ML21279A289
| ML21279A289 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 10/04/2021 |
| From: | Henderson J Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 21-325 | |
| Download: ML21279A289 (13) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 October 4, 2021 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 Serial No.:
21-325 SPS-LIC/SCN: RO Docket Nos.:
50-280 50-281 License Nos.: DPR-32 DPR-37 ANNUAL SUBMITTAL OF TECHNICAL SPECIFICATIONS BASES CHANGES PURSUANT TO TECHNICAL SPECIFICATION 6.4.J Pursuant to Technical Specification 6.4.J, "Technical Specifications (TS) Bases Control Program," Dominion Energy Virginia hereby submits changes to the Bases of the Surry Power Station TS implemented between October 1, 2020, and September 30, 2021.
Bases changes to the TS that were not previously submitted to the NRC as part of a License Amendment Request were reviewed and approved by the Facility Safety Review Committee (FSRC).
It was determined that the changes did not require a revision to the TS or operating licenses, nor did the changes involve a revision to the Updated Final Safety Analysis Report (UFSAR) or Bases that required Nuclear Regulatory Commission (NRC) prior approval pursuant to 10 CFR 50.59.
These changes have been incorporated into the TS Bases. A summary of these changes is provided in Attachment 1.
TS Bases changes that were submitted to the NRC for information along with associated License Amendment Request transmittals, submitted pursuant to 1 0CFR50.90, were also reviewed and approved by the FSRC. These changes have been implemented with the respective License Amendments.
A summary of these changes is provided in Attachment 2.
Current TS Bases pages reflecting the changes discussed in Attachments 1 and 2 are provided in Attachment 3.
Serial No.21-325 Docket Nos. 50-280, 50-281 Page 2 of 3 If you have any questions regarding this transmittal, please contact Stephen C.
Newman, Surry Power Station Licensing Group at (757) 365-3397.
Joh ny
,_,,....-u.,..vson Director Station Safety and Licensing Surry Power Station Attachments:
- 1. Summary of TS Bases Changes Not Previously Submitted to the NRC
- 2. Summary of TS Bases Changes Associated with License Amendments
- 3. Current TS Bases Pages Commitments made in this letter: None
cc:
U.S. Nuclear Regulatory Commission Region II Marquis One Tower 245 Peachtree Center Avenue NE Suite 1200 Atlanta, GA 30303-1257 State Health Commissioner Virginia Department of Health James Madison Building - 7th Floor 109 Governor Street Room 730 Richmond, VA 23219 Mr. J. Klos NRG Project Manager-Surry Power Station U. S. Nuclear Regulatory Commission Mail Stop O 9E 3 One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738 Mr. G. E. Miller NRG Senior Project Manager - North Anna Power Station U. S. Nuclear Regulatory Commission Mail Stop O 9E 3 One White Flint North 11555 Rockville Pike Rockville, MD 20852-2738 NRG Senior Resident Inspector Surry Power Station Serial No.21-325 Docket Nos. 50-280, 50-281 Page 3 of 3 Summary of TS Bases Changes Not Previously Submitted to the NRC Surry Power Station Units 1 and 2 Virginia Electric and Power Company (Dominion Energy Virginia)
None.
Serial No.21-325 Docket Nos. 50-280, 50-281 Page 2 of 2 Summary of TS Bases Changes Associated with License Amendments Surry Power Station Units 1 and 2 Virginia Electric and Power Company (Dominion Energy Virginia)
Serial No.21-325 Docket Nos. 50-280, 50-281 Page 2 of 2
- 1. Technical Specifications Amendment (TSA)
Nos.
302/302 (implemented 5/4/2021)
This amendment revised the Surry Power Station Units 1 and 2 TS Figures 3.1-1 and 3.1-2, "Surry Units 1 and 2 Reactor Coolant System Heatup Limitations" and "Surry Units 1 and 2 Reactor Coolant System Cooldown Limitations,"
respectively, to:
- 1) Update the cumulative core bum up applicability limit (Effective Full Power Years; EFPY) from 48 to 68 EFPY, and
- 2) Revise and relocate the limiting material property basis from the TS figures to the TS Basis. The cumulative core burnup applicability limit was also updated for the Low Temperature Overpressure Protection System (L TOPS) Setpoint, and L TOPS Enabling Temperature (T-enable) at Surry Units 1 and 2.
The associated TS Bases changes (pages 3.1-9 through 3.1-12) were part of a License Amendment Request (Ref.: Licensing Basis Design Change Request/
Technical Specification Change Request (LBDCR/ TSCR) 456, approved on 12/8/2020.
Because of related evaluations performed for the Subsequent License Renewal (SLR) application (SLRA), this amendment and bases were implemented concurrently with the approved SLR amendment (TSA 303, 303) on 5/4/2021.
Current TS Bases Pages TS Bases pages 3.1-9 through 3.1-12 Surry Power Station Units 1 and 2 Virginia Electric and Power Company (Dominion Energy Virginia)
TS 3.1-9 12/8/20 Heatup and cooldown limit curves are calculated using a bounding value of the nil-ductility reference temperature, RT NDT* at the end of 68 Effective Full Power Years (EFPY) for Units 1 and 2. The heatup and cooldown limit curves were calculated using the most limiting value of RTNDT (228.4°F) which occurred at the 1/4-T, 0° azimuthal location in the Unit 1 intermediate-to-lower shell circumferential weld. The limiting RT NDT at the 1/4-T location in the core region is greater than the RT NDT of the limiting unirradiated material. This ensures that all components in the Reactor Coolant System will be operated conservatively in accordance with applicable Code requirements.
The reactor vessel materials have been tested to dete1mine their initial RT NDT; the results are presented in UFSAR Section 4.1. Reactor operation and resultant fast neutron (E greater than 1 MEV) irradiation can cause an increase in the RT NDT* Therefore, an adjusted reference temperature, based upon the copper and nickel content of the material and the fluence was calculated in accordance with the recommendations of Regulatory Guide 1.99, Revision 2 "Effects of Residual Elements on Predicted Radiation Damage to Reactor Vessel Materials." The heatup and cooldown limit curves of Figures 3.1-1 and 3.1-2 include predicted adjustments for this shift in RT NDT at the end of 68 EFPY for Units 1 and 2 (as well as adjustments for location of the pressure sensing instrument).
Surveillance capsules will be removed in accordance with the requirements of ASTM E185-82 and 10 CFR 50, Appendix H. The surveillance specimen withdrawal schedule is shown in the UFSAR. The heatup and cooldown curves must be recalculated when the ~RT NDT determined from the surveillance capsule exceeds the calculated
~T NDT for the equivalent capsule radiation exposure, or when the service period exceeds 68 EFPY for Units 1 and 2 prior to a scheduled refueling outage.
Amendment Nos. 302 and 302
TS 3.1-10 12/8/20 Allowable pressure-temperature relationships for various heatup and cooldown rates are calculated using methods derived from Appendix Gin Section III of the ASME Boiler and Pressure Vessel Code as required by Appendix G to 10 CFR Part 50.
The general method for calculating heatup and cooldown limit curves is based upon the principles of the linear elastic fracture mechanics (LEFM) technology. In the calculation procedures a semi-elliptical surface defect with a depth of one-quarter of the wall thickness, T, and a length of one and one half Tis assumed to exist at the inside of the vessel wall as well as at the outside of the vessel wall. The dimensions of this postulated crack, referred to in Appendix G of ASME Section III as the reference flaw, amply exceed the current capabilities of inservice inspection techniques. Therefore, the reactor operation limit curves developed for this reference crack are conservative and provide sufficient safety margins for protection against non-ductile failure. To assure that the radiation embrittlement effects are accounted for in the calculation of the limit curves, the most limiting value of the nil ductility reference temperature, RT NDT, is used and this includes the radiation-induced shift, ~RT NDT, corresponding to the end of the period for which heatup and cooldown curves are generated.
The approach for calculating the allowable limit curves for various heatup and cooldown rates in the 1986 Edition of the ASME Code specifies that the total stress intensity factor, K1, for the combined thermal and pressure stresses at any time during heatup or cooldown cannot be greater than the reference stress intensity factor, KrR, for the metal temperature at that time. KrR is obtained from the reference fracture toughness curve, defined in Appendix G to the ASME Code. The KrR curve is given by the equation:
KIR = 26.78 + 1.223 exp [0.0145(T-RTNDT + 160)]
(1) where KrR is the reference stress intensity factor as a function of the metal temperature T and the metal nil ductility reference temperature RT NDT* Thus, the governing equation for the heatup-cooldown analysis is defined in Appendix G of the ASME Code as follows:
(1) where, KIM is the stress intensity factor caused by membrance (pressure) stress.
Amendment Nos. 302 and 302
Kit is the stress intensity factor caused by the thermal gradients TS 3.1-11 12/8/20 K1R is provided by the code as a function of temperature relative to the RT NDT of the material.
C = 2.0 for level A and B service limits, and C = 1.5 for inservice hydrostatic and leak test operations.
At any time during the heatup or cooldown transient, K1R is determined by the metal temperature at the tip of the postulated flaw, the appropriate value for RT NDT, and the reference fracture toughness curve. The thermal stresses resulting from temperature gradients through the vessel wall are calculated and then the corresponding thermal stress intensity factor, K1t, for the reference flaw is computed. From Equation (2) the pressure stress intensity factors are obtained and, from these, the allowable pressures are calculated.
The heatup limit curve, Figure 3.1-1, is a composite curve which was prepared by determining the most conservative case, with either the inside or outside wall controlling, for any heatup rate up to 60°F per hour. The cooldown limit curves of Figure 3.1-2 are composite curves which were prepared based upon the same type analysis with the exception that the controlling location is always the inside wall where the cooldown thermal gradients tend to produce tensile stresses while producing compressive stresses at the outside wall. The cooldown limit curves are valid for cooldown rates up to 100°F/hr.
The heatup and cooldown curves were prepared based upon the most limiting value of the predicted adjusted reference temperature at the end of 68 EFPY for Units 1 and 2. The adjusted reference temperature was calculated using materials properties data from the B&W Owners Group Master Integrated Reactor Vessel Surveillance Program (MIRVSP) documented in the most recent revision to BA W-1543 and reactor vessel neutron fluence data obtained from plant-specific analyses.
Amendment Nos. 302 and 302
TS 3.1-lla 12/8/20 The technical basis for the data points and the associated RT NDT values used to generate the heatup and cooldown curves is provided in WCAP-14177 (Reference 2) and were determined to be applicable to the 48 EFPY period of extended operation under first license renewal. The associated RT NDT values used to calculate the heatup and cooldown curves provided in WCAP-14177 (Reference 2) are based upon the Surry Unit 1 Intermediate to Lower Shell Circ Weld:
1/4-T, 228.4 °F and 3/4-T, 189.5°F The heatup and cooldown curves for operation through 48 EFPY were based upon the Kir methodology. These heatup and cooldown curves were subsequently evaluated using the Kie methodology for Subsequent License Renewal (SLR) at 68 EFPY in WCAP-18243-NP (Reference 3).
The limiting reactor vessel materials at 68 EFPY were determined to be the Surry Unit 1 Lower Shell Longitudinal Weld L2 at 1/4-T and the Surry Unit 2 Intermediate to Lower Shell Circumferential Weld at 3/4-T. The associated RT NDT values calculated at 68 EFPY are:
1/4-T, 219.4°F and 3/4-T, 179.8°F The data points and the associated RT NDT values used to generate the heatup and cooldown curves in TS Figures 3.1-1 and 3.1-2, respectively, are conservative based upon use of the Kie methodology. Therefore, the heatup and cooldown curves did not require revision as a result of SLR. However, the fluence applicability is updated from 48 EFPY to 68 EFPY.
Amendment Nos. 302 and 302
TS 3.1-12 12/8/20 The reactor boltup temperature is defined in 10 CFR 50, Appendix G as "The highest reference temperature of the material in the closure flange region that is highly stressed by the bolt pre load." The reactor vessel may be bolted up at a temperature greater than the initial RT NDT of the material stressed by the boltup (e.g., the vessel flange). As noted on Figures 3.1-1 and 3.1-2, the limiting boltup temperature is 10°F. An administrative minimum boltup temperature limit greater than 10°F is imposed in station procedures to ensure the Reactor Coolant System temperatures are sufficiently high to prevent damage to the reactor vessel closure head/vessel flange during the removal or installation of reactor vessel head bolts. The limiting boltup temperature and the administrative minimum boltup temperature limit are in effect when the reactor vessel head bolts are under tension.
References (1)
UFSAR, Section 4.1, Design Bases (2)
WCAP-14177, "Surry Units 1 and 2 Heatup and Cooldown Limit Curves for Normal Operation," (October 1994)
(3)
WCAP-18243, Rev. 2, "Surry Units 1 and 2 Heatup and Cooldown Limit Curves for Normal Operation," (July 2018)
Amendment Nos. 302 and 302