ML23025A125
| ML23025A125 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 01/25/2023 |
| From: | James Holloway Virginia Electric & Power Co (VEPCO) |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| 22-387 | |
| Download: ML23025A125 (1) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 January 25, 2023 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNITS 1 AND 2 LICENSE AMENDMENT REQUEST 10 CFR 50.90 Serial No.:
NRA/GDM:
Docket Nos.:
License Nos.:
22-387 RO 50-280 50-281 DPR-32 DPR-37 NRC APPROVAL OF METHODOLOGY CHANGE AND RECLASSIFICATION OF THE TURBINE BUILDING AS A TORNADO RESISTANT STRUCTURE RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION By letter dated April 14, 2022, [Agencywide Documents Access and Management System (ADAMS) Accession No. ML22104A125], as supplemented by letters dated May 11, 2022 and December 1, 2022 (ADAMS Accession Nos. ML22131A326 and ML22339A137, respectively), Virginia Electric and Power Company (Dominion Energy Virginia) submitted a license amendment request (LAR) for Surry Power Station (SPS) Units 1 and 2 requesting NRC approval of a methodology change and reclassification of the Turbine Building as a tornado resistant structure in the SPS Updated Final Safety Analysis Report (UFSAR). The reclassification is based on using a different methodology and acceptance criteria than those defined for other SPS tornado resistant (i.e., Tornado Criterion "T")
structures. The new methodology and acceptance criteria are considered a change to a method of evaluation and therefore requires prior NRC approval pursuant to 10 CFR 50.59(c)(2)(viii).
A clarification call was held on December 14, 2022, between the NRC technical review staff and Dominion Energy Virginia to discuss an NRC request for additional information (RAI).
At the conclusion of the call, Dominion Energy Virginia agreed to provide a docketed response to the RAI by January 27, 2023. The Dominion Energy Virginia response to the NRC RAI is provided in the attachment.
Serial No.22-387 Docket Nos. 50-280/281 LAR RAI Response Page 2 of 3 If you have any questions or require additional information, please contact Mr. Gary D. Miller at (804) 273-2771.
Respectfully, James E. Holloway Vice President - Nuclear Engineering and Fleet Support Commitments made in this letter: None
Attachment:
Response to NRC Request for Additional Information COMMONWEAL TH OF VIRGINIA
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COUNTY OF HENRICO
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The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by Mr. James E. Holloway, who is Vice President - Nuclear Engineering and Fleet Support, of Virginia Electric and Power Company. He has affirmed before me that he is duly authorized to execute and file the foregoing document in behalf of that company, and that the statements in the document are true to the best of his knowledge and belief.
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Ack now I edged before me this 2.S day of Ja...,,.. 6 My Commission Expires: Q"jus:t:: ~, ZoZ3
, 2023.
cc:
U.S. Nuclear Regulatory Commission - Region II Marquis One Tower 245 Peachtree Center Ave., NE Suite 1200 Atlanta, GA 30303-1257 Mr. L. John Klos NRC Project Manager - Surry U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, MD 20852-2738 Mr. G. Edward Miller NRC Senior Project Manager - North Anna U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, MD 20852-2738 NRC Senior Resident Inspector Surry Power Station State Health Commissioner Virginia Department of Health James Madison Building - 7th floor 1 09 Governor Street Suite 730 Richmond, VA 23219 Serial No.22-387 Docket Nos. 50-280/281 LAR RAI Response Page 3 of 3
Attachment Serial No.22-387 Docket Nos. 50-280/281 RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION LICENSE AMENDMENT REQUEST FOR NRC APPROVAL OF METHODOLOGY CHANGE AND RECLASSIFICATION OF THE TURBINE BUILDING AS A TORNADO RESISTANT STRUCTURE Virginia Electric and Power Company (Dominion Energy Virginia)
Surry Power Station Units 1 and 2
Serial No.22-387 Docket Nos. 50-280/281 Attachment RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION License Amendment Request for NRC Approval of Methodology Change and Reclassification of the Turbine Building as a Tornado Resistant Structure Surry Power Station Units 1 and 2 NRG COMMENT:
By letter dated April 14, 2022 (Agencywide Documents Access and Management System Accession No. ML22104A125), as supplemented by letters dated May 11, 2022 and December 1, 2022 (ML22131A326 and ML22339A137, respectively), Virginia Electric and Power Company, the licensee (Dominion Energy Virginia), submitted a License Amendment Request (LAR) to reclassify the Units 1 and 2 Turbine Buildings as tornado resistant structures. A clarification call was held on December 14, 2022 and the resultant request for additional information (RAJ) is released below.
To complete its review, the NRG staff RAJ is shown below. This request is now released formally with a 43-day calendar response period; thereby, these RA/s are due on Friday January 27, 2023.
Regulatory Basis:
The NRG issued construction permits for Surry, Units 1 and 2, before May 21, 1971.
Consequently, Surry, Units 1 and 2, were not subject to the requirements in Title 10 of the Code of Federal Regulations (10 CFR) Part 50, "Domestic Licensing of Production and Utilization Facilities," Appendix A, "General Design Criteria [GOG] for Nuclear Power Plants," (see SECY-92-223, "Resolution of Deviations Identified during the Systematic Evaluation Program," (ML003763736) dated September 18, 1992.) The conclusion was that Surry, Units 1 and 2, met the intent of the General Design Criteria (GDC) published in 1967 (draft GDCs). Specifically, the proposed LAR notes that the Turbine Building meets the intent of GOG 2 and GDC 4.
10 CFR Part 50, Appendix A, GDC 2, in part, requires that the design of structures, systems and components important to safety, reflects the appropriate combinations of the effects of normal and accident conditions with the effects of natural phenomena (e.g.,
earthquakes, tornadoes, hurricanes, floods, tsunami, and seiches) commensurate with their safety functions.
Page 1 of 4
Serial No.22-387 Docket Nos. 50-280/281 Attachment 10 CFR Part 50, Appendix A, GDC 4, in part, requires that the design of structures, systems and components important to safety, reflects the protection against dynamic effects, including the effects of missiles, pipe whipping, and discharging fluids, commensurate with their safety functions.
Background:
LAR Section 3.3.2.3 "Concrete Evaluation" only discussed structural analysis results for the equivalent membrane plus bending stress and shear stress in concrete elements. The staff also needs to review the stresses in the reinforcing steel to confirm the structures can withstand the loads due to natural phenomena (e.g., tornado loading). It appears that the proposed LAR does not provide information of the evaluation of the stresses in the reinforcing steel in the concrete.
NRG Request:
- 1. Provide the evaluation of reinforcing steel in the concrete, including the ratio of maximum compressive or tensile strength over the compressive or tensile capacity of the reinforcing steel.
Dominion Energy Virginia Response:
Reinforcing steel stresses were reviewed in the concrete slabs of the operating and mezzanine decks of the Surry Power Station (SPS) Turbine Building Steel Superstructure (TBSS). The ANSYS computer model of the SPS TBSS was adjusted to reflect the more realistic condition of cracked concrete by reducing flexural stiffness by 75%, based on ACI 318. In addition, the dynamic impact loading was reduced since the overhead cranes and their supporting steel crane runway structure will not fall until tornado wind speeds on the Turbine Building exceed 250-mph, as discussed in Dominion Energy Virginia's letter dated December 1, 2022 (ADAMS Accession No. ML22339A137).
Concrete stresses in the operating deck slab were noted to be limiting when compared to those in the mezzanine deck slab.
Rebar stresses were determined from the slab moments as calculated in the adjusted ANSYS computer model.
Several limiting locations of high stress were noted near geometric discontinuities where local stresses are expected to be higher than the average stress across the slab section. At these locations, the bending moments were averaged through an effective slab width to obtain an average moment from which tensile reinforcing steel stresses, fs, were calculated. All tensile and compressive reinforcing Page 2 of 4
Serial No.22-387 Docket Nos. 50-280/281 Attachment steel stresses in the operating deck reinforced concrete slab were shown to be less than the reinforcing steel stress limit of 0.9 times its specified yield strength (fy), as allowed by the ultimate strength design method in ACI 318-71.
Four (4) areas of relatively high reinforcing steel tensile stress were identified in the operating deck concrete slab, as shown in the encircled points of interest, P1 (+), P2(-),
P3(+), and P4(+), of Figures 1 and 2 below. The (+) or (-) signs next to the encircled points indicate positive (i.e., tension bottom steel) or negative (i.e., tension top steel) bending moments. The maximum stress ratio for tensile reinforcing steel occurred at P1 (+) and was calculated as follows, (fs = 21.4 ksi / fy = 40 ksi) = 0.54 < 0.9, which meets the requirements of ACI 318-71. Similarly, stress ratios for P2(-), P3(+), and P4(+), as shown in Figures 1 and 2, were calculated as 0.40, 0.46, and 0.22, respectively.
V Figure 1.
Normalized Bending Moment - South Wind Case X-axis Bending (Top) Y-axis Bending (Bottom)
Page 3 of 4
V Figure 2.
Serial No.22-387 Docket Nos. 50-280/281 Attachment Normalized Bending Moment - North Wind Case X-axis Bending (Top) Y-axis Bending (Bottom)
The analysis of the SPS TBSS did not credit any contribution from the 40 ksi yield compression reinforcing steel that exists in the concrete slabs for calculation of the moment capacity of the slabs. Therefore, by inspection, the maximum stress ratios for compressive reinforcing steel would be less than that in the tension reinforcing steel in all areas of the governing SPS TBSS operating deck slab. Based on the ~bove tensile reinforcing steel stress interaction ratio summary, all reinforcing steel stresses, compressive and tensile, are within the allowable limits of ACI 318-71.
Page 4 of 4