L-99-049, Forwards Summary of Any Change to or Error Discovered in Evaluation Models for ECCS or Application of Such Models, That Affect Fuel Cladding Temp Calculations for St Lucie Units 1 & 2 for Jan-Dec 1998,per 10CFR50.46(a)(3)(ii)
| ML17229B032 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 03/01/1999 |
| From: | Stall J FLORIDA POWER & LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| L-99-049, L-99-49, NUDOCS 9903080440 | |
| Download: ML17229B032 (5) | |
Text
CATEGORY 1 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSION NBR:9903080440 DOC.DATE: 99/03/01 NOTARIZED: NO FACIL:50-335 St. Lucie Plant, Unit 1, Florida Power
& Light Co.
50-389 St. Lucie Plant, Unit 2, Florida Power
& Light Co.,
AUTH.NAME AUTHOR AFFILIATION STALL,J.A.
Florida Power
& Light Co.
RECIP.NAME RECIPIENT AFFILIATION Records Management Branch (Document Control Desk)
I
SUBJECT:
Forwards summary of any change to or error discovered in evaluation models for ECCS or application of such models, that affect fuel cladding temp calculations for Unit 1
& 2, per 10CFR50.46(a) (3) (ii).
DTSTRTBUTTON CODE: A001D COPTER RECETVED:LTR i
ENCL J STSE:
TITLE: OR Submittal: General Distribution DOCKET I 05000335 05000389 E
NOTES:
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NOTE TO ALL "RIDSE RECIPIENTS:
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ON EXTENSION 415-2083 TOTAL NUMBER OF COPIES REQUIRED: LTTR 15 ENCL 14
Florida Power &Light Company, 6351 S. Ocean Drive, Jensen Beach, FL 34957 March 1, 1999 L-99-049 10 CFR 50.46 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Re:
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 Acceptance Criteria for Emergency Core Cooling Systems for LightWater Nuclear Power Reactors:
0 R 5046 nn lR Pursuant to 10 CFR 50.46(a)(3)(ii), the nature ofany change to or error discovered in the evaluation models for Emergency Core Cooling Systems (ECCS), or in the application of such models, that affect the fuel cladding temperature calculations for St. Lucie Units 1 and 2 is reported in the attachment to this letter. The estimated effect from any such change or error on the limitingECCS analysis for each unit is also addressed.
The data interval for the report is from January 1 through
'ecember 31, 1998.
Please note that a data point from 1999 is also identified and included in this report to ensure compliance with the 30-day notification requirement of 10 CFR 50.46(a)(3)(i).
Should there be any questions, please contact us.
Very truly yours, J. A. Stall Vice President St. Lucie Plant JAS/RLD Attachment PCS(
cc:
Regional Administrator, Region II,USNRC Senior Resident Inspector, USNRC, St. Lucie Plant 9903080440 99030k POR AOOCK 05000335 P
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 10 046 nn 1R L-99-049 ATTACHMENT Page 1 of3 Emergency core cooling system (ECCS) analyses for St. Lucie Unit 1 and St. Lucie Unit 2 are performed by Siemens Power Corporation (SPC) and Asea Brown Boveri-Combustion Engineering (ABB-CE), respectively.
The following information pertaining to the evaluation models for small break loss ofcoolant accidents (SBLOCA) and large break loss ofcoolant accidents (LBLOCA),and the application ofsuch models to each St. Lucie unit, is provided pursuant to 10 CFR 50.46(a)(3)(ii).
Asummaiy ofcalculated peak cladding temperature (PCT) changes is provided in Table 1. The data interval for this report is from January 1 through December 31, 1998*.
1.0 ST. LUCIEUNIT 1 1.1 The previously reported PCT for the SBLOCA was 1953'F. No modeling changes or errors were identified during 1998.
The limitingSBLOCA PCT remains at 1953'F.
1.2 Several errors/issues were identified impacting the LBLOCAPCT. The errors not previously reported in References 3.1 and 3.2 are summarized below. Table 1 provides the estimated impact of these errorsfissues on the St. Lucie Unit 1 LBLOCAcalculated PCT.
These estimates are obtained using the "Revised Model" forPWR LBLOCAevaluation, submitted by SPC to the NRC for review in August 1998. The limitingPCT with the estimated effect ofthe changes is 2058'F.
RDX2 lini n
ivi
- An error was discovered in the gadolinia-bearing fuel conductivity equation used in the PWR LOCAanalyses.
The conductivity equation described in XN-NF-79-56 (P)(A) was not replaced upon the approval of the gadolinia-bearing fuel conductivity equation described in XN-NF-85-92 (P)(A). The impact ofincorporating the currently approved conductivity equation in the RDX2LSE code is to reduce significantly the calculated PCT for, gadolinia rods. Since gadolinia rods are not limiting rods for St. Lucie Unit 1 LOCAanalyses, the impact ofthis error on the limitingPCT is O'.
PR F
c de fRFP:
The RFPAC code was discovered to calculate negative values for low pressure safety injection (LPSI) and high pressure safety injection combined flow rates when there was a time gap between termination ofsafety injection tank flow and initiation ofLPSI flow.
The error is found to occur only when the time gap is sufficient for the cold leg liquid to fall below 10% full. The impact ofthe RFPAC code correction on the limitingPCT is estimated to be 0 F.
- Notification ofthe error identified as "Corrosion Model in RODEX2 (SPC CR 6792)" was received in February 1999, but is contained in this report to satisfy the 30-day reporting requirement pursuant to 10 CFR 50.46(a)(3)(i), i.e., the adjustment ofPCT from the last acceptable evaluation model due to a cumulation ofthe absolute magnitude ofchanges remains greater than 50'F.
St. Lucie Units 1 and 2 Docket Nos. 50-335 and 50-389 10 FR 50 46 Ann 1R L-99-049 ATTACHMENT Page 2 of3 T
D E2 AxialN li i n: An error was discovered during the development ofnew LBLOCA methodology regarding the calculation of an unrealistically high PCT in the region at the upper extremity of the core when 3-inch axial nodes are modeled in that region in TOODEE2.
The unrealistically high PCT is caused by the unrealistically low heat transfer coefficients predicted by the FCTF heat transfer correlation above the 10.5-foot elevation. To assure a bounding PCT, SPC has decided to conservatively use increased nodalization at the top ofthe core. The impact ofthis change on the limitingPCT is estimated to be 0 F.
DX2 li i i
I i: An error was identified in the density correlation for gadolinia rods in the RDX2LSE code.
An evaluation ofthe impact for gadolinia rods showed a reduction in the calculated PCT for gadolinia rods.
Since gadolinia rods are not limitingrods for St.
Lucie Unit 1 LOCAanalyses, the impact ofthis error on the limitingPCT is O'.
i n l in R D: Two deficiencies were identified in the cladding corrosion calculation in RODEX2. There was an error in the MATPRO coding and an error in the value of corrosion enhancement factor. The impact ofthe two deficiencies on the limitingPCT is estimated to be -2'F.
D 2
E Fi i n R l l
I i
f r lini:
The fission gas release model in RDX2LSE was found to be incorrect for gadolinia rods.
The fission gas release calculations for gadolinia rods used the theoretical density for UO2 rods, resulting in an over prediction ofgadolinia rod fission gas release.
The correction ofthis error willresult in increased gap conductance and lower PCT forgadolinia rods.
Since gadolinia rods are not limitingrods for St. Lucie Unit 1 LOCA analyses, the impact ofthis error on the limitingPCT is O'.
- PC CCN dfg fd dgdgygggd fgg fg f
f ICECON. The errors are related to containment heat transfer, which could potentially impact the containment pressure.
Scoping calculations performed by SPC estimated the impact on PCT for dry containment plants to be O'.
2.0 ST. LUCIEUNIT2 In 1998, ABB-CEmade no changes to and discovered no errors in the ABB-CEECCS performance evaluation models.
The peak cladding temperature for the analysis ofrecord remains at 1915 F for SBLOCA, and 2171'F for LBLOCA.
3.0 REFERENCES
3.1 FPL Letter L-98-158, J. A. Stall to USNRC (DCD), Re: St. Lucie Unit 1, Docket 50-335; LBLOCAEvaluation Model, 30 D 10 50 46R; June 15, 1998.
3.2 FPL Letter L-98-194, J. A. Stall to USNRC (DCD), Re: St. Lucie Unit 1, Docket 50-335, LBLOCAEvaluation Model, 30 D 10 FR 5046; July 24, 1998
St. Lucie Units I and 2 Docket Nos. 50-335 and 50-389 10 FR 50 46 Ann l R L-99-049 ATTACHMENT Page3 of3 i~li: 1998 St. Lucie Units 1 and 2 SBLOCA and LBLOCAPCT Summary Unit 1 SBLOCA Summar 1997 10 CFR 50.46 Annual Re ort Change during 1998 1998 10 CFR 50.46 Annual Re ort PCT 'F 1953 1953 Unit 1 LBLOCASummar 1997 10 CFR 50.46 Annual Rcport RELAP4 excessive variabilit (SPC CR 6169) estimate -28'F. Reference 3.1 Chan e from ICECON code issue (SPC CR 6680). References 3.1 and 3.2 Change from RDX2LSE calculations ofgas release fraction and pcllct-cladding contact prcssure, and asymptotic fuel density input (SWMDEN) to RODEX2 (SPC CR 6655). Note: Change in PCT reviousl estimated < 20'F in Reference 3.2.
Chan efromRELAP4 deca heatre-normalization SPC CR6578
. Refcrence3.2 Chan e from RELAP4/RELAXfuel avera e tern erature SPC CR 6581
. Reference 3.2 Chan e from RODEX2 a
calculation SPC CR 6574
. Rcfcrcnce 3.2 Chan e from RDX2LSE adolinia conductivi model SPC CR 6419 Chan e from error in PREFILL subcode ofRFPAC SPC CR 6809 Change from TOODEE2 axial nodalization (SPC CR 6580)
Chan e from RDX2LSE adolinia fuel wei t calculation (SPC CR 6442)
Chan e from RODEX2 corrosion model SPC CR 6792 Chan e from RDX2LSE fission as release calculation for adolinia SPC CR 7087 Change from ICECON code errors (SPC CR 7083) 1998 10 CFR 50.46 Annual Rcport PCT F
2040
+15
-2 2058 Unit 2 SBLOCA Summar 1997 10 CFR 50.46 Annual Re ort Change during 1998 1998 10 CFR50.46 Annual Re ort PCT 'F 1915 1915 Unit 2 LBLOCASummar 1997 10 CFR 50.46 Annual Rc ort Chan edurin 1998 1998 10 CFR 50.46 Annual Re ort
- The impact ofthis error is conservatively not included in the limitingPCT value (Reference 3.1).
PCT 'F 2171
~
2171