SBK-L-21045, Submittal of 2020 Annual Radioactive Effluent Release Report

Submittal of 2020 Annual Radioactive Effluent Release Report

ML21120A158
Person / Time
Site:	Seabrook
Issue date:	04/30/2021
From:	Levander M NextEra Energy Seabrook
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
SBK-L-21045
Download: ML21120A158 (58)

Text

NEXTera ENERGY ~

SEABROOK April 30, 2021 Docket No. 50-443 SBK-L-21045 U.S. Nuclear Regulatory Commission Attn.: Document Control Desk Washington, DC 20555-0001 Seabrook Station 2020 Annual Radioactive Effluent Release Report Pursuant to 10CFR 50.36a(a).2 and Technical Specification 6.8.1.4, NextEra Energy Seabrook, LLC submits the Annual Radioactive Effluent Release Report for 2020. No changes were made to the Offsite Dose Calculation Manual (ODCM) since the previous submittal pursuant to Technical Specification 6.13.c.

The following information is provided in the enclosures:

Enclosure 1 Effluent release data as required by Regulatory Guide 1.21 Enclosure 2 Joint frequency distributions of wind speed, wind direction, and atmospheric stability Enclosure 3 Radiation dose assessment Should you have any questions regarding this letter, please contact David Robinson, Chemistry and Radiation Protection Department Manager, at (603) 773-7496.

Sincerely, NextEra Energy Seabrook, LLC dl/~

Matthew Levander Licensing Manager NextEra Energy Seabrook, LLC PO Box 300, Seabrook, NH 03874

U.S. Nuclear Regulatory Commission SBK-L-21045/ Page 2 cc: NRC Region I Administrator NRC Project Manager, Project Directorate I-2 NRC Senior Resident Inspector S. Wilson, Region I Inspector Steven Wessels, American Nuclear Insurers

Enclosure 1 Effluent Release Data as Required by Regulatory Guide 1.21

List of Appendices Appendix Title A Offsite Dose Calculation Manual B Process Control Program c Liquid Holdup Tanks D Radwaste Treatment Systems E Unplanned Releases

Appendix A Offsite Dose Calculation Manual Requirement: Technical Specification 6.13.2c requires that licensee initiated changes to the Offsite Dose Calculation Manual be submitted to the Commission in the Annual Radioactive Effluent Release Report for the period in which the change(s) was made effective. Include in this changes to the Radiological Environmental Program in accordance with Offsite Dose Calculation Manual (ODCM) - C.9.1.1 and - C.9.2.1.

Response: No changes were made to the ODCM in 2020.

AppendixB Process Control Program Requirement: The Offsite Dose Calculation Manual requires that licensee initiated changes to the Process Control Program be submitted to the Commission in the Annual Radioactive Effluent Release Report for the period in which the change(s) was made.

Response: No changes were made to the process control program in 2020.

AppendixC Liquid Holdup Tanks Requirement: Technical Specification 3.11.1.4 limits the quantity ofradioactive material contained in any outside temporary tank. With the quantity of radioactive material in any outside temporary tank exceeding the limits of Technical Specification 3 .11.1.4, a description of the events leading to this condition is required in the next Annual Efiluent Release Report in accordance with Tech. Spec. 6.8.1.4.

Response: From January 1, 2020 to December 31, 2020, there was no radioactive material stored in any temporary outdoor tank that exceeded the limits ofT. S. 3.11.1.4.

AppendixD Radwaste Treatment Systems Requirement: Technical Specification 6.14.la requires that licensee initiated changes to the Radwaste Treatment Systems (liquid, gaseous, and solid) be submitted to the Commission in the Annual Radioactive Effluent Release Report for the period in which the change was made.

Response: For 2020 NextEra Energy Seabrook LLC, will submit any changes to the Radwaste Treatment Systems (liquid, gaseous and solid) as part of the FSAR update.

AppendixE Unplanned Releases Requirement: Technical Specification 6.8.1.4 requires a list and description of unplanned releases from the site to UNRESTRICTED AREAS ofradioactive materials in gaseous and liquid effluents made during the reporting period.

• Submit all groundwater monitoring well sample results and a description of any significant onsite leaks/spills that impact groundwater Response: A review of the January 1, 2020 to December 31, 2020 period indicated there were no unplanned, unanticipated or abnormal releases from the site to unrestricted areas of radioactive materials of gaseous or liquid effluents. See next sheet for groundwater monitoring well results.

EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT Supplemental Information 2020 Facility: Seabrook Station Unit 1 Licensee: NextEra Energy Seabrook, LLC

1. Regulatory Limits A. Gaseous Effluents

a. 5.0 mrad per quarter gamma air dose.

b. 10.0 mrad per quarter beta air dose.

c. 7 .5 mrem per quarter to any organ.

B. Liquid Effluents

a. 1.5 mrem per quarter total body.

b. 5.0 mrem per quarter any organ.

c. 2.0 E-04 µCi/ml dissolved or entrained gas.

2. Effluent Concentration Limits Provide the ECL's used in determining allowable release rates or concentrations.

a. Fission and activation gases: 10 ECL

b. Iodines: 10 ECL

c. Particulates, half-lives >8 days: 10 ECL

d. Liquid Effluents: 10 ECL

3. Average Energy Not applicable

4. Measurements and Approximations of Total Radioactivity Provide the methods used to measure or approximate the total radioactivity in effluents and the methods used to determine radionuclide composition.

A. Fission and activation gases: Determined by gamma spectroscopy. Total error is based on stack flow error, analytical error, and calculated sampling error.

B. Iodines: Determined by collection on charcoal with subsequent gamma spectroscopy analysis. Total error is based on stack flow error, analytical error, and calculated sampling error.

C. Particulates: Determined by collection on fixed filter with subsequent gamma spectroscopy analysis. Strontium is determined by composite analysis of filters by liquid scintillation, gross alpha by proportional counter and iron 55 by liquid scintillation. Total error is based on stack flow error, analytical error, and calculated sampling error.

D. Liquid Effluents: Determined by gamma spectroscopy. A composite sample is analyzed for strontium by liquid scintillation, tritium by liquid scintillation, gross alpha by proportional counter and iron 55 by liquid scintillation. Total error is based on the volume discharge error and analytical error.

E. ND: None Detected or No Detectable Activity

5. Batch Releases Provide the following information relating to batch releases of radioactive materials in liquid and gaseous effluents.

A. Liquid

a. Number of batch releases: 90

b. Total time for batch releases: 17693 minutes

c. Maximum time period for batch release: 917 minutes

d. Average time period for batch release: 197 minutes

e. Minimum time period for batch release: 24 minutes

f. Average stream flow during periods of release of effluents into a flowing stream: 1.61 E+06 liters per minute B. Gaseous

a. Number of batch releases: 28

b. Total time for batch releases: 49289 minutes

c. Maximum time period for batch release: 10348 minutes

d. Average time period for batch release: 1760 minutes

e. Minimum time period for batch release: 16 minute

6. Abnormal Releases A. Liquid

a. Number of releases: 0

b. Total activity released: NIA B. Gaseous

a. Number of releases: 0

b. Total activity released: NIA

TABLE lA EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 GASEOUS EFFLUENTS-SUMMATION OF ALL RELEASES Unit Quarter Quarter Quarter Quarter Est. Total 1 2 3 4 Error,%

A. Fission and activation gases

1. Total releases Ci 6.06E-02 1.30E+OO 1.45E-02 3.15E-02 1.70E+01 I

2. Average release rate uCi/sec for period 7.79E-03 1.65E-01 1.82E-03 3.96E-03

3. Percent of applicable Technical Specification  %

limit 1.29E-03 2.66E-02 1.59E-04 7.66E-04 B. Iodines

1. Total release Ci 3.79E-07 1.15E-06 ND ND 1.50E+01 I

2. Average release rate uCi/sec for period 4.87E-08 1.46E-07 N/A N/A

3. Percent of applicable Technical Specification  %

limit 1.53E-01 5.65E-01 N/A NIA C. Particulates

1. Total release

2. Average release rate Ci 2.05E+OO 5.02E+OO 3.13E+OO 1.86E+OO 1.80E+01 I uCi/sec for period 2.64E-01 6.38E-01 3.94E-01 2.34E-01

3. Percent of applicable Technical Specification  %

limit 1.53E-01 5.65E-01 1.97E-01 2.25E-01

4. Total alpha radioactivity Ci ND ND ND ND D. Tritium

1. Total release

2. Average release rate Ci 1.09E+01 3.58E+01 1.42E+01 1.56E+01 1.60E+01 I uCi/sec for period 1.40E+OO 4.55E+OO 1.79E+OO 1.96E+OO

3. Percent of applicable Technical Specification  %

limit 1.53E-01 5.65E-01 1.97E-01 2.25E-01

TABLE lB EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 GASEOUS EFFLUENTS-ELEVATED RELEASES BATCH Nuclides Released U .t Quarter Quarter Quarter Quarter rn 1 2 3 4

1. Fission and activation gases arqon-41 Ci 5.69E-02 1.30E+OO 1.38E-02 3.04E-02 krypton-85 Ci ND ND ND ND krypton-85m Ci ND ND ND ND krvpton-87 Ci ND ND ND ND krypton-88 Ci ND 1.35E-05 ND ND xenon-131 m Ci ND ND ND ND xenon-133 Ci 2.93E-03 ND ND ND xenon-133m Ci ND ND ND ND xenon-135 Ci 7.28E-04 2.53E-03 6.31 E-04 1.04E-03 xenon-135m Ci ND ND ND ND xenon-138 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period Ci 6.06E-02 1.30E+OO 1.45E-02 3.15E-02

2. Iodines iodine-131 Ci ND ND ND ND iodine-132 Ci ND ND ND ND iodine-133 Ci ND ND ND ND iodine-135 Ci ND ND ND ND Total for period Ci O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO

3. Particulates strontium-89 Ci ND ND ND ND strontium-90 Ci ND ND ND ND cesium-134 Ci ND ND ND ND cesium-137 Ci ND ND ND ND barium-lanthanum-140 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period Ci O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO

TABLE lB EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 GASEOUS EFFLUENTS-ELEVATED RELEASES CONTINUOUS Quarter Quarter Quarter Quarter Nuclides Released Unit 1 2 3 4

1. Fission and activation gases argon-41 Ci ND ND ND ND krypton-85 Ci ND ND ND ND krypton-85m Ci ND ND ND ND krypton-87 Ci ND ND ND ND krypton-88 Ci ND ND ND ND xenon-131m Ci ND ND ND ND xenon-133 Ci ND ND ND ND xenon-133m Ci ND ND ND ND xenon-135 Ci ND ND ND ND xenon-135m Ci ND ND ND ND xenon-138 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period Ci O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO

2. Iodines iodine-131 Ci ND 1.15E-06 ND ND iodine-132 Ci ND ND ND ND iodine-133 Ci ND ND ND ND iodine-135 Ci ND ND ND ND Total for period Ci O.OOE+OO 1.15E-06 O.OOE+OO O.OOE+OO

3. Particulates strontium-89 Ci ND ND ND ND strontium-90 Ci ND ND ND ND cesium-134 Ci ND ND ND ND cesium-137 Ci ND ND ND ND barium-lanthanum-140 Ci ND ND ND ND cobalt-58 Ci ND 6.67E-06 4.35E-06 ND cobalt-60 Ci ND ND ND ND chromium-51 Ci ND ND ND ND manganese-54 Ci ND ND ND ND niobium-95 Ci ND ND ND ND iron-59 Ci ND ND ND ND carbon-14 Ci 2.05E+OO 5.02E+OO 3.13E+OO 1.86E+OO unidentified Ci ND ND ND ND Total for period Ci 2.05E+OO 5.02E+OO 3.13E+OO 1.86E+OO

TABLE 2A EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 LIQUID EFFLUENTS-SUMMATION OF ALL RELEASES Est. Total Unit Quarter 1 Quarter 2 Quarter3 Quarter 4 Error,%

A. Fission and activation products

1. Total releases Ci 4.04E-03 4.57E-03 5.47E-03 2.07E-04 7.00E+OO I

2. Average diluted concentration uCi/ml 1.87E-11 2.89E-11 2.11 E-11 8.57E-13 durina nArinrl

3. Percent of applicable limit  % 1.73E-02 1.59E-02 2.69E-03 4.35E-04 B. Tritium

1. Total release Ci 7.76E+02 6.24E+01 1.38E+01 1.76E+01 9.00E+OO I

2. Average diluted concentration uCi/ml 3.59E-06 3.95E-07 5.33E-08 7.29E-08 durina nArinrl

3. Percent of applicable limit  % 7.36E-03 1.16E-02 3.08E-03 4.70E-04 C. Dissolved and entrained gases

1. Total release Ci ND ND ND ND 1.90E+01 I

2. Average diluted concentration uCi/ml N/A N/A N/A N/A durinn neriod

3. Percent of applicable limit  % N/A N/A N/A N/A D. Gross alpha radioactivity

11. Total release Ci ND ND ND ND 11.00E+01 I E. Volume of waste liters 2.28E+07 2.97E+07 2.02E+07 2.14E+07 1.30E+OO released (prior to dilution)

F. Volume of dilution liters 2.16E+11 1.58E+11 2.59E+11 2.41 E+11 9.00E+OO water used durina period

TABLE 2B EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 LIQUID EFFLUENTS BATCH MODE Nuclides Released Unit Quarter 1 Quarter 2 Quarter 3 Quarter4 strontium-89 Ci ND ND ND ND strontium-90 Ci ND ND ND ND cesium-134 Ci ND ND ND ND cesium-137 Ci ND ND ND 2.03E-06 iodine-131 Ci ND ND ND ND iodine-133 Ci ND ND ND ND cobalt-57 Ci ND ND 1.45E-05 ND cobalt-58 Ci 2.37E-04 2.82E-03 2.95E-03 1.05E-04 cobalt-60 Ci 2.13E-04 1.27E-04 2.62E-04 2.02E-05 chromium-51 Ci ND ND ND ND iron-55 Ci 1.34E-03 9.66E-04 8.93E-04 ND iron-59 Ci ND ND ND ND zinc-65 Ci 2.03E-06 ND ND ND manganese-54 Ci ND 1.36E-05 9.81E-06 2.02E-06 zirconium-niobium-95 Ci ND 1.15E-06 6.22E-06 ND molybdenum-99 Ci ND ND ND ND technetium-99m Ci ND ND ND ND silver-11 Om Ci ND ND ND ND barium-lanthanum-140 Ci ND ND ND ND cerium-141 Ci ND ND ND ND antimony-122 Ci ND ND ND ND antimony-124 Ci ND 4.96E-06 ND ND antimony-125 Ci 2.25E-03 4.13E-04 1.34E-03 7.73E-05 antimony-126 Ci ND ND ND ND niobium-97 Ci ND ND ND ND tin-117m Ci ND ND ND ND sodium-24 Ci ND ND ND ND Tellurium-129m Ci ND ND ND ND Tellurium-132 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period(above) Ci 4.04E-03 4.34E-03 5.47E-03 2.07E-04 xenon-133 Ci ND ND ND ND xenon-135 Ci ND ND ND ND

TABLE 2B EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 LIQUID EFFLUENTS CONTINUOUS MODE Nuclides Released Unit Quarter 1 Quarter 2 Quarter 3 Quarter 4 strontium-89 Ci ND ND ND ND strontium-90 Ci ND ND ND ND cesium-134 Ci ND ND ND ND cesium-137 Ci ND ND ND ND iodine-131 Ci ND ND ND ND iodine-133 Ci ND ND ND ND cobalt-57 Ci ND ND ND ND cobalt-58 Ci ND 2.24E-04 ND ND cobalt-60 Ci ND ND ND ND iron-55 Ci ND ND ND ND iron-59 Ci ND ND ND ND zinc-65 Ci ND ND ND ND manganese-54 Ci ND ND ND ND chromium-51 Ci ND ND ND ND zirconium-niobium-95 Ci ND ND ND ND molybdenum-99 Ci ND ND ND ND technetium-99m Ci ND ND ND ND barium-lanthanum-140 Ci ND ND ND ND cerium-141 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period(above) Ci O.OOE+OO 2.24E-04 O.OOE+OO O.OOE+OO xenon-131m Ci ND ND ND ND xenon-133m Ci ND ND ND ND xenon-133 Ci ND ND ND ND xenon-135 Ci ND ND ND ND

TABLE lC EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 GASEOUS EFFLUENTS-GROUND LEVEL RELEASES CONTINUOUS Quarter Quarter Quarter Quarter Nuclides Released Unit 1 2 3 4

1. Fission and activation gases argon-41 Ci ND ND ND ND krypton-85 Ci ND ND ND ND krypton-85m Ci ND ND ND ND krypton-87 Ci ND ND ND ND krypton-88 Ci ND ND ND ND xenon-133 Ci ND ND ND ND xenon-135 Ci ND ND ND ND xenon-135m Ci ND ND ND ND xenon-138 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period Ci O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO

2. Iodines iodine-131 Ci ND ND ND ND iodine-133 Ci ND ND ND ND Ci Total for period Ci O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO

3. Particulates strontium-89 Ci ND ND ND ND strontium-90 Ci ND ND ND ND cesium-134 Ci ND ND ND ND cesium-136 Ci ND ND ND ND cesium-137 Ci ND ND ND ND barium-lanthanum-140 Ci ND ND ND ND cobalt-58 Ci ND ND ND ND cobalt-60 Ci ND ND ND ND chromium-51 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period Ci O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO

TABLE lC EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 GASEOUS EFFLUENTS-GROUND LEVEL RELEASES BATCH Quarter Quarter Quarter Quarter Nuclides Released Unit 1 2 3 4

1. Fission and activation gases argon-41 Ci ND ND ND ND krypton-85 Ci ND ND ND ND krypton-85m Ci ND ND ND ND krvoton-87 Ci ND ND ND ND krvpton-88 Ci ND ND ND ND xenon-131m Ci ND ND ND ND xenon-133m Ci ND ND ND ND xenon-133 Ci ND ND ND ND xenon-135 Ci ND ND ND ND xenon-135m Ci ND ND ND ND xenon-138 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period Ci O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO

2. Iodines iodine-131 Ci ND ND ND ND iodine-132 Ci ND ND ND ND iodine-133 Ci 3.79E-07 ND ND ND iodine-135 Ci ND ND ND ND Total for period Ci 3.79E-07 O.OOE+OO O.OOE+OO O.OOE+OO

3. Particulates strontium-89 Ci ND ND ND ND strontium-90 Ci ND ND ND ND cesium-134 Ci ND ND ND ND cesium-136 Ci ND ND ND ND cesium-137 Ci ND ND ND ND barium-lanthanum-140 Ci ND ND ND ND cobalt-57 Ci ND ND ND ND cobalt-58 Ci ND ND ND ND cobalt-60 Ci ND ND ND ND manqanese-54 Ci ND ND ND ND iron-59 Ci ND ND ND ND niobium/zirconium-95 Ci ND ND ND ND chromium-51 Ci ND ND ND ND technetium-99m Ci ND ND ND ND bromine-82 Ci ND ND ND ND unidentified Ci ND ND ND ND Total for period Ci O.OOE+OO O.OOE+OO O.OOE+OO O.OOE+OO

EFFLUENT AND WASTE DISPOSAL ANNUAL REPORT 2020 SOLID WASTE AND IRRADIATED FUEL SHIPMENTS A. SOLID WASTE SHIPPED OFFSITE FOR BURIAL OR DISPOSAL (Not irradiated fuel) 1 year

1. Type of waste Unit Est. Total Period Error,%

a. Spent resins, filter sludges, evaporator ml 3.55E+OO Bottoms, etc. Ci 1.24E+02 2.50E+Ol

b. Dry compressible waste, contaminated ml 4.08E+Ol 2.50E+Ol Equip, etc. Ci 4.97E-01

c. Irradiated components, control ml Rods, etc.

NIA NIA Ci

d. Other (describe) ml Ci NIA NIA

2. Estimate of major nuclide composition (by type of waste)

a. Ni-63  % 7.56E+Ol Co-60  % 1.58E+Ol Fe-55  % 5.17E+OO Ni-59  % l.87E+OO Sb-125  % 5.84E-01 Mn-54  % 4.79E-01 Co-57  % 1.56E-01 Cs-137  % 1.31E-01 Zn-65  % 3.54E-02 H-3  % 2.76E-02 C-14  % l.74E-02 Cs-134  % l.17E-02 Co-58  % 4.SlE-03 Sr-90  % 2.37E-03 Pu-241  % 2.22E-03 Ce-144  % 1.04E-04 Am-241  % 1.52E-05

b. Fe-55  % 2.14E+Ol Ni-63  % 1.98E+Ol Nb-95  % 1.56E+Ol Co-58  % 1.40E+Ol H-3  % 1.38E+Ol Zr-95  % 9.98E+OO Co-60  % 3.56E+OO Cr-51  % 5.81E-01 Mn-54  % 4.85E-01 Sb-125  % 3.51E-01 Sn-113  % 2.59E-01 Co-57  % 7.SSE-02 Cs-137  % 7.27E-02 Sn-117m  % 4.03E-02

c. NIA  % NIA

d. NIA  % NIA

3. Solid Waste Disposition Number of Waste Container Solidification Mode of Destination Shi2ments Class T}'.Ee Agent Trans2ortation General Energy Solutions 3 A NIA Truck Design Oak Ridge, Tenn Resin Solutions 2 B Cask NIA Truck Irwin, Tenn B. IRRADIATED FUEL SIDPMENTS (Disposition)

Number of Shi2ments Mode ofTrans2ortation Destination NIA NIA NIA C. REVIEW AND APPROVAL Prepared By: Date: 04121/2021 Reviewed By: ... Date:

Approved By: Date:

2020 Ground Water Monitoring Well Tritium Data Date/Time BD-1 BD-2 BD-3 BD-4 BD-5 BD-6 BU-1 SC-1 SD-1 SD-2 SD-3 SD-4 SD-5 SU-1 SW-1 SW-2 SW-3 SW-4 SW-5 SW-6 SU-10 SU-11 BU-10 BU-11 TW-1 TW-2 TW-3 (pCi/L' (pCi/L' (pCi/L (pCi/L' (pCi/L' (pCi/L' (pCi/L' (pCi/L' (pCi/L' (pCi/L (pCi/L' (pCi/L' (pCi/L (pCi/L' (pCi/L' (pCi/L' (pCi/L (pCi/L (pCi/Ll (pCi/Ll (pCi/Ll (pCi/Ll (pCi/L' (pCi/Ll (pCi/Ll (pCi/Ll (pCi/Ll 01/03/20 <557 <560 788 02/12/20 1310 <557 04/07/20 <551 <552 06/24/20 717 641 824 524 08/10/20 <597 <598 <597 <598 <598 <598 <598 10/23/20 <611 <613 <608 <609 <609 <611 <606 <608 NW <608 11/06/20 <619 <621 <617 <617 12/02/20 <601 <605 <628 12/03/20 <611 <614 12/04/20 <611 <595 <613 <611 12/08/20 <593 Paired well locations: Selected well locations:

BD-1 Southwest of plant, south of cooling tower outside PA fence SW-1 South of Fuel Storage Building (Indicator location) inside PA fence SD-1 I BD-2 South of plant near seawall inside PA fence SW-2 East of plant near Service Water Pump House inside PA fence SD-2 I BD-3 East of plant inside owner controlled area SW-3 Southwest of plant near Unit 1 to Unit 2 tunnel inside PA fence SD-3 I BD-4 Northeast of plant inside owner controlled area SW-4 South of waste process building I steam generator blowdown room inside PA fence SD-4 I BD-5 Southwest of plant, south of cooling tower inside owner controlled area SW-5 West of service water building inside PA fence SD-5 I BD-6 South of Unit 2 containment equipment hatch outside PA fence SW-6 Southwest of demineralized tank 259 inside PA fence SU-1 I BU-1 Northwest of plant (Background location) inside owner controlled area TW-1 Southeast of plant inside owner controlled area outside PA fence SU-10 I BU-10 North I northwest of plant inside PA fence TW-2 Southeast of plant inside owner controlled area outside PA fence SU-11 I BU-11 North of plant inside PA fence TW-3 Southeast of plant inside owner controlled area outside PA fence Definitions:

Note: All sample results in pCi/L S = Shallow C = Cross gradient U = up gradient W=well B = Bedrock D = down gradient T = temporary

Enclosure 2 Joint Frequency Distributions of Wind Speed, Wind Direction, and Atmospheric Stability

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 43.0 FT WIND DATA STABILITY CLASS A CLASS FREQUENCY (PERCENT) 4.58 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW W WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 C-3 0 0 0 0 0 0 1 0 1 0 1 0 0 0 0 5

( 1) .00 .00 .00 .00 .28 .00 .00 .28 .00 .28 .00 .28 .28 .00 .00 .00 .00 1. 42 (2) .00 .00 .00 .00 .01 .00 .00 .01 .00 .01 .00 .01 .01 .00 .00 .00 .00 .06 4-7 0 0 3 18 21 9 16 11 11 11 8 2 3 0 0 121 (1I .00 .00 .85 5.10 5.95 2.55 4.53 1.13 3.12 1.13 3.12 3.12 2.27 .57 .85 .00 .00 34.28 (2) .00 .00 .04 .23 .27 .12 .21 .05 .14 .05 .14 . 14 .10 .03 .04 .00 .00 1. 57 8-12 0 0 6 28 24 8 19 33 9 14 8 11 12 15 0 0 194 (1) .00 .00 1. 70 7.93 6.80 2.27 5.38 9.35 2.55 3. 97 2.27 3.12 3.40 4.25 1. 98 .00 .00 54. 96 (2) .00 .00 .08 .36 .31 .10 .25 .43 .12 .18 .10 .14 .16 .19 .09 .00 .00 2.52 13-18 0 0 1 1 1 0 6 5 0 3 2 5 5 0 0 0 33 (1) .00 .00 .28 .28 .28 .00 1. 70 1. 42 .00 .85 .57 1.13 1. 42 1.42 .00 .00 .00 9.35 (2) .00 .00 .01 .01 .01 .00 .08 .06 .00 .04 .03 .05 .06 .06 .00 .00 .00 . 43 19-24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 GT 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

( 1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 ALL SPEEDS 0 10 47 47 17 41 43 20 22 21 27 26 22 10 0 0 353 (1I .00 .00 2.83 13.31 13.31 4.82 11.61 12.18 5.67 6.23 5.95 7.65 7.37 6.23 2.83 .00 .00 100.00 (2) .00 .00 .13 .61 .61 .22 .53 .56 .26 .29 .27 .35 .34 .29 .13 .00 .00 4.58 (l)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD c~ CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 43.0 FT WIND DATA STABILITY CLASS B CLASS FREQUENCY {PERCENT) 1.80 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .oo .oo .00 .00 .00 .oo .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .oo .00 .00 .00 .oo .00 .00 .00 .00 .00 .00 .00 .00 .00 C-3 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 2 (1) .00 .00

• 72 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00

• 72 .00 .00 1.44 (2) .00 .00 .01 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .01 .00 .00 .03 4-7 1 0 1 2 2 3 6 1 4 3 0 4 1 2 0 0 0 30 (1) .72 .00 . 72 1. 44 1. 44 2.16 4.32 .72 2.88 2.16 .00 2.88 .72 1.44 .00 .00 .00 21.58 (2) .01 .00 .01 .03 .03 .04 .08 .01 .05 .04 .00 .05 .01 .03 .00 .00 .00 .39 8-12 0 0 0 6 4 6 9 3 5 6 13 5 16 8 2 0 0 83 (1) .00 .00 .00 4.32 2.88 4.32 6.47 2.16 3.60 4.32 9.35 3.60 11.51 5.76 1. 44 .00 .00 59. 71 (2) .00 .00 .00 .08 .05 .08 .12 .04 .06 .08 .17 .06 .21 .10 .03 .00 .00 1.08 13-18 0 0 0 0 0 0 1 1 0 4 4 1 5 7 1 0 0 24 (1) .00 .00 .00 .00 .00 .00 .72 . 72 .00 2.88 2.88 .72 3.60 5.04 . 72 .00 .00 17.27 (2) .00 .00 .00 .00 .00 .00 .01 .01 .00 .05 .05 .01 .06 .09 .01 .00 .00 .31 19-24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .oo .oo .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .oo .00 .00 .00 .oo .00 .00 .00 .00 .00 .00 .00 .00 .00 GT 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .oo .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo .00 .00 .00 .00 ALL SPEEDS 1 0 2 8 6 9 16 5 9 13 17 10 22 17 4 0 0 139 (1) . 72 .00 1. 44 5.76 4.32 6.47 11.51 3.60 6.47 9.35 12.23 7.19 15.83 12.23 2.88 .00 .00 100.00 (2) .01 .00 .03 .10 .08 .12 .21 .06 .12 .17 .22 .13 .29 .22 .05 .00 .00 1.80

{l)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE

{2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM {WIND SPEED LESS THAN OR EQUAL TO . 95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 43.0 FT WIND DATA STABILITY CLASS C CLASS FREQUENCY (PERCENT) 3.98 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ill .00 .00 .00 .00 .00 .00 .00 .00 . 00 . 00 . 00 . 00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 C-3 0 0 1 0 1 0 1 0 0 2 0 1 0 0 1 0 0 (1I .00 .00 .33 .00 .33 .00 .33 .00 .00 .65 .00 .33 .00 .00 .33 .00 .00 2.28 (2) .00 .00 .01 .00 .01 .00 .01 .00 .00 .03 .00 .01 .00 .00 .01 .00 .00 .09 4-7 0 2 3 3 6 2 3 8 16 8 4 3 1 0 68

( 1I .00 .33 . 65 . 98 1. 30 . 98 1. 95 . 65 .98 1.30 2.61 5.21 2.61 1. 30 .98 .33 .00 22.15 (2) .00 .01 .03 .04 .05 .04 .08 .03 .04 .05 .10 .21 .10 .05 .04 .01 .00 .88 8-12 2 3 10 23 12 12 3 8 19 19 23 21 2 0 173 111 .65 .65 .98 3.26 7.49 3.91 3.91 2.28 .98 2.61 6.19 6.19 7.49 6.84 2.28 .65 .00 56 .35 (2) .03 .03 .04 .13 .30 .16 .16 .09 .04 .10 .25 .25 .30 .27 .09 .03 .00 2.24 13-18 2 0 1 0 2 0 0 2 0 2 2 2 18 17 0 0 57 111 .65 .00 .33 .00 .65 .00 .00 .65 .00 .65 .65 .65 2.93 5.86 5.54 .00 .00 18.57 (2 I .03 .00 .01 .00 .03 .00 .00 .03 .00 .03 .03 .03 .12 .23 .22 .00 .00 .74 19-24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 111 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .33 .00 .33 .00 .00 .00 .65 I2 I .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .01 .00 .01 .00 .00 .00 .03 GT 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 ALL SPEEDS 3 7 13 30 15 19 11 6 16 29 39 40 44 28 3 0 307 (1I 1.30 .98 2.28 4.23 9.77 4.89 6.19 3.58 1.95 5.21 9.45 12.70 13.03 14.33 9.12 .98 .00 100.00 (2) .05 .04 .09 .17 .39 .19 .25 .14 . 08 . 21 .38 .51 .52 .57 .36 .04 .00 3.98 (l)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C~ CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 43.0 FT WIND DATA STABILITY CLASS D CLASS FREQUENCY (PERCENT) 39.24 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 0 1 0 0 1 0 0 0 0 0 0 1 0 0 3 (1) .00 .00 .00 .00 .03 .00 .00 .03 .00 .00 .00 .00 .00 .00 .03 .00 .00 .10 (2) .00 .00 .00 .00 .01 .00 .00 .01 .oo .00 .00 .00 .oo .oo .01 .00 .00 .04 C-3 5 9 9 14 1 2 7 9 19 10 14 21 24 27 21 8 0 200 (1) .17 .30 .30 .46 .03 .07 .23 .30 .63 .33 .46 .69 .79 .89 .69 .26 .00 6.61 (2) .06 .12 .12 .18 .01 .03 .09 .12 .25 .13 .18 .27 .31 .35 .27 .10 .00 2.59 4-7 47 31 40 60 71 49 103 79 61 49 81 129 116 107 136 54 0 1213 (1) 1.55 1.02 1.32 1. 98 2.35 1. 62 3.40 2.61 2.02 1. 62 2.68 4. 26 3.83 3.54 4.49 1. 78 .00 40.09 (2) .61 .40 .52 .78 .92 .64 1.34 1. 02 .79 .64 1.05 1. 67 1.50 1.39 1. 76 .70 .00 15.73 8-12 32 17 59 66 92 55 58 35 26 30 105 74 130 202 167 36 0 1184 (1) 1.06 .56 1. 95 2.18 3.04 1. 82 1. 92 1.16 .86 .99 3.47 2.45 4.30 6.68 5.52 1.19 .00 39.13 (2) .41 .22 .77 .86 1.19 . 71 .75 .45 .34 .39 1.36 .96 1. 69 2.62 2.17 .47 .00 15.35 13-18 7 4 42 3 20 13 0 3 6 8 28 17 50 83 92 2 0 378 (1) .23 .13 1.39 .10 .66 .43 .00 .10 .20 .26 .93 .56 1. 65 2.74 3.04 .07 .oo 12.49 (2) .09 .05 .54 .04 .26 .17 .00 .04 .08 .10 .36 .22 .65 1.08 1.19 .03 .00 4.90 19-24 0 0 15 0 6 0 0 0 1 0 1 1 0 10 11 0 0 45 (1) .00 .00 .50 .00 .20 .00 .00 .00 .03 .00 .03 .03 .oo .33 .36 .00 .00 1.49 (2) .00 .00 .19 .00 .08 .00 .00 .00 .01 .00 .01 .01 .oo .13 .14 .00 .00 .58 GT 24 0 0 2 0 0 0 0 0 0 0 1 0 0 0 0 0 0 3 (1) .00 .00 .07 .00 .oo .00 .00 .00 .00 .00 .03 .00 .oo .oo .00 .00 .00 .10 (2) .00 .00 .03 .00 .00 .00 .00 .00 .00 .00 .01 .00 .00 .00 .00 .00 .00 .04 ALL SPEEDS 91 61 167 143 191 119 168 127 113 97 230 242 320 429 428 100 0 3026 (1) 3.01 2.02 5.52 4.73 6.31 3.93 5.55 4.20 3.73 3.21 7.60 8.00 10.58 14.18 14.14 3.30 .00 100.00 (2) 1.18 .79 2.17 1.85 2.48 1.54 2.18 1. 65 1. 47 1.26 2.98 3.14 4.15 5.56 5.55 1.30 .00 39.24 (l)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD c~ CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 43.0 FT WIND DATA STABILITY CLASS E CLASS FREQUENCY (PERCENT) 33.90 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 4 2 1 1 2 2 0 2 2 2 0 2 5 2 1 1 0 29 (1) .15 .08 .04 .04 .08 .08 .00 .08 .08 .08 .00 .08 .19 .08 .04 .04 .00 1.11 (2) .05 .03 .01 .01 .03 .03 .00 .03 .03 .03 .00 .03 .06 .03 .01 .01 .00 .38 C-3 26 15 22 24 17 13 16 22 44 47 54 81 103 95 57 25 0 661 (1) .99 .57 .84 .92 .65 .50 .61 .84 1. 68 1.80 2.07 3.10 3.94 3.63 2.18 .96 .00 25.29 (2) .34 .19 .29 .31 .22 .17 .21 .29 .57 .61 .70 1.05 1.34 1.23 .74 .32 .00 8.57 4-7 37 26 32 38 45 15 48 68 77 84 170 259 175 107 106 68 0 1355 (1) 1.42 .99 1.22 1. 45 1. 72 .57 1. 84 2.60 2.95 3.21 6.50 9.91 6.69 4.09 4.06 2.60 .oo 51. 84 (2) .48 .34 .41 .49 .58 .19 .62 .88 1. 00 1.09 2.20 3.36 2.27 1.39 1.37 .88 .00 17.57 8-12 7 10 20 26 16 7 29 37 16 27 52 75 31 34 32 16 0 435 (1) .27 .38 .77 .99 .61 .27 1.11 1.42 .61 1.03 1. 99 2.87 1.19 1.30 1.22 .61 .00 16.64 (2) .09 .13 .26 .34 .21 .09 .38 .48 .21 .35 .67 .97 .40 .44 .41 .21 .00 5.64 13-18 0 1 7 11 3 2 17 4 6 33 7 2 5 3 0 0 107 (1) .00 .04 .23 .27 .42 .11 .08 .65 .15 .23 1.26 .27 .08 .19 .11 .00 .00 4.09 (2) .00 .01 .08 .09 .14 .04 .03 .22 .05 .08 .43 .09 .03 .06 .04 .00 .00 1.39 19-24 0 0 0 0 6 0 0 4 3 1 5 0 0 3 4 0 0 26 (1) .oo .00 .00 .DO .23 .DO .00 .15 .11 .04 .19 .00 .DO .11 .15 .00 .DO .99 (2) .00 .00 .OD .DO .08 .OD .00 .05 .04 .01 .06 .00 .DO .04 .05 .00 .DO .34 GT 24 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 1 (1) .00 .00 .00 .00 .00 .00 .00 .OD .00 .00 .04 .00 .DO .00 .00 .00 .00 .04 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .01 .00 .00 .00 .00 .00 .00 .01 ALL SPEEDS 74 54 81 96 97 40 95 150 146 167 315 424 316 246 203 110 0 2614 (1) 2.83 2.07 3.10 3.67 3. 71 1.53 3.63 5.74 5.59 6.39 12.05 16.22 12.09 9.41 7.77 4.21 .DO 100.00 (2) .96 .70 1.05 1.24 1.26 .52 1.23 1. 95 1.89 2.17 4.09 5.50 4.10 3.19 2.63 1. 43 .DO 33.90 (l)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C~ CALM (WIND SPEED LESS THAN OR EQUAL TO . 95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 43.0 FT WIND DATA STABILITY CLASS F CLASS FREQUENCY (PERCENT) 9.56 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW W WNW NW NNW VRBL TOTAL MPH CALM 1 2 3 1 0 0 1 5 3 3 5 1 0 35 (1) .14 .54 .27 .41 .14 .14 .00 .00 .14 .14 .68 .41 .41 .54 .68 .14 .00 4.75 (2) .01 .05 .03 .04 .01 .01 .00 .00 .01 .01 .06 .04 .04 .05 .06 .01 .00 .45 C-3 7 7 14 5 10 18 24 46 57 89 63 40 23 0 422 (1I .81 .95 .95 1. 90 1. 22 .68 1.36 .54 2.44 3.26 6.24 7.73 12.08 8.55 5.43 3.12 .00 57.26 (2) .08 .09 .09 .18 .12 .06 .13 .05 .23 .31 . 60 .74 1.15 .82 .52 .30 .00 5.47 4-7 1 2 0 7 1 12 7 7 13 21 54 30 28 54 14 0 257 (1) .14 .27 .00 .81 .95 .14 1. 63 .95 .95 1.76 2.85 7.33 4.07 3.80 7.33 1. 90 .00 34.87 (2) .01 .03 .00 .08 .09 .01 .16 .09 .09 .17 .27 . 70 . 39 . 36 .70 .18 .00 3.33 8-12 0 0 0 0 1 0 1 2 2 1 6 2 0 0 0 0 19 (1 I .00 .00 .00 .00 .14 .00 .14 .27 .27 .14 .81 .27 . 00 . 00 .54 .00 .00 2.58 (2) .00 .00 .00 .00 .01 .00 .01 .03 .03 .01 .08 .03 .00 .00 .05 .00 .00 .25 13-18 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .54 .00 . 00 . 00 .00 .00 .00 .54 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .05 .00 . 00 . 00 .00 .00 .00 .05 19-24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 . 00 . 00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 . 00 . 00 .00 .00 .00 .00 GT 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 . 00 . 00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 . 00 . 00 .00 .00 .00 .00 ALL SPEEDS 8 13 23 18 7 23 13 28 39 82 116 122 95 103 38 0 737 (1) 1. 09 1.76 1.22 3.12 2.44 .95 3.12 1.76 3.80 5.29 11.13 15.74 16.55 12.89 13.98 5.16 .00 100.00 (2) .10 .17 .12 .30 .23 .09 .30 .17 . 36 .51 1.06 1.50 1.58 1.23 1.34 .49 .00 9.56 (l)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 43.0 FT WIND DATA STABILITY CLASS G CLASS FREQUENCY (PERCENT) 6.94 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 3 1 0 0 0 0 1 4 2 1 1 6 5 7 5 3 0 39 (1) .56 .19 .00 .00 .00 .00 .19 .75 .37 .19 .19 1.12 .93 1.31 .93 .56 .00 7.29 (2) .04 .01 .00 .00 .00 .00 .01 .05 .03 .01 .01 .08 .06 .09 .06 .04 .00 .51 C-3 3 4 14 1 3 12 21 20 23 60 90 108 37 21 0 425 (1) .56 .75 .75 2.62 .75 .19 .56 2.24 3.93 3.74 4.30 11.21 16.82 20.19 6.92 3.93 .00 79.44 (2) .04 .05 .05 .18 .05 .01 .04 .16 .27 .26 .30 .78 1.17 1.40 .48 .27 .00 5.51 4-7 0 0 0 0 1 0 0 1 2 4 3 10 3 20 21 2 0 67 (1) .00 .00 .00 .oo .19 .00 .00 .19 .37 . 75 .56 1.87 .56 3.74 3.93 .37 .00 12.52 (2) .00 .00 .00 .00 .01 .00 .00 .01 .03 .05 .04 .13 .04 .26 .27 .03 .00 .87 8-12 0 0 0 0 0 0 0 0 1 0 1 0 0 2 0 0 0 4 (1) .00 .00 .00 .00 .00 .00 .00 .00 .19 .00 .19 .00 .00 .37 .00 .00 .00 .75 (2) .00 .00 .00 .00 .00 .00 .00 .00 .01 .00 .01 .00 .00 .03 .00 .00 .00 .05 13-18 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .oo .oo .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .oo .oo .00 .oo .00 .00 .00 .00 .00 .00 .00 19-24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo .oo .00 .00 .00 .00 .00 .00 .00 GT 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .oo .oo .00 .00 .00 .00 .00 .00 .00 .00 .oo (2) .00 .00 .00 .00 .oo .00 .oo .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo ALL SPEEDS 6 5 4 14 5 1 4 17 26 25 28 76 98 137 63 26 0 535 (1) 1.12 .93 .75 2.62 .93 .19 .75 3.18 4. 86 4.67 5.23 14.21 18.32 25.61 11. 78 4.86 .00 100.00 (2) .08 .06 .05 .18 .06 .01 .05 .22 .34 .32 .36 .99 1.27 1. 78 .82 .34 .00 6.94 (l)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD c~ CALM (WIND SPEED LESS THAN OR EQUAL TO . 95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 43.0 FT WIND DATA STABILITY CLASS ALL CLASS FREQUENCY (PERCENT) 100.00 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW W WNW NW NNW VRBL TOTAL MPH CALM 8 7 3 4 3 7 5 4 6 11 13 13 12 5 0 106 (1) .10 .09 .04 .05 .05 .04 .01 .09 .06 .05 .08 .14 .17 .17 .16 .06 .00 1.37 (2 I .10 .09 .04 .05 .05 .04 .01 .09 .06 .05 .08 .14 .17 .17 .16 .06 .00 1.37 C-3 40 35 44 66 33 21 37 48 102 104 137 221 307 293 157 77 0 1722 (1) .52 .45 .57 .86 .43 .27 .48 .62 1.32 1.35 1. 78 2.87 3. 98 3.80 2.04 1. 00 .00 22.33 (2) .52 .45 .57 .86 .43 .27 .48 .62 1.32 1. 35 1. 78 2.87 3.98 3.80 2.04 1.00 .00 22.33 4-7 86 60 78 127 151 80 191 162 165 161 294 483 341 270 323 139 0 3111 (1) 1.12 .78 1. 01 1. 65 1. 96 1. 04 2.48 2.10 2.14 2.09 3.81 6.26 4.42 3.50 4.19 1. 80 .00 40.34 (2) 1.12 .78 1. 01 1. 65 1. 96 1. 04 2.48 2.10 2.14 2.09 3.81 6.26 4.42 3.50 4.19 1. 80 .00 40.34 8-12 41 29 88 136 160 88 128 117 62 86 204 186 212 282 219 54 0 2092 (1) .53 .38 1.14 1. 76 2.07 1.14 1. 66 1.52 .80 1.12 2.65 2.41 2.75 3.66 2.84 .70 .00 27.13 (2) .53 .38 1.14 1. 7 6 2.07 1.14 1. 66 1. 52 .80 1.12 2.65 2.41 2.75 3.66 2.84 .70 .00 27 .13 13-18 9 5 50 11 34 16 9 28 10 23 73 31 71 118 113 2 0 603 (1) .12 .06 .65 .14 .44 .21 .12 .36 .13 .30 .95 .40 .92 1. 53 1. 47 .03 .00 7.82 (2) .12 .06 .65 .14 .44 .21 .12 .36 .13 .30 .95 .40 .92 1.53 1. 47 .03 .00 7.82 19-24 0 0 15 0 12 0 0 4 4 1 6 2 0 14 15 0 0 73 (1) .00 .00 .19 .00 .16 .00 .00 .05 .05 .01 .08 .03 .00 .18 .19 .00 .00 .95 (2) .00 .00 .19 .00 .16 .00 .00 .05 .05 .01 .08 .03 .00 .18 .19 .00 .00 .95 GT 24 0 0 2 0 0 0 0 0 0 0 2 0 0 0 0 0 0 4 (1I .00 .00 .03 .00 .00 .00 .00 .00 .00 .00 .03 .00 .00 .00 .00 .00 .00 .05 (2) .00 .00 .03 .00 .00 .00 .00 .00 .00 .00 .03 .00 .00 .00 .00 .00 .00 .05 ALL SPEEDS 184 136 280 344 394 208 366 366 348 379 722 934 944 990 839 277 0 7711 (1) 2.39 1.76 3.63 4.46 5.11 2.70 4.75 4.75 4.51 4.92 9.36 12.11 12.24 12.84 10.88 3.59 .00 100.00 (2) 2.39 1.76 3.63 4.46 5.11 2.70 4.75 4.75 4.51 4.92 9.36 12.11 12.24 12.84 10.88 3.59 .00 100.00 (l)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C~ CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 209.0 FT WIND DATA STABILITY CLASS A CLASS FREQUENCY (PERCENT) 5.29 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .DO .00 C-3 0 0 0 0 1 1 0 0 0 0 1 1 1 0 0 0 0 5 (1) .00 .00 .00 .00 .24 .24 .00 .00 .00 .00 .24 .24 .24 .00 .00 .00 .00 1.21 (2) .00 .00 .00 .00 .01 .01 .00 .00 .00 .00 .01 .01 .01 .00 .00 .00 .00 .06 4-7 1 0 0 12 10 12 12 10 5 2 5 6 6 1 0 0 0 82 (1) .24 .00 .00 2.91 2.42 2.91 2.91 2.42 1.21 .48 1.21 1.45 1.45 .24 .00 .00 .00 19.85 (2) .01 .00 .00 .15 .13 .15 .15 .13 .06 .03 .06 .08 .08 .01 .00 .00 .00 1.05 8-12 0 0 2 12 32 16 26 34 19 13 5 13 12 2 0 0 0 186 (1) .00 .00 .48 2.91 7.75 3.87 6.30 8.23 4.60 3.15 1.21 3.15 2.91 .48 .00 .00 .00 45.04 (2) .00 .00 .03 .15 .41 .20 .33 .44 .24 .17 .06 .17 .15 .03 .00 .00 .00 2.38 13-18 0 0 1 1 1 6 3 41 13 6 9 15 12 6 1 0 0 115 (1) .00 .00 .24 .24 .24 1.45 .73 9.93 3.15 1. 45 2.18 3.63 2.91 1.45 .24 .00 .00 27.85 (2) .00 .00 .01 .01 .01 .08 .04 .53 .17 .08 .12 .19 .15 .08 .01 .00 .00 1. 47 19-24 0 0 0 0 1 0 1 13 0 3 0 2 1 0 0 0 0 21 (1) .00 .00 .00 .00 .24 .00 .24 3.15 .00 .73 .00 .48 .24 .00 .00 .00 .00 5.08 (2) .00 .00 .00 .00 .01 .00 .01 .17 .00 .04 .00 .03 .01 .00 .00 .00 .00 .27 GT 24 0 0 0 0 0 0 0 0 0 0 0 1 3 0 0 0 0 4 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .24 .73 .00 .00 .00 .00 .97 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .01 .04 .00 .00 .00 .00 .05 ALL SPEEDS 1 0 3 25 45 35 42 98 37 24 20 38 35 9 1 0 0 413 (1) .24 .00 .73 6.05 10.90 8.47 10.17 23.73 8.96 5.81 4.84 9.20 8.47 2.18 .24 .00 .00 100.00 (2) .01 .00 .04 .32 .58 .45 .54 1.26 .47 .31 .26 .49 .45 .12 .01 .00 .00 5.29 (l)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 209.0 FT WIND DATA STABILITY CLASS B CLASS FREQUENCY (PERCENT) 1. 73 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo C-3 0 0 0 0 0 1 0 0 0 1 0 0 0 0 2 0 0 4 (1) .00 .00 .00 .00 .00 .74 .00 .00 .00 .74 .00 .00 .00 .00 1.48 .00 .00 2.96 (2) .00 .00 .00 .00 .00 .01 .00 .00 .00 .01 .00 .00 .00 .00 .03 .00 .00 .05 4-7 0 0 0 1 1 0 2 1 2 0 0 1 2 0 0 1 0 11 (1) .00 .00 .00 .74 .74 .oo 1.48 .74 1.48 .00 .00 .74 1. 48 .00 .00 .74 .00 8.15 (2) .00 .00 .00 .01 .01 .oo .03 .01 .03 .00 .00 .01 .03 .00 .00 .01 .00 .14 8-12 0 0 0 4 6 7 3 3 7 5 4 3 3 1 0 0 50 (1) .00 .00 .00 2.96 2.96 4.44 5.19 2.22 2.22 5.19 3.70 2.96 2.22 2.22 .74 .00 .00 37.04 (2) .00 .00 .00 .05 .05 .08 .09 .04 .04 .09 .06 .05 .04 .04 .01 .00 .00 .64 13-18 0 0 0 1 0 0 6 8 2 3 5 7 10 6 3 0 0 51 (1) .00 .00 .00 .74 .00 .00 4.44 5.93 1. 48 2.22 3.70 5.19 7.41 4.44 2.22 .00 .00 37.78 (2) .00 .00 .00 .01 .00 .00 .08 .10 .03 .04 .06 .09 .13 .08 .04 .00 .00 .65 19-24 0 0 0 0 0 0 0 2 0 3 2 1 3 6 0 0 0 17 (1) .00 .00 .00 .00 .00 .00 .00 1.48 .00 2.22 1.48 .74 2.22 4.44 .00 .00 .00 12.59 (2) .00 .00 .00 .00 .00 .00 .00 .03 .00 .04 .03 .01 .04 .08 .00 .00 .00 .22 GT 24 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0 0 0 2 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 1. 48 .00 .00 .00 .00 1.48 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo .oo .oo .03 .00 .00 .00 .00 .03 ALL SPEEDS 0 0 0 6 5 7 15 14 7 14 12 13 20 15 6 1 0 135 (1) .00 .00 .00 4.44 3.70 5.19 11.11 10.37 5.19 10.37 8.89 9.63 14.81 11.11 4.44 .74 .00 100.00 (2) .00 .00 .00 .08 .06 .09 .19 .18 .09 .18 .15 .17 .26 .19 .08 .01 .00 1. 73 (l)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM (WIND SPEED LESS THAN OR EQUAL TO . 95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 209.0 FT WIND DATA STABILITY CLASS C CLASS FREQUENCY (PERCENT) 3.88 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 (1) .00 .00 .00 .00 .00 .00 .00 .33 .00 .00 .00 .oo .00 .00 .00 .00 .00 .33 (2) .00 .00 .00 .00 .00 .oo .00 .01 .00 .00 .00 .oo .00 .00 .00 .00 .00 .01 C-3 0 0 0 0 0 0 0 0 1 0 0 1 0 0 1 0 0 3 (1) .00 .00 .00 .00 .oo .00 .oo .oo .33 .oo .oo .33 .00 .00 .33 .00 .00 .99 (2) .00 .00 .00 .00 .00 .oo .oo .oo .01 .oo .oo .01 .00 .00 .01 .00 .00 .04 4-7 0 0 2 1 2 1 6 1 0 0 2 5 4 0 1 1 0 26 (1) .00 .00 .66 .33 .66 .33 1. 98 .33 .00 .00 .66 1. 65 1.32 .00 .33 .33 .00 8.58 (2) .00 .00 .03 .01 .03 .01 .08 .01 .00 .00 .03 .06 .05 .00 .01 .01 .00 .33 8-12 2 3 2 8 11 14 16 7 5 6 11 21 20 9 2 3 0 140 (1) .66 .99 .66 2.64 3.63 4.62 5.28 2.31 1. 65 1. 98 3.63 6.93 6.60 2.97 . 66 .99 .00 46.20 (2) .03 .04 .03 .10 .14 .18 .20 .09 .06 .08 .14 .27 .26 .12 .03 .04 .00 1. 79 13-18 0 0 1 3 3 2 1 6 5 1 8 9 12 16 20 2 0 89 (1) .00 .00 .33 .99 .99 .66 .33 1. 98 1. 65 .33 2.64 2.97 3.96 5.28 6.60 .66 .00 29.37 (2) .00 .00 .01 .04 .04 .03 .01 .08 .06 .01 .10 .12 .15 .20 .26 .03 .00 1.14 19-24 2 0 1 0 0 0 0 2 1 1 1 2 4 11 12 0 0 37 (1) .66 .00 .33 .00 .00 .00 .00 .66 .33 .33 .33 .66 1.32 3.63 3.96 .00 .00 12.21 (2) .03 .00 .01 .00 .00 .oo .00 .03 .01 .01 .01 .03 .05 .14 .15 .00 .00 .47 GT 24 0 0 0 0 0 0 0 0 0 0 0 1 5 1 0 0 0 7 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo .oo .33 1. 65 .33 .00 .00 .00 2.31 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .01 .06 .01 .00 .00 .00 .09 ALL SPEEDS 4 3 6 12 16 17 23 17 12 8 22 39 45 37 36 6 0 303 (1) 1.32 .99 1. 98 3.96 5.28 5.61 7.59 5.61 3. 96 2.64 7.26 12.87 14.85 12.21 11. 88 1. 98 .00 100.00 (2) .05 .04 .08 .15 .20 .22 .29 .22 .15 .10 .28 .50 .58 .47 .46 .08 .00 3.88 (l)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM (WIND SPEED LESS THAN OR EQUAL TO . 95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 209.0 FT WIND DATA STABILITY CLASS D CLASS FREQUENCY (PERCENT) 38.34 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 3 (1) .00 .03 .03 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .03 .00 .10 (2) .00 .01 .01 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .01 .00 .04 C-3 1 5 6 7 3 2 1 3 5 4 7 6 5 10 7 7 0 79 (1) .03 .17 .20 .23 .10 .07 .03 .10 .17 .13 .23 .20 .17 .33 .23 .23 .00 2.64 (2) .01 .06 .08 .09 .04 .03 .01 .04 .06 .05 .09 .08 .06 .13 .09 .09 .00 1.01 4-7 14 21 20 27 31 33 63 33 27 20 34 44 53 33 46 27 0 526 (1) .47 .70 . 67 .90 1.04 1.10 2.10 1.10 .90 .67 1.14 1. 47 1. 77 1.10 1.54 .90 .00 17.57 (2) .18 .27 .26 .35 .40 .42 .81 .42 .35 .26 .44 .56 .68 .42 .59 .35 .00 6.74 8-12 53 38 51 66 56 60 75 68 66 42 76 91 93 108 139 79 0 1161 (1) 1. 77 1.27 1. 70 2.21 1.87 2.00 2.51 2.27 2.21 1.40 2.54 3.04 3.11 3.61 4.64 2.64 .00 38.79 (2) .68 .49 .65 .85 . 72 .77 .96 .87 .85 .54 .97 1.17 1.19 1.38 1. 78 1. 01 .00 14.87 13-18 24 24 38 20 29 14 30 41 23 20 77 53 97 161 184 25 0 860 (1) .80 .80 1.27 .67 .97 .47 1.00 1.37 .77 .67 2.57 1. 77 3.24 5.38 6.15 .84 .00 28.73 (2) .31 .31 .49 .26 .37 .18 .38 .53 .29 .26 .99 .68 1.24 2.06 2.36 .32 .00 11.02 19-24 8 8 22 2 11 10 4 3 5 2 29 13 44 54 68 1 0 284 (1) .27 .27 .74 .07 .37 .33 .13 .10 .17 .07 .97 .43 1.47 1.80 2.27 .03 .00 9.49 (2) .10 .10 .28 .03 .14 .13 .05 .04 .06 .03 .37 .17 .56 .69 .87 .01 .00 3.64 GT 24 0 4 16 0 3 1 0 1 1 0 3 2 16 21 12 0 0 80 (1) .00 .13 .53 .00 .10 .03 .00 .03 .03 .00 .10 .07 .53 .70 .40 .00 .00 2.67 (2) .00 .05 .20 .00 .04 .01 .oo .01 .01 .00 .04 .03 .20 .27 .15 .00 .00 1.02 ALL SPEEDS 100 101 154 122 133 120 173 149 127 88 226 209 308 387 456 140 0 2993 (1) 3.34 3.37 5.15 4.08 4.44 4.01 5.78 4.98 4.24 2.94 7.55 6.98 10.29 12.93 15.24 4.68 .00 100.00 (2) 1.28 1.29 1. 97 1.56 1. 70 1.54 2.22 1. 91 1. 63 1.13 2.89 2.68 3.95 4.96 5.84 1. 79 .00 38.34 (l)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM (WIND SPEED LESS THAN OR EQUAL TO . 95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 209.0 FT WIND DATA STABILITY CLASS E CLASS FREQUENCY (PERCENT) 34.51 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 1 1 0 1 0 0 0 0 0 0 1 0 0 0 4 (1) .00 .00 .00 .04 .04 .00 .04 .00 .00 .00 .00 .00 .00 .04 .00 .00 .00 .15 (2) .00 .00 .00 .01 .01 .00 .01 .00 .00 .00 .00 .00 .00 .01 .00 .00 .00 .05 C-3 3 7 8 13 6 5 10 3 5 9 5 11 9 13 8 6 0 121 (1) .11 .26 .30 .48 .22 .19 .37 .11 .19 .33 .19 .41 .33 .48 .30 .22 .00 4.49 (2) .04 .09 .10 .17 .08 .06 .13 .04 .06 .12 .06 .14 .12 .17 .10 .08 .00 1.55 4-7 37 33 25 27 26 16 28 32 42 36 36 38 42 49 56 35 0 558 (1) 1.37 1.22 .93 1. 00 .97 .59 1. 04 1.19 1.56 1.34 1.34 1. 41 1.56 1.82 2.08 1.30 .00 20. 71 (2) .47 .42 .32 .35 .33 .20 .36 .41 .54 .46 .46 .49 .54 .63

• 72 .45 .00 7.15 8-12 69 56 31 24 19 16 28 64 82 102 148 178 119 121 104 62 0 1223 (1) 2.56 2.08 1.15 .89 .71 .59 1. 04 2.38 3.04 3.79 5.49 6.61 4.42 4.49 3.86 2.30 .00 45.40 (2) .88

• 72 .40 .31 .24 .20 .36 .82 1.05 1.31 1. 90 2.28 1.52 1.55 1.33 .79 .00 15.67 13-18 9 12 8 17 6 5 15 41 25 40 111 123 84 82 51 15 0 644 (1) .33 .45 .30 .63 .22 .19 .56 1.52 .93 1.48 4.12 4.57 3.12 3.04 1.89 .56 .00 23.90 (2) .12 .15 .10 .22 .08 .06 .19 .53 .32 .51 1. 42 1.58 1. 08 1. 05 .65 .19 .00 8.25 19-24 0 2 4 2 12 1 6 20 7 21 5 8 14 8 1 0 115 (1) .00 .07 .15 .07 .45 .04 .22 .74 .26 .15 .78 .19 .30 .52 .30 .04 .00 4.27 (2) .00 .03 .05 .03 .15 .01 .08 .26 .09 .05 .27 .06 .10 .18 .10 .01 .00 1.47 GT 24 0 0 4 1 7 1 2 9 4 0 1 0 0 0 0 0 0 29 (1) .00 .00 .15 .04 .26 .04 .07 .33 .15 .00 .04 .00 .00 .00 .00 .00 .00 1. 08 (2) .00 .00 .05 .01 .09 .01 .03 .12 .05 .00 .01 .00 .00 .00 .00 .00 .00 .37 ALL SPEEDS 118 110 80 85 77 44 90 169 165 191 322 355 262 280 227 119 0 2694 (1) 4.38 4. 08 2.97 3.16 2.86 1. 63 3.34 6.27 6.12 7.09 11. 95 13.18 9.73 10.39 8.43 4.42 .00 100.00 (2) 1.51 1. 41 1. 02 1.09 .99 .56 1.15 2.16 2.11 2.45 4.12 4.55 3.36 3.59 2.91 1.52 .00 34.51

( 1) =PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 209.0 FT WIND DATA STABILITY CLASS F CLASS FREQUENCY (PERCENT) 9.62 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 C-3 1 0 1 5 2 3 3 6 1 7 2 0 6 5 4 4 0 50 (1) .13 .00 .13 .67 .27 .40 .40 .80 .13 .93 .27 .00 .80 .67 .53 .53 .00 6.66 (2) .01 .00 .01 .06 .03 .04 .04 .08 .01 .09 .03 .00 .08 .06 .05 .05 .00 . 64 4-7 13 6 9 4 7 8 11 18 23 21 17 14 21 13 8 14 0 207 (1) 1. 73 .80 1.20 .53 .93 1.07 1.46 2.40 3.06 2.80 2.26 1. 86 2.80 1. 73 1.07 1.86 .00 27.56 (2) .17 .08 .12 .05 .09 .10 .14 .23 .29 .27 .22 .18 .27 .17 .10 .18 .00 2.65 8-12 24 8 5 3 6 3 4 9 17 37 56 40 45 56 26 22 0 361 (1) 3.20 1. 07 .67 .40 .80 .40 .53 1.20 2.26 4.93 7.46 5.33 5.99 7.46 3.46 2.93 .00 48.07 (2) .31 .10 .06 .04 .08 .04 .05 .12 .22 .47 . 72 .51 .58 .72 .33 .28 .00 4.62 13-18 10 0 0 0 1 0 0 12 1 6 19 14 17 12 15 15 0 122 (1) 1.33 .00 .00 .00 .13 .00 .00 1. 60 .13 .80 2.53 1.86 2.26 1. 60 2.00 2.00 .00 16.25 (2) .13 .00 .00 .00 .01 .00 .00 .15 .01 .08 .24 .18 .22 .15 .19 .19 .00 1.56 19-24 0 0 0 0 0 0 0 0 0 2 0 1 0 0 7 1 0 11 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .27 .00 .13 .00 .00 . 93 .13 .00 1. 46 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .03 .00 .01 .00 .00 .09 .01 .00 .14 GT 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo .00 .00 .00 .00 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .oo .00 .00 .00 .00 ALL SPEEDS 48 14 15 12 16 14 18 45 42 73 94 69 89 86 60 56 0 751 (1) 6.39 1. 86 2.00 1. 60 2.13 1.86 2.40 5.99 5.59 9. 72 12.52 9.19 11.85 11. 45 7.99 7.46 .00 100.00 (2) .61 .18 .19 .15 .20 .18 .23 .58 .54 .94 1.20 .88 1.14 1.10 .77 . 72 .00 9.62 (l)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 209.0 FT WIND DATA STABILITY CLASS G CLASS FREQUENCY (PERCENT) 6.64 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW w WNW NW NNW VRBL TOTAL MPH CALM 0 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 2 (1) .00 .19 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .19 .00 .00 .39 (2) .00 .01 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .00 .01 .00 .00 .03 C-3 2 1 2 4 2 3 4 2 6 5 3 3 4 5 6 2 0 54 (1) .39 .19 .39 .77 .39 .5S .77 .39 1.16 .97 .5S .5S .77 .97 1.16 .39 .00 10.42 (2) .03 .01 .03 .05 .03 .04 .05 .03 .OS .06 .04 .04 .05 .06 .OS .03 .00 .69 4-7 7 6 10 6 6 6 7 s 22 24 22 27 lS 15 10 4 0 19S (1) 1.35 1.16 1. 93 1.16 1.16 1.16 1.35 1.54 4.25 4.63 4.25 5.21 3.47 2.90 1. 93 .77 .00 3S.22 (2) .09 .OS .13 .OS .OS .OS .09 .10 .2S .31 .2S .35 .23 .19 .13 .05 .00 2.54 S-12 5 3 1 1 1 1 4 14 15 26 31 35 26 lS 7 12 0 200 (1) .97 .5S .19 .19 .19 .19 .77 2.70 2.90 5.02 5.9S 6. 76 5.02 3.47 1.35 2.32 .00 3S.61 (2) .06 .04 .01 .01 .01 .01 .05 .lS .19 .33 .40 .45 .33 .23 .09 .15 .00 2.56 13-lS 3 0 1 0 0 0 0 1 1 6 6 6 s s 12 0 59 (1) .5S .00 .19 .00 .00 .00 .00 .19 .19 1.16 1.16 1.16 1.35 1.54 1.54 2.32 .00 11.39 (2) .04 .00 .01 .00 .00 .00 .00 .01 .01 .OS .OS .OS .09 .10 .10 .15 .00 .76 19-24 0 0 0 0 0 0 0 0 0 1 2 0 0 1 1 0 0 5 (1) .00 .00 .00 .00 .00 .00 .00 .00 .00 .19 .39 .00 .00 .19 .19 .00 .00 .97 (2) .00 .00 .00 .00 .00 .00 .00 .00 .00 .01 .03 .00 .00 .01 .01 .00 .00 .06 GT 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 (1) .00 .00 .00 .00 .00 .00 .00 .oo .oo .oo .oo .00 .00 .00 .00 .00 .00 .oo (2) .00 .00 .00 .00 .00 .00 .00 .00 .oo .00 .00 .00 .00 .00 .00 .00 .00 .00 ALL SPEEDS 17 11 14 11 9 10 15 25 44 62 64 71 55 47 33 30 0 51S (1) 3.2S 2.12 2.70 2.12 1. 74 1. 93 2.90 4.S3 S.49 11. 97 12.36 13. 71 10.62 9.07 6.37 5.79 .00 100.00 (2) .22 .14 .lS .14 .12 .13 .19 .32 .56 .79 .S2 .91 .70 . 60 .42 .3S .00 6.64 (l)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)=PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C= CALM (WIND SPEED LESS THAN OR EQUAL TO . 95 MPH)

SEABROOK JAN20-DEC20 MET DATA JOINT FREQUENCY DISTRIBUTION (210-FOOT TOWER) 209.0 FT WIND DATA STABILITY CLASS ALL CLASS FREQUENCY (PERCENT) 100.00 WIND DIRECTION FROM SPEED N NNE NE ENE E ESE SE SSE s SSW SW WSW W WNW NW NNW VRBL TOTAL MPH CALM 2 1 1 0 1 1 0 0 0 0 1 1 0 10 (1) .00 .03 .01 .01 .01 .00 .01 .01 .00 .00 .00 .00 .00 .01 .01 .01 .00 .13 (2) .00 .03 .01 .01 .01 .00 .01 .01 .00 .00 .00 .00 .00 .01 .01 .01 .00 .13 C-3 7 13 17 29 14 15 18 14 18 26 18 22 25 33 28 19 0 316 (1) .09 .17 .22 .37 .18 .19 .23 .18 .23 .33 .23 .28 .32 .42 .36 .24 .00 4.05 (2) . 09 .17 .22 .37 .18 .19 .23 .18 .23 .33 .23 .28 .32 .42 .36 .24 .00 4.05 4-7 72 66 66 78 83 76 129 103 121 103 116 135 146 111 121 82 0 1608 I 1l .92 .85 .85 1. 00 1. 06 . 97 1. 65 1.32 1. 55 1. 32 1. 4 9 1. 73 1. 87 1.42 1.55 1. 05 .00 20.60 (2) .92 .85 .85 1. 00 1. 06 .97 1. 65 1. 32 1. 55 1. 32 1. 49 1. 73 1. 87 1. 42 1.55 1. 05 .00 20.60 8-12 153 108 92 118 129 116 160 199 207 233 332 382 318 317 279 178 0 3321 (1) 1. 96 1. 38 1.18 1. 51 1. 65 1. 49 2.05 2.55 2.65 2.98 4.25 4.89 4.07 4.06 3.57 2.28 .00 42.54 (2) 1. 96 1. 38 1.18 1.51 1. 65 1.49 2.05 2.55 2.65 2.98 4.25 4.89 4.07 4.06 3.57 2.28 .00 42.54 13-18 46 36 49 42 40 27 55 150 70 82 235 227 239 291 282 69 0 1940 (1) .59 .46 .63 .54 .51 .35 .70 1. 92 .90 1. 05 3.01 2.91 3.06 3.73 3.61 .88 .00 24.85 (2) .59 .46 .63 .54 .51 .35 .70 1. 92 .90 1. 05 3.01 2.91 3.06 3.73 3.61 .88 .00 24.85 19-24 10 10 27 24 11 11 40 13 16 55 24 60 86 96 3 0 490 I 1l .13 .13 .35 .05 .31 .14 .14 .51 .17 .20 .70 .31 .77 1.10 1.23 .04 .00 6.28 (2) .13 .13 .35 .05 .31 .14 .14 .51 .17 .20 . 70 .31 .77 1.10 1. 23 .04 .00 6.28 GT 24 0 4 20 1 10 2 2 10 5 0 4 4 26 22 12 0 0 122 (1) .00 .05 .26 .01 .13 .03 .03 .13 .06 .00 .05 .05 .33 .28 .15 .00 .00 1.56 (2) .00 .05 .26 .01 .13 .03 .03 .13 .06 .00 .05 .05 .33 .28 .15 .00 .00 1. 56 ALL SPEEDS 288 239 272 273 301 247 376 517 434 460 760 794 814 861 819 352 0 7807 (1) 3.69 3.06 3. 48 3.50 3.86 3.16 4.82 6. 62 5.56 5.89 9.73 10.17 10.43 11.03 10.49 4.51 .00 100.00

12) 3.69 3.06 3.48 3.50 3.86 3.16 4.82 6.62 5.56 5.89 9.73 10.17 10.43 11.03 10.49 4.51 .00 100.00 (l)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PAGE (2)~PERCENT OF ALL GOOD OBSERVATIONS FOR THIS PERIOD C~ CALM (WIND SPEED LESS THAN OR EQUAL TO .95 MPH)

Enclosure 3 Radiation Dose Assessment

SEABROOK STATION RADIOLOGICAL EFFLUENT TMP ACT ASSESSMENT FOR 2020 (Annual Radioactive Efiluent Release Repo1t)

Prepared for NextEra Energy Seabrook, LLC P.O. Box300 Seabrook, NH 03874 by Framatome Inc.

Lynchburg, VA 24506 Framatome Document No. 103-3921-000 Date:. _ _~4/~1=2/~2~1_ _ _ __

f Reviewer: -~""'--']f,'>-U<~~ft....,.r,t/J,"'-"'-:v-/-L,7/jl-h"R......,')JAL.,.10L.><'11_ _ __

Ted Messier, Framatome Inc.

Meteorologist

/~ /

Approver:-~~~------:::::-_-_-::--=--....._~~---- Date: _'t---'--+--/~/l_=-1/_J._l__

Ryan Hosler, Framatome Inc. """' I I Supervisor

Reference:

Framatome Calculation 32-9326441-000

Seabrook Station Radiological Effluent Impact Assessment For 2020 (Annual Radioactive Effluent Release Report)

I. Summary Seabrook Technical Specification Sections 6.7.6.g.4 & 9 require that limitations be placed on the quarterly and annual doses or dose commitments to Members of the Public from radioactive materials in liquid and gaseous effluents released from the station to Unrestricted Areas at or beyond the site boundary conforming to the dose objectives of Appendix I to 10 CFR Part 50. Technical Specification 6.7.6.g.8 requires that limitations on the quarterly and annual air doses resulting from noble gases released in gaseous effluents to areas beyond the site boundary also conform to Appendix I to 10 CFR Part 50. In a similar fashion, Technical Specification 6. 7 .6.g.11 requires limitations on the annual dose or dose commitment to any Member of the Public due to radioactivity and radiation from uranium fuel cycle sources conforming to the EPA Radiation Standards in 40 CFR Part 190. The following table details the above referenced effluent dose limits.

DOSE OBJECTIVE CRITERIA FOR COMPLIANCE EFFLUENT TYPE DOSE TYPE QUARTERLY LIMITS ANNUAL LIMITS Total Body 1.5 mrem 3 mrem LIQUIDS (IOCFR50, APP. I)

Max. Organ 5 mrem 10 mrem Gamma Air 5 mrad 10 mrad NOBLE GAS (IOCFR50, APP. I)

BetaAir 10 mrad 20 mrad GAS PARTICULATE (IOCFR50, APP. I) Max. Organ 7.5 mrem 15 mrem Total Body & organ TOTAL DOSE 25 mrem (40CFR190)

[liquids, gas, direct]

Thyroid --- 75 mrem Technical Specification 6.8.1.4 and the Seabrook Offsite Dose Calculation Manual (ODCM) Part A, Section 10.2, provide that the Station's Annual Radioactive Effluent Release Report include a demonstration of compliance with the above off-site dose limitations, as well as the determination of dose impacts to Members of the Public who may be associated with permitted activities inside the site boundary.

Doses resulting from actual liquid and gaseous effluents from Seabrook Station during 2020 were calculated in accordance with Method II as defined in the Station ODCM. The calculation methods follow the models in Regulatory Guide 1.109 (Reference 1). The assessments included maximum whole body doses and organ doses from all liquid releases, maximum offsite organ doses resulting from airborne Iodine, Tritium, Carbon-14 and particulate radionuclides with half-lives greater than eight days, and maximum offsite beta air and gamma air doses from airborne noble gases. Calculated dose impacts from airborne effluents included atmospheric dispersion estimates utilizing concurrent meteorology recorded by the Station's on-site meteorological tower. In addition, the potential direct dose from fixed radiation

sources from both plant operations and dry fuel storage were evaluated as part of the assessment required under 40 CFR Part 190 for doses from the uranium fuel cycle.

Doses were also calculated for three special receptor locations inside the site boundary where the public might be granted access for recreational or educational purposes. The Science and Nature Center is located in the southwest portion of the site and offers educational opportunities on nuclear power and the environment. The Fitness Center is located in the Hi-Rise office building, approximately 384 meters WSW from the plant vent stack. A third on-site location considered is the Firing Range for security force training (including local law enforcement), which straddles the West site boundary at approximately 974 meters from the plant vent stack. Another location which had been included in the past was the "Rocks" boat launching ramp in an area northeast of the main plant facilities with access to Brown's Creek and the tidal marsh that borders the site. This location has been dropped from consideration of public on-site activities due to restricted public access limitation as a result of security and safety concerns and abandonment of the boat launching ramp.

All calculated liquid and gaseous pathway doses for the 2020 reporting period are well below the dose criteria of 10 CFR Part 50, Appendix I, and the dose limits for effluent releases stated in the ODCM. In addition, the total dose to the most limiting Member of the Public due to the combined exposure to plant liquid and gaseous effluents and direct radiation from fixed plant and dry fuel storage sources was below the dose standards of 40 CFR Part 190.

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II. Method for Calculating the Total Body and Maximum Organ Doses Resulting from Liquid Releases Liquid waste generated during plant operations is processed and discharged to the environment via the station's circulating water cooling system. The cooling system utilizes an offshore-submerged multi-port diffuser discharge for rapid dissipation and mixing of liquid effluents in the ocean environment. A 22-port diffuser section of the discharge system is located in approximately 50 to 60 feet of water with each nozzle 7 to 10 feet above the sea floor. Eleven riser shafts, with two discharge nozzles for each diffuser, are spaced about 100 feet apart over a distance of about 1000 feet. Water is discharged in a generally eastward direction away from the shoreline through the multiport diffuser, beginning at a location over one mile offshore. During power operations, these high velocity jets passively entrain about ten volumes of fresh water into the near field jet-mixing region before the plume reaches the water surface.

This arrangement also effectively prevents the discharge plume (at least to the 1 degree or 40 to 1 dilution isopleth) from impacting the shoreline over the tidal cycle.

During shutdown periods, the high velocity jet mixing created by the normal circulating water flow at the diffuser nozzles is reduced. However, mixing within the discharge tunnel water volume is significantly increased due to the long transit time for batch discharges to travel the three miles from the plant through the 19-foot diameter tunnels to the diffuser nozzles. Additional mixing of the effluent in the near field assures that an equivalent overall 10 to 1 dilution occurs by the time the effluent reaches the ocean surface.

The exposure pathways considered in the calculations of total body and maximum organ doses resulting from liquid discharges from Seabrook Station are limited to ingestion of aquatic foods and exposure to shoreline deposits. The dose calculations do not include the ingestion of potable water or irrigated vegetation as potential exposure pathways because the liquid effluents from the plant are discharged into salt water.

The dose assessment models utilized in the Offsite Dose Calculation Manual (Reference 2) are taken from Regulatory Guide 1.109 (Reference 1). The total body and organ doses are evaluated for each of the four age groups (i.e., infant, child, teen and adult) to determine the maximum total body dose and maximum organ dose via all existing exposure pathways (i.e., fish and aquatic invertebrate ingestion, and shoreline exposure) to an age-dependent individual from all detected radionuclides in plant releases. The values for the various factors considered in the model equations are provided in Regulatory Guide 1.109 and the ODCM (see Table D). The flow rate (F) of the liquid effluent and the radionuclide activities (Qi) are measured specifically prior to each liquid release. The values for half-lives for radionuclides (Tl/2) and their radioactive decay constants ("1) have been taken from Kocher (Reference 3).

Table A presents the calculated liquid pathway doses for each calendar quarter and total for the year. The calculated annual doses as a percent of the applicable regulatory limits are shown in Table C.

The estimated quarterly and annual doses resulting from liquid effluents to members of the public are well below all dose limit criteria.

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III. Method for Calculating the Gamma and Beta Air Doses from Noble Gases Gamma and beta air doses due to noble gases in gaseous effluents are calculated for several receptor locations when noble gases are recorded in effluents. Those locations include the points in each of the sixteen principle compass directions of estimated highest off-site ground level air concentration of radioactive material, site boundary (or closest point on the opposite shoreline in directions which are bordered by the tidal marsh), nearest resident, nearest vegetable garden, and nearest milk animal within five miles. The special on-site receptor locations (Science and Nature Center, the Fitness Center and the Firing Range) are evaluated for whole body dose to an individual from the noble gas component of effluents predicted to pass nearby.

Atmospheric dispersion factors (i.e., X/Q factors) calculated from recorded concurrent site meteorological data (i.e., meteorological data measurements taken during the time of the release) are used in the estimation of receptor specific air concentrations due to station effluents. The atmospheric dispersion estimations utilize methodology generally consistent with US NRC Regulatory Guide 1.111 (Reference 4).

Beta air doses use undepleted X/Qs and assume a semi-infinite plume at the point of exposure. Gamma air doses are calculated using the finite cloud model presented in "Meteorology and Atomic Energy - 1968" (Reference 5). That model is implemented through the definition of an effective gamma atmospheric dispersion factor [X/QY] (Reference 6) and the replacement of the undepleted X/Q in the infinite cloud dose equation by [X/QY].

The release point of effluents is also considered in the atmospheric dispersion calculation. The primary vent stack is treated as a "mixed-mode" release, as defined in Regulatory Guide 1.11 1 (Reference 4). These effluents are considered to be part-time ground-level I part-time elevated releases, depending on the ratio of primary vent stack exit velocity relative to the speed of prevailing wind. All other release points (e.g., Turbine Building and Chemistry lab hoods) are considered ground-level releases. The beta air and gamma air dose calculations are consistent with the models presented in Regulatory Guide 1.109 (Reference 1). The values for the dose factors, DFir and DFi~, have been taken from Table B-1 in Regulatory Guide 1.109.

Table A presents the calculated maximum off-site gamma air and beta air doses for each calendar quarter and year. The calculated annual doses as a percent of the applicable regulatory limit are shown in Table C. The estimated quarterly and annual air doses resulting from noble gas effluents are well below all dose limit criteria.

4

IV. Method for Calculating the Critical Organ Dose Resulting from Iodines, Tritium, Carbon-14 and Particulates with T 112 Greater than 8 Days in Gaseous Releases Regulatory Guide 1.109 (Reference 1) dose models are applied in the calculation of the critical organ doses from Iodines, Tritium, Carbon-14 and particulate radionuclides released into the atmosphere during the reporting period. Atmospheric dispersion and deposition factors (i.e., depleted X/Q and D/Q factors) calculated with concurrent meteorological data (i.e., meteorological data measurements taken during the time of the release) are used in the determination of gaseous pathway doses. The dispersion models are described in Section B.7.3.2 & B.7.3.3 of the Seabrook ODCM.

Potential exposure pathways associated with gaseous effluent are (i) external irradiation from radioactivity deposited on the ground surface, (ii) inhalation, and (iii) ingestion of vegetables (both fresh leafy and stored) and milk. Dose estimates were determined for the site boundary and for the locations of the nearest resident, vegetable garden, and milk animal in each of the sixteen principle compass directions. The locations of the nearest resident, vegetable garden and milk animal in each sector were identified by the 2020 Annual Land Use Census as required by ODCM Control C.9.2.1 (see Table F). Conservatism in the dose estimates was maintained by assuming that the vegetable garden pathway was active at each milk animal location. Milk animals were assumed to receive their entire intake from pasture during the second and third quarters. This is a conservative assumption because most dairy operations utilize supplemental feeding when animals are on pasture, or actually restrict animals to full time silage feeding throughout the entire year. Table E provides the reference sources for dose model parameter assumptions used in the dose assessment.

In June 2009, the NRC issued Revision 2 of Regulatory Guide 1.21 (Reference 7) which introduced the term "principal radionuclide" in a risk informed or dose context. A radionuclide can be considered a principal radionuclide if it contributes either (1) greater than 1 percent of the 10 CFR Part 50, Appendix I design objective dose for all radionuclides in the type of effluent being considered, or (2) greater than 1 percent of the activity of all radionuclides in the type of effluent being considered. In addition to natural production in the environment, Carbon-14 is also produced in nuclear reactors as a function of power output, but at amounts much less than those generated naturally or from past weapons testing. Since the time of the earlier publication of Regulatory Guide 1.21 (Revision 1) in 197 4, commercial nuclear power plants have decreased total radioactive effluents (other than Carbon-14) through improved fuel performance and waste management practices to the point today that Carbon-14 could be considered a principal radionuclide under today's definition, and therefore has been included in the assessment of dose to the public from gaseous effluent releases for 2020.

The primary exposure pathways associated with Carbon-14 include inhalation and ingestion of food products that have incorporated Carbon-14 (in the form of C02) via photosynthesis. A full year's consumption of food products are assumed to be grown from the highest impacted garden during the growing season (2°d and 3rd quarters). It is also assumed that the garden grows sufficient mass to support ingestion throughout the year (i.e., the annual dose to the individual is from consumption during all four quarters).

The maximum organ doses from all radionuclides in this category of gaseous effluents were determined by summing the contributions from all exposure pathways at each location, and sorting in descending order.

5

Doses were calculated for the whole body, GI-LLI, bone, liver, kidney, thyroid, lung, and skin for adults, teenagers, children, and infants. The estimated quarterly and annual organ doses at the location of the maximally exposed individual are reported in Table A.

The estimated organ doses from Iodines, Tritium, Carbon-14 and Particulates in gaseous effluents are well below the 10 CFR Part 50, Appendix I dose criteria for the reporting period. (See Table C for calculated dose as a percentage of annual limits.)

6

V. Total Dose (40 CFR Part 190) 40 CFR 190 states that the annual dose equivalent should not exceed 25 mrem to the whole body, 75 mrem to the Thyroid, or 25 mrem to any other organ of any Member of the Public at and beyond the site boundary from all uranium fuel cycle sources. To show compliance with this standard, the maximum doses for both the liquid and gaseous pathways from Seabrook Station are added together with the whole body dose from noble gas releases and any direct radiation component attributed to station fixed sources to the maximum receptor location. This includes the addition of spent fuel storage in a Dry Fuel Storage (DFS) facility that began operations in July 2008 with the first transfer of spent fuel assemblies into storage arrays. A second transfer of spent fuel assemblies to the DFS occurred between August and September, 2013. A third spent fuel transfer campaign was conducted during September and October of 2017. The DFS facility is located on Seabrook Station property approximately 0.38 miles West-Southwest of the Unit 1 Containment Building. Since there are no other uranium fuel cycle facilities within five miles of Seabrook Station, no additional impacts from sources beyond Seabrook Station need be considered.

The sum of the maximum annual whole body doses to Members of the Public from all exposure pathways for liquid and gaseous effluents, plus the direct external dose from plant and dry fuel storage fixed sources, was 8.09E-02 mrem to a hypothetical individual at or beyond the site boundary. The maximum organ dose (including the thyroid) to any age group from all exposure pathways including direct radiation was 3.30E-Ol mrem.

Table B illustrates the total dose projections from all station sources to the maximum potential off-site individual for the year 2020 and demonstrates compliance with the EPA' s environmental radiation standard for the uranium fuel cycle per 40 CFR Part 190. (See Table C for total dose as a percentage of annual limits.)

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VI. References

1. Regulatory Guide 1.109, Revision 1, "Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purposes of Evaluating Compliance with 10CFR Part 50, Appendix I", USNRC, October 1977.

2. Seabrook Station Program Manual: Offsite Dose Calculation Manual (ODCM), Revision 40.

3. Kocher, D.C., "Dose-Rate Conversion Factors for Exposure to Photons and Electrons", Health Physics, Vol. 45, No. 3, Sept. 1983.

4. Regulatory Guide 1.111, Revision 1, "Method for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine Releases from Light-Water Cooled Reactors",

USNRC, July 1977.

5. Slade, D.H., "Meteorology and Atomic Energy- 1968", USAEC, July 1968.

6. Hamawi, J.N., "AEOLUS-2 A Computer Code for the Determination of Continuous and Intermittent-Release Atmospheric Dispersion and Deposition of Nuclear Power Plant Effluents in Open-Terrain Sites, Coastal Sites, and Deep-River Valleys for the Assessment of Ensuing Doses and Finite-Cloud Gamma Radiation Exposures", Entech Engineering, Inc., March 1988.

7. Regulatory Guide 1.21, Revision 2, "Measuring, Evaluating, and Reporting Radioactive Material in Liquid and Gaseous Effluents and Solid Waste", USNRC, June 2009.

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Table A Seabrook Station 2020 Annual Radioactive Effluent Release Report MaximumCaloff-Site Doses and Dose Commitments to Members of the Public Dose (mrem)(b)

Release Type 1st 2nd 3rd 4th Year(c)

Quarter Quarter Quarter Quarter 2020 Liquid Effluents:

Total Body Dose 2.53E-04 2.19E-04 3.64E-05 6.16E-06 5.15E-04 (1) (1) (1) (1)

Max Organ Dose 2.89E-04 4.53E-04 9.24E-05 7.87E-06 8.42E-04 (2) (3) (3) (3)

Airborne Effluents:

7.77E-02 8.90E-02 7.99E-02 8.26E-02 3.29E-Ol Organ Dose from Carbon-14, Iodines, (4) (4) (4) (4)

Tritium, and Particulates (T 112 > 8 days)

Noble Gases Beta Air 5.26E-06 2.80E-04 l.14E-06 2.73E-06 2.89E-04 (mrad) (5) (6) (7) (8)

Gamma Air 2.83E-05 5.23E-04 3. l 7E-06 6.79E-06 5.61E-04 (mrad) (5) (6) (7) (8)

Direct Dose Offsite From 0 0 0 0 0 Station Operation(e)

Doses (mrem) at Receptor Locations Inside Site Boundary<dl:

Science and Nature Center (SW, 488m):

6.26E-06 2.41E-05 7.30E-06 2.39E-06 4.00E-05 Max Organ Dose (mrem)

The Firing Range (W, 974m) 8.77E-05 l .92E-04 l.36E-04 8.30E-05 4.99E-04 Max Organ Dose The Fitness Center (WSW, 384m):

Max Organ Dose (mrem) 3.36E-04 6.74E-04 3. l lE-04 2.25E-04 1.55E-03 9

Table A (continued)

Seabrook Station 2020 Annual Radioactive Effluent Release Report Maximum<*J Off-Site Doses and Dose Commitments to Members of the Public NOTES:

(a) "Maximum" means the largest fraction of corresponding 10CFR50, Appendix I, dose design objective.

(b) The numbered footnotes indicate the age group, organ, and location (compass sector and distance from the primary vent in meters) of the critical receptor, where appropriate, based on the most limiting radionuclide dose contributor (C-14).

(1) Adult (2) Liver of an adult (3) GI-LLI of an adult (4) Bone of a child, NNW 103 5 (5) SSE 914 m (6) SE 2276 m (7) W 1005 m (8) ENE 2276 m (c) "Maximum" dose for the year is the sum of the maximum doses for each quarter. This results in a conservative yearly dose estimate, but still well within the limits of 10CFR50.

(d) For each special receptor location, the whole body and organ doses calculated for the airborne effluent releases were adjusted by the occupancy factors (i.e., 0.0014 for the Science and Nature Center and 0.0416 for the Fitness Center and Firing Range). The most limiting on-site location with respect to dose is estimated to be the Fitness Center located in the Hi-Rise office building due to relatively close location to the plant vent stack.

(e) Only station sources (both plant and dry fuel storage) are considered since there are no other fuel cycle facilities within five miles of Seabrook Station site. Dosimeter data collected in 2020 for the closest off-site environmental TLD locations in each sector (as listed in Tables B.4-1 and B.4-2 of Seabrook's ODCM) were compared to preoperational data for the same locations. No statistical difference above random background variability which could be attributed to station sources was identified.

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Table B Seabrook Station 2020 Annual Radioactive Effluent Release Report Total Dose to Maximum Off-Site Individual (40CFR190)

Total Body Maximum Organ(a)

Release Source (mrem) (mrem)

Liquids 5.ISE-04 8.42E-04 Noble Gases 3.73E-04 3.73E-04 Gaseous Iodines, Tritium, C-14 &

8.0IE-02 3.29E-Ol Particulates (T 112 > 8 days)

Direct Radiation 0 0 Annual Total 8.09E-02 3.30E-Ol (a) Maximum organ includes consideration of the thyroid.

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Table C Seabrook Station 2020 Annual Radioactive Effluent Release Report Calculated 2020 Maximum Doses versus Applicable Limits Applicable ODCM Calculated Percent ODCM Annual Annual (2020) of Receptor Control Limit Dose Limit Offsite Liquid Effluents Whole Body Dose C.6.2.1 3 mrem 5.15E-04 mrem 0.0172%

Organ Dose C.6.2.1 IO mrem 8.42E-04 mrem 0.0084%

Airborne Effluents Organ Dose (iodines, H-3, C-14 and part.) C.7.3.1 15 mrem 3.29E-Ol mrem 2.19%

Gamma Air Dose (noble gases) C.7.2.1 IO mrad 5.61E-04 mrad 0.0056%

Beta Air Dose (noble gases) C.7.2.1 20 mrad 2.89E-04 mrad 0.00145%

All Station Sources (a)

Whole Body Dose C.8.1.1 25 mrem 8.09E-02 mrem 0.324%

Organ Dose C.8.1.1 25 mrem 3.30E-Ol mrem 1.32%

Onsite (Science & Nature Center, 488m SW)

C.7.3.l(bl 4.00E-05 mrem 0.00027%

Organ Dose (iodines, H-3, C-14 and part.) 15 mrem Onsite (The Firing Range, 974m W)

Organ Dose (iodines, H-3, C-14 and part.) C.7.3.l(bl 15 mrem 4.99E-04 mrem 0.0033%

Onsite (Fitness Center, 384m WSW)

Organ Dose (iodines, H-3, C-14 and part.) C.7.3.1 (bl 15 mrem l.55E-03 mrem 0.0103%

(a) The "all station sources" doses are the sum of the whole body doses and maximum organ doses from liquid, noble gas, and gaseous iodines/tritium/carbon-14/particulate releases as well as direct radiation from fixed station sources (both plant facilities and dry fuel storage).

(b) ODCM Part A, Section 10.2 states that the annual effluent report shall include an assessment of the radiation doses from radioactive liquids and gaseous effluents to members of the public due to their activities inside the site boundary during the report period. The referenced limits (C.7.2. l & C.7.3.1) are the acceptable doses from liquid and gaseous effluents to areas at and beyond the site boundary and are considered to be appropriate for comparison purposes.

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Table D Seabrook Station 2020 Annual Radioactive Effluent Release Report Sources of the Values of Factors Used in Liquid Dose Equations I Factor I Definition I Source I u.p Usage factor Table B.7-1, Station ODCM Section B. 7 .1, Station ODCM (value=O. l for MP Mixing ratio aquatic foods and 0.025 for shoreline)

Bip Equilibrium bioaccumulation factor Table A-1, Reg. Guide 1.109 Daipi Dose factor Tables E-11 through E-14, Reg. Guide 1.109

~ Nuclide transit time Table E-15, Reg. Guide l.109 Transfer coefficient from water to Kc Reg. Guide 1.109 sediment Period of activity buildup in sediment tb Table B.7-2, Station ODCM or soil w Shoreline width factor Table A-2, Reg. Guide l.109 (value= 0.5) 13

Table E Seabrook Station 2020 Annual Radioactive Effluent Release Report Sources of Values for the Factors Used in Dose Equations for Gaseous Releases Factor Definition Source Period of activity buildup in sediment tb or soil Table B.7-2, Station ODCM Nuclide decay constant Ao Kocher (Reference 3)

Ground plane dose factor DFGii Table E-6, Reg. Guide 1.109 Atmospheric dispersion factor (non-

[X/Q] depleted) Calculated following Reg. Guide 1.111 (X/Q]D Atmospheric dispersion factor (depleted) Calculated following Reg. Guide 1.111 Breathing rate R. Table B.7-3, Station ODCM Inhalation dose factor DFAii* Tables E-7 through E-10, Reg. Guide 1.109 Nuclide deposition rate di Reg. Guide 1.109 p Soil surface density Table B.7-2, Station ODCM Crop, leafy vegetable, or pasture

t. grass exposure period Table B.7-2, Station ODCM Average time from crop harvest to th consumption Table B.7-2, Station ODCM Agricultural productivity by unit area Yv Table B.7-2, Station ODCM Fraction of deposited activity r retained on crops, leafy vegetables, or Table E-15, Reg. Guide 1.109 pasture grass Stable element transfer coefficient Biv from soil to produce, leafy vegetable, Table E-1, Reg. Guide 1.109 or pasture grass Fractional equilibrium ratio p Reg. Guide 1.109 Ambient absolute humidity H Table B.7-2, Station ODCM 14

Table E (continued)

Seabrook Station 2020 Annual Radioactive Effluent Release Report Sources of Values for the Factors Used in Dose Equations for Gaseous Releases Factor Definition Source Stable element transfer coefficient Fm from feed to milk Tables E-1 and E-2, Reg. Guide 1.109 Average time from feed to milk to tr consumption Reg. Guide 1.109 Fraction of the year that animals fp graze on pasture Table B.7-2, Station ODCM Fraction daily feed pasture grass f, Table B.7-2, Station ODCM Stable element transfer coefficient Fr from feed to meat Table E-1, Reg. Guide 1.109 Average time from meat animal t, slaughter to consumption Table E-15, Reg. Guide 1.109 DFiiia Ingestion dose factor Tables E-11 through E-14, Reg. Guide 1.109 Annual intake of produce u~ Table B.7-3, Station ODCM u: Annual intake of milk Table B.7-3, Station ODCM u~ Annual intake of meat Table B.7-3, Station ODCM u~ Annual intake of leafy vegetables Table B.7-3, Station ODCM Ingestion rate fractions for garden fg produce Reg. Guide 1.109 Ingestion rate fractions for garden fi leafy vegetables Reg. Guide 1.109 Rate constant for activity removal Aw from plant and leaf surfaces by Table E-15, Reg. Guide 1.109 weathering Qp Animal consumption rate Table E-3, Reg. Guide 1.109 15

Table F Seabrook Station 2020 Annual Radioactive Effluent Release Report Receptor Locations* for Seabrook Station Milk Animals Nearest Nearest within 5 Mile Resident Garden Radius Sector km (miles) km (miles) km (miles)

N 2.78 (1.73) 3.99 (2.48) ---

NNE 3.09 (1.92) 3.20 (1.99) ---

NE 2.92 (1.82) 4.24 (2.63) ---

ENE 2.31 (1.44) 2.53 (1.57) ---

E 2.56 (1.59) --- ---

ESE 2.43 (1.51) --- ---

SE 2.36 (1.46) 4.69 (2.91) ---

SSE 1.65 (1.02) --- ---

s 1.21(0.75) 1.25 (0.77) ---

SSW 1.12 (0.69) 1.22 (0. 76) ---

SW 1.13 (0.70) 1. 73 (1.08) --

WSW 1.87 (1.16) 2.33 (1.45) ---

w 1.25 (0.78) 1.55 (0.96) ---

WNW 1.11 (0.69) 3.08 (l.92) ---

NW 1.22 (0.76) 3.14 (1.95) 6.93 (4.30)

NNW 1.04 (0.64) 2.07 (1.29) --

• Locations based on 2020 Land Use Census.

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