ML17349A682

LER 93-001-00:on 930114,Westinghouse Notified Util That Wet Annular Burnable Absorber Assemblies Not Mfg Per Design Specs.Caused by Failure to Translate Design Requirement to Drawing.Absorber Design modified.W/930216 Ltr

ML17349A682
Person / Time
Site:	Turkey Point
Issue date:	02/16/1993
From:	Plunkett T, Tomonto R FLORIDA POWER & LIGHT CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
L-93-034, L-93-34, LER-93-001-02, LER-93-1-2, NUDOCS 9302220351
Download: ML17349A682 (10)

Text

ACCELERA"1+3 DOCVMENT DIST VTION SYSTEM REGULA Y INFORMATION DISTRIBUTI SYSTEM (RIDS)

ACCESSION NBR:9302220351 'OC.DATE: 93/02/16 NOTARIZED: NO DOCKET FACIL:50-250 Turkey Point Plant, Unit 3, Florida Power and Light C 05000250 AUTH. NAME AUTHOR AFFILIATION TOMONTO,R.J. Florida Power & Light Co.

PLUNKETT,T.F. Florida Power & Light Co.

RECZP.NAME RECIPIENT AFFILIATION

SUBJECT:

LER 93-001-00:on 930114,Westinghouse notified util that wet annular burnable absorber assemblies not mfg per design specs. Caused by failure to translate design requir'ement to D drawing. Absorber design modified.W/930216 ltr.

DISTRIBUTION CODE: 'ZE22T COPIES RECEIVED:LTR ENCL SIZE:

TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL D PD2-2 LA 1 1 PD2-2 PD 1 1 RAGHAVANiL 1 1 D INTERNAL'. ACNW 2 2 AEOD/DOA 1 1 AEOD/DSP/TPAB 1 1 AEOD/ROAB/DSP* 2 2 S-NRR/DET/EMEB 7E 1 1 NRR/DLPQ/LHFB10 1 1 NRR/DLPQ/LPEB10 1 1 NRR/DOEA/OEAB 1 1 NRR/DREP/PRPB11 2 2 NRR/DST/SELB 8D 1 1 NRR/DST/SICB8H3 1 1 NR /J3SX/SPLB8D1 1 1 NRR/DST/SRXB 8E 1 1 R FILE 02 1 1 RES/DSIR/EIB 1 1 N FILE 01 1 1 EXTERNAL: EG&G BRYCEiJ.H 2 2 L ST LOBBY WARD 1 '1 NRC PDR 1 1 NSIC MURPHYiG.A 1 1 NSIC POOREiW. 1 1 NUDOCS FULL TXT 1 1 D

D D

NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE! CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

FULL TEXT CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUIRED: LTTR 29 ENCL 29

L f

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FPL FEB i lI 198'-'-93-034 10 CFR 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Gentlemen:

Re: Turkey Point Units 3 and 4 Docket No. 50-250 and 50-251 Reportable Event: 93-001 Date of Event: January 15, 1993 Axiall Mis ositioned Wet Annular Burnable Absorber WABA Rods The attached Licensee Event Report is being provided pursuant to the requirements of 10 CFR 50.73 (a)(2) (ii) (A) to provide information on the subject event.

Very truly yours,

//-. P/uAkc/7 6 T. F. Plunkett Vice President Turkey Point Nuclear TFPNRJTNrt Attachment cc: Stewart D. Ebneter, Regional Administrator, Region II, USNRC Senior Resident Inspector, USNRC, Turkey Point Plant gp{j(j35 9302220351 930216 PDR ADOCK 05000250 S PDR an FPL Group company

LICENSEE EVENT REPORT (LER}

FAcILITY NAKE l1)

DOCKET NUMBER ll) FACE lS)

Turkey Point Unit 3 05000250 1 or 6

,TITIE <<) Axially Mispositioned Wet Annular Burnable Absorber (WABA) Rods EVENT DATE lS) LER NUMBER(6) RPT DATE l7) OTHER FACILITIES INVOIVED l8)

MON DAY YR YR SEQ 6 Rl HON DAY YR FACILITY NAMES DOCKET 6 lS) 15 93 93 001 00 2 16 93 TURKEY POINT UNIT 4 05000251 OPERATING MODE lB) 10 CFR 50.73 a 2 ii A PONER LEVEL l10) 100 LICENSEE CONTACT FOR THIS LER (12)

R. J. Tomonto, Licensing Engineer TELEPHONE NUMBER 305-246-7327 COMPLETE ONE LINE FOR EACH COMPONENT PAILURE DESCRIBED IN THIS REPORT {13)

CAUSE SYSTEM COMPONENT MANUFACTURER NPRDS2 CAUSE SI STEM COMPONENT MANUFACTURER NPRDS2 SUPPLEMENTAL REPORT EXPECTED l14) NO 0 YES 8 EXPECTED SUBMISSION DATE l15)

DAY YEAR

)If yes, cceylete EXPECTED SUBMISSION DATE) July 15 1993 ABSTRACT l16)

On January 14, 1993, with Turkey Point Units 3 and 4 in Mode 1 (POWER OPERATION) at 100% power, Florida Power and Light (FPL) was notified by Westinghouse Electric Corporation (nuclear fuel supplier) that the wet annular burnable absorber (WABA) assemblies were not manufactured according to the design specification. Both units were operating in Cycle 13. Specifically, beginning with Unit 3 Cycle 12 reload, FPL introduced a new fuel assembly design feature involving debris resistant fuel rods. The debris resistant design involved increasing the length of the solid fuel rod end cap and repositioning the active fuel height up 1.368 'inches from the bottom of the fuel rod. The reload design for Unit 3 Cycle 13 and Unit 4 Cycle 13 required the absorber section of the WABAs be repositioned on center to match the corresponding repositioned active fuel height. During the startup of Turkey Point Unit 3 Cycle 13, FPL measured a higher local peaking factor (Fq) and a more top-peaked beginning of cycle axial power distribution than predicted by core models. As a result of further investigations, Westinghouse determined that the absorber section of the WABA had not been manufactured in accordance with design specification for the fuel reload.

At no point was either Unit 3 or Unit 4 operating in a condition outside of the design bases of the plants.

This LER is reportable under 10 CFR 50.73 (a) (2)(ii) (A).

LICENSEEQGiXT REPORT (LER) TEXT HTIEUATIOE FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 3 05000250 93-001-00 02 OF 06 I. DESCRIPTION OF THE EVENT The following chronology of events was developed.

12/29/92 Unit 3 was in Mode 1 at 100% Power (POWER OPERATION) and Unit 4 was, in Mode 1 at 100% Power Florida Power and Light (FPL) reviewed the Unit 3 flux map at 100% power (following the initial return to power after a refueling outage), equilibrium xenon, steady-state conditions and found an increase in local peaking factor (Fq), and a more top-peaked beginning of cycle (BOC) axial power distribution than predicted by core models.

12/30/92 FPL reviewed the INCORE-3D code and the trace alignment through procedure. FPL investigated the possibility that the absorber 1/13/93 . section of the wet annular burnable absorber (WABA) rods (EIIS-AC) (IEEE-ABS) was not centered with the fuel assembly active fuel height.

1/14/93 Westinghouse confirmed that the WABA rods were not manufactured in accordance with design requirements. Westinghouse's calculations showed that the WABAs rods were offset -1.368" from the center of the active fuel.

1/15/93 Based on the preliminary results obtained from FPL and Westinghouse core models, and engineering judgement, it was determined that current operation for both units was acceptable.

Westinghouse was directed to confirm this conclusion based on performing the Final Acceptance Criteria (FAC) analysis using as-built parameters. A satisfactory interim operability assessment was completed.

1/17/93 Westinghouse completed the FAC analysis using BOC operation data (rod position and power versus time) . Westinghouse concluded from the FAC analysis that all operation for both units'as bounded by the design basis for the entire fuel cycle; FPL introduced a debris resistant fuel assembly (DRFA) (EIIS AC)'esign beginning in Unit 3 Cycle 12 and continuing in Unit 4 Cycle 13 and Unit 3 Cycle 13 reloads. The DRFA design incorporates the following design features compared to the standard Westinghouse optimized fuel assembly (OFA) design:

solid bottom fuel rod end plug was increased in length by approximately 1.381 inches, total fuel stack height remained unchanged (with the exception of the positioning within the fuel rod),

fuel assembly spacer grids were repositioned, and guide tube dashpot was shortened and guide tube flow hole locations were changed, to accommodate the repositioning of the spacer grids.

LZCENSEEPENT REPORT (LER) TEXT NTZNUATZON FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 3 05000250 93-001-00 03 oF 06 The Westinghouse DRFA design is unique to Turkey Point and no other licensee using Westinghouse fuel has incorporated the same fuel assembly design.

Other PWR fuel suppliers utilize this same design.

In Unit 3 Cycle 12 a study of the use of offset WABA's concluded that the effects of this offset was not significant. The presence of the offset WABA

-rods were not discernable during the Unit 3 Cycle 12 startup, since the number of.WABA rods (96) did not significantly alter the expected performance of the core.

The Unit 4 Cycle 13 reload included the first Unit 4.batch of fuel with debris resistant fuel. The reload design included 368 WABA rods, distributed in 36 fuel assemblies. The largest number of WABA rods in an individual assembly was 20 rods. The location of the WABA assemblies within the core was evenly distributed across the core and exposed to an average power condition. A discrepancy in peaking factors was not observed in the Unit 4 Cycle 13 fluxmaps, since the number of WABA rods and their effect on axial flux shape did not significantly alter the expected performance of the core. The results of Westinghouse's FAC reanalysis concluded that the core limits'were maintained (Fq) during the cycle with the offset WABAs and the offset WABAs did not compromise plant safety.

The Unit 3 Cycle 13 reload represented the second fuel region (in Unit 3) with debris resistant fuel. The reload design included 512 WABA rods, distributed in 28 fuel assemblies. The largest number of WABA rods in an individual assembly was 20 rods. Th'e location of the WABA assemblies within the core was centered around the middle of the core, corresponding to the highest power density in the core. As highlighted above, FPL discovered; during the initial fluxmap at 100% power steady state conditions, a discrepancy between the predicted and measured total peaking factor (Fq) .

Subsequent investigation of the deviation led to the conclusion that the WABA rods were incorrectly positioned by -1.368 inches relative to the active fuel stack. A safety evaluation was performed to evaluate the acceptability of operation of both units for the remainder of these cycles (Unit 3 Cycle 13 and Unit 4 Cycle 13) .

This LER is reportable under 10 CFR 50.73 (a) (2) (ii) (A) .

II. CAUSE OF THE EVENT The root cause of this event was that Westinghouse failed to translate a specific design requirement for centering the WABAs to the fabrication drawing.

The following factors contributed to the event:

FPL correctly specified 0.0 inch WABA offset in the reload specification for Unit 3 Cycle 13 and Unit 4 Cycle 13 reload.

However, FPL did not highlight this dimension as a change to Westinghouse.

2; Westinghouse performed an evaluation of the Unit 3 Cycle 12 reload with offset WABAs and concluded that the offset was not significant.

This evaluation was later misinterpreted as a general design guideline.

3. The Westinghouse design review process failed to address the location of the WABAs as a design criterion.

LICENSEEQIEMT REPORT (LER) TEXT ETIEORTIOE FACILITY NAME DOCKET NUMBER LER NtjMBER PAGE No; TURKEY POINT UNIT 3 . 05000250 93-001-00 04 OF 06 XIZ. JQGLLYSZS OF THE EVENT A. Turke Point Unit 4 C cle 13 0 eration Turkey Point Unit 4 Cycle 13 reload design was evaluated using existing core design models with NRC approved methodology. These models were revised to account for the WABA offset and used to verify that the full cycle of

~

operation was bounded by the existing Reload Safety Evaluation. This verification involved evaluating the impact of the WABA offset on the Cycle 13 Reload Safety Analysi's Checklist (RSAC) parameters-and on the axial power distribution analysis to determine the impact on Departure from Nucleate Boiling (DNB) and Fq.

-The RSAC parameters represent a comparison of the nuclear design inputs to the safety analysis input.;, No accidents were required to be re-evaluated the design inputs are bounded by the safety analysis inputs. The impact of if the WABA offset- on each of the Cycle 13 RSAC parameters was analyzed or assessed for its impact on the current RSAC. The nu'clear design inputs foz the WABA offset case were bounded by the current RSAC.

Axial power shapes were analyzed using the NRC approved Final Acceptance

. Criteria (FAC) methodology. This analysis was,re-performed for the entire =

fuel cycle. For a variety of plant 'operational maneuvers, this analysis generates thousands of power shapes which represent a family of adverse xenon and power distributi'ons which are possible during Condition I and Condition II events. The FAC re-analysis verified that Fq limits remained below the Technical Specification limits during.all Mode 1 operation provided that axial flux distribution (AFD) and rod insertion limits are maintained within the limits allowed by the Technical Specifications.

In summary, all statements and conclusions presented in the original Reload Safety Evaluation (RSE) remain valid for the entire operating cycle. The Unit 4 Cycle 13 core design with offset" WABAs meets all safety parameter limits, thereby ensuring met.that all pertinent design and licensing basis acceptance criteria are B. Turke Point Unit 3 C cle. 13 0 eration Similar to Unit 4, the Unit 3 Cycle 13 reload was evaluated using core models which were revised to account for the offset WABA. The RSAC parameter evaluation and FAC analysis were performed from 1000 Megawatt-days/Metric-ton Uranium (MWD/MTU) to the End of Cycle (EOC). The current burnup exceeds 1000 MWD/MTU. The nuclear design inputs for the WABA offset case were bounded by the current RSAC.

To ensure that Technical specification compliance had been maintained for Unit 3 Cycle 13 from BOC to 1000 MWD/MTU, past operation data (i.e., actual power history and rod movement) was reviewed and modelled using an approved three-dimensional nuclear code. The analysis demonstrated that the Fq Technical'pecification limit was not violated during actual operation and the plant was always within the design basis.

Within the conditions of the Technical Specification, the potential did exist that Unit 3 could have operated outside the design basis;their however, at no point did either Turkey Point Units 3 or 4 operate outside design bases.

LICENS REPORT (LER) TEXT INTINUATION FACILITY NAME DOCKET NUMBER LER NUMBER PAGE NO.

TURKEY POINT UNIT 3 05000250 93-001-00 05 oF 06 C. Re ortabilit Determination Reportability was evaluated under 10 CFR 50.73 (a) (2) . The details to follow will address the 'basis of the determination of a reportable event under 10 CFR 50.73 (a) (2) (ii) (A) .

10 CFR 50.73 (a) (2) (ii) (A) states: Any event or condition that resulted in the condition of the nuclear power plant, including its principal safety barriers, being seriously degraded, or that resulted in the nuclear power plant being in an unanalyzed condition that significantly compromised plant safety.

For both Unit 3 Cycle 13 and Unit 4 Cycle 13, the mispositioned WABA rods placed the units in an unanalyzed condition. Both Westinghouse and FPL recognize the fact that the nuclear design analysis and conclusions reached in the reload safety evaluations (RSE) for these cycles were based upon the burnable absorber section of the WABA rods'eing centered at the midplane of the active fuel. As a result, a change from this assumption, which in itself is less conservative, has placed this event in an unanalyzed condition.

The'ignificance of this unanalyzed condition is evaluated by using the criteria that an unanalyzed condition that significantly compromises plant safety exists if (1) the condition potentially affecting a component, system, or structure is of more than minor safety significance; and (2) the condition potentially could (a) increase the. probability of occurrence or the consequences of an accident or malfunction of equipment. Engineering judgment and experience may be used when evaluating the condition for reportability under this criteria.

The evaluation of the safety significance of the mispositioned WABA rods for Unit 3 Cycle 13 (BOC to 1000 MWD/MTU) is presently=under review. In consideration of this review, the following information is provided:

7

~ The results from the FAC analysis performed by Westinghouse concluded that Fq*K(z) could potentially have been violated by up to approximately 11% based on the WABA offset at approximately 10.6'f the active core height (maximum Fq of 2.425 at 10.6'), if the unit had operated in a load-follow mode with the worst combination of axial power shape and rod position.

~ Based on an Fq of 2.425 and the Westinghouse Power Shapes Sensitivity Methodology (PSSM) for Loss of Coolant Accidents (LOCA), the Peak Clad Temperature (PCT) would have increased approximately 61'F from the current analysis. By FPL letter L-92-338; dated December 18, 1992, FPL submitted to the NRC a summary of the current analysis of record for Large Break LOCA of 2129'F. Therefore the PCT would have been approximately 2190'F (for this extreme case), which is less than the 10 CFR 50.46 (b)(1) criteria of 2200'F.

~ The current non-LOCA accident analyses of record have approximately 1%

margin in the DNBR limit. The axial power shapes in the FAC analysis for Turkey Point Unit 3 Cycle 13 at BOC are more limiting than those used in the current Non-LOCA analyses and these power shapes would exceed the current it is judged that using DNBR limit.

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TURKEY POINT UNIT 3 05000250 93-001-00 06 OF 06 However, the Non-LOCA analyses were recently reanalyzed using the Revised Thermal Design Procedure (RTDP) which leaves a DNBR margin of approximately 15%. Although these analyses are currently undergoing internal FPL review and are not considered the analyses of record, is judged that there is sufficient margin in DNB space to accommodate it any possible reduction in the DNBR. In the reanalyses the Fq used is 2.5 with a 5% flow reduction and an F-delta-h of 1.7. The current Fq and F-delta-h limits are 2.32 and 1.62, respectively.

For the Unit 3 Cycle 13 core design with offset WABAs, the analysis using actual plant operating history data and rod movement demonstrated that the.

Fq Technical Specification limit was not violated during actual operation at BOC (0 to 1000 MWD/MTU) and the plant was always within the design basis.

FPL has concluded this LER is reportable under 10 CFR 50.73 (a) (2) (ii) (A),

pending the completion and FPL's internal review of the RTDP analysis. As discussed above, upon completion of the review of the RTDP analysis, FPL anticipates sufficient margin will exist to accommodate any possible reduction due to the mispositioned WABAs. Upon completion of FPL's review of the RTDP Analysis, FPL will submit a supplemental LER. This supplemental LER shall be submitted to the NRC by July 15, 1993.

IV. CORRECTIVE ACTIONS Westinghouse modified the design of the WABAs for Turkey Point Unit 4 Cycle 14 to correctly position the absorber section relative to the active fuel height.

2. FPL performed an oversight review to determine if the error in the Westinghouse fuel design process could have/should have been identified by the licensee. This oversight review included Engineering and Quality Assurance (QA) activities.

3. For each future reload, a Reload Oversight Plan will be prepared that reflects the physical and neutzonic changes to the fuel for that cycle. This effort will be implemented beginning with the Unit 3, Cycle 14 reload.

FPL performed a review of the burnable absorber positioning at St.

Lucie Units 1 and 2, to determine its applicability to other FPL nuclear fuel suppliers. No problem was identified.

5. FPL will revise Nuclear Engineering quality instruction (JPN QI) 3.1.8, "Engineering Package (EP) for Fuel Reloads" to facilitate identification of changes to core components or core response. This revision will be completed by April 16, 1993.

V. M)DITIONAL INFORMATION None.