NL-04-1981, Response to NRC Questions Regarding Request to Revise Technical Specifications and Pressure and Temperature Limits Report
| ML043000339 | |
| Person / Time | |
|---|---|
| Site: | Vogtle  |
| Issue date: | 10/22/2004 |
| From: | Gasser J Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-04-1981 | |
| Download: ML043000339 (10) | |
Text
Jeffrey T.Gasser Southern Nuclear Executive Vice President Operating Company, Inc.
and Chief Nuclear Officer 40 Inverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 Tel 205.992.7721 Fax 205.992.6165 SOUTHERN A October 22, 2004 COMPANY Energy to Serve Your World Docket Nos.: 50-424 NL-04-1981 50-425 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Vogtle Electric Generating Plant Response to NRC Questions Regarding Request to Revise Technical Specifications and Pressure and Temperature Limits Report Ladies and Gentlemen:
On February 26, 2004, Southern Nuclear Operating Company (SNC) submitted a proposed change to revise the Vogtle Electric Generating Plant (VEGP) Unit I and Unit 2 Technical Specifications (TS) related to the Pressure and Temperature Limits Report (PTLR). In conjunction with this change, SNC submitted revised PTLRs for Unit I and Unit 2 for review and approval by the NRC. In addition, SNC submitted TS Bases changes associated with the proposed changes to the TS for information.
On March 31 and April 12,2004, SNC received facsimiles from the NRC regarding the VEGP February 26, 2004, submittal. These facsimiles contained 3 questions and I question, respectively. On July 8, 2004, SNC submitted a response to these NRC questions.
On August 23, 2004, SNC received another facsimile from the NRC containing 3 additional questions regarding the VEGP February 26, 2004 submittal. The SNC responses to these NRC questions are enclosed.
As stated in the initial SNC submittal of February 26, 2004, SNC requests approval of the proposed license amendment by February 15, 2005, so that the revised limits can be implemented for the start-up of Unit I following the refueling outage, currently scheduled for March 2005. The proposed changes will be implemented within 90 days of issuance of the amendment.
4y6O\
U. S. Nuclear Regulatory Commission NL-04-1981 Page 2 Mr. J. T. Gasser states he is an Executive Vice President of Southern Nuclear Operating Company, is authorized to execute this oath on behalf of Southern Nuclear Operating Company and to the best of his knowledge and belief, the facts set forth in this letter are true.
This letter contains no NRC commitments. If you have any questions, please advise.
Respectfully submitted, SOUTHERN NUCLEAR OPERATING COMPANY JetreYT. Gasser Slrn to andsubscribe(lbefore mne dris 9 Iay o 2004.
Mv conmission expires: ___4_-___
JTG/DRG/daj
Enclosure:
SNC Response to NRC Questions Regarding Vogtle Electric Generating Plant Units 1 and 2 Technical Specification Revision and PTLR Submittal cc: Southern Nuclear Operating Company Mr. D. E. Grissette, Vice President - Plant Vogtle Mr. W. F. Kitchens, General Manager - Plant Vogtle RType: CVC7000 U. S. Nuclear Regulatorv Commission Dr. W. D. Travers, Regional Administrator Mr. C. Gratton, NRR Project Manager - Vogtle Mr. G. J. McCoy, Senior Resident Inspector- Vogtle State of Georgia Mr. L. C. Barrett, Commissioner- Department of Natural Resources
Enclosure SNC Response to NRC Questions Rcgarding V7ogtlc Electric Generating Plant Units I and 2 Technical Specification Revision and PTLR Submittal
SNC Responsc to NRC Questions Regarding Vogtle Electric Generating Plant Units 1 and 2 Technical Specification Revision and PTLR Submittal Pressure-Temperature (P-T) limits (TAC Nos. MC2225 and MIC2226) 1.1 NRC Onestion Figure 5-1 (for 26 EFPY) of WCAP-15068, Revision 3, "Vogtle Electric Generating Plant Unit 1 Ileatup and Cooldown Limit Curves for Normal Operation," shows that the heatup curve for 1000 F/hr maintains a constant pressure of 748 psig from 60°F to 90°F; instead of a smooth, pressure varying P-T limit curve derived directly from the American Society of Mechanical Engineers (ASMIE) Code,Section XI, Appendix G methodology as described in Section 3 of this NN'CAP. Provide the basis and detailed calculations for this part of the P-T limit curve. A similar concern applies to Figure 5-3 (for 36 EFPY) of W'CAP-15068, Revision 3 and Figure 5-1 (for 26 EFPY) and Figure 5-3 (for 36 EFPi) of WCAP-15161, Revision 3, "Vogtle Electric Generating Plant Unit 2 Ileatup and Cooldown Limit Curves for Normal Operation." No justification is required for these P-T limit curves if it is the same as that for Figure 5-1 of WCAP-15068, Revision 3. However, if this concern results in a revision of the proposed P-T limits, all four figures mentioned above should be revised.
SNC Response Table I below showvs the actual pressure data for the l/4T, 3/4T and Steady State PT Curves generated by Westinghouse for the Vogtle Unit 1 26 EFPY PT curves (I 00 0 F/hr and Steady State). Figure I is a graphical representation of that data.
The Westinghouse computer program compares the pressure from each column and takes the minimum data point at each given temperature. Additionally, if the curve drops to a minimum pressure point after Temp = 601F, then the preceding pressures are also set to that minimum pressure point. As can be seen below, the minimum pressure from 60'F to 95°F is 748 psig. Therefore the curve is conservatively set to this minimum pressure point from Temp = 60°F to 95°F. This occurs similarly for all of the Vogtle Unit I and Unit 2 PT Curves.
Enclosure Page I of 7
SNC Response to NRC Questions Regarding Vogtle Electric Generating Plant Units I and 2 Technical Specification Revision and PTLR Submittal Table 1: Raw Data Comparison for Vogtle Unit 1: 26 EFPY 100'F/hr 100 0 F/hr Temp. 1/4T Press. 3/4T Press. SS Press.
(oF) (psig) (psig) (psig) 60 765 813 759 65 799 795 775 70 832 779 792 75 864 766 812 80 895 756 833 85 926 750 857 90 957 748 883 95 987 748 912 100 1019 752 944 105 1051 759 979 110 1084 769 1018 115 1119 782 1062 120 1156 799 1109 125 1195 818 1162 130 1237 842 1221 135 1282 868 1285 140 1331 899 1356 145 1384 934 1435 150 1441 974 1522 155 1504 1018 1618 160 1572 1068 1725 165 1647 1124 1842 170 1730 1186 1972 175 1820 1254 2116 180 1919 1331 2274 185 2028 1415 2449 Bolded values are the minimum calculated between the 3 curves at each temperature Enclosure Page 2 of 7
SNC Response to NRC Questions Regarding Vogtle Electric Generating Plant Units I and 2 Technical Specification Revision and PTLR Submittal HU Curve Comparison 3000 2500 -
2000 -
1500 ;- 3/4TCurve 1000 -
500 0.
0.000 50.000 100.000 150.000 200.000 Temperature Figure 1: Graphical Representation of the Data Comparison from Table I Enclosure Page 3 of 7
SNIC Response to NRC Questions Regarding Vogtle Electric Generating Plant Units I and 2 Technical Specification Revision and PTLR Submittal 1.2 NRC Ouestion There are moderate discrepancies between your P-T limits and those calculated by the staff using the formulas (not the alternative Ke, formula) in Section 3 of this WCAP. For the 1000 F/hr cooldown curve, please provide RPN' bulk water temperature, 1/4T metal temperature, KIm, and Kit for P-T pairs (582 psi, 650 F) and (948 psi, 110°F); for the 1000 F/hir heatup curve, provide reactor pressure vessel (RPZ) bulk water temperature, 3/4T metal temperature, Klm, and Kit for P-T pairs (733 psi, 100°F) and (2344 psi, 225 01).
Further, provide the thermal diffusivity that you used in ylour thermal calculations.
SNC Response The parameters requested above (RPV bulk water temperature, I/4T metal temperature, 3/4T metal temperature and the corresponding Kit values) that are contained in WCAP-15068 Rev. 3 are identified below and indicated as such. The parameters requested above, including the thermal stresses that are not contained in WCAP-15068, Rev. 3 are also provided below.
36 EFPY Heatup (I 000 F/hr) at an RPV bulk water temperature of I00 0 F:
- 1/4T metal temperature = 83.970 F (WN'CAP-15068, Rev. 3 Table A3)
- I/4T KIT = -9.1227 KSI Sq. Rt. In (WNICAP-15068, Rev. 3 Table A3)
- Thermal Stress = -1825.45 psi
- 1/4T Kip = 27.3182 KSI Sq. Rt. In
- 3/4T metal temperature = 68.280 F (WN'CAP-15068, Rev. 3 Table A3)
- 3/4T Kir = 6.7187 KSI Sq. Rt. In (WN'CAP-15068, Rev. 3 Table A3)
- Thermal Stress = 2248.60 psi
- 3/4T Kip = 19.3129 KSI Sq Rt. In 36 EFPY I leatup (1000 F/hr) at an RPV bulk water temperature of 2250 F:
- I/4T metal temperature = 200.737F
- 1/4T KIT = -15.09 KSI Sq. Rt. In
- Thermal Stress = -3147.89 psi
- I/4T Kl,, = 87.7759 KSI Sq. Rt. In
- 3/4T metal temperature = 174.540 F
- 3/4T K1 1 = 11.41 KSI Sq. Rt. In
- Thermal Stress = 3786.72 psi
- 3/4T Kip = 61.7711 KSI Sq. Rt. In Enclosure Page 4 of 7
SNC Response to NRC Questions Regarding Vogtlc Electric Generating Plant Units 1 and 2 Technical Specification Revision and PTLR Submittal 36 EFPY Cooldown (1 00°F/hr) at an RPV bulk water temperature of 650 F:
- 1/4T metal temperature = 89.52 0 F (WCAP-15068, Rev. 3 Table A4)
- 1/4T Krr = 15.1398 KSI Sq. Rt. In (WCAP-15068, Rev. 3 Table A4)
- Thermal Stress = 3250.63 psi
- 1/4T Kip = 15.9099 KSI Sq. Rt. In 36 EFPY Cooldown (l00 0 F/hr) at an RPV bulk, water temperature of I IOF:
- 1/4T metal temperature = 135.30'F (WCAP-15068, Rev. 3 Table A4)
- 1/4T Krr = 15.7553 KSI Sq. Rt. In (WCAP-15068, Rev. 3 Table A4)
- Thermal Stress = 3383.14 psi
- 1/4T Kip = 25.9151 KSI Sq. Rt. In The thermal stress and stress intensity calculation is performed internally by the computer program, and is not an external input.
As discussed in the first paragraph after Equation 6 on page 3-3 of WCAP-15068, Rev. 3, the OPERLIM computer code uses the alternative methods for calculating Krr, i.e., Equations 4 and 5 on pages 3-2 and 3-3 of WCAP-15068, Rev. 3.
The Westinghouse computer program manual does not have an input term called "Thermal Convection," however, it does contains an input term called "Film Coefficient," and that value is 7,000 BTU/hr ft2 'F for all RPV bulk water temperatures. The thermal calculation uses other material properties (e.g., thermal conductivity, etc.) at the initial temperature and final temperature. The computer program then interpolates between the initial and final temperature values and does not provide values at any temperatures as an output. Therefore, the requested values cannot be obtained or provided at the specified temperatures. This is why the Krr and thermal stress values, along with the specific wall temperatures are provided.
Enclosure Page 5 of 7
SNC Response to NRC Questions Regarding Vogtle Electric Generating Plant Units I and 2 Technical Specification Revision and PTLR Submittal Exemption to eliminate the RPV closure head and vessel flange requirements (TAC Nos. NMC2227 and MC2228) 2.1 NRC Ouestion Confirm that the results plotted in Figure 4-1 and 4-2 of WN'CAP-16142-P, Revision 1, "Reactor Vessel Closure Ilead/Vessel Flange Requirements Evaluation for V'ogtle Units 1 and 2," are based on a heatup rate of 100F/hr and the operating RPV pressure. In addition, the submitted information is not enough for the staff to assess the changing margin diiriiig the heatup or cooldown. Please revise Figures 4-1 and 4-2 by applying the ASMIE Code, Section Xi, Appendix G structural factor of 2 to the applied stress intensity factors due to pressure and boltup loading and the ASMIE Code, Section Xi, Appendix G structural factor of 1 to the applied stress intensity factor due to thermal loading. For both torus to flange region wveld (Cut 3) and (onme to torus region wveld (Cut 2), provide the RPV temperatures at a/t ratios of 0.1 and 0.25 at the following specific moments of time after heatup or cooldown:
82, 207.4, 344.2, 355, 375, and 405 minutes after heatup; 421 minutes after cooldown; and the steady state condition at 406 minutes). The staff needs these crack-tip temperature values to calculate the appropriate Kc values.
SNC Response The results plotted in Figure 4-1 and 4-2 of WCAP- 161 42-P, Revision I, "Reactor Vessel Closure I-lead/Vessel Flange Requirements Evaluation for Vogtle Units I and 2," are based on a heatup rate of 1 00F/hr and the operating RPV pressure.
The key margins in WCAP-16 142-P, Revision I are discussed in Section 4, Flange Integrity. The results for the applied stress intensity factors are given in Figure 4-1 for Cut 3 and in Figure 4-2 for Cut 2, as stated in the fourth paragraph on Page 4-1.
As can be seen in the two figures, the limiting condition for the end of heatup occurs at Cut 2, in Figure 4-2. At 344.2 minutes, near the end of heatup, the value for a flaw at 10 percent of the wall is 49.2 1, as stated on Page 4-1. The Boltup is actually more severe for Cut 3 in Figure 4-1, and gives a value of 24.84, which is also stated on Page 4- 1. This was why the results for both locations were included in WCAP-16142-P, Revision 1.
Enclosure Page 6 of 7
SNC Response to NRC Questions Regarding Vogtle Electric Generating Plant Units I and 2 T'eclmnical Specification Revision and PTLR Submittal The calculations were done for the most limiting material in the flange area, RTNDI
= 20 'F, as shown in Table 3-1. Calculations were done for the two most limiting conditions, the end of heatup, and boltup alone. The margin results shown below are a ratio of the fracture toughness to the applied K.
- Boltup: Klc/K1 = 79.3/24.84 = 3.19, KIA/K = 49.0/24.84 = 1.97
- Ileatup: K(-/K, = 200/49.21 = 4.06, KIA/Kj = 200/49.21 = 4.06 These results are for the most limiting location and the most limiting material properties, for a postulated flaw depth of 10 percent of the flange thickness.
Margins calculated for any other locations would be higher.
Margins are also discussed in Section 5 of WCAP-16142-13, Revision 1. In Section 5, a calculation was performed to determine the boltup temperature needed to maintain a safety factor of 2 on stress, and a postulated flaw size of 10% of the flange wall thickness, using K,(. toughness. The boltup temperature was determined to be 20 'F, and therefore a room (ambient) boltup temperature is easily justified.
Enclosure Page 7 of 7