ML040890328

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Cycle 10 End of Life Moderator Temperature Coefficient Limit Report
ML040890328
Person / Time
Site: South Texas STP Nuclear Operating Company icon.png
Issue date: 03/23/2004
From: Leazar D
South Texas
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-04001698
Download: ML040890328 (16)
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{{#Wiki_filter:Nuclear Operating Company South Tws Pro/ed Ekdnc Genamlxi Slat/on PO..Br 289 Idsmivth. This 77483 We March 23, 2004 NOC-AE-04001698 1 OCFR50.90 STI 31715152 File No. G25 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Unit 2 Docket No. STN 50-499 Unit 2 Cycle 10 End of Life Moderator Temperature Coefficient Limit Report

Reference:

Letter, J. J. Sheppard to U.S. Nuclear Regulatory Commission, "End of Life Moderator Temperature Coefficient," dated October 31, 2002 (NOC-AE-02001425) As a condition for approval of the conditional elimination of the most negative end of life moderator temperature coefficient measurement technical specification change as stated in the referenced correspondence, STP committed to submit the following information for the first three uses of this methodology at STP:

1. A summary of the plant data used to confirm that the Benchmark Criteria of Table 3-2 of WCAP-1 3749-P-A, Safety Evaluation Supporting the Conditional Elimination of the Most Negative EOL Moderator Temperature Coefficient Measurement, have been met; and,
2. The Most Negative EOL Moderator Temperature Coefficient Limit Report (as found in Appendix D of WCAP-13749-P-A).

The information is attached. This transmittal is the second of the three submittals. The results of the Unit 1, Cycle 11 surveillance were transmitted on January 13, 2003. If there are any questions regarding this information, please contact Mr. Duane Gore at (361) 972-8909. D.A. Leazar

Manager, Nuclear Fuel and Analysis Attachments:
1. Plant Data Used to Confirm Benchmark Requirements
2. Most Negative End of Life Moderator Temperature Coefficient Limit Report for South Texas Unit 2, Cycle 10

NOC-AE-04001698 Page 2 cc: (paper copy) (electronic copy) Bruce S. Mallett Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Richard A. Ratliff Bureau of Radiation Control Texas Department of Health 1100 West 49th Street Austin, TX 78756-3189 Jeffrey Cruz U. S. Nuclear Regulatory Commission P. 0. Box 289, Mail Code: MN1 16 Wadsworth, TX 77483 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP L. D. Blaylock City Public Service David H. Jaffe U. S. Nuclear Regulatory Commission R. L. Balcom Texas Genco, LP A. Ramirez City of Austin C. A. Johnson AEP Texas Central Company Jon C. Wood Matthews & Branscomb C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704 Plant Data Used to Confirm Benchmark Requirements

Attachment I Page I of 5 Plant Data Used to Confirm Benchmark Requirements are Satisfied This attachment presents a comparison of the South Texas Unit 2 Cycle 10 core characteristics with the requirements for use of the Conditional Exemption of the Most Negative EOL Moderator Temperature Coefficient Measurement Methodology and presents plant data that support that the Benchmark Criteria presented in WCAP-13749-P-A are met. The Conditional Exemption of the Most Negative EOL Moderator Temperature Coefficient Measurement Methodology is described in WCAP-13749-P-A. This report was approved by the NRC with two requirements:

  • only PHOENIX/ANC calculation methods are used for the individual plant analyses relevant to determinations for the EOL MTC plant methodology, and
  • the predictive correction is reexamined if changes in core fuel designs or continued MTC calculation/measurement data show significant effect on the predictive correction.

The PHOENIX/ANC calculation methods were used for the South Texas Unit 2, Cycle 10, core design and relevant analyses. Also, the Unit 2, Cycle 10, core design does not represent a major change in core fuel design. Therefore, the Predictive Correction of-3 pcm/IF remains valid for this cycle. The Unit 2, Cycle 10, core meets both of the above requirements. A description of the data collection and calculations required to complete the Table 3 Worksheet of the Most Negative Moderator Temperature Coefficient Limit Report is presented. Then the following data tables are provided:

  • Table 1 - Benchmark Criteria for Application of the 300 ppm MTC Conditional Exemption Methodology (per WCAP-1 3749-P-A)
  • Table 2 - Flux Map Data: Assembly Powers and Core Tilt Criteria
  • Table 3 - Core Reactivity Balance Data
  • Table 4 - Low Power Physics Test Data (Beginning of Cycle, Hot Zero Power): Isothermal Temperature Coefficient (ITC)
  • Table 5 - Low Power Physics Test Data (Beginning of Cycle, Hot Zero Power): Individual Control Bank Worth

Attachment I Page 2 of 5 Table 1 Benchmark Criteria for Application of the 300 ppm MTC Conditional Exemption Methodology (per WCAP-13749-P-A) Parameter Criteria Assembly Power (Measured Normal Reaction Rate) Measured Incore Quadrant Power Tilt (Low Power) Measured Incore Quadrant Power Tilt (Full Power) Core Reactivity (Cb) Difference BOL HZP ITC Individual Control Bank Worth Total Control Bank Worth +0.1 or 10% + 4 % +/- 1000 pcm + 2 pcm/IF +/- 15 % or+/- I00 pcm +/-10%

Attachment I Page 3 of 5 Table 2 Flux Map Data:Assembly Powers and Core Tilt Criteria Assembly Power Measured Incore Quadrant Power Tilt Benchmark Criteria Flux Map Number Measured to Predicted Error Criteria Satisfied Benchmark Criteria Criteria Power Tilt Requirement Satisfied Requirement % Diff 4.5 210001 Meas - Pred 0.053 % Diff 4.1 210002 Meas - Pred 0.052 % Diff 4.0 210003 Meas - Pred 0.051 % Diff 3.7 210004 Meas - Pred 0.045 % Diff 3.2 210005 Meas - Pred 0.038 % Diff 3.2 210006 Meas - Pred 0.038 % Diff 3.3 210007 Meas - Pred -0.034 % Diff 3.3 210008 Meas - Pred -0.031 % Diff 4.0 210009 Meas - Pred 0.034 % Diff 4.6 210010 Meas - Pred 0.040 % Diff 4.2 210011 Meas - Pred 0.036 % Diff 4.7 210012 Meas - Pred 0.038 % Diff 4.9 210013 Meas - Pred -0.042 % Diff 5.2 210014 Meas - Pred 0.043 % Diff 4.7 210015 Meas-Pred 0.041 % Diff 4.8 210016 Meas-Pred 0.041 Yes Yes Yes Yes Yes Yes % Diff within +/- 10% OR M-P within +/- 0.1 Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Max 1.00648 Min 0.99172 Max 1.00507 Min 0.99358 Max 1.00572 Min 0.99282 Max 1.00565 Min 0.99430 Max 1.00506 Min 0.99504 Max 1.00302 Min 0.99744 Max 1.00108 Min 0.99899 Max 1.00122 Min 0.99873 Max 1.00244 Min 0.99891 Max 1.00394 Min 0.99846 Max 1.00204 Min 0.99885 Max 1.00282 Min 0.99667 Max 1.00762 Min 0.99433 Max 1.00566 Min 0.99714 Max 1.00368 Min 0.99585 Max 1.00571 Min 0.99530 Max 1.00453 Min 0.99780 Maps at < 90% Reactor Power Max Power Tilt S 1.04 And Min Power Tilt 2 0.96 OR Maps at > 90% Reactor Power Max Power Tilt S 1.02 And Min Power Tilt 2 0.98 Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes % Diff 5.5 Yes 210017 Meas - Pred 0.045

Attachment I Page 4 of 5 Table 3 Core Reactivity Balance Data Core Reactivity Difference (Critical boron) Reactivity Benchmark Criteria Surveillance Deviation Date/Time (pcm) Requirement Satisfied 12/12/02 13:51 143.4 Yes 04/09/03 15:00 -0.6 Yes 04/29/03 15:15 -96.1 Yes 05/06/03 15:53 -110.0 Yes 05/28/03 09:00 -113.7 Yes 06/25/03 16:45 -200.3 Yes 07/25/03 11:25 -293.2 Yes 08/20/03 15:33 -325.9 Reactivity Yes 09/17/03 15:32 -329.1 Deviation within Yes 10/08/03 16:22 -348.1 Yes 11/05/03 16:00 -344.5 Yes 12/09/03 07:56 -323.8 Yes 12/30/03 14:33 -169.6 Yes 01/29/04 11:25 -122.1 Yes 02/18/04 13:55 -103.9 Yes 03/17/04 14:55 -46.3 Yes

Attachment I Page 5 of 5 Table 4 Low Power Physics Test Data (Beginning of Cycle, Hot Zero Power): Isothermal Tcmperature Coefficient (ITC) Error BnhakCiei Measured Predicted (Measured - Predicted) Benchmark Criteria (pcm/°F)* (pcm/°F)* (pcm/pF)* Requirement Satisfied BOC HZP ITC -2.43 -3.12 0.69 ITC Error Yes within +/-2 pcm/0F

  • Note: I pcm = I x 10-5 AK/K Table 5 Low Power Physics Test Data (Beginning of Cycle, Hot Zero Power):

Individual Control Bank Worth Benchmark Criteria Measured Predicted A Error Bank (pcm)* (pcm)* (pcm)* % Error Requirement Satisfied Shutdown Bank A 241.2 243.9 -2.7 -1.1% Yes Shutdown Bank B 690.0 715.7 -25.7 -3.6% % Error Yes Shutdown Bank C 381.7 377.3 4.4 1.2% within +/-15% Yes Shutdown Bank D 378.1 371.2 6.9 1.9% Yes Shutdown Bank E 479.7 472.2 7.5 1.6% OR Yes Control Bank A 903.9 890.5 13.4 1.5% Yes Control Bank B 599.8 586.2 13.6 2.3% A Error Yes Control Bank C 797.7 792.2 5.5 0.7% within +/-100 pcm Yes Control Bank D 494.1 479.3 14.8 3.1% o _Yes Total Control 4966.2 4928.5 37.7 0.8% within E10% Yes

  • Note: I pcm= I x O 5AK/K

Most Negative End of Life Moderator Temperature Coefficient Limit Report for South Texas Unit 2, Cycle 10

Page I of 7 Most Negative End of Life Moderator Temperature Coefficient Limit Report for South Texas Unit 2, Cycle 10 (Measured 300 ppm Burnup, as per WCAP-13749-P-A, Appendix D) PURPOSE: The purpose of this document is to present cycle-specific best estimate data for use in confirming the most negative end of life moderator temperature coefficient (MTC) limit in Technical Specification 3.1.1.3. This document also summarizes the methodology used for determining if a HFP 300 ppm MTC measurement is required. PRECAUTIONS AND LIMITATIONS: The EOL MTC elimination data presented in this document apply to South Texas Unit 2 Cycle 10 only and may not be used for other operating cycles. The following reference is applicable to this document: Fetterman, R. J., Slagle, W. H., Safety Evaluation Supporting the Conditional Exemption ofthe Most Negative EOL Moderator Temperature Coefficient Measurement, WCAP-1 3749-P-A, March, 1997. PROCEDURE: All core performance benchmark criteria listed in Table I must be met for the current operating cycle. These criteria are confirmed from startup physics test results and routine HFP boron concentration and flux map surveillance performed during the cycle. If all core performance benchmark criteria are met, then the Revised Predicted MTC may be calculated per the algorithm given in Table 2. The required cycle specific data are provided in Table 2 and Figure 1. This methodology is also described in Reference 1. If all core performance benchmark criteria are met, and the Revised Predicted MTC is less negative than COLR Limit 2.4.3, then a measurement is not required. Note that Figure 1 is not entirely linear. However, the deviation is slight enough that linear interpolation between adjacent points from the data at the bottom of the Figure is acceptable. Page 2 of 7 Table 1 Benchmark Criteria for Application of the 300 ppm MTC Conditional Exemption Methodology Parameter Criteria Assembly Power (Measured Normal Reaction Rate) Measured Incore Quadrant Power Tilt (Low Power) Measured Incore Quadrant Power Tilt (Full Power) Core Reactivity (Cb) Difference BOL HZP ITC Individual Control Bank Worth Total Control Bank Worth O0.1 or 10% +/-4% +2 % +/- 1000 pcm +/- 2 pcm/ 0F +/-15%or+/- I00pcm +/-10% Page 3 of 7 Table 2 Algorithm for Determining the Revised Predicted Near-EOL 300 ppm MTC The Revised Predicted MTC = Predicted MTC + AFD Correction-3 pcm/IF where: Predicted MTC is calculated from Figure 1 at the bumup corresponding to the measurement of 300 ppm at RTP conditions, AFD Correction is the more negative value of: { 0 pcm/IF, ( AAFD

  • AFD Sensitivity) }

AAFD is the measured AFD minus the predicted AFD from an incore flux map taken at or near the burnup corresponding to 300 ppm. AFD Sensitivity = 0.05 pcm / 'F / AAFD Predictive Correction is -3 pcm/IF, as included in the equation for the Revised Predicted MTC. Page 4 of 7 Table 3 Worksheet for Calculating the Predicted Near-EOL 300 pplm MTC Unit: 2, Cycle 10 Date: 03/18/2004 Time: 0027 Reference for Cycle-Specific MTC Data: A41010-00533UB Rev.C, The Nuclear Design and Core Management of the South Texas Unit 2 Nuclear Power Plant Cycle 10. Part A. Predicted MTC A.1 Cycle Average Burnup Corresponding to the HFP ARO equilibrium xenon CB of 300 ppm. 14251.0 MWD/MTU A.2 Predicted HFP ARO MTC corresponding to burnup (A.1) -35.5 pcm/nF Part B. AFD Correction B.1 Burnup of most recent HFP, equilibrium conditions incore flux map 14226.8 MWD/MTU B.2 Measured HFP AFD at bumup (B.1) Reference incore flux map: ID: 210017 Date: 03/17/04 -1.59 % AFD B.3 Predicted HFP AFD at burnup (B.1) -2.62 % AFD B.4 MTC Sensitivity to AFD 0.05 pcm/IF/AAFD B.5 AFD Correction, more negative of { 0 pcmi/F, B.4 *(B.2 - B.3)} 0 pcm/IF Part C. Revised Prediction C-1 Revised Prediction (A.2 + B.5 - 3) -38.5 pcm/IF C.2 Surveillance Limit (COLR 2.3.3) -53.6 pcm/IF If C.1 is less negative than C.2, then the HFP 300 ppm MTC measurement is not required per Specification 4.1.1.3. Page 5 of 7 Figure 1 Predicted HFP FOP 300 ppm MTC vs. Cycle 10 Burnup -33.5 34 2 CL E- .- 35 ) -34.5 b-35 -35 E-0

¢

-356 wp E* I I I I I I I I I I I II I I I I I ' F I I I - 111111 I]t 'K IV 1TrI -*-- I ii t >SL=1 +/- -36.5 11000 12000 13000 14000 15000 16000 CYCLE BURNUP (MWD/MTU) Cycle Burnup (MWD/MTU) 11000 12000 14000 16000 Moderator Temperature Coefficients (pcm/ 0F) -33.95 -34.44 -35.39 -36.30 Page 6 of 7 Table 4 Data Collection and Calculations Required to Complete the Table 3 Worksheet of the Most Negative Moderator Temperature Coefficient Limit Report Data at the 300 ppm Boron Point . RCS Boron at 300 ppm at 00:27 on 03/18/04. . Burnup at 300 ppm: 14251.0 MWD/MTU (A.1)

  • Predicted MTC: -35.5 pcm/IF (A.2)

Data from Last Flux Map:

  • Flux Map Number: 210017 (B.2)
  • Reactor Power 100% RTP Note: The monthlyfluxc map was performed at about the same time the unit reached the 300 ppm concentration value. Data from thisflux map was usedfor the AFD Correction.
  • Burnup 14226.8 MWD/MTU (B.1)
  • Measured Axial Offset (MAO): -1.59% (13.2)

Note: The Westinghouse BEA CON computer code (similar to the Westinghouse INCORE code) determines Axial Offset (AO), not Axial FILx Difference (AFD). Therefore, the AO must be conierted to AFD before use. The relationship betiween AO andAFD is AFD = Axial Offset

  • Fractional Power
  • Axial Flux Difference Lower Predicted AO (LPAO):

-2.58% at 14000 MWD/MTU Higher Predicted AO (HPAO): -2.89% at 16000 MWD/MTU Predicted AO (PAO) = PA0=- B @lfavsuedAO @BlURoowerPrediciedAO x (HPAO-LPA O )+ LPAO B/U@ /IigherPredictedA0 -BIUs LowerPredictedAO PAO = (14251.0 - 14000)/(16000 - 14000) * (-2.89% + 2.58%) - 2.58% = -2.62% (B.3) A AFD = (MAO-PAO)

  • 100%

(-1.59% + 2.62%)

  • 100%

1.03% Page 7 of 7 Table 4 (cont.) Data Collection and Calculations Required to Complete the Table 3 Worksheet of the Most Negative Moderator Temperature Coefficient Limit Report Determination of the Revised Predicted Moderator Temperature Coefficient (MTC) AFD Sensitivity: 0.05 pcm/IF/ AAFD AFD Correction: 0 pcm/IF (B.5) where: AFD Correction is the more negative of the following: 0 pcm/IF or (AAFD

  • AFD Sensitivity) 0 pcm/IF or (1.03%
  • 0.05 pcm/IF/ AAFD) 0 pcm/0F or 0.052 pcm/IF

.-. 0 pcm/IF Revised Predicted MTC = Predicted MTC + AFD Correction - 3 pcm/nF = -35.5 pcm/IF + 0.0 pcm/IF -3 pcmi/F = -38.5 pcm/IF (C.1)}}

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