RC-99-0192, Forwards Updated 1999 ECCS Evaluation Model Revs Rept for VC Summer Nuclear Station.Rept Is Being Submitted Pursuant to 10CFR50.46,which Requires Licensees to Notify NRC of Corrections to or Changes in ECCS Evaluation Models

Forwards Updated 1999 ECCS Evaluation Model Revs Rept for VC Summer Nuclear Station.Rept Is Being Submitted Pursuant to 10CFR50.46,which Requires Licensees to Notify NRC of Corrections to or Changes in ECCS Evaluation Models

ML20216J655
Person / Time
Site:	Summer
Issue date:	09/28/1999
From:	Gabe Taylor SOUTH CAROLINA ELECTRIC & GAS CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
RC-99-0192, NUDOCS 9910060015
Download: ML20216J655 (11)

Text

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A SCANA COMPANY RC-99-0192 4

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9 U. S. Nuclear Regulatory Commission

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• P +1 Gentlemen:

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Subject:

VIRGIL C. SUMMER NUCLEAR STATION a DOCKET NO. 50/395

.:} OPERATING LICENSE NO. NPF-12 j!i m[ -

M 9 ECCS EVALUATION MODEL REVISIONS REPORT (ECC 1003)

Mwyj,Taylorj h oesided

Nudeotopmre,L.U, Attached is the updated (1999) Emergency Core Cooling System (ECCS) d Evaluation Model Revisions Report for the Vir0il C. Summer Nuclear Station b ., i (VCSNS). This report is being submitted pursuant to 10CFR50.46, which

$f j requires licensees to notify the NRC of corrections to or changes in the ECCS g Evaluation Models of greater than 50 F.

e, p , jdp h I declare that the statements and matters set forth herein are true and correct to

'i  ; > 1 the best of my knowledge, information, and belief.

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'isaMC'alineseoiicatecpf if you have any questions, please call Mr. Michael J. Zaccone at (803) 345-

, vigilC. Summer Nudem 51dion j 4328.

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W. F. Conway J. B. Knotts, Jr.

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J. J. Galan (w/o att.) NSRC l* , . j R. J. White DMS (RC-99-0192)

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E NUCLEAR EXCELLENCE- A SUMMER TRADITIONI 1

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Docum:nt Control D:sk ECC 1003

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~ STATE OF SOUTH CAROLINA  :

TO WIT :

COUNTY OF FAIRFIELD-  :

I hereby certify that on the 28 M day of l NAd.c 19.f_L, before me, the subscriber, a Notary Public of the State of South Cardlina personally appeared Gary J. Taylor, being duly swom, and states that he is the Vice President, Nuclear Operations of the South Carolina Electric & Gas Company, a corporation of the State of South Carolina, that he provides the foregoing response for the purposes therein set forth, that the statements made are true and correct to the best of his knowledge, information, and.

belief, and that he was authorized to provide the response on behalf of said Corporation.

WITNESS my Hand and Notarial Seal Notar/Public

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My Commission Expires #4EsJd[fs,2005, Date

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i Atttchm:nt to Docum:nt Control D:sk ECC 1003 RC-99-0192 Page 1,of 9 CHANGES TO THE WESTINGHOUSE ECCS EVALUATION MODELS INTRODUCTION Provisions in 10 CFR 50.46 require the reporting of corrections to or changes in the ECCS Evaluation Model(EM) approved for use in performing safety analyses for the Loss of Coolant Accident (LOCA). This report describes corrections and revisions to the Westinghouse ECCS EM which are applicable to the V. C. Summer Nuclear Station (VCSNS). The current approved Westinghouse ECCS ems are listed in Table 1 and i consist of several computer codes with specific functions.

Westinghouse has completed the evaluation of severalitems related to the Westinghouse ECCS EM listed in Table 1. Table 2 lists changes or corrections to each of these items.

Tables 3 and 4 summarize the changes or corrections in the ECCS Evaluation Model since the last notification and the associated change in the peak clad temperature I (PCT). The Large Break model changes are considered significant under 10 CFR I 50.46.

Table 5 summarizes the changes made to the ECCS Evaluation Model since the last notification under 10 CFR 50.59.

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' Attachm::nt to Docum::nt Control D:sk ECC 1003 RC-99-0192 I Rage Rof 9.

TABLE 1

SUMMARY

OF WESTINGHOUSE ECCS EVALUATION MODELS

. FOR VCSNS NAME: 1981 MODEL WITH BASH l

APPLICATION: Analysis of Large Break LOCA l CODES USED: PURPOSE:

' SATAN-VI _ Blowdown hydraulic transient BASH Reflood hydraulic transient LOCBART- Hot assembly thermohydraulics and fuel rod thermal transient WREFLOOD/ COCO /LOTIC Coritainment pressure transient NAME: 1931 SBLOCA MODEL  !

i APPLICATION: Analysis of Small Break LOCA CODES USED: PURPOSE:

l NOTRUMP System Hydraulic transient l SBLOCTA Fuel rod thermal transient  !

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- Attrchment to Docum:nt Control'D:sk i T ECC 1003 RC-99-0192

Rage Sof 9 J TABLE 2 CHANGES OR CORRECTIONS TO THE VIRGIL C. SUMMER NUCLEAR STATION ECCS EVALUATION MODELS NOT PREVIOUSLY REPORTED.

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LOCBART Spacer Grid Single Phase Heat Transfer Error LOCBART Zirc-Water Oxidation Error Accumulator Line/ Pressurizer Surge Line Data._

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t i Attachment to Document Control D:sk'

. ECC 1003 RC-99-0192 P. age 4.of 9 LCOBART SPACER GRID SINGLE-PHASE HEAT TRANSFER ERROR Backaround As' discussed in Reference 1, the Yao-Hockreiter-Leach correlation is used in the LOCBART code to compute the single-phase heat transfer enhancement for axial elevations located downstream of spacer grids. The Safety Evaluation Report to Reference 1 requires that e length-averaged value be used to specify the heat transfer coefficient for a given fluid cell, since use of a local value corresponding to the forward edge or the rear edge of the cell could be non-conservative. it was determined that the ,

length-averaging in LOCBART was not being done correctly in all cases. This error correction was determined to be a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.

Estimated Effect The effect of this error on existing results was determined on a plant specific basis and is shown in Table 4.

Reference

1. WCAP-10484-P-A, " Spacer Grid Heat Transfer Effects During Reflood", M. Y. 5 Young, et. al., March 1991.

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Attachment ta Docum:nt Control Desk ECC 1003 RC-99-0192 7 . Eage 5..of 9 LOCBART ZlRC-WATER OXIDATION ERROR Backaround As discussed in Referer.ce 1, a logic error in the LOCBART code caused the Baker-Just metal-water reaction calculations to be performed three times per timestep.

Correcting the error was found to reduce the total cladding oxidation while increasing the heat deposition in the cladding. The error correction was determined to be a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.

Estimated Effect The effect of this error on existing results was determined on a plant specific basis and is shown in Table 4.

Reference

1. NSD-NRC-99-5845," Closure of Westinghouse Interim Report No.98-029", H.

A. Sepp, August 27,1999.

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Att:chment to Document Control Desk ECC 1003

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Rage 6 of 9 i ACCUMULATOR LINE/ PRESSURIZER SURGE LINE DATA

. Backaround An issue.was identified where the accumulator line piping schedule installed at a plant was different than the design value. This discovery led to a review of various geometric data related to the accumulator lines and pressurizer surge lines, and these revised data were compared to the LOCA analysis values to determine the effect on existing analysis results. For cases where erroneous data were identified, this issue was determined to be a Non-Discretionary Change in accordance with Section 4.1.2 of WCAP-13451.

Estimated Effect For Small Break LOCA, the nature of this issue leads to an estimated PCT impact of O'F. For Appendix K Large Break LOCA, the effect of this issue on existing results was determined on a plant specific basis and is shown in Table 4.

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~ Attachment to Document Control Desk ECC 1003 RC-99-0192 Page 7.of 9 TABLE 3 Small Break Peak Clad Temperature Margin Utilization Revision Date: 09/29/99

' Plant Name: Virgil C. Summer E' val. Model: NOTRUMP Fuel: Vantage + -

Utility Name: - South Carolina Electric & Gas FO=2.45 FAH=1.62 SGTP=10% j Reference

• Clad Temperature Notes A. CURRENT ANALYSIS OF RECORD (2/94) 2 PCT = 1823*F 1 B. PRIOR PERMANENT ECCS MODEL 4 APCT= 107*F

' ASSESSMENTS l

C. 10 CFR 50.59 SAFETY EVALUA CONS Table 5-A APCT= 44*F  !

1 D. 199710 CFR 50.46 MODEL ASSESSMENTS (Permanent Assessment of PCT Margin)

1. None APCT= 0*F E. TEMPORARY ECCS MODEL ISSUES . j

1. None APCT= 0*F l

F. OTHER MARGIN ALLOCATIONS

1. Burst and Blockage / Time in Life APCT= 134*F 2 LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT = 2108*F

/

• - References for the Peak Clad Temperature Margin Utilization summary can be found in Table 5-B,

. Notes:

ti AOR performed for core power = 2900 MWt and A75 steam generators.

2. This assessment is a function of base PCT plus permanent margin allocation and as such will increase / decrease with margin allocation changes.

..i r Att:chment to Docum:nt Control D:sk ECC 1003 RC-99-0192 Page 8 of 9 TABLE 4 Large Break Peak Clad Temperature Margin Utilization Revision Date: 09/29/99 Plant Name: Virgil C. Summer Eval. Model: BASH Fuel: Vantage +

Utility Name: South Carolina Electric & Gas FO=2.40 . FAH=1.62 SGTP=10%

Reference

• Clad Temperature Notes A. CURRENT ANALYSIS OF RECORD (10/95) 3 PCT = 2099'F 1 B. PRIOR PERMANENT ECCS MODEL APCT= 0F ASSESSMENTS

1. None C. 10 CFR 50.59 SAFETY EVALUATIONS Table 5 A APCT= 0F 1, 2 D. 199910 CFR 50.46 MODEL ASSESSMENTS I (Permanent Assessment of PCT Margin)

1. St Error (Plant Specific) Reanalysis 5 APCT= -90 F 1, 3

2. Accumulator Line/ Pressurizer Surge Line 5 APCT= +153 F 1, 4 Data, LOCBART Spacer Grid Single Phase Heat Transfer Error, LOCBART Zirc-tVater Oxidation Error, and Reanalysis of Limiting AOR E. TEMPORARY ECCS MODEL ISSUES

1. None APCT= 0*F F. OTHER MARGIN ALLOCATIONS

1. None APCT= 0*F LICENSING BASIS PCT + MARGIN ALLOCATIONS PCT = 2162*F i

References for the Peak Clad Temperature Margin Utilization summaries can be found in Table S-B.

Notes:

1. AOR is for A75 steam generators and core power = 2900 MWt.

2. An Accumulator Pressure and Water Volume Uncertainties evaluation was performed under 10CFR50.59.

The impact on PCT was + 71 F based on a FQ of 2.5 and FdH of 1.62. Its effect has been included in the plant specific reanalysis for 199910CFR50.46 Model Assessments.

3. This plant specific reanalysis -addressed the correction of Safety injoction Performance inputs. These results incorporated the SATAN /LOCTA Fluid Conditions Translation Error (reported previously) and the  !

Accumulator Pressure and Water Volume Uncertainties Evaluation. IFBA fuel is limiting compared to l non-IFBA fuel. '

4. This plant specific reanalysis was based on the SI Error reanalysis. It modeled a reduction in FO from 2.5 to 2.4, a reduction in FdH from 1.7 to 1.62, and a reduction P-bar-HA from 1.514 to 1.443. It also addressed the following issues: Accumulator Line/ Pressurizer Surge Line Data, LOCBART Spacer Grid Single-Phase Heat Transfer Error, and LOCBART Zirc Water Error. IFBA fuel is limiting compared to non-IFBA fuel. I

f Att: chm:nt to Docum:nt Control Desk ECC 1003 RC-99-0192 Page 9 of 9 l

' TABLE 5 TABLE 5A - 10 CFR 50.59 Safety Evaluations Revision Date: 09/29/99 I J

Plant '" 3: Virgil C. Summer Utility Name: South Carolina Electric & Gas 1

Reference Clad Temperature Notes

1. SMALL BREAK ECCS SAFETY EVALUATIONS A. Increased Accumulator Pressure and Water 1 APCT= 34'F 1 B.

Volume Uncertainties Mid-enriched Annular Axial Blankets

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4 APCT= 10'F TOTAL 10 CFR 50.59 SMALL BREAK ASSESSMENTS PCT = 44'F

11. LARGE BREAK ECCS SAFETY EVALUATIONS A. Increased Accumulator Pressure and Water 1 APCT= 0'F 2, 3

- Volume Uncertainties TOTAL 10 CFR 50.59 LARGE BREAK ASSESSMENTS PCT = 0'F Notes:

1. The SBLOCA evaluation for increased accumulator pressure and water volume uncertainties caused the limiting break equivalent diameter to shift from 2-inch to 3-inch. The 34 F value does not include the effect on SBLOCA burst / blockage behavior.

2. The LBLOCA evaluation for increased accumulator pressure and water volume uncertainties causes the limiting power shape to shift from chopped cosine to top-skewed.

3. See Table 4, Note 2.

TABLE SB - References

1. CGE-98-037, " Safety Evaluation for increased Pressure and Level Uncertainties", October 15, 1998.

2. CGE-93-C054-SGUL, "SECL-93-036, Rev.1," March 9,1994.

3. CGE-95-0009-SGUL, " Revised Large Break LOCA Results for Uprating Submittal," October 24,1995.

4. 97CG-G0062, " South Carolina Electric and Gas Company, Virgil C. Surnmer Nuclear Station,

Cycle 11 RSE and Extended Burnup Operation Report," September 1E 1997. j

5. CAB-99-138, Revision 2, "V. C. Summer Cycle 12 Final Cec .>perating Limits Report, j Revision 2", August 31,1999. i l

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