ML23192A215
| ML23192A215 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 06/27/2023 |
| From: | James Holloway Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 23-045 | |
| Download: ML23192A215 (1) | |
Text
VIRGINIA ELEcTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 June 27, 2023 U. S. Nuclear Regulatory Commission Attention: Document Control De-Sk Washington, DC 20555-0001 VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 10 CFR 50.54(q) 10 CFR 50.90 Serial No.:
23-045 NRA/GDM:
RO Docket Nos.:
50-338/339 License Nos.: NPF-4/7 PROPOSED EMERGENCY PLAN REVISION - RELOCATION OF THE TECHNICAL SUPPORT CENTER (TSC)
SUPPLEMENTAL INFORMATION - LOCA DOSE CALCULATION
SUMMARY
REPORT AND ELIMINATION OF CO2 FIRE SUPPRESSION SYSTEM By letter dated January 13, 2023, (ADAMS Accession No. ML23013A195), Virginia Electric and Power Company (Dominion Energy Virginia) submitted a license amendment
. request (LAR) to revise the North Anna Power Station (NAPS) Units 1 and 2 Emergency Plan. The proposed change would relocate the Technical Support Center (TSC) from its current location adjacent to the Main Control Room (MCR) to the building located outside the Protected Area (PA) previously used as the site Local Emergency Operations Facility (LEOF).
LOCA Dose Calculation Summary Report In support of the LAR, a dose calculation was completed to confirm the projected dose to personnel in the proposed TSC from a design basis Loss of Coolant Accident (LOCA) with a release to the environment would be less than the dose limit of five (5) rem Total Effective Dose Equivalent (TEDE). Subsequent to the LAR submittal, the NRC requested supplemental information summarizing the inputs to the LOCA dose calculation to facilitate its review. In response to the NRC request, a NAPS TSC LOCA Dose Summary Report has been prepared and is provided in Attachment 1 for the NRC's information and review. The dose analysis and X/Q input and output files supporting the LOCA dose calculation are included in the enclosed CD-ROM, and Attachment 2 provides a list and descriptions of the various files included on the CD-ROM. Attachment 3 includes a figure showing the site arrangement including the relocated TSC location. This figure provides the site geometry related to calculation of the X/Q dispersion factor for the relocated TSC.
Elimination of CO2 Fire Suppression System It was also stated in the LAR that a carbon dioxide (CO2) fire suppression system would be installed for the high efficiency gas absorption (HEGA) filter installed in the relocated XI_/ 5
/\
. A-* DD (p
/VI~
Serial No.: 23-045 Docket Nos.: 50-338/339 Page 2 of 3 TSC's ventilation system. Following the submittal of the LAR, it was determined the CO2 fire suppression system is not required due to the availability of other fire protection measures and equipment being installed.
Consequently, the CO2 fire suppression system has been removed from the relocated TSC design modification. The technical basis for this decision is provided in Attachment 4. The marked-up LAR page indicating the proposed revision and the LAR replacement page incorporating the revision are provided in Attachments 5 and 6, respectively.
Should you have any questions or require additional information, please contact Mr. Gary D. Miller at (804) 273-2771.
Respectfully, Cr-James E. Holloway Vice President - Nuclear Engineering and Fleet Support Commitments contained in this letter: None.
Attachments:
- 1. Relocated Technical Support Center LOCA Dose Summary Report 1-A. Updated North Anna Core Inventory
- 2. Lists and Descriptions of Files Included on the Enclosed CD-ROM Supporting the Relocated TSC LOCA Dose Calculation
- 3. North Anna X/Q Geometry for the Relocated TSC
Enclosure:
CD-ROM - LOCA Dose Analysis and X/Q Input and Output Files COMMONWEAL TH OF VIRGINIA
)
)
COUNTY OF HENRICO
)
The foregoing document was acknowledged before me, in and for the County and Commonwealth aforesaid, today by 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.
Acknowledged before me this 27~ day of ~he.
, 2023.
My Commission Expires: Ouj\.,,l.b.\-- ~ l, "Z.o:2.,3
- GARY DON MILLER Notary Public Commonvvealth of Virginia As9. # 7629412 j
My Comm1ss1on Expiras August 31, 2cg_
Serial No.: 23-045 Docket Nos.: 50-338/339 Page 3 of 3 cc:
U. S. Nuclear Regulatory Commission - Region II (w/o Enclosure)
Attn: Regional Administrator Marquis One Tower 245 Peachtree Center Avenue, NE., Suite 1200 Atlanta, Georgia 30303-1257 Mr. G. Edward Miller NRC Senior Project Manager - North Anna Power Station U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, Maryland 20852-2738 Mr. L. John Klos (w/o Enclosure)
NRC Project Manager - Surry Power Station U.S. Nuclear Regulatory Commission One White Flint North Mail Stop 09 E-3 11555 Rockville Pike Rockville, M~ryland 20852-2738 NRC Senior Resident Inspector (w/o Enclosure)
North Anna Power Station State Health Commissioner (w/o Enclosure)
Virginia Department of Health James Madison Building - 7th floor 109 Governor Street, Suite 730 Richmond, Virginia 23219 Old Dominion Electric Cooperative (w/o Enclosure)
R-North-Anna-Correspondence@odec.com Serial No.23-045 Docket Nos.: 50-338/339 RELOCATED TECHNICAL SUPPORT CENTER LOCA DOSE
SUMMARY
REPORT PROPOSED EMERGENCY PLAN REVISION - RELOCATION OF THE TECHNICAL SUPPORT CENTER (JSC)
Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna Power Station Units 1 and 2
Serial No.23-045 Docket Nos.: 50-338/339 RELOCATED TECHNICAL SUPPORT CENTER LOCA DOSE
SUMMARY
REPORT NORTH ANNA POWER STATION UNITS 1 AND 2 TABLE OF CONTENTS Page No.
1.0 Introduction and Background........................................................................................ 2 2.0 Purpose.......................................................................................................................... 2 3.0 General Methodology.................................................................................................... 2 4.0 TSC Dose Results......................................................................................................... 3 5.0 Impact Assessment....................................................................................................... 4 6.0 References................................................................................................................... 14 -A: Updated North Anna Core Inventory LIST OF TABLES Page No.
Table 4-1: Summary ofTSC Dose Results......................................................................4 Table 5-1: Summary of Changes for TSC Relocation X/Q Calculation............................ 5 Table 5-2: Summary of Changes for TSC Relocation LOCA Dose.................................. 8 Page 1 of 14
Serial No.23-045 Docket Nos.: 50-338/339 RELOCATED TECHNICAL SUPPORT CENTER LOCA DOSE
SUMMARY
REPORT NORTH ANNA POWER STATION UNITS 1 AND 2 1.0 Introduction and Background As part of the Subsequent License Renewal (SLR) efforts at North Anna Power Station (NAPS), the Technical Support Center (TSC) is being relocated to the former Local Emergency Operations Facility (LEOF} Building. NUREG-0737, Item 11.B.2 (Reference
[1]), requires that dose to TSC personnel during a Loss of Coolant Accident (LOCA) remain below the control room dose limit of 1 O CFR 50, General Design Criterion (GDC) 19, which is 5 rem Total Effective Dose Equivalent (TEDE) for licensees that have adopted the Alternative Source Term (AST). Relocation of the TSC therefore requires a reanalysis of the consequences of a LOCA with respect to personnel in the new TSC location.
2.0 purpose This report summarizes the differences in inputs and assumptions used in analyzing the dose consequences to TSC personnel in the new location and the licensing basis AST implementation.
3.0 General Methodology The ARCON96 models docketed in Reference [4] were used as the basis for determining the atmospheric dispersion factors to the new TSC location. The previously analyzed release locations were reviewed for applicability and conservatism with respect to the new TSC location then updated to reflect the new TSC receptor location. The results of these updated ARCON96 models were extracted for use in the RADTRAD-NAI dose models.
The basis for the LOCA dose analysis is documented in Reference [8] and approved by the Nuclear Regulatory Commission (NRC) in Reference [9]. The analysis of record RADTRAD-NAI models developed for containment leakage, Emergency Core Cooling System (ECCS) leakage, and Refueling Water Storage Tank (RWST) backleakage were therefore used as the basis for the TSC LOCA dose analysis. Only the necessary modifications to add the TSC and an updated source term were made to the models.
These modifications included adding the TSC compartment, filtered intake pathway, and a TSC exhaust pathway.
The TSC RADTRAD-NAI models produced the inhalation and immersion doses for personnel within the TSC during the event. An additional dose location within the RADTRAD-NAI models determined the immersion dose from the radioactive cloud Page2 of 14
surrounding the building to estimate shine from the cloud.
Serial No.23-045 Docket Nos.: 50-338/339 The relevant nuclide inventories with respect to the containment (sprayed and unsprayed), TSC filter, TSC compartment, and environmental integral were extracted from the RADTRAD-NAI leakage case outputs for use in the MicroShield, MicroSkyshine, and MCNP5 computer models. Two MicroShield/MicroSkyshine models determined the shine dose to TSC personnel from containment. A MCNPS model determined the shine dose to TSC personnel from the nuclide buildup on the TSC HVAC filters.
Each of the individual leakage case doses and shine component doses were summed to produce the overall TSC personnel dose for the thirty-day event.
4.0 TSC Dose Results The results of the TSC Relocation LOCA dose and the AST implementation for TSC dose are summarized in Table 4-1. As expected, the increase in TSC distance from the release points combined with changes in shielding and equipment configurations resulted in a considerably lower TSC dose.
The TSC Relocation analysis considered both an automatic Safety Injection (SI) signal-based isolation and a manual isolation at sixty minutes. The SI-based case aligned with the assumption of receipt of an SI signal at the TSC used in the AST implementation for TSC dose; however, the new TSC location will not be provided with an SI signal. The sixty minute manual isolation case ensured that TSC personnel can withstand additional time without air filtration in the event of manual TSC HVAC isolation during a LOCA. The results of both cases are presented in Table 4-1.
Although it is common for the containment skyshine component to be a smaller dose contributor than the containment direct shine, a number of conservatisms in the relocation analysis resulted in the skyshine being greater. These skyshine conservatisms included but are not limited to lack of credit for TSC wall or roof shielding due to preset code geometries, use of fewer time edits for the containment inventory resulting in conservatively high prediction of skyshine from 4 to 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br />, and use of low steam density for the core inventory to minimize self-shielding.
Inclusion of the TSC roof shielding would reasonably reduce the skyshine component by approximately 90%.
Page 3 of 14
Serial No.23-045 Docket Nos.: 50-338/339 Table 4-1: Summary of TSC Dose Results TSC Dose Jrem TEDEl LOCA Dose Component TSC Relocation SI-based 60-min ASTTSC Isolation Isolation Containment Leaka~e 0.0262 0.4250 0.8000 ECCS Leakage 0.0114 0.0491 0.1200 RWST Leakaee 0.0007 0.0007 0.0057 Containment Direct Shine 0.0019 0.0019 0.047 Containment Skvshine 0.2660 0.2660 0.3810 Cloudshine1 0.0368 0.0368 0.6165 Filter Shine 0.0311 0.0311 0.1600 Containment Shine throul!b. Main Steam Line Penetrations
__ 2 0.0050 SI Piping under Main Steam Valve House & QS Pump 0.1940 House HydroJ;P;en Re-combiner Vault 0.0040 Total 0.38 0.82 2.33 1 Cloudsbine was reported individually for each of the three release cases. The individual values are summed here for comparison, to the cloudsbine/plume calculation.
2 Sources indicated with a result of"-" were deemed negligible with respect to the new TSC location due to source/receptor geometry.
5.0 Impact Assessment TSC relocation dose inputs were compiled from several references to produce a conservatively high TSC dose. Table 5-1 and Table 5-2 below summarize the inputs of the TSC relocation dose and compare them to the existing AST implementation. These tables may assist in determining the impact of changes to the licensing basis AST implementation.
The RADTRAD-NAI models used in the TSC relocation analysis were upconverted for use in RADTRAD-NAI Version 1.3 and benchmarked to the results of the analysis of record. This change represents a licensing basis change from Version 1.0 patch 3 to Version 1.3 for the LOCA dose *analysis. The process of converting and benchmarking the models required a time step sensitivity to ensure alignment with previous results, as well as proper calculation of the Exclusion Area Boundary (EAB) worst two-hour dose.
The RADTRAD-NAI models of the NAPS LOCA releases may be used as a starting point for subsequent analysis of other personnel locations with respect to the LOCA accident.
Additionally, the nuclide inventory and dose conversion files reflect a licensing basis change from SCALE 4.4a to SCALE 6.2.3 for determination of the core source term. The updated core source term incorporated a wider range of enrichments and a higher core average burnup within the constraints of the rated thermal power plus calorimetric Page 4 of 14
Serial No.23-045 Docket Nos.: 50-338/339 uncertainty. Having been part of the up-conversion of RADTRAD-NAI models, these files may also be used as a starting point for subsequent RADTRAD-NAI Version 1.3 analyses.
Table 5-1: Summary of Changes for TSC Relocation X/Q Calculation Meteorological Data Period Lower Wind Instrument Height (m)
Upper Wind Instrument Height (m)
Wind Speed Unit of Measure Release Type Building Area (m2)
Effluent Vertical Velocity (m/s)
Vent/Stack Radius (m)
Vent/Stack Flow (m3/s)
Wind Direction Sector Width Terrain Elevation Difference (m)
Minimum Wind Speed (mis)
Surface Roughness (mis)
Sector Averaging Constant Hours in Averages Minimum Number of Hours TSC Intake Hei ht m Containment Source Source Treatment Sigma-Y (m)
Si a-Z m 1997-2001 10.04 48.43 Meters/second (m/s)
Ground 1516.6 0.00 TableA-2, 5 0.0 TableA-2, 5 0.0 TableA-2, 5 90° TableA-2, 5 0.0 TableA-2, 5 0.5 TableA-2, 5 0.20 TableA-2, 5 4.3 TableA-2 5 1, 2, 4, 8, 12, 24, 96, 168, 360,720 TableA-2, 5 1, 2, 4, 8, 11, 22, 87, 152, 324,648 TableA-2, 5 Page5of 14 6.8 Diffuse 6.86 6.14 1997-2001 In ut 1.1, 4 10.04 Table 1, 4 48.43 Table 1 4 Meters/second (m/s) 4 Ground Section 3.1 4 0.00 TableA-2, 5 0.0 TableA-2, 5 0.0 TableA-2, 5 90° TableA-2, 5 0.0 TableA-2, 5 0.5 TableA-2, 5 0.20 TableA-2, 5 4.3 TableA-2, 5 1, 2, 4, 8, 12, 24, 96, 168,360, 720 TableA-2, 5 1, 2, 4, 8, 11, 22, 87, 152,324,648 TableA-2, 5 3.96 Table 1, [4]
Diffuse 6.86 6.14
Sources Considered Source Release Heights (m)
Ul Containment Vent Stack A VentStackB Ul Blowout Panel UlRWST Ul ui ment Hatch Intake-to-Source Distances (m)
Ul Containment to TSC Vent Stack A to TSC Vent Stack B to TSC Ul Blowout Panel to TSC Ul RWST to TSC Ul ui ment Hatch to TSC Direction from Intake to Source (degrees)
Ul Containment VentStackA VentStackB Ul Blowout Panel UlRWST Ul E ui ment Hatch True North Correction (degrees)
Included in directions above
-~;;::::'.',~..,\"a~'.<~Ll~!:!~~j~~!!1~~~;(.**
Ul RWST Vent to TSC Emergency Intake X/Q 0-2 hours 2-8 hours 8-24 hours 24-96 hours 96-720hours Vent Stack A to TSC Emergency Intake X/Q 0-2 hours 2-8 hours 8-24hours 24-96hours 96-720hours Ul Containment UlRWST Ul Equip. Hatch Ul Blowout Panel VentStackA Vent StackB 6.87 35.28 35.28 15.70 19.68 8.36 371.25 444.54 439.24 425.44 377.91 379.14 280 284 285 278 285 278
-23.207 6.13E-05 4.98E-05 1.67E-05 l.47E-05 1.22E-05 5.02E-05 3.41E-05 1.18E-05 9.70E-06 8.17E-06 Page 6 of 14 Serial No.23-045 Docket Nos.: 50-3381339 Ul/U2 Containment AB Louvers Ul/U2RWST Primary Ventilation Blowout Panels VentStackA Vent StackB Section 3.1.3.1, 2 Table 1, [4}
6.4 35.28 35.28 15.70 19.68 8.36 36.28 32.87 26.17 68.73 44.03 152.43 233.73 233.67 185.14 114.72 2.40E-03 l.SSE-03 5.27E-04 4.20E-04 2.97E-04 4.02E-03 3.24E-03 1.25E-03 9.48E-04 7.40E-04
Vent Stack B to TSC Emergency Intake X/Q 0 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 2-8 hours 8-24 hours 24-96 hours96-720 hours Ul Blowout Panel to TSC Emergency Intake XJQ 0-2 hours 2-8 hours 8-24 hours 24-96hours 96-720hours Ul Containment to TSC Emergency Intake X/Q 0-2 hours 2-8 hours 8 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 24 -** 96 hours0.00111 days <br />0.0267 hours <br />1.587302e-4 weeks <br />3.6528e-5 months <br /> 96 720hours Ul Equipment Hatch to TSC Emergency Intake X!Q 0-2 hours 2-8 hours 8-24 hours 24-96 hours 96 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> 5.12E-05 3.46E-05 1.20E-05 9.93E-06 8.28E-06 5.16E-05 4.25E-05 1.36E-05 1.24E-05 1.03E-05 5.63E-05 4.62E-05 l.52E-05 1.36E-05 l.13E-05 5.88E-05 4.88E-05 l.61E-05 1.44E-05 1.21E-05 Serial No.23-045 Docket Nos.: 50-338/339 5.67E-03 4.46E-03 1.73E-03 l.33E-03 l.0lE-03 1.16E-03 9.43E-04 3.85E-04 2.63E-04 1.97E-04 1.34E-03 9.43E-04 3.74E-04 2.64E-04 2.03E-04 Not explicitly considered - excluded by geometry and only used for fuel handling accident releases.
1 For TSC specific inputs, "Implementation of AST" refers to the use of AST acceptable inputs in the TSC dose analyses rather than docketed inputs with respect to the TSC dose.
2 The True North correction of -36 degrees from Reference [4] was based on protractor measurement from a site drawing. The True North correction of-23.207 degrees was based on an indicated value from a different site drawing that was converted from Plant North to Va North and Va North to True North based on USGS data.
3 The RWST vent X/Qs are the only X/Q values used to determine dose to the relocated TSC. X/Qs for the current TSC are shown for comparison to the values calculated for the relocated TSC.
Page 7 of 14
Serial No.23-045 Docket Nos.: 50-338/339 Table 5-2: Summary of Changes for TSC Relocation LOCA Dose Core inventory Fuel Design Fuel T e
Thermal Power (MWt)
Including 0. 6% calorimetric uncertain End of Cycle Core Average Bumup GWD/MTU Release from fuel Containment Leakage Chemical Release Form (Section 3.5 of Reg. Guide 1.183)
ECCS Leakage Chemical Release Form (Appendix A of Reg. Guide 1.183, [7])
RWST Leakage Chemical Release Form A endixA of Re. Guide 1.183, 7)
Dose conversion factors Containment net free air volume (ft3) 110 isotopes total Added:
Am-242, Ba-141, Co-58, Co-60, Cs-134m, Eu-154, Eu-155, La-143, Np-238, Pd-109, Pm-151, Pr-144m, Pu-243, Sb-124, Sb-126, Tc-101, Te-133m, Te-134, Y-94, and Y-95 Removed: Ag-11 Om, Cs-135, Kr-89, and Xe-137 (Reproduced in -A Westinghouse 17xl 7 RFA-2 4.2-5.0 0.462 2958 42.0 4.85% elemental 0.15% organic 97% elemental 3% organic 97% elemental 3% or anic FGR 11 and 12 1.916 million Page 8 of 14 94 isotopes Table 3.1-3, {2]
Westinghouse 17xl 7 RFA-2 Section 15.3.1.4, 6 4.4-4.55 0.466 2958 Table 15.4-9, {6}
38.9 Tables 2 and 4, 95% aerosol 4.85% elemental 0.15% organic Table 3.1-1, 2 97% elemental 3% organic Section 3.1.5.2, 2 97% elemental 3% or anic FGR 11 and 12 Att. 1 Section 4, {8 1.916 million Att. 1 Section 4.2, 8
Fraction of containment volume that is sprayed (%)
73 seconds - 40 minutes 40 minutes - 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> 6 hours Exchange rate between sprayed and unsprayed (cfm) 73 seconds - 40 minutes 40 minutes - 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> 1.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> - 720 hours0.00833 days <br />0.2 hours <br />0.00119 weeks <br />2.7396e-4 months <br /> (2x Unsprayed Volume/hr, Assumption 3.3, A. A of Re. Guide 1.183, 7 Natural deposition coefficient for aerosol in uns ra ed re ion of containment our-1 Beginning of containment spray and mixin between s ra ed and uns ra ed Duration of containment spray (hours)
Organic Iodine Elemental Iodine (time to reach DF = 200)
Particulate/aerosol Spray removal coefficient (hours*1)2 Organic iodide Elemental iodine Particulate/ aerosol 73 seconds -0.556 hours0.00644 days <br />0.154 hours <br />9.193122e-4 weeks <br />2.11558e-4 months <br /> 0.556 0.667 hours0.00772 days <br />0.185 hours <br />0.0011 weeks <br />2.537935e-4 months <br /> 0.667 - 0.833 hour0.00964 days <br />0.231 hours <br />0.00138 weeks <br />3.169565e-4 months <br />s2 0.833-1.11 hour1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />s1 1.11 - 1.39 hour4.513889e-4 days <br />0.0108 hours <br />6.448413e-5 weeks <br />1.48395e-5 months <br />s2 1.39 - 1.50 hour5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />s2 1.50 - 1.80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br /> 1.80 - 1.88 hours0.00102 days <br />0.0244 hours <br />1.455026e-4 weeks <br />3.3484e-5 months <br /> 1.88 - 1.97 hours0.00112 days <br />0.0269 hours <br />1.603836e-4 weeks <br />3.69085e-5 months <br /> 1.97 -2.35 hours4.050926e-4 days <br />0.00972 hours <br />5.787037e-5 weeks <br />1.33175e-5 months <br /> 2.35 - 3.82 hours9.490741e-4 days <br />0.0228 hours <br />1.35582e-4 weeks <br />3.1201e-5 months <br /> 3.82-5.46 hours5.324074e-4 days <br />0.0128 hours <br />7.60582e-5 weeks <br />1.7503e-5 months <br /> 5.46 - 7.13 hour1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />s2 Containment leak rate (percent per day) first hour 1-6 hours Filter efficienc,
Control Room Organic iodine Elemental iodine Particulate/aerosol 37.6%
83.8%
73.1%
39,867 10,347 17,180 Not analyzed 73 seconds NIA 2.33 720 Zero 10 5.832 6.167 12.34 12.45 12.45 12.34 11.87 7.565 5.285 2.821 1.534 1.370 1.350 0.10 0.04 95%
95%
98%
Page 9 of 14 Serial No.23-045 Docket Nos.: 50-338/339 Att. I Section 4.2, {8]
37.6%
83.8%
73.1%
39,867 10,347 17,180 Table 15.4-9, {6}
Not analyzed Section 15.4. 1. 9.2, 6 73 seconds Att. 1 Table 4.2-1, 8 Att. 1 Sections 4, 4.3, [8]
NIA 2.33 7202 Att. 1 Table 4.3-3, [8]
Zero 10 5.832 6.167 12.34 12.45 12.45 12.34 11.87 7.565 5.285 2.821 1.534 1.370 1.350 Att. 1 Table 4.1-1, {8}
0.10 0.04 Att. 1 Section 4, [8]
95%
95%
98%
Technical Support Center for dose detennination3 Organic iodine Elemental iodine Particulate/aerosol for filter inventory (shine dose analysis)
Organic iodine Elemental iodine Particulate/aerosol Auxiliary Building (PREACS)
Organic iodine Elemental iodine Particulate/aerosol Effective volume (:ft:3)
Filtered inflow from environment (c:fin) first hour after first hour Unfiltered inleakage (cfin)
Time delay (minutes)
To isolate To ressurize Recirculation Flow ( cfin)
Vent Stack to CR Emergency Intake X/Q (sec/m3) 0-2 hours 2-Shours 8-24 hours 24-96hours 96-720hours RWST Vent to CR Emergency Intake XJQ (sec/m3) 0-2hours 2-8hours 8-24 hours 24-96hours 96-720hours 95%
95%
95%
99%
99%
99%
79,100 0
900 250 0
60 0
3.75E-03 2.65E-03 1.03E-03 7.77E-04 5.70E-04 2.18E-03 l.42E-03 4.898-04 3.848-04 2.72E-04 Page 10 of 14 Serial No.23-045 Docket Nos.: 50-338/339 99%
99%
99%
99%
99%
99%
Att.1 Section 4, [8]
90%
95%
98%
- . :--~~~::**::~~ ~~~:~?\~-:;_~,~
~'.*. '::~ :.... -... _;*..
79,100 Att. 1 Section 4. 9, 8 Att. 1 Section 4, [8]
0 900 250 Att. 1 Section 4, 8 Table 1.3-1, [2]
0 60 0
Att. 1 Section 4, 8 Table 5, [4]
3.75E-03 2.65E-03 l.03E-03 7.77E-04 5.70E-04 Table 5, [4]
2.18E-03 1.42E-03 4.89E-04 3.84E-04 2.728-04
Containment to CR Emergency Intake X/Q (sec/m3) 0 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 2-8 hours 8 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 24-96 hours 96-720hours Filtered inflow ( cfm)
Operational Flow Range Before isolation (unfiltered)
After isolation Immediate Isolation Cases Unfiltered inleaka e cfm Time delay to enter emergency operation/isolation/filtration (minutes)
Recirculation Flow cfm)
Construction Details Wall Thickness (ft)
Wall Material Roof Thickness (ft)
Roof Material Building Pressure in Emergency Operation inw..
Entryway Details Breathing rates ( cubic meters/second)
Control room (all the time)
TSC (all the time) offsite 0-8 hours 8-24hours after 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> Control Room Occupancy factors First day
. between 1 to 4 days after 4 da: s TSC Occupancy factors 0-24 hours 24-96hours 96-720hours 1.23E-03 9.02E-04 3.57E-04 2.SSE-04 l.91E-04 405-1000+/- 10%
1100 365 Constant 11004 0
0.5 (60 and 90 minute manual isolations also anal ed 0
1.0 Grout-filled CMU, Brick, and Mortar 1.0 Concrete 0.125 Vestibule with Double Doors Section 4.1.3, {7}
3.5 x I0-4 3.5 X 10-4 Section 4.1.3, {7]
3.5 X 104 1.8 X 104 2.3 X 10-4 Section 4.2.6, {7}
1.0 0.6 0.4 1.0 1.0 1.0 Page 11 of 14 Serial No.23-045 Docket Nos.: 50-338/339 Table 5, [4]
l.23E-03 9.02E-04 3.57E-04 2.55E-04 1.91E-04 1000 0
0 0
1.0 Concrete 1.0 Concrete Positive Vestibule with Double Doors Att. 1 Section 4, {8}
3.5 X 10-4 3.5 X 104 Att. 1 Section 4, [8]
3.5 X 104 1.8 X 104 2.3 X 104 Att. 1 Section 4, {8}
1.0 0.6 0.4 1.0 0.6 0.4
Offsite X/Qs { sec/m3)
Exclusion Area Boundary 0-720 hours Low Population Zone 0-8 hours 8-24hours 24-96hours 96-720hours Unfiltered ECCS leakage (cc/hr)5 Automatic HV AC Isolation Case 0-720hours Manual HV AC Isolation Case 0-1 hour 1-720hours Filtered ECCS leakage (cc/hr) [PREACS]5 Automatic HV AC Isolation Case 0-720 hours Manual HV AC Isolation Case 0-1 hour 1-720 hours Containment sump liquid volume (ft')
840-1,500 seconds 1,500 - 1,900 seconds 1,900 - 2,500 seconds 2,500 - 3,000 seconds 3,000 - 4,000 seconds 4,000 - 5,000 seconds 5,000 - 6,000 seconds 6,000 - 8,000 seconds 8 000+ seconds RWST Breathing Rate (Suppression Pool Model)
Flow rate (cfm)
Duration hours RWST Decontamination Factor Fraction of activity in ECCS liquid leakage released as airborne ECCS back-leakage into RWST during recirc (cc/hr)'
Maximum RWST air volume {ft')
3.lOE-04 1.lOE-05 7.30E-06 3.00E-06 8.20E-07 1700 17,200 0
0 0
17 200 16,800 25,700 31,400 39,900 46,800 60,000 68,800 73,200 76000 3.7 0.533-720 40 10%
2400 (480 + 1920) 6.5850E+04 Page 12 of 14 Serial No.23-045 Docket Nos.: 50-338/339 Table 1, [3]
3.lOE-04 l.lOE-05 7.30E-06 3.00E-06 8.20E-07 1700 [CR & LPZ]
17,200 [BAB]
0 AB 0 [CR&LPZ]
0 [BAB]
17,200 AB Att. 1 Table 4.4-1, [8]
16,800 25,700 31,400 39,900 46,800 60,000 68,800 73,200 76 000 Att. 1 Section 4.5, [8]
3.7 0.533-720 40 Att. 1 Section 4. 5, 8 10%
Section 3.1.5.2, 2 480 via recirc lines 1920 via LHSI suction line Att. 1 Section 4.5, 8 6.5850E+04 (492,600 gal)
Section 4.5, 8
Sources of shine dose to TSC personnel Containment Construction Wall Concrete Thickness (ft)
Wall Steel Liner Thickness (in)
Dome Concrete Thickness (ft)
Dome Steel Liner Thickness in Containment shine, Containment skyshine, plume/cloud, and HV AC filters 4.5 0.375 2.5 0.5 Serial No.23-045 Docket Nos.: 50-338/339 Containment shine, Containment sk.yshine, SI piping,Hydrogen Recombiner Vault, plume/cloud, HV AC filters Not listed Not listed 2.5 Not listed 1 For TSC specific inputs, "Implementation of AST" refers to the use of AST acceptable inputs in the TSC dose analyses rather than docketed inputs with respect to the TSC dose.
2 Due to a previous limitation in RADTRAD-NAI, table inputs could not exceed 10 time-dependent values; therefore, an aerosol removal coefficient value of 12.34 hr-1 was conservatively used from 0.667 - 1.50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />. Also, the last entry of 1.35 hr1 remains in effect until problem duration of720 hours. Since containment is subatmospheric by 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />, this has no impact on the result.
3 The TSC charcoal filter efficiency was reduced due to the new TSC location having 2" charcoal filters versus the existing TSC use of 411 charcoal filters. Assumed HEPA filter efficiency for particulate removal is conservative.
4 Filtration is delayed 30 seconds for damper operation in the immediate isolation cases for the new TSC.
5 ECCS leakage modeling is described in references [2] and [8]. The ECCS leakage analysis has not changed from Reference
[8]. The analysis has two limiting scenarios relevant to the TSC dose: 1) allowable unfiltered ECCS leakage of 1700 cc/hr, or
- 2) allowable filtered ECCS leakage of 17,200 cc/hr with filtration delayed 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. Modeled leak rates are twice the allowable (3400 cc/hr unfiltered and 34,400 cc/hr), which were input into RADTRAD-NAI as 0.002 cfin and 0.02025 cfin, respectively.
Evolution is modeled by specifying a source fraction of 0.1. Filtration ofECCS leakage is accomplished by manual initiation of the Auxiliary Building ventilation (PREACS) filters at 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />.
6 RWST allowable leakage is 1200 cc/hr. RWST modeled leakage of2400 cc/hr was input into RADTRAD-NAI as 3.533E-5 cfm after reduction based on DF of 40 inside the tank.
Page 13 of 14
6.0 References Serial No.23-045 Docket Nos.: 50-338/339
- 1.
NUREG-0737, "Clarification of TMI Action Plan Requirements", November 1980.
- 2.
Letter from Virginia Electric and Power Company to the USNRC (Serial No. 04-494A) dated November 3, 2004, "Virginia Electric and Power Company (Dominion),
North Anna Power Station Units 1 and 2, Response to Request for Additional Information, Proposed Technical Specification Changes, Implementation of Alternate Source Term Revised Dose Analysis and Technical Specification Changes." [ML043150026]
- 3.
Letter from the USNRC to Virginia Electric and Power Company dated June 15, 2005, "North Anna Power Station, Units 1 and 2 - Issuance of Amendments on Implementation of Alternate Source Term (TAC Nos. MC0776 and MC0777)."
[ML05159051 O]
- 4.
Letter from Virginia Electric and Power Company to the USNRC (Serial No. 03-464A) dated November 20, 2003, "Virginia Electric and Power Company, North Anna Power Station Units 1 and 2, Proposed Technical Specification Changes, Implementation of Alternate Source Term, Request for Additional Information."
[ML033350516]
- 5.
Regulatory Guide 1.194, Revision 0, "Atmospheric Relative Concentrations for Control Room Radiological Habitability assessments at Nuclear Power Plants", June 2003.
- 6.
North Anna Updated Final Safety Analysis Report, Revision 58, September 2022.
- 7.
Regulatory Guide 1.183, Revision 0, "Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors", July 2000.
- 8.
Letter from Virginia Electric and Power Company to the USN RC (Serial No.06-849) dared October 3, 2006, "Virginia Electric and Power Company (Dominion), North Anna Power Station Units 1 and 2, Proposed Technical Specification Change and Supporting Safety Analyses Revisions to Address Generic Safety Issue 191."
[M L062850195]
- 9.
Letter from the USNRC to Virginia Electric and Power Company dated March 13, 2007, "North Anna Power Station, Units 1 and 2 -
Issuance of Amendments Regarding Technical Specification Changes Per Generic Safety Issue (GSI) 191 (TAC Nos. MD3197 and MD3198)." [ML070720043]
Page 14 of 14
-A Updated North Anna Core Inventory Isotope No.
Isotope Activity (Ci) 1 Kr-83m l.O0E+07 2
Kr-85 9.09E+o5 3
Kr-85m 2.23E+07 4
Kr-87 4.28E+07 5
K.r-88 5.80E+o7 6
Xe-13lm 9.6lE+05 7
Xe-133 1.60E+08 8
Xe-133m 5.03E+o6 9
Xe-135 4.96E+o7 10 Xe-135m 3.49E+07 11 Xe-138 l.41E+08 12 Br-82 2.97E+05 13 Br-83 9.98E+06 14 Br-84 1.74EI 07 15 I-130 1.58E+06 16 I-131 7.99E+07 17 1-132 l.16E+o8 18 I-133 l.64E+08 19 I-134 1.85E+08 20 I-135 l.57E+08 21 Rb-86 1.80E+05 22 Rb-88 5.89E+07 23 Rb-89 7.73E+07 24 Cs-134 1.68E+07 25 Cs-134m 4.73E+06 26 Cs-136 3.82E+06 27 Cs-137 9.72E+06 Page 1 of 4 Serial No.23-045 Docket Nos.: 50-338/339
Isotope No.
Isotope 28 Cs-138 29 Sb-125 30 Sb-126 31 Sb-127 32 Sb-129 33 Te-125m 34 Te-127 35 Te-J27m 36 Te-129 37 Te-129m 38 Te-131 39 Te-131m 40 Te-132 41 Te-133 42 Sr-89 43 Sr-90 44 Sr-91 45 Sr-92 46 Ba-137m 47 Ba-139 48 Ba-140 49 Ba-141 50 Pd-109 51 Ag-111 52 Mo-99 53 Rh-103m 54 Rh-105 55 Rh-106 56 Ru-103 Page 2 of4 Activity (Ci) 1.54E+o8 8.22E+o5 3.51E+o4 7.69E+o6 2.30E+o7 l.7SE+o5 6.90E+o6 5.43E+o5 2.19E+o7 3.75E+o6 6.8SE+o7 1.56E+o7 l.14E+o8 8.28E+o7 8.08E+o7 7.09E+06 l.OOE+o8 1.07E+o8 9.25E+o6 1.47E+o8 1.42E+o8 1.32E+o8 2.93E+07 5.52E+o6 1.49E+o8 l.28B+o8 8.41E+o7 5.37E+o7 l.29E+o8 Serial No.23-045 Docket Nos.: 50-338/339 -A
Isotope No.
Isotope 57 Ru-105 58 Ru-106 59 Tc-99 60 Tc-99m 61 Tc-101 62 Ce-141 63 Ce-143 64 Ce-144 65 Np-239 66 Pu-238 67 Pu-239 68 Pu-240 69 Pu-241 70 Am-241 71 Cm-242 72 Cm-244 73 Eu-156 74 La-140 75 La-141 76 La-142 77 La-143 78 "Nb-95 79 "Kb-95m 80 Nb-97 81 Nb-97m 82 Nd-147 83 Pm-147 84 Pm-148 85 Pm-148m Page 3 of 4 Activity (Ci) 9.19E+07 4.66E+07 l.23E+03 l.32E+08 1.38E+08 l.33E+o8 I.26E+08 l.03E+08 1.60£+09 3.61E+05 2.64E+04 2.66E+04 l.30E+07 l.33E+04 4.87E+o6 6.17E+05 2.17E+07 l.47E+08 l.33E+08 l.29E+08 l.25E+08 l.38E+08 l.51E+06 l.37E+08 l.30E+o8 5.25E+07 l.46E+07 1.74E+07 2.94E+06 Serial No.23-045 Docket Nos.: 50-338/339 -A
Isotope No.
86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 Isotope Pm-149 Pr-143 Pr-144 Pr-144m Sm-153 Y-90 Y-91 Y-91m Y-92 Y-93 Y-94 Y-95 Zr-95 Zr-97 Sb-124 Te-133m Te-134 Co-58 Co-60 Eu-154 Eu-155 Pm-151 Am-242 Np-238 Pu-243 Page 4 of 4 Activity (Ci) 4.39E+o7 l.22E+08 l.04E+08 l.46E+06 3.79E+o7 7.37E+06 l.04E+08 5.90E+07 l.08E+08 l.21E+08 l.27E+o8 l.32E+08 l.37E+08 l.36E+08 7.34E+04 8.32E+07 l.49E+o8 0.00E+00 0.00E+00 6.63E+05 3.58E+o5 l.58E+07 8.68E+o6 3.75E+o7 4.30E+07 Serial No.23-045 Docket Nos.: 50-338/339 -A Serial No.23-045 Docket Nos.: 50-338/339 LISTS AND DESCRIPTIONS OF FILES INCLUDED ON THE ENCLOSED CD-ROM SUPPORTING THE RELOCATED TSC LOCA DOSE CALCULATION Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna Power Station Units 1 and 2
Serial No.23-045 Docket Nos.: 50-338/339 LISTS AND DESCRIPTIONS OF FILES INCLUDED ON THE ENCLOSED CD-ROM SUPPORTING THE RELOCATED TSC LOCA DOSE CALCULATION CD-ROM contents:
The enclosed CD-ROM contains a zip file named North Anna Computer 1O.zip. The following table describes the contents of the zip file on the enclosed CD-ROM.
North Anna Computer Files File Name Description
- >lW)T~~Affiles (.p~f;;
- .11if;,dwp/.dd,:ftft,*.oht)°.
- . **i,...,*, :t
.~:<]~ ~-;*,~
. :..::... t~*.. ; _.,: *. '..';..i,:,:;;.,:,.. ;
c.;:, '_.,, *~.... *:..
_t,,;"_, -,-~*'. - :;. ".
naps_ ctmt _ TSC.psf LOCA containment leakage model for TSC dose with automatic isolation at thirty seconds.
Naps_eccs_TSC.psf LOCA ECCS leakage model for TSC dose with automatic isolation at thirty seconds.
Naps_ rwst _TSC.psf LOCA RWST leakage model for TSC dose with automatic isolation at thirty seconds.
Naps __ ctmt_TSC_jso!60.psf LOCA containment leakage model for TSC close with manual isolation at 60 minutes into the accident.
Naps_eccs_TSC_Isol60.psf LOCA ECCS leakage model for TSC dose with manual isolation at 60 minutes into the accident.
N aps_nvst __ T..'iC _Jso/60.psf LOCA RWST leakage model for TSC dose with manual isolation at 60 minutes into the accident.
Naps_ ctmt _ TSC _Isol90.psf LOCA containment leakage model for TSC dose with manual isolation at 90 minutes into the accident.
Naps_ eccs _ TSC _jsol90.psf LOCA ECCS leakage model for TSC dose with manual isolation at 90 minutes into the accident.
Naps _rwst _ TSC _Isol90.psj LOCA RWST leakage model for TSC dose with manual isolation at 90 minutes into the accident.
Naps_ctmt_TSC.. }9.p~f LOCA containment leakage model for maximum TSC filter loading with automatic isolation at thirty seconds.
Naps _eccs _TSC _99.psf LOCA ECCS leakage model for maximum TSC filter loading with automatic isolation at thirty seconds.
Naps_ rwst _TSC _JJ9.psf LOCA RWST leakage model for maximum TSC filter loading with automatic isolation at thirty seconds.
NAPS_Core.nif Nuclide inventory file upconverted and reformatted for use with RADTRAD-NAI Version 1.3.
NAPSJgrl 1&12.inp Dose conversion factor file.
Page 1 of 3
File Name Na __pwr _ dba.rft Na_iodine _ only.rft cont shine XX.msd Filename.mxd Filename.pd/
cont _sky_ XX.sky Cont _sky_ XX.pd/
NI CNTLEOF.RSF NI CNTLEOF.log NlCNTLEOF.cfd NA VTALEOF.RSF NA VTALEOF.log NA VTALEOF.cfd NAVTBLEOF.RSF NA VTBLEOF.log NAVTBLEOF.cfd NlBLPLEOF.RSF NlBLPLEOF.log NlBLPLEOF.cfd NlRWTLEOF.RSF Description Serial No.23-045 Docket Nos.: 50-338/339 Release fraction timing file for containment leakage during a LOCA.
Release :fraction timing file for ECCS leakage and RWST backleakage during a LOCA.
Micro Shield case file for determination of containment shine to TSC personnel.
Four subcases are derived from the base model for various times in hours from the start of the event indicated by the two-digit suffix (XX).
External source files for use in MicroShield.
MicroShield Output files.
Case file for determination of skyshine from containment to TSC personnel. Two subcases are derived from the base model for various times in hours from the start of the event indicated by the two-digit suffix (XX).
MicroSkyshine Output File ARCON96 run specification file for UI source ARCON96 output file for Ul source ARCON96 cumulative frequency distribution file for Ul source ARCON96 run specification file for VA source ARCON96 output file for VA source ARCON96 cumulative frequency distribution file for VA source ARCON96 run specification file for VB source ARCON96 output file for VB source ARCON96 cumulative frequency distribution file for VB source ARCON96 run specification file for B 1 source ARCON96 output file for Bl source ARCON96 cumulative frequency distribution file for B 1 source ARCON96 run specification file for RI source Page 2 of 3
File Name NlRWTLEOF.log NlRWTLBOF.cfd NlEQHLEOF.RSF NlEQHLEOF.log
. NlEQfilEOF.cfd NA9701MET2 Description ARCON96 output file for Rl source Serial No.23-045 Docket Nos.: 50-338/339 ARCON96 cumulative frequency distribution file for Rl source ARCON96 run specification file for El source ARCON96 output file for El source ARCON96 cumulative frequency distribution file for El source North Anna Meteorological Data file Page 3 of 3 Serial No.23-045 Docket Nos.: 50-338/339 NORTH ANNA X/Q GEOMETRY FOR THE RELOCATED TSC Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna Power Station Units 1 and 2
NORTH ANNA X/Q GEOMETRY FOR THE RELOCATED TSC WC£ WTit RSlllt LEOF Unit 1 Unit2 VA VB 81 RWST EQ Prooosed TSC Unit 1 Containment Unit 2 Containment Ventilation Stack A Ventilation Stack B Blowout panel Unit 1 Unit 1 Refuelina Water Storaae Tank Eauioment Hatch Ap,-VA.N HIIIIS£St RAn IIAU.F"IS.
Serial No.23-045 Docket Nos.: 50-338/339 Serial No.23-045 Docket Nos.: 50-338/339 TECHNICAL BASIS FOR ELIMINATION OF TSC CO2 FIRE PROTECTION SYSTEM Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna Power Station Units 1 and 2
Serial No.23-045 Docket Nos.: 50-338/339 TECHNICAL BASIS FOR ELIMINATION OF TSC CO2 FIRE PROTECTION SYSTEM The relocated TSC facility is designed to meet the requirements of NUREG-0696, "Functional Criteria for Emergency Response Facilities," (1981), and NUREG-0737, Supplement 1, "Requirements for Emergency Response Capability," (1982). NUREG-0696 specifies the need for a TSC ventilation system that includes charcoal filters but does not specify requirements for fire protection of the filters. However, other documents provide limited guidance for the fire protection of charcoal filters including Regulatory Guide (RG) 1.189, 11Fire Protection for Nuclear Power Plants," (2009) and ASME AG-1, 11Code on Nuclear Air and Gas Treatment," (2019). RG 1.189 states that any filter (not installed in an Engineered-Safety-Featured Atmosphere Cleanup System) that includes combustible materials and is a potential exposure fire hazard that may affect components important to safety should be protected as determined by the fire hazards analysis. The same direction is provided within section AB-5170 of ASME AG-1, which indicates designated filter fire protection systems are to be provided based on the plant fire hazard analysis. Additional guidance is provided within RG 1.140, "Design, Inspection, and Testing Criteria for Air Filtration and Adsorption Units of Normal Atmosphere Cleanup Systems in Light-Water-Cooled Nuclear Power Plants," (2016) which states prevention and mitigation of auto-ignition should be considered and includes a water~based fire suppression system as an option if needed. The fire hazard analysis in the North Anna Appendix R Report currently identifies a localized CO2 fire suppression system for the activated carbon filter in the existing TSC. However, a CO2 fire suppression system is not necessary for the relocated TSC since the TSC: 1) is not required for safe shutdown,
- 2) contains other fire protection measures, and 3) is unlikely to experience a HEGA filter fire.
The installation of a designated fire suppression system in the HEGA filter would be to extinguish a fire that developed in the activated carbon bed. However, it is unlikely a fire would occur in this area of the HVAC system during normal system operation as it is only in use during an accident condition in which the outside air needs to be filtered of radiological contaminants. If the need for radiological filtration arises, the possibility for a fire in the HEGA filter increases due to the resulting decay heat from the radionuclides deposited on the activated carbon beds. If the decay heat is significant, the activated carbon could reach its ignition temperature thus causing a fire.
Consequently, to determine if the ignition temperature could be reached, the total decay heat load was calculated based on the radionuclide inventory across all filters in the HVAC system. It assumes that energy from all potential emissions or reactions are locally deposited, which is conservative as photon-based emissions are likely to escape the filter media. Based on these assumptions, the total decay heat load across all filters was calculated to be 9.01E-04 watts or 3.0SE-03 BTU/hr. Even by conservatively assuming the entirety of this heat load is gained by a single carbon bed in the HEGA filter, this heat load is very small and is unlikely to increase the temperature of the activated charcoal filter by any significant amount. In addition to this minimal heat load, the TSC HVAC system is capable of providing 1,000 cubic feet per minute (CFM) airflow during emergency operation. Such airflow through the HEGA filter would provide sufficient cooling of the decay heat load and limit the temperature increase of the activated carbon beds. Thus, there is no significant increased fire risk in the activated carbon beds due to the filtered Page 1 of 3
radionuclides.
Serial No.23-045 Docket Nos.: 50-338/339 In the event a fire does ignite in the TSC Penthouse where the HEGA filter is located, there is no risk to the safe shutdown of the plant as it does not contain safety-related equipment or any equipment required for fire safe shutdown. The remainder of the relocated TSC and the adjacent Training Building also do not contain any such equipment, and thus pose no risk to safe shutdown if a TSC Penthouse fire were to somehow spread to these areas.
Should a HEGA filter fire occur without a designated CO2 suppression system installed, the activated carbon would be damaged and would require replacement once the fire had been extinguished. If the filter fire were extinguished via water suppression, the filter efficiency would be significantly reduced due to the resulting saturation and increased local humidity. These issues could be mitigated by a CO2 suppression system and result in a more timely recovery of the filter; however, there is no requirement specifying a recovery time for atmospheric cleanup systems following a fire. Additionally, as the new TSC does not contain any safe shutdown equipment, it can be evacuated if the space becomes unfit for human habitation. In the unlikely event TSC occupants are exposed to radioactive contaminants during a HEGA filter fire (or after it has been extinguished), the area can be evacuated without risk to safe shutdown of the plant.
If a fire does occur in the charcoal filter, there are several fire protection measures in place that alleviate the need for a dedicated CO2 suppression system. The HEGA filter is fitted with heat detection that alarms at the relocated TSC fire protection panel, the existing fire protection panel in the adjacent Training Building, and the Security Alarm Station (SAS). Upon reaching a temperature of 190°F, the heat detection actuates the Emergency Power Off (EPO) panel which de-energizes both the emergency supply fan and motor operated dampers, isolating the HEGA filter.
Additionally, cross-zoned smoke detectors are installed in the supply and return ventilation ducts and in the Penthouse area. These detectors alarm in the same locations as the heat detection. Upon smoke detection by two of the cross-zoned smoke detectors, the air handling unit (AHU) is de-energized and motor operated dampers are modulated closed to limit the spread of smoke or fire to other areas of the TSC. As the HEGA filter is located upstream of the supply duct smoke detector, a fire at that location would trip theAHU.
In addition, the Penthouse is served by the TSC pre-action fire suppression system. This system is designed in compliance with NFPA 13 and consists of four sprinklers with a design area of discharge that covers the entirety of the Penthouse. These sprinklers are actuated automatically by the local area smoke detectors. Fire protection is also provided by the station Fire Brigade in accordance with station Fire Protection Program requirements. The Fire Brigade has access to the two Training Building fire hydrants1 1-FP-HYD-100 and 1-FP-HYD-101, to aid in the suppression of fires in the TSC and TSC Penthouse should they be required. Hydrant 1-FP-HYD-100 is located on the west side of the Training Building, approximately 182 feet from the Penthouse, and hydrant 1-FP-HYD-101 is located on the east side of the Training Building, approximately 228 feet from the Penthouse.
Page2 of3
Serial No.23-045 Docket Nos.: 50-338/339 The construction and location of the Penthouse also offers some passive fire protection that can slow the spread of a fire from the space. The Penthouse is located on the roof of the TSC and only its floor is adjacent to the remainder of the TSC facility. The floor of the Penthouse is constructed of 12-inch-thick reinforced concrete and designed to prevent the spread of radiological contaminants to the occupied areas of the TSC. As a result, the floor can also impede the spread of fire. Per the Concrete Reinforcing Steel Institute - (CRSI) [2015], "Fire Resistance of Reinforced Concrete Buildings," Table 1 of Technical Note ETN-B-1-16, a reinforced siliceous concrete floor with a thickness of about 6.2 inches provides a 3-hour fire rating. Given the Penthouse floor thickness of 12 inches, it provides an equivalent construction of greater than 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, which would slow the spread of a fire from the Penthouse to the remainder of the TSC. Note that because the Penthouse floor is not a rated fire barrier, its associated penetrations are not designed to a particular fire rating and are thus assumed to not be fire rated.
Based on the equipment installed in the Penthouse, it is expected the associated fire loading maintains an Equivalent Fire Severity (EFS) of Low since a fire area is considered to have a Low EFS when its associated fire load is below 100,000 BTU/ft2. The TSC Penthouse occupies a space of approximately 490.6 square feet and would thus require a heat release of 49,060,000 BTU to reach this fire loading threshold. Conservatively assuming that all of the combustible equipment in the Penthouse is general plastic (heat of combustion of 15,750 BTU/lb), approximately 3,115 lbs of general plastic is required to meet this heat release. The combustible equipment installed in the Penthouse is limited to the HVAC filters (prefilter, HEPA filter, and activated carbon from the HEGA filter), a variable frequency drive and small electronic devices such as smoke and heat detectors.
Since the combined weight of the filter equipment and variable frequency drive is approximately 172 lbs, the combustible equipment in the Penthouse remains well below 3,115 lbs, and therefore, the EFS of the space is determined to be Low.
Conclusion Based on this evaluation, a designated CO2 fire suppression system for the TSC HEGA activated carbon filter is neither required nor warranted. The probability of ignition of the HEGA filter is minimal based on the insignificant radiological decay heat load and sufficient emergency operation airflow. In the unlikely event auto-ignition of the charcoal filter were to occur, heat and/or cross-zone smoke detection initiates an alarm and de-energizes the emergency fan or AHLI and closes all motor operated dampers to isolate the filter fire from the remainder of the TSC. A filter fire is unlikely to spread into the TSC general area due to the installed pre-action sprinkler system, and the existing separation between the Penthouse and the remainder of the TSC. Consequently, the CO2 fire suppression system is no longer being installed in the relocated TSC contrary to the discussion included in the Ventilation paragraph in Attachment 1, page 12 of 30, of Section 3.1.6, Habitability, of the License Amendment Request (LAR) dated January 13, 2023, (ADAMS Accession No. ML23013A195). The marked-up LAR page indicating the proposed change and the revised LAR replacement page incorporating the proposed change are provided in Attachments 5 and 6, respectively.
Page 3 of 3 Serial No.23-045 Docket Nos.: 50-338/339 MARKED-UP LAR PAGE INDICATING DELETION OF THE CO2 FIRE SUPPRESSION SYSTEM Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna Power Station Units 1 and 2
Ventilation Serial No.22-036 Docket Nos.: 50-338/339 Page 12 of 30 The ventilation system for the proposed TSC is designed to meet the requirements of NUREG-0696 (Reference 1} and NUREG-0737, Supplement 1 (Reference 2). Upon facility activation, the ventilation system will be manually placed in emergency operating mode via a hand switch. When placed in emergency operating mode, bubble tight motor operated dampers will align makeup air through a filtration system and deenergize exhaust fan circuits. The filter bank consists of a HEPA filter in series with a high efficiency gas absorption (HEGA) filter with a nominal flow rate of 1000 cfm. The HEPA filter removes particulate radioactive air contaminants, and the HEGA removes remaining pollutants such as iodine compounds. The HEGA filter temperature is monitored by a heat detector.
If a flame is detected, the CO.a SuppFession system floods COa into the duet mounted filter housing to e~inguish the flame. The humidity of the makeup air stream is controlled via a sensor and electric duct heater. During emergency operation, the exhaust fans will be de-energized and isolated via dampers enabling the building's static pressure controller to modulate the filter fan speed to maintain the conditioned space at 0.125 inches water gauge (WG) relative to the outside air pressure to prevent infiltration of outside air. The ventilation system design has been suitably sized to provide heating and cooling that is capable of maintaining facility temperature at approximately 75 °F dry bulb+/- 3 °F during the summer and 72 °F dry bulb +/- 3 °F during the winter. The ventilation system is provided with an alarm function that will alert TSC staff of a component failure in the Emergency HVAC system. A LOCA dose calculation was completed to determine the ability of the proposed TSC shielding and ventilation design to meet the specified occupancy dose requirements. Results of this calculation are described below.
Radiological Monitoring The proposed TSC will be provided with radiation monitoring to provide continuous indication of the dose rate and airborne radioactivity in the TSC during an emergency, as well as alerting personnel of adverse conditions as required per NUREG-0696 (Reference 1 ). The RMS consists of a Mirian radiation monitor to detect airborne radioactivity, and two Mirion DRM-2 general area radiation monitors. The Mirian radiation monitor will include a particulate, an iodine, and a noble gas detector and will be able to distinguish the presence or absence of radioiodines at concentrations as low as 10-7 µci/cc. The monitor will be located in the Dose Assessment Room and will continuously sample the facility atmosphere from locations throughout the TSC and provide an audible alarm to alert TSC personnel of adverse conditions. The two Mirian DRM-2 general area radiation monitors will be wall mounted at separate locations on the TSC Operation Floor and will provide an audible alarm to alert TSC personnel of adverse conditions.
REVISED LAR REPLACEMENT PAGE Serial No.23-045 Docket Nos.: 50-338/339 INDICATING DELETION OF THE CO2 FIRE SUPPRESSION SYSTEM Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna Power Station Units 1 and 2
Ventilation Serial No.22-036 Docket Nos.: 50-338/339 Page 12 of 30 The ventilation system for the proposed TSC is designed to meet the requirements of NUREG-0696 (Reference 1) and NUREG-0737, Supplement 1 (Reference 2). Upon facility activation, the ventilation system will be manually placed in emergency operating mode via a hand switch. When placed in emergency operating mode, bubble tight motor operated dampers will align makeup air through a filtration system and deenergize exhaust fan circuits. The filter bank consists of a HEPA filter in series with a high efficiency gas absorption (HEGA) filter with a nominal flow rate of 1000 cfrn. The HEPA filter removes particulate radioactive air contaminants, and the HEGA removes remaining pollutants such as iodine compounds. The HEGA filter temperature is monitored by a heat detector. The humidity of the makeup air stream is controlled via a sensor and electric duct heater. During emergency operation, the exhaust fans will be de-energized and isolated via dampers enabling the building's static pressure controller to modulate the filter fan speed to maintain the conditioned space at 0.125 inches water gauge (WG) relative to the outside air pressure to prevent infiltration of outside air. The ventilation system design has been suitably sized to provide heating and cooling that is capable of maintaining facility temperature at approximately 75 °F dry bulb +/- 3 °F during the summer and 72 °F dry bulb +/- 3 °F during the winter. The ventilation system is provided with an alarm function that will alert TSC staff of a component failure in the Emergency HVAC system. A LOCA dose calculation was completed to determine the ability of the proposed TSC shielding and ventilation design to meet the specified occupancy dose requirements. Results of this calculation are described below.
Radiological Monitoring The proposed TSC will be provided with radiation monitoring to provide continuous indication of the dose rate and airborne radioactivity in the TSC during an emergency, as well as alerting personnel of adverse conditions as required per NU REG-0696 (Reference 1 }. The RMS consists of a Mirian radiation monitor to detect airborne radioactivity, and two Mirion DRM-2 general area radiation monitors. The Mirion radiation monitor will include a particulate, an iodine, and a noble gas detector and will be able to distinguish the presence or absence of radioiodines at concentrations as low as 1 o-7 µci/cc. The monitor will be located in the Dose Assessment Room and will continuously sample the facility atmosphere from locations throughout the TSC and provide an audible alarm to alert TSC personnel of adverse conditions. The mo Mirian DRM-2 general area radiation monitors will be wall mounted at separate locations on the TSC Operation Floor and will provide an audible alarm to alert TSC personnel of adverse conditions.
Enclosure Serial ~o.22-045 Docket Nos.: 50-338/339 CD-ROM - LOCA DOSE ANALYSIS AND X/Q INPUT AND OUTPUT FILES Virginia Electric and Power Company (Dominion Energy Virginia)
North Anna Power Station Units 1 and 2