. Lucie Plant JAS/JWR Attachment cc: Regional Administrator, USNRC, Region II

,ij Senior Resident Inspector, USNRC, St. Lucie Plant c

/4 97i2030i'tt9 97ii26 PDR ADQCK 05000335 8 PDR lbltttliltjtlllttltajiNI an FPL Group company

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB No. 31604I104 (4.95) EXRRES 04I30/SS ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATOR INFORMATION COLLECTION REQUEST: 60.0 HRS. REPORTED LESSON LEARNED ARE INCORPORATED INTO THE UCENSING PROCESS AND FE LICENSEE EVENT REPORT (LER) BACK TO INDUSTRY. FORWARD COMMINTS REGARDING BURDEN ESTIMAT TO THE INFORMATION AND RECORDS MANAGEMENT BRANCH IT.S F33)

US.NUCLEARREGIAATORY COMMISSION. WASHINGTON. DC 206664001 AND TO THE PAPERWORK REDUCTION PROJECT 13160%1041, OFFICE OI

{See reverse for required number of MANAGEMENTAND BUDGET. WASHINGTON. DC 20603.

digits/characters for each block)

FACIUTY NAME Hi DOCKET NUMBER 121 PAGE 131 ST LUCIE UNIT 1 05000335 1 OF4 TITLE (41 Inadvertant Core Alteration Prohibited by Technical Specifications Due to Stuck Control Element Assembly (CEA)

SEQUENTIAL REVISION FACILIlYNAME DOCKETNUMBER MONTH DAY MONTH OAY YEAR NUMBER NUMBER FACILITYNAME DOCKETNUMBER 10 27 97 97 010 00 11 26 97 OPERATING MODE (9) 20.2201 (b) 20.2203{a)(2)(v) 50.73(a) (2) (i) 50.73(a) (2) (viii)

POWER LEVEL {10) 000 20.2203 (0) (2) (I) 20.2203(a) (3) (ii) 50.73(a)(2)(iii) 73.71 OTHER 20.2203(a) (2)(iii) 50.36(c)(1) 50.73(a) (2)(v) Specify in Abstract befow or in NRC Form 366A 20.2203 (0) (2) (iv) 50.36(c)(2) 50.73(a)(2)(vii)

NAME TELEPHONE NUMBER Snclude Area Code)

Jack Revell, Licensing Engineer (561) 467-7169 CAUSE SYSTEM COMPONENT MANUFACTURER REPORTABLE REPORTABLE TO NPRDS CAUSE SYSTEM COMPONENT MANUFACTURER TO NPRDS AC RCT C490 MONTH OAY YEAR EXPECTED YES SUBMISSION X {If yes, complete EXPECTED SUBMISSION DATE). No DATE {15) 02 04 98 ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) {16)

On October 27, 1997, St. Lucie Unit 1 was in Mode 6 with the reactor head removed in preparation for defueling. The containment equipment hatch and personnel access airlock were open, as allowed by Technical Specifications. Personnel commenced Upper Guide Structure (UGS) withdrawal from the reactor vessel in accordance with procedures. As the UGS cleared the alignment pins, a Control Element Assembly (CEA) was discovered attached to the UGS, and had been unexpectedly withdrawn from the core. This constituted a core alteration without the containment penetration status required by Technical Specifications. Containment integrity was set within about 20 minutes of discovery of the stuck CEA.

The cause of the CEA remaining attached to the UGS could not immediately be determined. A safety evaluation was performed and a procedural revision made to continue the UGS move. Reactor cavity water level was raised to increase shielding. Anticipating elevated containment radiation levels, the Containment Isolation System (CIS) was manually actuated prior to continuing the lift.

The UGS lift recommenced on October 28. A remote camera situated beneath the UGS monitored the progress, and the CEA remained attached throughout the transit. Once the transit to the refueling cavity was completed, the CEA was recovered from the UGS. The root cause of the event is still under investigation. Further corrective actions will be identified once the root cause is determined.

NRC FORM 366 (4-95)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSIO (4.95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION YEAR SEQUENTIAL REVISION ST LUCIE UNIT 1 05000335 2 OF 4 97 010 00 TEXT ilfmore speceis required, use eddnionel copies of NRC Form 366A/ I17I DESCRIPTION OF THE EVENT On October 27, 1997, St. Lucie Unit 1 was in Mode 6 with the reactor head [EIIS:AB:RCT] removed in preparation for reactor defueling. The containment equipment hatch and personnel access airlock [EIIS:NH] were open, as allowed by Technical Specifications. Control Element Assemblies (CEAs) [EIIS:AA]had been unlatched by personnel in accordance with procedure OP1-0110022, 'Coupling'and Uncoupling of CEA Extension Shafts'.

At approximately 1510, the reactor cavity water level was raised to 55 feet 6 inches to maintain adequate shielding in preparation for lifting the Upper Guide Structure (UGS) [EIIS:AC]. Normally during the lift, only the UGS lift rig is raised above the surface of the water.

At approximately 1658, contract personnel commenced UGS withdrawal from the reactor vessel in accordance with procedure 1-M-0015, 'Reactor Vessel Maintenance - Sequence of Operations'. During the evolution, a camera mounted at the reactor vessel flange level was used to verify lift alignment and clearance. At approximately 1744, as the UGS cleared the alignment pins, a CEA was discovered attached to the UGS, and had been unexpectedly withdrawn from the core. Operations ordered containment integrity to be set, and this was achieved by 1805.

The cause of the CEA remaining attached to the UGS could not immediately be determined. A safety evaluation was performed which concluded that there would be no adverse impact on plant safety or operation should the CEA fall onto the core while completing the UGS move. Procedure 1-M-0015, 'Reactor Vessel Maintenance-Sequence of Operations', was revised to accommodate movement of the UGS with a CEA attached. Since the UGS and lift rig were to be lifted much higher than normal, reactor cavity water level was adjusted to 60 feet to increase shielding. This action was completed at approximately 2222 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.45471e-4 months <br />.

In anticipation of receiving high enough containment radiation levels to initiate a Containment Isolation Actuation Signal (CIAS), unnecessary personnel leA containment and the Containment Isolation System (CIS) [EIIS:JM]

was manually actuated at approximately 0253 on October 28. This was a preplanned actuation performed in accordance with procedure OP1-1600023, 'Refueling Sequencing Guidelines'.

NAC FOAM 366A I4.95)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSIO I4.96)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION YEAR SEQUENTIAL REVISION ST LUCIE UNIT 1 05000335 3 OF 4 97 010 00 TEXT flfmore speceis required, use edditionel copies of NRC Form 366A/ I17)

The UGS lift recommenced at approximately 0320 with only essential personnel in containment. A remote camera situated beneath the UGS monitored the progress, and the CEA remained firmly attached throughout the transit.

At approximately 0324, CIAS channels indicated that containment radiation levels had reached the CIAS initiation threshold. Channel MD, with the most direct exposure to the UGS, registered an area radiation rate of approximately 7 REM per hour, while the other three channels indicated approximately 100 millirem per hour.

CIS actuates automatically with two channels greater than or equal to 90 millirem per hour.

Once the transit to the refueling cavity was completed, attempts were made to free the CEA but were initially unsuccessful. Subsequently, the CEA was disengaged by operating personnel. The CEA was retrieved and moved to the spent fuel pool for storage. It was identified as CEA 24, a Type 1, full length CEA manufactured by Combustion Engineering.

CAUSE OF THE EVENT The cause of the event was failure of the CEA to detach from the UGS. It is currently undetermined whether the CEA was partially latched or friction fit to the CEA Extension Shaft. The root cause is still under investigation.

A supplement to this LER will be issued describing the findings of root cause evaluation for the stuck CEA.

ANALYSIS OF THE EVENT This event is reportable under 10 CFR 50.73 (a)(2)(i)(B) as "Any operation or condition prohibited by the plant's Technical Specifications." The Technical Specification violated is Unit 1 Technical Specification 3.9.4:

"The containment penetrations shall be in the following status:

a. The equipment door closed and held in place by a minimum of four bolts,

b. A minimum of one door in each airlock is closed, and C. Each penetration providing direct access from the containment atmosphere to the outside atmosphere shall be... (several configurations given).

APPLICABILITY: During CORE ALTERATIONS or movement of irradiated fuel within the containment."

NRC FORM 366A I4.96)

NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSIO I4-95)

LICENSEE EVENT REPORT (LER)

TEXT CONTINUATION YEAR SEQUENTIAL REVISION ST LUCIE UNIT 1 05000335 4 OF 4 97 010 00 TEXT llfmore space is required, use additional copies of NRC Form 366A/ I 17I The Technical Specifications define "core alteration" as "movement or manipulation of any fuel, sources, reactivit control components, or other components affecting reactivity within the reactor vessel with the vessel head removed and fuel in the vessel." Normally, lifting a UGS is not a core alteration, since the UGS does not contain fuel, sources, or components that control or affect reactivity. However, since a reactivity control component (a CEA) was moved with the UGS in this event, a core alteration was performed. Moreover, the core alteration was performed without the containment penetration status required by the Technical Specification. Penetrations were placed in the required state within approximately 20 minutes of discovery of the stuck CEA.

The CIS actuation was not reportable under 10 CFR 50.72, since the actuation was part of a preplanned sequence addressed by procedure. The CIS is designed to mitigate the consequences of accidents which release large amounts of energy within the containment structure. There was no such accident in this case, and the CIS actuation was intentional rather than the result of accident conditions.

Withdrawal of the stuck CEA from the reactor core did not place the plant in an unanalyzed condition, nor did it place the plant in a condition outside its design basis. Plant procedures address the case of a single CEA not inserted in the core, and substantial shutdown margin was maintained during the course of this event.

LER 97-001-00 for St. Lucie Unit 2 documented an event with radiological conditions similar to this event. In the Unit 2 event, an expected CIS actuation occurred as the UGS was withdrawn from the reactor. The elevated radiation levels were caused by irradiated incore instrumentation segments [EIIS:IG] which had broken during removal of incores. The Unit 2 event, however, was unlike this event in that there was no core alteration.

I CORRECTIVE ACTIONS Immediate corrective actions included stopping the UGS lift and evaluating dose rates. A condition report was issued and a team was designated to determine the cause of the stuck CEA. The team reviewed potential failure modes and related industry experience, but has not had access to the CEA's extension shaft for evaluation. The unlatch procedure was also reviewed and verified to have been properly performed. Further corrective actions for the stuck CEA will be identified in a supplement to this LER once the root cause has been determined.

NAC FOAM 366A I4.95)