ML25034A109

Enclosure 1: Response to NRC Rai/Rci Environmental Review

ML25034A109
Person / Time
Site:	Dresden
Issue date:	02/03/2025
From:	Constellation Energy Generation
To:	Office of Nuclear Reactor Regulation
Shared Package
ML25034A107	List: ML25034A108 ML25034A109 RS-25-002, Enclosure 2: RAI AQU-06 Documents, Long Term Aquatic Monitoring Program and Impringement and Entrainment Studies
References
RS-25-002
Download: ML25034A109 (1)

Text

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 1 of 113 Table of Contents RCI AQN-01............................................................................................................................... 4 RCI AQN-02............................................................................................................................... 5 RCI AQN-03............................................................................................................................... 6 RCI AQN-04............................................................................................................................... 7 RCI NOI-01................................................................................................................................ 8 RCI NOI-02................................................................................................................................ 9 RCI NOI-03...............................................................................................................................10 RCI GE-02................................................................................................................................11 RCI SW-01................................................................................................................................12 RCI SW-04................................................................................................................................13 RCI SW-05................................................................................................................................14 RCI SW-06................................................................................................................................15 RCI SW-08................................................................................................................................16 RCI SW-11................................................................................................................................18 RCI SW-12................................................................................................................................20 RCI SW-14................................................................................................................................21 RCI SW-15................................................................................................................................22 RCI SW-16................................................................................................................................23 RCI SW-17................................................................................................................................24 RCI GW-01...............................................................................................................................25 RCI GW-04...............................................................................................................................26 RCI TER-01..............................................................................................................................27 RCI TER-03..............................................................................................................................28 RCI TER-04..............................................................................................................................29 RCI TER-06..............................................................................................................................30 RCI TER-08..............................................................................................................................31 RCI TER-10..............................................................................................................................32 RCI TER-11..............................................................................................................................33 RCI TER-14..............................................................................................................................34 RCI AQU-02..............................................................................................................................35 RCI AQU-03..............................................................................................................................36

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 2 of 113 RCI AQU-07..............................................................................................................................37 RCI AQU-08..............................................................................................................................38 RCI FPE-02..............................................................................................................................39 RCI FPE-08..............................................................................................................................40 RCI FPE-09..............................................................................................................................41 RCI FPE-10..............................................................................................................................42 RCI FPE-14..............................................................................................................................43 RCI FPE-15..............................................................................................................................44 RCI HCR-01..............................................................................................................................45 RCI HCR-02..............................................................................................................................46 RCI HCR-03..............................................................................................................................47 RCI HCR-04..............................................................................................................................48 RCI HCR-05..............................................................................................................................49 RCI HCR-06..............................................................................................................................50 RCI HCR-09..............................................................................................................................51 RCI HCR-10..............................................................................................................................52 RCI HCR-11..............................................................................................................................53 RCI HCR-12..............................................................................................................................54 RCI HCR-13..............................................................................................................................55 RCI HCR-16..............................................................................................................................56 RCI HCR-17..............................................................................................................................57 RCI SOC-01..............................................................................................................................58 RCI SOC-02..............................................................................................................................59 RCI HH-01................................................................................................................................60 RCI HH-02................................................................................................................................61 RCI HH-03................................................................................................................................62 RCI HH-04................................................................................................................................63 RCI HH-05................................................................................................................................64 RCI EJ-01.................................................................................................................................65 RCI WM-01...............................................................................................................................66 RCI WM-02...............................................................................................................................67 RCI WM-03...............................................................................................................................68 RCI WM-04...............................................................................................................................69 RCI WM-05...............................................................................................................................70 RCI WM-06...............................................................................................................................73 RCI WM-07...............................................................................................................................74

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 3 of 113 RCI SNF-01..............................................................................................................................75 RCI GHG-CC-01.......................................................................................................................76 RCI GHG-CC-02.......................................................................................................................77 RCI SAMA-RCI-1 [Info Need SAMA-1]......................................................................................78 RCI SAMA-RCI-2 [Info Need SAMA-3]......................................................................................79 RCI SAMA-RCI-3 [Info Need SAMA-7]......................................................................................80 RAI GEN-01..............................................................................................................................81 RAI NOI-01...............................................................................................................................86 RAI SW-02................................................................................................................................88 RAI SW-03................................................................................................................................89 RAI TER-05..............................................................................................................................90 RAI AQU-06..............................................................................................................................91 RAI AQU-08..............................................................................................................................95 RAI FPE-01...............................................................................................................................98 RAI FPE-03............................................................................................................................. 100 RAI FPE-04............................................................................................................................. 101 RAI FPE-05............................................................................................................................. 103 RAI FPE-06............................................................................................................................. 106 RAI FPE-11............................................................................................................................. 108 RAI HCR-07............................................................................................................................ 111 RAI GHG-CC-04..................................................................................................................... 112

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 4 of 113 Topic: Air Quality NRC RCI Number: AQN-01 Please confirm that DNPS conducts firefighting training for its personnel to manage potential emergencies. The open burn permit is to have the ability to train firefighters in controlled situations.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 5 of 113 Topic: Air Quality NRC RCI Number: AQN-02 Please confirm that Table 3.3-10 of CEGs ER accounts for all the emission sources listed in Table 3.3-9 of the ER. Additionally, please confirm that 2023 annual air emissions are as follows:

Particulate Matter: 23.50 tons Particulate Matter less than 10 microns: 22.18 tons Sulfur Dioxide: 0.01 tons Nitrogen Oxides: 7.79 tons Carbon Monoxide: 3.29 tons Volatile Organic Matter: 0.35 tons CEG Response:

CEG confirms this information is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 6 of 113 Topic: Air Quality NRC RCI Number: AQN-03 Please confirm that CEG has not received any notices of violation or non-compliances associated with DNPSs Federally Enforceable State Operation Permit (FESOP) from 2023 to October 2024.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 7 of 113 Topic: Air Quality NRC RCI Number: AQN-04 Confirm the following information provided in response to document need AQN-4: On March 31, 2024, CEG submitted an application to the Illinois Environmental Protection Agency for the renewal of DNPSs FESOP No. 73020783. DNPSs FESOP No. 73020783 is administratively extended and currently being reviewed by the Illinois Environmental Protection Agency. The March 31, 2024, renewal application requested removal of exempt emission units from FESOP No. 73020783 including the small diesel-powered emergency generators (1,500 horsepower each or smaller) and the gasoline storage and handling. The March 31, 2024, renewal application did not request additional sources be added to DNPSs FESOP No. 73020783. The open burn permit was renewed and issued on February 23, 2024. The permit allows a maximum of 350 gallons of gasoline, 100 gallons of propane, 1,000 pounds of wood/straw, 250 gallons of

1. 1 and #2 distillate oil/kerosene, 100 pounds of paper per session for firefighting training.

CEG Response:

CEG confirms this information is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 8 of 113 Topic: Noise NRC RCI Number: NOI-01 Section 3.4 of the ER states that, in 2017, DNPS completed a two-phase noise evaluation which found that cooling tower noise levels were 58 dBA at the nearest residence and exceeded Illinois nighttime limits of 51 dBA for residential receivers. The ER also identifies that CEG will support the planting of 150 evergreen trees to mitigate noise to offsite residences. As discussed during the Noise breakout session and in response to information need NOI-1, please confirm:

in 2016, CEG installed sound absorbing filters at the south/southeast areas of the hot canal cooling tower # 3 to reduce noise from falling water; the week of September 16, 2024, CEG planted 150 black hill evergreen trees; the planted trees are located between the hot and cold canal and Dresden Road to mitigate noise beyond the hot/cold canal; the initial size of the trees is 4-5 feet (ft) tall and 1-2 ft wide, but the trees are expected to grow to 40+ ft and 20+ ft wide at a rate of 6-12 inches per year.

CEG has a Noise Exceedance Mitigation Action Plan in place to implement actions to achieve and maintain compliance with state noise pollution regulations, which consists of: CEG will conduct noise surveys/evaluations after the trees reach sufficient maturity to ensure compliance with applicable state noise pollution regulations; based on the planting date, initial tree size, and the minimum expected growth rate of approximately 6 inches per year, CEG estimates a 5-year growth period is recommended prior to performing noise surveys/evaluations; when possible, operation of the cooling towers will be limited to daytime hours (7 am to 10 pm).

CEG has not received a notice of violation or non-compliance from the Pollution Control Board with respect to noise levels because of operations at DNPS.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 9 of 113 Topic: Noise NRC RCI Number: NOI-02 Confirm that noise surveys were not conducted prior to installing the cooling towers in 1999, 2000, or 2003.

CEG Response:

CEG confirms that noise surveys were not conducted prior to installing the cooling towers in 1999 and 2000; however, there was one noise survey conducted in 2002, to collect sound measurements after a cooling tower installation.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 10 of 113 Topic: Noise NRC RCI Number: NOI-03 Confirm that CEG has not received any noise complaints since 2022 through October 2024 with respect to DNPS operations.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 11 of 113 Topic: Geologic Environment NRC RCI Number: GE-02 As described in the subsurface exploration report for the independent spent fuel storage installation (ISFSI) expansion site, borings at the site included rock coring in five boreholes. A minimum of 25 ft of rock coring was performed at each of these borings. Boring logs describe the sandstone encountered as highly to moderately weathered and fractured. Boring logs describe the limestone encountered as moderately fractured. In some boreholes, the upper approximately 1 ft of sandstone was described as more weathered and fractured than the underlying sandstone rock. Please confirm the above summary is accurate.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 12 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-01 During the audit, the NRC staff reviewed the 2023 surface water withdrawal data. Please confirm that the 2023 monthly surface withdrawal volumes in Table 1 and the 2023 annual surface water withdrawal volume in Table 2 are correct.

Table 1 Table 2 Year Month Intake Volume (million gallons)

Average Gallons per Minute Year Annual Intake Volume (million gallons) 2023 Jan 2,589.12 58,000 2023 196,017.66 2023 Feb 2,338.56 58,000 2023 Mar 2,589.12 58,000 2023 Apr 2,505.60 58,000 2023 May 2,589.12 58,000 2023 Jun 40,990.14 948,846 2023 Jul 45,398.88 1,017,000 2023 Aug 45,398.88 1,017,000 2023 Sep 43,934.40 1,017,000 2023 Oct 2,589.12 58,000 2023 Nov 2,505.60 58,000 2023 Dec 2,589.12 58,000 CEG Response:

CEG confirms this information is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 13 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-04 Please confirm that DNPS does not contribute to any of the water quality impairments listed in ER Section 3.6.4.1 because DNPS does not discharge any constituents that could contribute to these impairments.

CEG Response:

CEG confirms this statement is correct.

References:

IEPA (Illinois Environmental Protection Agency). 2022. 2020/2022 Integrated Report Web App.

Retrieved from <https://illinois-epa.maps.arcgis.com/apps/webappviewer/index.html?id=773c1711e0e9417ea7cd6cad8afb66e a> (accessed December 31, 2024).

IEPA. DRAFT 2024 Illinois Integrated Water Quality Report & Section 303(d) List. Retrieved from <https://epa.illinois.gov/topics/water-quality/watershed-management/tmdls/303d-list.html>

(accessed December 31, 2024).

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 14 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-05 Please confirm the following statements regarding tritium concentrations measured in surface water via the DNPS radiological environmental monitoring program (REMP).

CEG is aware that Braidwood Station routinely discharges radioactive effluent, including tritium, into the Kankakee River upstream of DNPS.

CEG does not have a documented analysis to confirm that the routine radioactive effluent discharges from Braidwood Station are the source of tritium detections at DNPS REMP sampling location D-57, which is located upstream of DNPS on the Kankakee River.

CEG Response:

DNPS is located downstream of Braidwood, which discharges liquid effluent to the Kankakee River. CEG confirms it does not have documented analysis to confirm whether the 2022 fourth quarter tritium detection of 2,540 pCi/L at D-57 resulted from a release from Braidwood.

However, as reported in Table C-I.2 of the Annual Radiological Environmental Operating Report (AREOR) for year 2023 (CEG 2024), the maximum tritium detection at location D-57 was 1,140 pCi/L. Concentrations detected were consistent with those detected in previous years.

References:

CEG. 2024. Dresden Nuclear Power Station Units 1, 2, and 3, 2023 Annual Radiological Environmental Operating Report. May 2024. ADAMS Accession No. ML24135A077.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 15 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-06 Please confirm that discharge of tritiated groundwater from recovery well RW DN-100S to National Pollutant Discharge Elimination System (NPDES) Outfall 002 is accounted for in the Annual Radioactive Effluent Release Reports (ARERRs) as a continuous release in the Liquid Effluents Continuous Mode tables for Units 2 and 3 (e.g., Tables 32 and 34 of the 2023 ARERR) and that quarters with no continuous release data indicate that there was no pumping from the recovery well and that measured CBG well tritium concentrations were below the detection limit.

CEG Response:

CEG confirms these statements are correct with the following clarification: Quarters with no continuous release data in the Liquid Effluents Continuous Modes tables indicate that measured CBG well tritium concentrations were below the detection limit and that either there was no pumping from the recovery well or that tritium was not detected in samples collected from the recovery well above the detection limit.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 16 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-08 Please confirm that stormwater tritium loading reported in the ARERRs was calculated based on the following procedures:

The monthly volume of stormwater discharge was calculated as: precipitation depth (inches)

• assumed runoff fraction of 30%

• contributing surface area of 100,000 square feet. Months where tritium concentrations measured at the CBG well were below the detection limit do not contribute to the annual stormwater volumes reported in the ARERRs. Precipitation depths were obtained from the Goose Lake weather station (https://gooselakeweather.com/).

The monthly tritium loading was calculated by multiplying the monthly stormwater discharge volume by the measured tritium concentration at the CBG well. Months when tritium concentrations were below the detection limit did not contribute to the tritium loading calculations.

During the audit, the NRC staff reviewed 2020 through 2023 tritium monitoring data for the CBG well. Please confirm that the tritium concentrations for the CBG well presented in the table below are correct.

Storm Sewer Manhole CBG Date uCi/mL Flag 1/29/2020 1.26E-06 2/26/2020 1.10E-06 4/14/2020 2.09E-06 5/20/2020 1.51E-06 6/17/2020 1.50E-06 7/21/2020 1.38E-06 8/19/2020 1.42E-06 9/29/2020 1.76E-06 10/20/2020 1.15E-06 11/11/2020 1.13E-06 12/8/2020 2.33E-06 1/19/2021 2.98E-06 2/23/2021 1.54E-06 3/10/2021 1.77E-06 4/13/2021 9.82E-07 5/6/2021 9.48E-07 6/9/2021 1.03E-06 7/21/2021 9.48E-07 8/10/2021 1.28E-06 9/22/2021 1.60E-06 10/19/2021 9.82E-07 11/10/2021 9.48E-07 12/8/2021 1.13E-06

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 17 of 113 1/14/2022 1.00E-06 2/8/2022 9.48E-07 3/16/2022 1.47E-06 4/18/2022 9.48E-07 5/23/2022 9.48E-07 6/7/2022 1.77E-06 7/26/2022 1.99E-06 8/16/2022 1.99E-06 9/26/2022 1.99E-06 10/24/2022 1.74E-06 11/15/2022 1.82E-06 12/5/2022 2.23E-06 1/18/2023 1.74E-06 2/8/2023 1.74E-06 3/15/2023 1.99E-06 4/17/2023 1.99E-06 6/21/2023 1.74E-06 7/18/2023 1.74E-06 8/15/2023 1.74E-06 9/21/2023 1.74E-06 10/18/2023 1.74E-06 11/14/2023 1.94E-06 12/5/2023 1.68E-06 CEG Response:

CEG confirms the above information is correct with the following clarifications: precipitation depths for these calculations are obtained from either the Goose Lake weather station or MET tower data, and the assumed runoff fraction of 30 percent is correct except for year 2019, for which the monthly volume of stormwater discharge was calculated as total time (minutes per month) multiplied by an assumed constant discharge of 10 gpm.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 18 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-11 Please confirm the following statements about surface water losses reported in Section 3.6.3.1 of the ER:

Estimated water losses reported in Section 3.6.3.1 of the ER were derived by calculating the difference between monthly diversions (closed cycle) or withdrawals (open cycle) and monthly discharge, as reported in Energy Information Administration (EIA) reports for DNPS.

Consumptive losses due to mechanical draft cooling tower (MDCT) operation are based on hours of operation during a given time period (i.e., quarterly, or annually).

Estimated losses from cooling pond evaporation and seepage are based on differencing estimated MDCT losses from total losses.

Additionally, please confirm the following information provided in DNPSs annual air emission reports regarding operation of the 54 cooling tower cells and discussed during the Water Resources breakout session:

In 2019, the total combined hours of operation were 90,057 hours6.597222e-4 days <br />0.0158 hours <br />9.424603e-5 weeks <br />2.16885e-5 months <br /> and the percent throughput for the months of March through May was 11.88%; June through August was 87.64%; and September through November was 0.48%.

In 2020, the total combined hours of operation were 64,440 hours0.00509 days <br />0.122 hours <br />7.275132e-4 weeks <br />1.6742e-4 months <br /> and the percent throughput for the months of June through August was 99.73% and for September through November was 0.27%.

In 2021, the total combined hours of operation were 70,164 hours0.0019 days <br />0.0456 hours <br />2.71164e-4 weeks <br />6.2402e-5 months <br /> and the percent throughput for the months of June through August was 95.48% and for September through November was 4.52%.

In 2022, the total combined hours of operation were 80,792 hours0.00917 days <br />0.22 hours <br />0.00131 weeks <br />3.01356e-4 months <br /> and the percent throughput for the months of June through August was 71.77%, March through May was 4.91%, and September through November was 23.03%.

In 2023, the total combined hours of operation were 145,198 hours0.00229 days <br />0.055 hours <br />3.27381e-4 weeks <br />7.5339e-5 months <br /> and the percent throughput for the months of March through May was 10.07%; June through August was 60.54%; and September through November was 16.52%.

Operation of the MDCTs is determined based on-site procedures, which include predictive modeling tools.

CEG Response:

CEG confirms these statements about surface water losses reported in Section 3.6.3.1 of the DNPS SLR ER are correct, with the following clarification: Total estimated water losses from cooling lake evaporation reported in the EIA forms are estimates, as required by the EIA report process. The rates of water loss from evaporation and seepage from the cooling lake as cited in Section 3.6.3.1 of the DNPS SLR ER, however, are more accurate estimates (approximately 45 cfs during closed-cycle mode and 50 cfs during indirect open-cycle mode). These values are

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 19 of 113 cited from the Post-Shutdown Decommissioning Activities Report (PSDAR) Section 2.2 (EGC 2021), and they are reported in the Environmental Impact Statement (EIS) Section 4.1.1 (NRC 2004) and the LR ER Section 4.1 (EGC 2003).

CEG confirms the information regarding the 54 cooling tower cells is correct.

References:

EGC (Exelon Generation Company, LLC). 2003. Dresden Units 2 & 3 and Quad Cities Units 1 &

2 License Renewal Application, Appendix E, Dresden Nuclear Power Station Environmental Report. January 2003. ADAMS Accession No. ML030090217.

EGC. 2021. Dresden Nuclear Power Station, Units 2 and 3 - Post-Shutdown Decommissioning Activities Report. July 2021. ADAMS Accession Package No. ML21179A042.

NRC. 2004. Generic Environmental Impact Statement for License Renewal of Nuclear Plants.

NUREG-1437, Supplement 17. Final Report Regarding Dresden Nuclear Power Station, Units 2 and 3. June 2004. ADAMS Accession No. ML041890266.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 20 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-12 Please confirm that average monthly values of 2,538.6 and 45,024.4 million gallons per month for closed and open cycle operational modes, reported in ER Section 3.6.3.1, Page 3-103, correspond to surface water withdrawal volumes, not consumptive use.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 21 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-14 Please confirm that "withdrawals" and "diversions" reported in ER Section 3.6.3 both describe the volume of surface water abstracted from the Kankakee/Des Plaines Rivers via the Unit 2/3 Intake Canal, and that "withdrawal" is used to describe abstractions during open-cycle mode while "diversion" is used to describe abstractions during close-cycle mode, per guidance from the EIA as described in the document located at:

https://www.eia.gov/survey/form/eia_923/instructions_schedule8d.pdf.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 22 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-15 Please confirm the following statements about DNPS's stormwater pollution prevention plan (SWPPP):

SWPPP inspections are conducted quarterly and at least once per year a SWPPP inspection is conducted when stormwater discharge is occurring.

The SWPPP will be revised if there is a change in construction operation or maintenance that may affect the discharge of significant quantities of pollutants, a quarterly or annual inspection identifies the need for an amendment, or a discharge violates a condition in the NPDES permit.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 23 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-16 Please confirm the following statements about the spill prevention, control, and countermeasure (SPCC) plan for DNPS:

CEG is required to review and evaluate the SPCC plan at least once every 5 years or immediately after a reportable quantity oil spill event.

The SPCC plan will be amended within 6 months of a change in facility design, construction, operation, or maintenance occurs that may significantly affect the facilitys potential for offsite discharge of oil.

The SPCC plan outlines procedures for the assessment, reporting, and management for hazardous material spills.

The SPCC plan for DNPS covers procedures and controls for hazardous spill prevention, routine inspection procedures, and training programs for site personnel.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 24 of 113 Topic: Water Resources - Surface Water Resources NRC RCI Number: SW-17 Please confirm that DNPS operates, inspects, and maintains the DNPS Cooling Pond Dam and its appurtenances in accordance with approved plans and in accordance with the latest edition of the Rules for Construction and Maintenance of Dams adopted by the Illinois Department of Transportation.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 25 of 113 Topic: Water Resources - Groundwater Resources NRC RCI Number: GW-01 During the May 2023 annual cooling lake and circulating water canal examination, water surface elevations were reported to be about 522 ft in the cooling lake at the spillway, 506.25 ft in the hot canal, and 510.50 ft in the cold canal (both canal elevations at the Dresden Road bridge over the canals). Elevations in the piezometers located around the cooling lake ranged from 506.4 to 520.9 ft during the May 2023 examination. Please confirm this information is accurate.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 26 of 113 Topic: Water Resources - Groundwater Resources NRC RCI Number: GW-04 35 Illinois Administrative Code (IAC) 1010.200 (effective May 2, 2008) requires licensees to report unpermitted releases of station-generated liquids that result in tritium concentrations of 200 pCi/L or more outside of the licensee-controlled area, which is the DNPS property boundary. Monitoring under the radiological groundwater protection program and the REMP are used to ensure this requirement is met. An internal procedure is also maintained for reporting unpermitted releases of radionuclides in accordance with 35 IAC 1010.200 requirements.

Please confirm this information is accurate.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 27 of 113 Topic: Terrestrial Resources NRC RCI Number: TER-01 As discussed during the environmental audit and in response to information need TER-01, DNPS has four total cooling towers: three for the hot canal and one for the cold canal. All cooling towers onsite are equipped with drift eliminators. Please confirm the above summary is accurate.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 28 of 113 Topic: Terrestrial Resources NRC RCI Number: TER-03 As discussed during the environmental audit and in response to information need TER-03, the meteorological evaluation tower (MET) is 418 feet above ground level (AGL) with two sets of red lights on the structure. The top lights are solid, while lights in the middle are blinking. Please confirm the above summary is accurate.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 29 of 113 Topic: Terrestrial Resources NRC RCI Number: TER-04 As discussed during the environmental audit and in response to information need TER-04, there are eight structures onsite that are 100 ft or more above ground level (AGL). Within the Federal Aviation Administration Digital Obstruction File for Illinois (https://www.faa.gov/air_traffic/flight_info/aeronav/digital_products/dof/), there are three registered buildings/structures: Unit 1 Chimney, Unit 2/3 Chimney, and the Meteorological (MET) Tower. The height and structure type of all structures 100 ft or more AGL is as follows:

MET tower 418 ft Unit 1 Chimney 300 ft Unit 2/3 Chimney 300 ft Unit 2/3 Turbine Building Stack 159.38 ft Unit 1 Reactor Building 151 ft Unit 2/3 Reactor Building 141.54 ft Unit 2/3 Turbine Building 105.5 ft Heating Boiler Stack 100.5 ft Please confirm the above summary is accurate.

CEG Response:

CEG confirms these statements are correct, with the clarification that Unit 2/3 Chimney is 310 ft.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 30 of 113 Topic: Terrestrial Resources NRC RCI Number: TER-06 As discussed during the environmental audit and in response to information need TER-06, 7 osprey platforms were installed by the Illinois and Kankakee rivers, 16 blue bird nest boxes were installed by the DNPS cooling pond, and purple martin gourd house structures were relocated south of the training buildings in 2020. Please confirm the above summary is accurate.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 31 of 113 Topic: Terrestrial Resources NRC RCI Number: TER-08 As discussed during the environmental audit and in response to information need TER-08, no bat mortalities occurred during the past 5 years (2018-2023). Please confirm the above summary is accurate.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 32 of 113 Topic: Terrestrial Resources NRC RCI Number: TER-10 As discussed during the environmental audit and in response to information need TER-10, if injured or dead avian or wildlife species are found onsite, onsite environmental personnel and personnel from the U.S. Fish and Wildlife Service (USFWS), the State Game Commission, or the Illinois Department of Natural Resources conservation warden are notified, as applicable.

Photos may be taken to help with identification. For injured wildlife or avian species, records are kept of pertinent details of the responding wildlife professional. For bird nests on equipment or structures, personnel will determine if the nest is active and what species it belongs to. If the nest is non-active and it belongs to a non-protected species, the nest removal may occur, and a deterrent may be placed. Please confirm the above summary is accurate.

CEG Response:

CEG confirms these statements are correct with the following clarification. If injured or dead avian wildlife species are found onsite, onsite environmental personnel and personnel from the U.S. Fish and Wildlife Service (USFWS), the State Game Commission, the Illinois Department of Natural Resources conservation warden, or a trained wildlife professional are notified, as applicable.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 33 of 113 Topic: Terrestrial Resources NRC RCI Number: TER-11 As discussed during the environmental audit and in response to information need TER-11, DNPS has osprey, purple martin, blue bird, bats, invasive species removal, living lands and water plantings, and pollinator management projects onsite. There are approximately 430 acres of grassland habitat onsite, which includes 12 acres dedicated to milkweed plantings and management, and 4 acres for native nut bearing hardwoods species restoration. Onsite there are approximately 7 acres of active invasive species prevention and monitoring, which includes mowing targeted invasive species and applying herbicide. Purple martins are using an average of 31 gourds for nesting since 2012 and bluebirds are using approximately 8-12 boxes since 2019. Please confirm the above summary is accurate.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 34 of 113 Topic: Terrestrial Resources NRC RCI Number: TER-14 As discussed during the environmental audit and in response to information need TER-14, DNPS has invasive species present throughout the site from near the roadway to the old fields and grasslands to the canals. Management of invasive species includes mechanical removal, herbicide application, and burning. The management technique depends on the density of the invasive species population, species present, and environment. Please confirm the above summary is accurate.

CEG Response:

CEG confirms these statements are correct with the following clarification. Management of invasive species includes mechanical removal and herbicide application. No prescribed burning occurs at DNPS as part of invasive species removal.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 35 of 113 Topic: Aquatic Resources NRC RCI Number: AQU-02 Please confirm that bathymetric surveys of the intake canal are performed during every fueling outage, and on the discharge canals every four refueling outages. Please confirm that maintenance dredging would be required, and that the appropriate permitting would be acquired, if sediment accumulates to levels that reduce the Ultimate Heat Sink (UHS) volume below 1,800,000 gallons. Finally, please confirm that no dredging has occurred, to date, in the UHS.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 36 of 113 Topic: Aquatic Resources NRC RCI Number: AQU-03 Please confirm that potential future construction and maintenance activities would follow CEG protocol to include CEGs Environmental Review Procedure, Environmental Screening Checklist, Environmental Evaluation Guidance, and the Excavation, Trenching, and Shoring Procedure.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 37 of 113 Topic: Aquatic Resources NRC RCI Number: AQU-07 Please confirm that in 2018, the estimated impingement of the Kankakee River was over five times higher than those recorded in 2017. Additionally, please confirm that CEG believes this increase correlates with a marked reduction in later summer river flow, compared to 2017, which likely led to higher concentrations of fish in localized areas, increasing their susceptibility to impingement and thus contributing to the elevated impingement results for 2018.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 38 of 113 Topic: Aquatic Resources NRC RCI Number: AQU-08 Please confirm that no aquatic surveys or studies have been conducted regarding Outfall 004 related to thermal effluent and that a collective decision was made between coordinating agencies and CEG that surveys and/or studies were not necessarily due to the short annual operation of Outfall 004 and no anticipated effects on aquatic resources. Additionally, please confirm the following regarding the Cooling Lake Siphon Line(s):

the siphon will not operate past March 15th each year to avoid interference with fish spawning; the maximum amount of thermal effluent allowed is 0.5 billion BTU per hour; if pond temperature is less than or equal to 47.5 degrees Fahrenheit (F) all three pipes may run; if pond temperature is greater than 47.5 degrees F and less than or equal to 54.5 degrees F only two pipes may run; if pond temperature is greater than 54.5 degrees F and less than or equal to 77 degrees F only one pipe may run; the diameter of each pipe is 3 feet, and the pipes run along the bottom of the Kankakee River stretching across its width containing holes to release thermal effluent; the siphons draw water from the cooling pond at a rate of 50 cubic feet per second per pipe; that fishing nets are used to prevent cooling lake fish from travelling from the cooling lake, through the siphon, to the Kankakee River; the plant operates in closed cycle when the siphons are in operation; and the siphon lines create small vortexes in the cooling lake that can be heard at the road nearby (Cottage Rd).

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 39 of 113 Topic: Federally Protected Ecological Resources NRC RCI Number: FPE-02 Please confirm that no surveys have been conducted to identify suitable roosting trees for listed bats, including the Indiana bat (Myotis sodalis), northern long-eared bat (Myotis septentrionalis),

and tricolored bat (Perimyotis subflavus). Additionally, please confirm that all forested portions of the site are considered potentially suitable habitat for the Indiana bat, northern long-eared bat, and tricolored bat.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 40 of 113 Topic: Federally Protected Ecological Resources NRC RCI Number: FPE-08 As discussed during the environmental audit and in response to information need FPE-08, please confirm the following: 1) that no targeted surveys have been conducted to identify the presence of the federally listed plant species on the DNPS site; 2) that the federally listed eastern fringed prairie orchid (Platanthera leucophaea), lakeside daisy (Hymenoxys herbacea),

and leafy prairie-clover (Dalea foliosa) have not been observed on-site; 3) that no species of violets (Viola spp.) have been observed on site; and 4) that none of these species were observed during the 2018 invasive species survey.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 41 of 113 Topic: Federally Protected Ecological Resources NRC RCI Number: FPE-09 Please confirm that the DNPS Facilities Maintenance mows the following locations: 1) the grass parcels surrounding the training building; 2) the grass parcels between the contractor lot and Dresden Road; 3) the grass parcel in front of the administrative building; 4) the grass parcel in front of the Technical Support Center; 5) the grass parcel just east of the motorcycle pad; and 6) the grass parcel east of the contractor parking lot. Additionally, please confirm that if milkweed is identified on site, Facilities Maintenance is instructed to avoid mowing in the area immediately around the milkweed plant.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 42 of 113 Topic: Federally Protected Ecological Resources NRC RCI Number: FPE-10 Please confirm that there are no current known areas prone to erosion. Additionally, please confirm that if erosion does develop, several best management practices (BMPs) and control measures would be implemented from the SWPPP and SPCC Plan to include: 1) seeding; 2) mulching; 3) sodding; and 4) structural controls.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 43 of 113 Topic: Federally Protected Ecological Resources NRC RCI Number: FPE-14 Please confirm that bats have not been observed or detected during the emergence surveys conducted each spring, summer, and fall since the installation of the six bat boxes in the spring of 2022.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 44 of 113 Topic: Federally Protected Ecological Resources NRC RCI Number: FPE-15 As discussed during the environmental audit and in response to information need FPE-15, please confirm the following: 1) that herbicide application does not occur in any areas except the banks of the cooling lake, the banks of the water canals, and the portions of the DNPS site that are maintained by mowing, 2) that all herbicide application is targeted and used for the purpose of invasive plant management, and 3) CEG considers potential adverse impacts of herbicide application when selecting chemical, formulation, and application method, 4) all herbicides are applied by trained and licensed applicators, who apply chemicals according to label instructions, EPA guidelines, and applicable regulations.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 45 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-01 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-01, please confirm the following:

Site preparation for Unit 1 began November 28, 1956, and construction was completed September 23, 1959.

Unit 2 construction permit is dated December 29, 1965, and listed an estimated completion date from August 1, 1968, to June 1, 1969.

For Unit 3, the Construction Permit Application was submitted February 10, 1966, and listed an estimated completion date between August 1, 1969, and June 1, 1970.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 46 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-02 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-02, please confirm that the acreage of the built facility area within the Extended Area Boundary (EAB) is approximately 343 acres. The only facilities outside of the EAB are the meteorology tower and the cooling canals/lakes, which date back to DNPS' original construction phases ranging from the late 1950s to 1970.

CEG Response:

CEG confirms these statements are correct.

References:

None Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 47 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-03 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-03, please confirm the following:

The Pokagon Band of Potawatomi Indian lands are approximately 34 miles outside of the DNPS 50-mile radius.

After NRCs acceptance of CEGs ER, the Prairie Band Potawatomi Nation received Federal recognition, becoming the first Federally recognized Tribe in Illinois. Consistent with its earlier engagement with Federally recognized Tribes, CEG sent a letter to the Prairie Band Potawatomi Nation in February 2023 informing them about the SLR. To date, CEG has not received a response from the Tribe.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 48 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-04 During the environmental audits Historic and Cultural Resources breakout session and in the follow-up response to information need HCR-04, please confirm that for the construction of the ISFSI expansion project, CEG staff implemented its procedures and determined that monitoring by archaeologists or Tribal monitors was not required because the area is considered to be previously disturbed from construction of DNPS. Confirm that CEG notified the Illinois State Historic Preservation Office by letter dated February 6, 2020, about the expansion but did not receive a reply.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 49 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-05 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-05, please confirm the following information:

CEG owns the easement where two potentially National Register eligible archaeological sites are located. Commonwealth Edison (ComEd) owns, operates, and maintains the transmission lines on CEG property.

Should ComEd need to perform ground-disturbing activities within the DNPS transmission line corridor, ComEd would notify CEG. CEG would then follow existing protocols and procedures to engage with ComEd and outline the responsibilities and work activities prior to any work being performed. Any ground-disturbing or maintenance activities conducted onsite would also follow CEGs environmental protocols and procedures for identifying and protecting historic and cultural resources.

CEG Response:

CEG confirms this information is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 50 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-06 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-06, please confirm that:

No additional archaeological or architectural surveys were completed in support of the SLR.

CEG has not received any responses from the notification letters sent to federally recognized Tribes identifying any Traditional Cultural Properties within the area of potential effect (APE).

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 51 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-09 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-09, please confirm that if erosion is observed, CEG would follow their protocol as identified in HCR-11.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 52 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-10 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-10, please confirm that Exelon/CEG cultural resources information is kept within DNPS electronic data management system. If CEG is performing excavations, its procedure Excavation, Trenching, and Shoring (SA-AA-117) instructs CEG staff to review previously performed cultural, historical and paleontological resources and previous surveys to make sure excavation does not disturb identified resources.

Prior to starting a project that requires land disturbance in a previously undisturbed area, CEG staff would contact the Illinois State Historic Preservation Office to perform a review, regardless of whether or not a previous cultural resources survey has been performed in the area.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 53 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-11 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-11, please confirm that CEG does not have a specific inadvertent discovery plan for human remains. CEGs procedure Excavation, Trenching, and Shoring (SA-AA-117) includes definitions on cultural, historical and paleontological resources. If human remains are discovered, work would be stopped immediately and site security would be notified, who would then contact local law enforcement. Law enforcement would report the discovery to the county coroner. The coroner would determine if further investigation were needed. If the coroner determines that the remains are over 100 years old, the Illinois Historic Preservation Agency (IHPA) would take over jurisdiction. If the remains are believed to be less than 100 years old, the coroner would maintain jurisdiction. In Illinois, the Human Skeletal Remains Protection Act protects burials, burial markers (including Native American mounds),

and burial artifacts from disturbance, including vandalism, defacement, destruction, sale, exchange, excavation, or removal. CEG commits to uphold state law and cooperate in investigations and subsequent recommended actions.

CEG Response:

CEG confirms that there is no specific inadvertent discovery plan for human remains. CEGs procedure Excavation, Trenching and Shoring (SA-AA-117) includes definitions on cultural, historical, and paleontological resources. If suspected human remains would be discovered, work would be stopped immediately, the area would be secured, and site security would be notified. CEG would ensure notifications to the appropriate offsite agencies would be made, as applicable.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 54 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-12 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-12, please confirm that there are no planned ground-disturbing approved projects for DNPS at this time.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 55 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-13 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-13, please confirm that 150 trees were planted along the east side of the hot canal in September 2024. Prior to engaging in ground-disturbing activities, the project went through CEGs environmental screening process. No cultural resource surveys were conducted prior to the plantings, as the area is considered previously disturbed associated with construction of the hot canal. The tree planting location is over 1,750 meters from the Illinois and Michigan Canal National Register of Historic Places (NRHP) District and over 1,800 meters southwest of the Dresden Island Lock and Dam NRHP District. CEG considers that the trees would not visually impact the two Districts owing to topography and existing land cover. Additionally, please confirm that no further tree plantings are planned at this time.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 56 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-16 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-16, please confirm that CEGs procedure Excavation, Trenching, and Shoring (SA-AA-117) outlines work practices for excavation, trenching and shoring and includes CEGs Excavation Permit. Section 3.8.3 of the procedure states that if cultural resources are identified during excavation, then Environmental Personnel COORDINATE actions involving the salvage and/or disposition of the resources and RELEASE the excavation site to resume work once these activities are completed. Section 4.1.2 states that if work is being done in an area previously surveyed, Environmental Personnel are required to review the previous survey to make sure excavation does not disturb identified resources (CM-7).

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 57 of 113 Topic: Historic and Cultural Resources NRC RCI Number: HCR-17 As discussed during the environmental audits Historic and Cultural Resources breakout session and in response to information need HCR-17, confirm that CEGs procedure EN-AA-103-0001, Rev 009, Environmental Evaluations, outlines the requirements for Cultural, Historic and Paleontological (CHP) resource evaluation.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 58 of 113 Topic: Socioeconomics NRC RCI Number: SOC-01 As discussed during the environmental audit and in response to information need SOC-01, the total tax revenue payments for 2023 are $26,530,811, as were calculated for prior years in ER Table 3.9-2.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 59 of 113 Topic: Socioeconomics NRC RCI Number: SOC-02 As discussed during the environmental audit and in response to information need SOC-02, annual grant payments were $3,800,000 in 2022. Please confirm annual grant payments of

$3,800,000 ($1.9 million per reactor) to the Illinois Emergency Management Agency and Office of Homeland Security (IEMAOHS) from 2018-2021 and in 2023.

CEG Response:

CEG confirms this statement is correct with the following clarification. The payments were required annual payments, not grant payments.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 60 of 113 Topic: Human Health NRC RCI Number: HH-01 As discussed during the environmental audit and in response to information need HH-01, please confirm CEG has not observed algae blooms in the area surrounding DNPS discharge to the Illinois river encountered elevated levels of fecal coliform or been notified by any local state or federal agencies of algae blooms or waterborne diseases in relation to DNPS. Also confirm that temperatures are monitored for triggering cooling tower operation but not within the cooling lake and that the entire cooling lake perimeter is fenced to deny access to members of the public.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 61 of 113 Topic: Human Health NRC RCI Number: HH-02 As discussed during the environmental audit and in response to information need HH-02, please confirm there have been no Occupational Safety and Health Administration (OSHA) recordable injuries since the end of 2022 and the submission of the ER.

CEG Response:

CEG confirms this statement is correct with the following clarification. One OSHA recordable event occurred in November 2024, outside the timeframe specified in the RCI.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 62 of 113 Topic: Human Health NRC RCI Number: HH-03 As discussed during the environmental audit and in response to information need HH-03, please confirm that there has been a lack of public health concerns in the receiving waters of DNPS by the Illinois Department of Public Health and that CEG and the Illinois Environmental Protection Agency have an ongoing relationship in regard to NPDES discharges.

CEG Response:

CEG confirms this statement is correct with the following clarification. In September 2023, CEG received a letter from the Illinois Department of Public Health, which restated the lack of public health concerns attributable to thermophilic organisms in Grundy, Kendall, and Will Counties.

References:

CEG. 2024. Dresden Nuclear Power Station, Units 2 and 3, Subsequent Operating License Renewal, Appendix E, Applicants Environmental Report. April 2024. ADAMS Accession No. ML24108A0110.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 63 of 113 Topic: Human Health NRC RCI Number: HH-04 Based on information discussed during the audit and in response to information need HH-04 regarding CEGs corporate electrical safety program procedures, please confirm that CEG ensures that DNPS's in-scope transmission lines satisfy National Electrical Safety Code standards through adherence to station electrical safety procedures.

CEG Response:

CEG confirms that maintenance of the in-scope transmission lines performed by utility or specialty vendor personnel is in accordance with the Illinois Administrative Code Title 83 Section 305.20, which follows portions of the 2017 edition of the NESC cited in RCI HH-05.

Work by CEG staff near or under the energized overhead lines follows the guidance specified in the fleet electrical safety procedure for overhead power lines and hazardous induced voltages.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 64 of 113 Topic: Human Health NRC RCI Number: HH-05 As discussed during the environmental audit and in response to information need HH-05, please confirm that CEGs fleet safety procedure complies with the Illinois Administrative Code Title 83 Section 305.20 that a) apply to electric utilities and those telecommunications carriers subject to Section 8-505 of the Public Utilities Act [220 ILCS 5/8-505] and b), which follows portions of the 2017 edition of the National Electrical Safety Code namely:

Section 2, Definitions of Special Terms; Section 9, Grounding Methods of Electric Supply and Communications Facilities; Part 2, Sections 20 to 27, Safety Rules for the Installation and Maintenance of Overhead Electric Supply and Communication Lines; and Part 3, Sections 30 to 39, Safety Rules for the Installation and Maintenance of Underground Electric Supply and Communication Lines.

CEG Response:

CEG confirms that maintenance of the in-scope transmission lines performed by utility or specialty vendor personnel is in accordance with the cited requirements.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 65 of 113 Topic: Environmental Justice NRC RCI Number: EJ-01 As discussed during the environmental audit and in response to information need EJ-01, please confirm that the Dresden Clean Energy Center engaged in a social science research project from the Pacific Northwest National Laboratory (a division of the U.S. Department of Energy's Environmental Justice Risk and Environmental Assessment Group) to conduct focus groups with members of the public, local businesses, and organizations from August 19, 2023, through August 25, 2023. The purpose of the focus groups was to conduct interviews regarding their perceptions of the storage of spent nuclear fuel at DNPS. The goal was to engage community members living nearby a temporary spent nuclear fuel storage site about their views on spent nuclear fuel storage. CEG does not have access to the results of these focus groups as they have not yet been made available.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 66 of 113 Topic: Waste Management NRC RCI Number: WM-01 ER Section 2.2.6.1 discusses radioactive liquid waste management systems. As discussed during the audit, please confirm the following:

ER Section 2.2.6.1 states that the processed wastewater may be discharged to the river through the discharge canal. As discussed during the audit, the plant has not had a routine (batch or continuous) radioactive liquid effluent discharge since 2009. The plant may discharge if needed, but since 2009, instead of being discharged as effluent, processed water from the equipment drain system and floor drain system has been recycled into the condensate system.

ER Section 2.2.6.1 describes a maximum recycle system; however, this system is retired. Instead, the water from the equipment drain system is routed to a system referred to as advanced liquid processing (ALP). After being processed by the APL, water is sampled and routed back to the Condensate Storage Tanks (CSTs) to be either discharged (if needed) or recycled into the condensate system.

ER Section 2.2.6.1 describes portable waste treatment systems. As discussed during the audit, the portable waste treatment systems are only used when temporary waste treatment systems are needed in specific locations and are not part of the routine system.

CEG Response:

CEG confirms the remaining statements are correct, with the following clarification. The maximum recycle system is not retired, but idle.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 67 of 113 Topic: Waste Management NRC RCI Number: WM-02 ER Section 2.2.6.5 notes that DNPS provides onsite storage of mixed waste and ER Section 2.2.7 discusses hazardous and universal wastes. Please confirm the following:

There are no other wastes, besides mixed waste, stored in the mixed waste storage location.

There are no proposed upgrades or changes planned for the hazardous or mixed waste program during the SLR term.

The increased volume of nonhazardous waste disposed of in 2020 compared to other years in the period of 2018-2022 is due to housekeeping activities in preparation for potential decommissioning at that time.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 68 of 113 Topic: Waste Management NRC RCI Number: WM-03 ER Section 2.2.6.3 discusses the Radioactive Solid Waste Management Systems. As discussed during the audit, please confirm the following:

There are no proposed upgrades or changes to the solid low-level waste (LLW) management program during the SLR term.

DNPS does not currently store any greater-than-class C (GTCC) waste onsite.

There is sufficient storage space for GTCC waste should it need to be stored.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 69 of 113 Topic: Waste Management NRC RCI Number: WM-04 DNPS is subject to the reporting provisions of 40 CFR Part 110 as it relates to the discharge of oil in such quantities as may be harmful pursuant to Section 311(b)(4) of the Federal Water Pollution Control Act. In section 9.5.3.6 of the ER, the applicant discusses reportable spills and states that for the period of 2018-2023, there were nonreportable releases that have triggered this notification requirement. As discussed during the audit, please confirm there have been no reportable releases to date which would trigger notification requirement to date since the ER submittal.

CEG Response:

CEG confirms the remaining statements are correct, with the following clarification. For the period of 2018-2024, there were no reportable releases that have triggered this notification requirement.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 70 of 113 Topic: Waste Management NRC RCI Number: WM-05 NRC Regulatory Guide (RG) 1.21, Revision 3, defines abnormal release and abnormal discharge as follows:

An abnormal release is an unplanned or uncontrolled release of licensed radioactive material into the onsite environs. Abnormal releases may be categorized as either batch or continuous, depending on the circumstances.

An abnormal discharge is an unplanned or uncontrolled discharge of licensed radioactive material to the unrestricted area.

As part of the audit, NRC staff reviewed site procedure CY-DR-170-2020, Abnormal Radiological Release, which defines abnormal release as "an unplanned or uncontrolled radiological release from the site boundary." During the audit, the licensee stated that this definition has not changed from the period from 2018 to 2024. The Offsite Dose Calculation Manual (ODCM), Revision 16, published in December 2019 states under REC 12.8.1. REC 12.8.1 On-site groundwater and storm sewers shall be sampled and analyzed for tritium to provide indication of unmonitored or abnormal radioactive releases. The ODCM, Revision 17, published in June 2021 has the same REC 12.8.1 as Revision 16.

ER Section 3.10.3 states that while there were no abnormal radioactive releases in 2018, 2020, 2021, and 2022, there were 16 abnormal liquid releases and 4 abnormal gaseous releases in 2019 as documented in the Annual Effluent Reports. For 2018-2022, DNPS effluents were well within ODCM and federally required limits. In reviewing the reports spanning from 2018 to 2023, the NRC staff observe that this difference appears to be a result of the differing formats of the reports rather than an indication that anything significantly different occurred in 2019 in comparison to the other years in terms of effluent releases or discharges. This is with the exception of the West Tritium Remediation well, which was put into service in September 2019.

The 2018 Radioactive Effluent Release Report states that there were zero abnormal releases, but it lists the following as unmonitored releases. The tables in which these discharges appear in the report are listed in parenthesis after the release.

2018 Liquid unmonitored releases:

1. Storm Sewer System (Tables for Unit 2 and Unit 3 Storm Sewer System)

2. Sewage Treatment Plant Effluent (Table for Unit 1 Sewage Treatment Plant) 2018 Gaseous unmonitored releases (Table for Units 1,2,3 Ground Gaseous Releases):

1. Unit 1 Main Turbine Floor and Unit 1 Fuel Building

2. Chemistry Laboratory Ventilation Effluent

3. Units 2/3 Heating Steam System

4. East Turbine Building Ventilation The 2019 Radioactive Effluent Release Report categorizes effluent releases that are "not typical or expected" as abnormal. These are documented in the 2019 Dresden Abnormal Release (DAR) report, which the NRC reviewed as part of the environmental audit. The 2019 Effluent

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 71 of 113 report does not have a separate category of unmonitored releases. The 2019 Effluent report lists the following under abnormal releases:

2019 Liquid abnormal releases:

1. Storm Sewer System (Table 3.2(2) and Table 3.2(3) Unit 2 and 3 Continuous)

2. Sewage Treatment Plant Effluent (Table 3.2(2) and Table 3.2(3) Unit 2 and 3 Continuous)

3. West Tritium Remediation Well (Table 3.2(2) and Table 3.2(3) Unit 2 and 3 Continuous) 2019 Gaseous abnormal releases:

1. Unit 1 Main Turbine Floor and Unit 1 Fuel Building (Table 2.2. A (1) Unit 1 Continuous for Ground Level)

2. Chemistry Laboratory Ventilation Effluent (Table 2.2.B (2) and 2.2.B (3) Unit 2 and 3 Continuous for Elevated Level)

3. Units 2/3 Heating Steam System (Table 2.2.A (2) and Table 2.2.A (3) Unit 2 and 3 Continuous for Ground Level)

4. East Turbine Building Ventilation (Table 2.2.A (2) and Table 2.2A (3) Unit 2 and 3 Continuous for Ground Level)

The 2020 Effluent Report states that there were zero abnormal releases but lists the same releases as the 2019 report under a section titled "Effluent Monitoring" along with the routine pathways. The same format is used for the 2021, 2022, and 2023 reports.

2020 Liquid effluent releases:

1. Storm Sewer System (Table 3.2(2) and Table 3.2(3) Unit 2 and 3 Continuous)

2. Sewage Treatment Plant Effluent (Table 3.2(2) and Table 3.2(3) Unit 2 and 3 Continuous)

3. West Tritium Remediation Well (Table 3.2(2) and Table 3.2(3) Unit 2 and 3 Continuous) 2020 Gaseous effluent releases:

1. Unit 1 Main Turbine Floor and Unit 1 Fuel Building (Table 2.2.A(1) Unit 1 Continuous for Ground Level)

2. Chemistry Laboratory Ventilation Effluent (Table 2.2.B(2) and 2.2.B(3) Unit 2 and 3 Continuous for Elevated Level)

3. Units 2/3 Heating Steam System (Table 2.2.A(2) and Table 2.2.A(3) Unit 2 and 3 Continuous for Ground Level)

4. East Turbine Building Ventilation (Table 2.2.A(2) and Table 2.2A(3) Unit 2 and 3 Continuous for Ground Level)

The licensee clarified during the audit that these release pathways do not meet the sites definition of abnormal release because the releases are expected to occur and are not unplanned or uncontrolled.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 72 of 113 Please confirm the following:

a) Confirm that even though the ER states that there were 16 abnormal liquid releases and 4 abnormal gaseous releases in 2019, there were no significant changes in the releases of the plant compared to the previous year 2018 or the following years 2020-2023 with the exception of the West Tritium Remediation Well, which was put into service in September 2019 and is a planned continuous release.

b) Confirm that the releases listed as abnormal in 2019 do not meet the sites definition for abnormal because they are not unexpected, unplanned or uncontrolled; they do not meet the RG 1.21, Revision 3 definition of abnormal release because they are not unplanned or uncontrolled.

c) Confirm that the tables listed above are accurate for where the amounts released are reflected in the reports for these pathways.

d) Confirm if there have been any reportable unplanned or uncontrolled releases or discharges of radioactive materials (radioactive liquid or gaseous releases) since the ER was written.

CEG Response:

CEG confirms statements a) through d) are correct with the clarification that there have been no reportable unplanned or uncontrolled releases or discharges of radioactive materials (radioactive liquid or gaseous releases) since the ER was written through December 18, 2024.

References:

EGC (Exelon Generation Company). 2019. Dresden Nuclear Power Station 2018 Radioactive Effluent Release Report and ODCM (Offsite Dose Calculation Manual). April 2019. ADAMS Accession No. ML19116A206.

EGC. 2019. Dresden Offsite Dose Calculation Manual, Revision 16. December 2019. ADAMS Accession No. ML20125A018.

EGC. 2020. Dresden Nuclear Power Station 2019 ARERR (Annual Radioactive Effluent Release Report). April 2020. ADAMS Accession No. ML20125A019.

EGC. 2021. Dresden Nuclear Power Station 2020 ARERR. April 2021. ADAMS Accession No. ML21321A286.

CEG (Constellation Energy Generation, LLC). 2022. Dresden Nuclear Power Station 2021 ARERR and ODCM. April 2022. ADAMS Accession No. ML22112A108.

CEG. 2023. Dresden Nuclear Power Station 2022 ARERR. May 2023. ADAMS Accession No. ML23121A240.

CEG. 2024. Dresden Nuclear Power Station 2023 ARERR. April 2024. ADAMS Accession No. ML24127A098.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 73 of 113 Topic: Waste Management NRC RCI Number: WM-06 As discussed during the audit, please confirm there have been no inadvertent releases or spills of nonradioactive contaminants to date that would trigger a notification requirement since the DNPS SLR ER submittal.

CEG Response:

CEG confirms this statement is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 74 of 113 Topic: Waste Management NRC RCI Number: WM-07 As discussed during the additional audit breakout session (on December 3, 2024), please confirm the following:

a) Although Section 3.6.4.2 of the ER indicates that 6,000 cubic meters of soil were disposed of onsite, the actual volume of soil totaled approximately 3,820 cubic meters.

b) No sewage treatment drying bed waste was placed in this disposal area; therefore, no permits from the State of Illinois were required.

c) There are no plans to add materials in this disposal area.

d) Any material remaining from the disposal site at the time of license termination will be accounted for in demonstrating compliance with the criteria for decommissioning in 10 CFR 50.82 and 10 CFR part 20, subpart E.

CEG Response:

CEG confirms these statements are correct with the following clarifications for a) and d).

a) In its 2014 application for the 10 CFR 20.2002 disposal site, which was approved by the NRC in December 2015 (NRC 2015), CEG estimated that 6,000 cubic meters of soils containing trace quantities of residual radioactive materials were accumulated at DNPS from various projects conducted between 2006 and 2012 (EGC 2014). CEG confirms that, based on the available records generated per the site procedure implementing the requirements of the 10 CFR 20.2002 Disposal Permit and maintained in accordance with 10 CFR 50.75(g), the actual volume of soil that was disposed of at the disposal site totals approximately 3,820 cubic meters.

d) The dose contribution from the disposal site will be accounted for at the time of license termination to meet the criteria for decommissioning in 10 CFR, Part 20, Subpart E, per the requirements of 10 CFR 50.82(a)(11)(ii).

References:

NRC. 2015. Dresden Nuclear Power Station, Units 2 and 3 - Request for 10 CFR 20.2002 Alternate Disposal Approval (CAC Nos. MF3644 and MF3645). December 2015. ADAMS Accession No. ML14353A033.

EGC. 2014. Dresden Nuclear Power Station, Units 2 and 3. Request to Dispose of Slightly Contaminated Soil in Accordance With 10 CFR 20.2002. March 2014. ADAMS Accession No. ML14077A140.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 75 of 113 Topic: Spent Nuclear Fuel NRC RCI Number: SNF-01 The ER Section 2.2.6.4 states that The station has two separate ISFSIs. The East ISFSI is comprised of two sections and has space for 10 additional casks. The West ISFSI is one pad and has space for 13 additional casks. As of November 2023, DNPS has completed construction on an expansion of the West ISFSI that will provide adequate storage to operate through the subsequent period of extended operation (SPEO) for Units 2 and 3. As discussed during the audit please confirm the following:

a) There are three ISFSIs on the site. The East ISFSI, the West ISFSI, and the South ISFSI (which is referred to as the West ISFSI expansion in the ER).

b) The West ISFSI second pad construction has been completed.

c) The South ISFSI has one completed pad that can accommodate fuel up until approximately 2031. Land immediately to the north and adjacent to the South pad is planned for future ISFSI expansion. This additional pad in the South ISFSI would have enough capacity to accommodate dry storage needs, but the pools would still be necessary for spent fuel storage accounting for this additional expansion that is planned.

If further expansion is deemed necessary, there are locations within the site on previously disturbed land that could be available.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 76 of 113 Topic: Greenhouse Gas and Climate Change NRC RCI Number: GHG-CC-01 Please confirm that the highest employee count from 2018 through 2022 was 800 employees and that the estimated greenhouse gas emissions from worker vehicles are 3,168 metric tons of carbon dioxide equivalent.

CEG Response:

CEG confirms these statements are correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 77 of 113 Topic: Greenhouse Gas and Climate Change NRC RCI Number: GHG-CC-02 As discussed during the environmental audits Greenhouse Gas Emissions and Climate Change breakout session and in response to information need GHG-CC-2, please confirm:

Sulfur hexafluoride (SF6) is used for main condenser tube leak testing, main control room tracer gas testing, and in circuit breakers.

Process carbon dioxide (CO2) is used in the emergency fire suppression system and main generator hydrogen purging during outages.

CEG has procedures for performing of main condenser tube leak testing, control room tracer gas testing, and maintenance and inspections of the SF6 circuit breakers.

Emissions calculations are based on emission factors from the Environmental Protection Agencys 2023 emission factors for greenhouse gas inventories table and hours of operation for combustion sources, sulfur hexafluoride usage and/or leaks, carbon dioxide gas usage, and fugitive emissions from refrigerants.

For 2023, direct emissions are 2,662 metric tons of carbon dioxide equivalents and 53,594 metric tons of carbon dioxide equivalents for purchased electricity.

For direct greenhouse gas emissions, the relative percentage of each source accounted are as follows:

2023 2022 2021 2020 2019 2018 Station Combustion Sources 98.05 90.85 99.21 89.78 75.99 89.75 SF6 0

0 0

5.59 21.02 0

CO2 0.21 0.71 0.14 0.24 0.33 0

Hydrofluorocarbons/perfluorocarbons (HFCs/PCFs) refrigerants 0

6.04 0

1.98 2.16 0

Ozone Depleting Chemicals Refrigerants 1.74 2.4 0.65 2.4 0.5 10.25 CEG Response:

CEG confirms this information is correct.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 78 of 113 Topic: Severe Accident Mitigation Alternatives NRC RCI Number: SAMA-RCI-1 [Info Need SAMA-1]

Section 4.15.2.1 of the subsequent license renewal (SLR) ER provides risk estimates for internal events, including internal flooding as well as fire, seismic, external flooding, and high wind/tornado events. The extent to which other external events were considered and their basis for exclusion, if applicable, as new and significant information is not clear from the information documented within the ER. Confirm that such events were considered and determined to not represent new and significant information.

CEG Response:

It is confirmed that in addition to the internal events, internal flooding, fire, seismic, external flooding, and high wind/tornado hazards, the Dresden analysis considered other external events and that they were determined to not represent new and significant information. The list of external events hazards that was included in the analysis was developed from a review of Tables D-1 and D-2 in Appendix D of RG 1.200, Rev. 3 (Reference [1]), the discussion in NUREG-1855 (Reference [2]) related to the hazards that should be evaluated to assess uncertainties in plant PRAs, and information on the site region and plant design.

References:

Reference [1]. NRC. 2020. Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities. Draft Regulatory Guide DG-1362. Proposed Revision 3 to Regulatory Guide 1.200. June 2020. ADAMS Accession No. ML19308B636.

Reference [2]. NRC. 2017. Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decisionmaking. Final Report. NUREG-1855. Revision 1. March 2017. ADAMS Accession No. ML17062A466.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 79 of 113 Topic: Severe Accident Mitigation Alternatives NRC RCI Number: SAMA-RCI-2 [Info Need SAMA-3]

Section 4.15.2.1 of the SLR ER provides a CDF estimate for high wind/tornado events that is estimated to be no more than 2.00E-05 per year per unit. The extent to which such events were considered as new and significant information relative to the SAMA analysis is not clear from the information documented within the ER. Confirm that such events were considered and determined to not represent new and significant information (i.e., would not result in a SAMA that yields a significant risk reduction).

CEG Response:

The Dresden analysis considered high wind/tornado events and those SAMAs with the potential to reduce the risk of those events and it was determined that they did not represent new and significant information.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 80 of 113 Topic: Severe Accident Mitigation Alternatives NRC RCI Number: SAMA-RCI-3 [Info Need SAMA-7]

The dispositions for SLR SAMAs 48 and 54 within Table 4.15-5 of the ER state that the seismic PRA model failed to properly quantify and that the same reduction as the internal events model was assumed. The basis of this assumption is not clear from the information documented within the ER. Confirm that the evaluation of SAMAs 48 and 54 would yield the same conclusion (i.e.,

would not result in a SAMA that yields a significant risk reduction) had the seismic risk had been directly considered or quantified.

CEG Response:

Review of the seismic risk profile and the contributors associated with SAMAs 48 and 54 indicate that if the SAMAs had been fully quantified using the seismic model, the conclusion would be the same as documented in the ER, which is that neither SAMA 48 nor SAMA 54 would reduce plant risk by 50 percent or more (i.e., they do not yield significant reductions in plant risk).

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 81 of 113 Topic: General NRC RAI Number: GEN-01 REQUIREMENT: 10 CFR 51.53(c)(3)(iv) indicates that an applicants ER must contain any new and significant information regarding the environmental impacts of license renewal of which the applicant is aware.

ISSUE: Appendix B of the draft SEIS will list the permits and licenses issued by Federal, State, and local authorities for activities at DNPS, as identified in Table 9.1-1 of the ER, dated April 17, 2024 (ML24108A011). In preparing the SEIS, the NRC staff must consider whether there have been any changes to operating permits or other requirements.

REQUEST: Provide the relevant updates to ER Table 9.1-1 that have occurred since the ER was submitted in April 2024. This includes any permits that have expired since submitting the license renewal application to the NRC. Please provide the status of those permits and or renewals.

CEG Response:

An updated DNPS SLR ER Table 9.1-1 Environmental Authorizations for Current DNPS Operations through December 2024 is provided below.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 82 of 113 Table 9.1-1 Current DNPS Authorizations (Sheet 1 of 3)

Agency Authority Requirement Number Expiration Dates Authorized Activity NRC AEA

[10 CFR Part 50]

DNPS license to operate Units 2 & 3 DPR-19 & DPR-25 12/22/29 1/12/31 Operation of DNPS Units 2 & 3 EPA/IEPA CWA Section 401

[33 USC 1341]

Certification of water quality standards N/A N/A Discharge into waters of the U.S., permitted under the Illinois NPDES permit DOT 49 USC 5180

[49 CFR Part 107, Subpart G]

Registration 051022550113EG 6/30/2025 Hazardous material shipment Tennessee Department of Environment and Conservation (TDEC)

TDEC Rule 0400-20-10-.32 License to ship radioactive material T-IL001-L23 12/31/2024 Renewed Annually Shipment of radioactive material to a licensed disposal/processing facility in Tennessee Utah Department of Environmental Quality Utah Administrative Code R313-26 General site access permit for radioactive waste disposal 0110000029 3/18/2025 Renewed Annually Delivery of radioactive waste to a land disposal facility in Utah

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 83 of 113 Table 9.1-1 Current DNPS Authorizations (Sheet 2 of 3)

Agency Authority Requirement Number Expiration Dates Authorized Activity IEPA Federal RCRA [42 USC 6912] and IEPA Title 35 IAC, Parts 700-739 Hazardous waste generator registration ILD000665489 9/1/2025 (As required by 40 CFR 262.18)

Authorizes facility to operate as a hazardous waste generator IEPA IEPA, Title 35 of IAC, Subtitle C and/or D, Chapter 1, and the CWA NPDES permit IL0002224 8/31/2021 Administratively Extended Discharges of stormwater, wastewater, and treated water to waters of the state IEPA IEPA, Title 35 of IAC, Subtitle C, Chapter 1, and the CWA NPDES permit 1LG870020 9/30/2027 Pesticide application point-source discharges IEPA IEPA, Title 35 IAC, Subtitle B, Chapter 1, and the CAA Air emission permit 063806AAC 3/31/2024 Administratively Extended Operate air emission sources: 2 natural gas-fired auxiliary boilers #1 and #2 with distillate oil back-up, 5 large diesel-powered emergency generators, 54 cooling tower cells and gasoline storage and handling

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 84 of 113 Table 9.1-1 Current DNPS Authorizations (Sheet 3 of 3)

Agency Authority Requirement Number Expiration Dates Authorized Activity IDNR 17 IAC, Chapter 1, Subchapter H, Part 3702 Permit DS 2000233 N/A Authorized to operate and maintain the Dresden Nuclear Station Cooling Pond Dam IDPH and SDWA IDPH, Title 77 IAC, Chapter 1, Part 900 Drinking Water System Code, Ill Pollution Control Board 35 IAC Part 611, Primary Drinking Water Standards Permit Water System No. IL3083196 N/A Non-transient, non-community water system IDPH IDPH, Title 77 IAC, Chapter 1, Subchapter R, Part 900.45 Certification Operator ID 21818 12/31/2026 Operate non-transient, non-community public water system IEPA IEPA Title 35 IAC, Subtitle B, Chapter 1, Part 237 Open burn permit firefighter training 43083 02/23/2025 Open burn for firefighter training

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 85 of 113

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 86 of 113 Topic: Noise NRC RAI Number: NOI-01 REQUIREMENT: 10 CFR 51.53(c)(3)(iv) indicates that an applicants ER must contain any new and significant information regarding the environmental impacts of license renewal of which the applicant is aware.

ISSUE: The environmental report identified that the cooling towers are the primary contributing noise source from operation of DNPS to nearby recreation and residential receptors. Section 3.4 of the ER states that in 2017, DNPS completed a two-phase noise evaluation which found that cooling tower noise levels were 58 dBA at the nearest residence and exceeded Illinois nighttime limits of 51 dBA for residential receivers. The ER also identifies that CEG will support the planting of 150 evergreen trees to mitigate noise to offsite residences. Section 4.3.4 of the ER concludes that the impacts from the subsequent license renewal term would be SMALL. Section 4.3.4 of the ER, however, does not address the reduction in sound levels at the nearest resident during the subsequent license period anticipated as a result of the implemented mitigation measures. In response to information need NOI-01, CEG stated that they have a noise exceedance mitigation action plan for DNPS. The action plan includes conducting noise measurements when the trees reach sufficient maturity, which is estimated to be 5 years from the planting date (September 2024), to ensure compliance with state noise pollution regulations.

Additionally, documents provided in response to information need SW-5 identify that there are three siphon lines that draw water from the DNPS cooling lake to the Kankakee River and create small vortexes in the cooling lake that can sometimes be heard at the road. However, the ER did not identify this as a noise source.

REQUEST:

a) Provide a discussion that estimates quantitatively the sound level(s) at the nearest resident during the subsequent license renewal period that considers the planted trees. As part of the discussion include a basis and assumptions for the estimate(s) provided.

b) Discuss if CEG plans to update the noise exceedance mitigation action plan for DNPS, as needed, to ensure compliance with state noise pollution regulations after noise measurements are completed.

c) Provide a copy of the 2017 two-phase noise evaluation.

d) With respect to the vortexes that form in the cooling lake when the siphon line is in use, are sound levels at the road or residents located across the three siphon pipes available? If so, please provide this information.

CEG Response:

a) The SLR period will start in 2029/2031 which allows for 5-7 years for the planted black spruce trees to mature. The average conservative growth rate of a black spruce tree is approximately 6 inches per year. (USDA 2025) Noise reduction from tree buffers is estimated to be between 5 dBA to 8 dBA. Prior to the tree planting in September 2024, CEG installed a berm in 2004 along the south side of the Hot Canal Cooling Tower (HCCT) #3.

When combined with a landform, conservation tree buffers have been found to significantly increase buffer effectiveness (AASHTO 2025; Bentrup 2008). The Illinois code limits nighttime noise in nine octave bands which are approximately equivalent to 51 dBA at night

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 87 of 113 for residential receivers. Based on the planting date, initial tree size, and approximate growth rate, CEG estimates that the tree plantings are expected to reach sufficient maturity in 5 years to reduce the noise levels near Illinois nighttime limits for residential receivers.

Noise measurements will be conducted approximately 5 years after planting to determine quantitatively the sound level(s) at the nearest resident during the subsequent license renewal period that considers the planted trees.

b) The noise mitigation exceedance plan and associated noise measurements are being tracked in CEGs Corrective Action Program (CAP). Updates are included in this action tracking, as applicable.

c) A copy of the 2017 two-phase noise evaluation is provided in Enclosure 3.

d) Sound levels at the road and at residential areas located across the three siphon pipes are not available. The Siphon Line is operated seasonally for de-icing and not operated year-round.

References:

AASHTO (American Association of State Highway and Transportation Officials). 2025. Noise Overview. Retrieved from < https://environment.transportation.org/focus-areas/noise/noise-overview/> (accessed January 10, 2025).

Bentrup, G. 2008. Conservation buffers: design guidelines for buffers, corridors, and greenways.

Gen. Tech. Rep. SRS-109. Retrieved from < https://research.fs.usda.gov/treesearch/33522>

(accessed on January 17, 2025).

Viereck, Leslie A. and William F. Johnston. 2025. Picea mariana (Mill.) B. S. P., Black Spruce.

Retrieved from < https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_1/picea/mariana.htm>

(accessed on January 10, 2025).

Associated Documents:

Shiner and Associates. 2017. Exelon Dresden Unit 2 and 3 Cooling Towers Environmental Noise Assessment.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 88 of 113 Topic: Water Resources - Surface Water Resources NRC RAI Number: SW-02 REQUIREMENT: 10 CFR 51.45(b) and 51.53(c)(2) require that the ER include a description of the affected environment.

ISSUE: The NRC staff is preparing a SEIS that considers the plant-specific environmental impacts of subsequent license renewal for DNPS. As part of preparing the SEIS, the NRC staff must be able to review the recent intake and discharge water temperature data as it is relevant to assessing surface water impacts.

REQUEST: Provide plots of average monthly intake and discharge temperatures over the 2018-2023 period.

CEG Response:

Plots of average monthly intake and discharge temperatures over the 2018 - 2023 period are listed in the Associated Documents below and provided in Enclosure 3.

References:

None.

Associated Documents:

DNPS SLR ER Figure 3.6-4, Average Monthly Discharge Temperatures, 2018-2023 DNPS SLR ER Figure 3.6-5, Average Monthly Intake Temperatures, 2018-2023.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 89 of 113 Topic: Water Resources - Surface Water Resources NRC RAI Number: SW-03 REQUIREMENT: 10 CFR 51.45(b) and 51.53(c)(2) require that the ER include a description of the affected environment.

ISSUE: The NRC staff is preparing a SEIS that considers the plant-specific environmental impacts of subsequent license renewal for DNPS. As part of preparing the SEIS, the NRC staff must provide a description of the cooling water intake system pathway. The ER does not include a figure that illustrates the cooling water intake system pathway.

REQUEST: Provide a figure that illustrates the cooling water intake system pathway as described in the ER and during the environmental audit.

CEG Response:

A figure illustrating the cooling water intake system pathway is provided in the DNPS LR ER as Figure 3-2. A figure illustrating the cooling water intake system pathway and operating modes is listed in Associated Documents below and provided in Enclosure 3.

References:

EGC (Exelon Generation Company, LLC). 2003. Dresden Units 2 & 3 and Quad Cities Units 1

& 2 License Renewal Application. Appendix E, Applicants Environmental Report, Operating License Renewal Stage, Dresden Nuclear Power Station Units 2 and 3. January 2003. ADAMS Accession No. ML030090234.

Associated Documents:

Lake Lift Station Cooling Modes, Cooling Mode Flowpaths.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 90 of 113 Topic: Terrestrial Resources NRC RAI Number: TER-05 REQUIREMENT: 10 CFR 52.45(d) require the ER to include discussion of the status of compliance with applicable environmental quality standards imposed by Federal, State, regional and local agencies. In addition, 10 CFR 51.53(c)(3)(iv) indicates that an applicants ER must contain any new and significant information regarding environmental impacts of license renewal of which the applicant is aware.

ISSUE: The NRC staff is preparing a SEIS that considers the environmental impacts of subsequent license renewal for DNPS. As part of the preparing the SEIS, the staff must consider whether the has been any new information related to terrestrial resources. During the October 2024 environmental audit and Terrestrial Resources breakout session, CEG discussed avian injuries and mortalities onsite for the past 10 years.

REQUEST: Please provide a summary of bird mortalities or injuries (species, date, cause if known, associated structures or buildings, if any; final outcome) in chronological order from 2013 to 2024. Please provide a statement that there were no bird mortalities or injuries at the DNPS site for the following years: 2014, 2016, 2017-2023.

CEG Response:

A summary of bird mortalities or injuries (species, date, cause if known, associated structures or buildings, if any; final outcome) in chronological order from 2013 to 2024 is provided in the table below. There were no bird mortalities or injuries at the DNPS site for the following years: 2014, 2016, 2017-2023.

Incident Year Incident Date Bird Species Number of Individuals Condition of Individuals Associated Buildings or Structures Cause of Injury or Death 2013 5/23/2013 Unspecified Unspecified Dead Chemical Cleaning Building Unknown 2015 4/29/2015 Unspecified 1

Dead Chemical Cleaning Building Unknown 2024 5/19/2024 Osprey (Pandion haliaetus) 1 Unresponsive NA Unknown

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 91 of 113 Topic: Aquatic Resources NRC RAI Number: AQU-06 REQUIREMENT: The NRCs regulation at 10 CFR 51.53(c)(3)(ii)(B) requires that if the applicants plant utilizes a once-through cooling or cooling pond water intake and discharge system, the applicant shall provide a copy of current Clean Water Act (CWA) 316(b) Best Technology Available (BTA) determinations and, if applicable, a 316(a) variance in accordance with 40 CFR part 125, or equivalent State permits and supporting documentation. If the applicant cannot provide these documents, it shall assess the impact of the proposed action on fish and shellfish resources resulting from impingement mortality and entrainment and thermal discharges.

If the NPDES permitting authority has made BTA determinations for the nuclear power plant pursuant to CWA Section 316(b) in accordance with the current regulations at 40 CFR Part 122 (Ref. 55) and 40 CFR Part 125 (Ref. 56), which were promulgated in 2014 (79 FR 48300) (Ref.

57), and the plant has implemented any associated requirements or those requirements would be implemented before the license renewal period, no additional analysis is required. In such cases, provide with the ER copies of the NPDES permit, CWA Section 316(b) BTA determinations, studies and information submitted to the NPDES permitting agency pursuant to 40 CFR 122.21(r), and relevant correspondence with the permitting agency.

ISSUE: Because the Illinois Environmental Protection Agency has not yet made CWA 316(b)

BTA determinations for DNPS, the NRC staff requires additional information in order to assess the impact of the proposed action on fish and shellfish resources resulting from impingement mortality and entrainment. The NRC staff also requires additional information concerning DNPSs CWA 316(a) variance in order to assess the impacts of thermal discharges on aquatic organisms.

REQUEST: Please provide copies of the following documents:

1991-2014 Long term Aquatic Monitoring Program a) EA Engineering, Science, and Technology, Inc., PBC (EA). 2001. Dresden Nuclear Station Aquatic Monitoring 2000, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

b) EA Engineering, Science, and Technology, Inc., PBC (EA). 2002. Dresden Nuclear Station Aquatic Monitoring 2001, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

c) EA Engineering, Science, and Technology, Inc., PBC (EA). 2003. Dresden Nuclear Station Aquatic Monitoring 2002, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

d) EA Engineering, Science, and Technology, Inc., PBC (EA). 2004. Dresden Nuclear Station Aquatic Monitoring 2003, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

e) EA Engineering, Science, and Technology, Inc., PBC (EA). 2005. Dresden Nuclear Station Aquatic Monitoring 2004, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 92 of 113 f) EA Engineering, Science, and Technology, Inc., PBC (EA). 2006. Dresden Nuclear Station Aquatic Monitoring 2005, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

g) EA Engineering, Science, and Technology, Inc., PBC (EA). 2007. Dresden Nuclear Station Aquatic Monitoring 2006, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

h) EA Engineering, Science, and Technology, Inc., PBC (EA). 2008. Dresden Nuclear Station Aquatic Monitoring 2007, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

i) EA Engineering, Science, and Technology, Inc., PBC (EA). 2010. Dresden Nuclear Station Aquatic Monitoring 2008, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

j) EA Engineering, Science, and Technology, Inc., PBC (EA). 2012. Dresden Nuclear Station Aquatic Monitoring 2011, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

k) EA Engineering, Science, and Technology, Inc., PBC (EA). 2014. Dresden Nuclear Station Aquatic Monitoring 2013, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

l) EA Engineering, Science, and Technology, Inc., PBC (EA). 2015. Dresden Nuclear Station Aquatic Monitoring 2014, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

Impingement and Entrainment Studies a) EA Engineering, Science, and Technology, Inc., PBC (EA). 2015. Freshwater Mussel Survey in the Illinois River near the Dresden Nuclear Station (RM 271-272.5). Report by EA to Exelon Nuclear Company, Warrenville, IL.

b) EA Engineering, Science, and Technology, Inc., PBC (EA). 2007. Impingement Mortality Characterization Study (2005-2007) Dresden Station. Final Draft. November 2007.

Report by EA to Exelon Nuclear Company, Warrenville, IL.

c) EA Engineering, Science, and Technology, Inc., PBC (EA). 2007. Entrainment Characterization Study (2005-2007) Dresden Station. Final Draft. October 2007. Report by EA to Exelon Nuclear Company, Warrenville, IL.

d) EA Engineering, Science, and Technology, Inc., PBC (EA). 2019. Impingement Characterization Report for Dresden Nuclear Power Station. Report by EA to Exelon Generation Company, Dresden Nuclear Station, Morris, IL.

e) EA Engineering, Science, and Technology, Inc., PBC (EA). 2019. Entrainment Characterization Report for Dresden Nuclear Power Station. Report by EA to Exelon Generation company, Dresden Nuclear Station, Morris, IL.

NPDES/316(b) Demonstrations a) AECOM. 2016. 40 CFR 122.21(r) (2-8) NPDES Application Requirements for Facilities with Cooling Water Intake Structures Exelon Generation Company, LLC, Dresden Nuclear Power Station, Morris, Illinois. May.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 93 of 113 b) AECOM. 2019. 40 CFR 122.21(r)(10) NPDES Application Requirements for Facilities with Cooling Water Intake Structures. Report by AECOM to Exelon Generation Company, LLC, Dresden Generating Station, Morris, IL.

c) AECOM. 2019. 316(b) Executive Summary. Report by AECOM to Exelon Generating Company, LLC, Dresden Generating Station, Morris, IL.

Thermal Effluent Studies a) Dresden Nuclear Station (DNS). 2015. Draft Dresden Nuclear Station 316(a)

Demonstration [including all appendices]. May 29, 2015.

CEG Response:

Per a RAI AQU-06 clarification call held on 1/24/25 with the NRC project manager and subject matter experts and a subsequent email on 1/27/25, revisions were made to the list of requested documents for RAI AQU-06. The updated requested documents related to the Long-Term Aquatic Monitoring Program are listed in Associated Documents below and provided in. The requested documents related to Impingement and Entrainment Studies are listed in Associated Documents below and provided in Enclosure 2 with the clarification that the correct date for EA Engineering, Science, and Technology, Inc., PBC (EA). 2007. Entrainment Characterization Study (2005-2007) Dresden Station is (2005-2006). The requested documents related to the NPDES/316(b) Demonstrations are listed in Associated Documents below and provided in Enclosure 3. The requested document related to the Thermal Effluent Study is listed in Associated Documents below and provided in Enclosure 3.

References:

None.

Associated Documents:

EA Engineering, Science, and Technology, Inc., PBC (EA). 2012. Dresden Nuclear Station Aquatic Monitoring 2011, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

EA Engineering, Science, and Technology, Inc., PBC (EA). 2014. Dresden Nuclear Station Aquatic Monitoring 2013, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

EA Engineering, Science, and Technology, Inc., PBC (EA). 2015. Dresden Nuclear Station Aquatic Monitoring 2014, RM 270.5-273.0. Report by EA to Exelon Nuclear Company, Dresden Nuclear Station, Morris, IL.

EA Engineering, Science, and Technology, Inc., PBC (EA). 2015. Freshwater Mussel Survey in the Illinois River near the Dresden Nuclear Station (RM 271-272.5). Report by EA to Exelon Nuclear Company, Warrenville, IL.

EA Engineering, Science, and Technology, Inc., PBC (EA). 2007. Impingement Mortality Characterization Study (2005-2007) Dresden Station. Final Draft. November 2007. Report by EA to Exelon Nuclear Company, Warrenville, IL.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 94 of 113 EA Engineering, Science, and Technology, Inc., PBC (EA). 2007. Entrainment Characterization Study (2005-2006) Dresden Station. Final Draft. October 2007. Report by EA to Exelon Nuclear Company, Warrenville, IL.

EA Engineering, Science, and Technology, Inc., PBC (EA). 2019. Impingement Characterization Report for Dresden Nuclear Power Station. Report by EA to Exelon Generation Company, Dresden Nuclear Station, Morris, IL.

EA Engineering, Science, and Technology, Inc., PBC (EA). 2019. Entrainment Characterization Report for Dresden Nuclear Power Station. Report by EA to Exelon Generation Company, Dresden Nuclear Station, Morris, IL.

AECOM. 2016. 40 CFR 122.21(r) (2-8) NPDES Application Requirements for Facilities with Cooling Water Intake Structures Exelon Generation Company, LLC, Dresden Nuclear Power Station, Morris, Illinois. May.

AECOM. 2019. 40 CFR 122.21(r)(10) NPDES Application Requirements for Facilities with Cooling Water Intake Structures. Report by AECOM to Exelon Generation Company, LLC, Dresden Generating Station, Morris, IL.

AECOM. 2019. 316(b) Executive Summary. Report by AECOM to Exelon Generating Company, LLC, Dresden Generating Station, Morris, IL.

Dresden Nuclear Station (DNS). 2015. Draft Dresden Nuclear Station 316(a) Demonstration.

May 29, 2015.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 95 of 113 Topic: Aquatic Resources NRC RAI Number: AQU-08 REQUIREMENT: The NRCs regulation at 10 CFR 51.53(c)(3)(ii)(B) requires that if the applicants plant utilizes a once-through cooling or cooling pond water intake and discharge system, the applicant shall provide a copy if applicable, a 316(a) variance in accordance with 40 CFR Part 125, or equivalent State permits and supporting documentation. If the applicant cannot provide these documents, it shall assess the impacts of the proposed action on fish and shellfish resources resulting fromthermal discharges.

Additionally, 10 CFR 51.53(c)(3)(ii)(E) requires the following: all license renewal applicants shall assess the impact of refurbishment, continued operations, and other license-renewal-related construction activities on important plant and animal habitats. Additionally, the applicant shall assess the impact of the proposed action on federally protected ecological resources in accordance with Federal laws protecting such resources, including but not limited to, the Endangered Species Act, the Magnuson-Stevens Fishery Conservation and Management Act, and the National Marine Sanctuaries Act. 10 CFR Part 51.41 requires that licensees submit information that may be useful in aiding the Commission in complying with Section 102(2) of NEPA with information in an environmental report that should contain sufficient data to aid the Commission in its development of an independent analysis (10 CFR 51.41(c)).

ISSUE: As of December 13, 2024, the USFWS proposed critical habitat for the Sheepnose mussel in the Kankakee River. Outfall 004 discharges Cooling Lake thermal effluent into the Kankakee River for up to two, 14-day periods annually. The CWA 316(a) variance is only applicable to the primary discharge of DNPS, and not Outfall 004. With the new proposed designation of critical habitat in the Kankakee River, and the potential for mixing of thermal effluent into the Kankakee River, the NRC staff is seeking additional information for their review.

REQUEST: Please provide copies of the following studies/document(s):

Outfall 004 Siphon Run Reports a) Will County Emergency Management Agency (WCEMA). 2024. Will County Kankakee River Ice Management Project Season Operating Report 2024. Report by WCEMA to Constellation. Will County, IL.

b) Constellation, LLC. 2023. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 23-0005. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

c) Constellation, LLC. 2022. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 22-0008. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

d) Constellation, LLC. 2021. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 21-0010. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

e) Constellation, LLC. 2020. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 20-0008. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 96 of 113 f) Constellation, LLC. 2019. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 19-0010. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

g) Constellation, LLC. 2018. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 18-0010. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

h) Constellation, LLC. 2017. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 17-0014. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

i) Constellation, LLC. 2016. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 16-0020. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

j) Constellation, LLC. 2015. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 15-0031. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

k) Constellation, LLC. 2014. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 14-0043. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

U.S. Army Corps of Engineers Initial Study on Siphon Lines a) U.S. Army Corps of Engineers. 1993. River Ice Management Project Operations and Maintenance Manual. Will County Office of Emergency Services, Will County, IL.

CEG Response:

The requested documents related to the Outfall 004 Siphon Run Reports are listed in Associated Documents below and provided in Enclosure 3. The requested document related to the U.S. Army Corps of Engineers Initial Study on Siphon Lines is listed in Associated Documents below and provided in Enclosure 3.

References:

None.

Associated Documents:

Will County Emergency Management Agency (WCEMA). 2024. Will County Kankakee River Ice Management Project Season Operating Report 2024. Report by WCEMA to Constellation. Will County, IL.

Constellation, LLC. 2023. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 23-0005. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Constellation, LLC. 2022. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 22-0008. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 97 of 113 Constellation, LLC. 2021. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 21-0010. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Constellation, LLC. 2020. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 20-0008. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Constellation, LLC. 2019. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 19-0010. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Constellation, LLC. 2018. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 18-0010. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Constellation, LLC. 2017. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 17-0014. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Constellation, LLC. 2016. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 16-0020. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Constellation, LLC. 2015. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 15-0031. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

Constellation, LLC. 2014. Siphon Line Report Dresden Nuclear Generating Station NPDES Permit Number IL0002224 PMLTR 14-0043. Report by WCEMA for CEG to Illinois Environmental Protection Agency. Dresden Nuclear Station, Morris, IL.

U.S. Army Corps of Engineers. 1993. River Ice Management Project Operations and Maintenance Manual. Will County Office of Emergency Services, Will County, IL.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 98 of 113 Topic: Federally Protected Ecological Resources NRC RAI Number: FPE-01 REQUIREMENT: 10 CFR 51.53(c)(3)(ii)(E) requires the following: all license renewal applicants shall assess the impact of refurbishment, continued operations, and other license-renewal-related construction activities on important plant and animal habitats. Additionally, the applicant shall assess the impact of the proposed action on federally protected ecological resources in accordance with Federal laws protecting such resources, including but not limited to, the Endangered Species Act (ESA), the Magnuson-Stevens Fishery Conservation and Management Act, and the National Marine Sanctuaries Act. The implementing regulations for Section 7(a)(2) of the ESA define action area as all areas affected directly or indirectly by the Federal action and not merely the immediate area involved in the action (50 CFR 402.02). The action area effectively bounds the analysis of federally listed species and critical habitats because only species and habitats that occur within the action area may be affected by the Federal action.

ISSUE: The ER does not describe or define the ESA action area for the proposed DNPS subsequent license renewal.

REQUEST: Please describe the ESA action area for the proposed DNPS subsequent license renewal.

CEG Response:

Endangered Species Act (ESA) Action Area for DNPS Proposed SLR Term ESA action areas are areas affected directly or indirectly by the federal action and not merely the immediate area involved in the action, as described in 50 CFR 402.02. The action area bounds the analysis of federally listed species and critical habitats because only federally listed species and critical habitats that occur within the action area may be affected by the federal action. For the purpose of assessing the potential impacts of the license renewal on federally listed species, the action area is defined below.

Terrestrial Region The terrestrial region of the action area consists of 1,280 acres of the DNPS site. The site consists of grassland/herbaceous areas, which is the largest terrestrial land use/land cover category, accounting for approximately 22 percent of the site. This is followed by developed areas at approximately 16 percent, woody wetlands at approximately 5 percent, and pasture/hay at approximately 4 percent. The remaining five terrestrial land use/land cover categories account for approximately 5 percent of the site.

The remaining 48 percent of the DNPS site consists of open water, the majority of which is associated with Dresden Cooling Lake and is included in the aquatic action area as described below.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 99 of 113 Aquatic Region The aquatic region of the action area envelopes the following areas of the DNPS site:

Dresden Cooling Lake, all intake and discharge canals associated with DNPS operations, the entire width of Kankakee River from the intake canal entrance at 41.388889° latitude, 88.263611° longitude downstream to the Kankakee River/Des Plaines River confluence (i.e., Illinois River), and the Illinois River from the Kankakee River/Des Plaines River confluence downstream to Dresden Island Lock and Dam.

According to the DNPS 316(a) demonstration, a major portion of the Illinois River cross-section between the DNPS discharge and the Dresden Island Lock and Dam maintains temperatures adequate to support biological communities under both typical summer and adverse river conditions (See RAI AQU-06, Dresden Nuclear Station (DNS). 2015. Draft Dresden Nuclear Station 316(a) Demonstration, Appendix D. May 29, 2015.) Thus, Dresden Island Lock and Dam is conservatively included as the downgradient extent of the aquatic region of the action area.

Therefore, for the purposes of ESA analysis, the aquatic region of the DNPS action area includes the entire width of the Kankakee River from the intake canal entrance downstream to the Dresden Island Lock and Dam.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 100 of 113 Topic: Federally Protected Ecological Resources NRC RAI Number: FPE-03 REQUIREMENT: 10 CFR 51.53(c)(3)(ii)(E) requires the following: all license renewal applicants shall assess the impact of refurbishment, continued operations, and other license-renewal-related construction activities on important plant and animal habitats. Additionally, the applicant shall assess the impact of the proposed action on federally protected ecological resources in accordance with Federal laws protecting such resources, including but not limited to, the Endangered Species Act, the Magnuson-Stevens Fishery Conservation and Management Act, and the National Marine Sanctuaries Act. 10 CFR Part 51.41 requires that licensees submit information that may be useful in aiding the Commission in complying with Section 102(2) of NEPA with information in an environmental report that should contain sufficient data to aid the Commission in its development of an independent analysis (10 CFR 51.41(c)).

ISSUE: The USFWS released an updated Northern Long-eared Bat and Tricolored Bat Range-Wide Determination Key (DKey) on October 23, 2024. A DKey is a logically structured set of questions to assist a user in determining whether a proposed action qualifies for a predetermined consultation outcome based on USFWS standing analysis. DKeys typically contain a series of yes/no questions concerning the proposed action. The NRC staff requires more information to complete the DKey and determine the potential effects of the proposed DNPS subsequent license renewal on the northern long eared and tricolored bats.

REQUEST: Please provide a copy of the responses to the latest version of the Northern Long-eared Bat and Tricolored Bat Range-Wide DKey that was released on November 7, 2024, for the continued operations of DNPS during the proposed license renewal term. The Northern Long-eared Bat and Tricolored Bat Range-Wide DKey can be accessed on the USFWSs Information for Planning and Consultation (IPaC) database at: https://ipac.ecosphere.fws.gov/.

Supplementary information on the DKey can be obtained at:

https://www.fws.gov/library/collections/northern-long-eared-bat-and-tricolored-bat-range-wide-determination-key.

CEG Response:

A copy of the responses to the latest version of the Northern Long-eared Bat and Tricolored Bat Range-Wide DKey that was released on November 7, 2024, for the continued operations of DNPS during the proposed license renewal term, is listed in Associated Documents below and provided in Enclosure 3.

References:

None.

Associated Documents:

Northern Long-eared Bat and Tricolored Bat Range-Wide DKey.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 101 of 113 Topic: Federally Protected Ecological Resources NRC RAI Number: FPE-04 REQUIREMENT: 10 CFR 51.53(c)(3)(ii)(E) requires the following: all license renewal applicants shall assess the impact of refurbishment, continued operations, and other license-renewal-related construction activities on important plant and animal habitats. Additionally, the applicant shall assess the impact of the proposed action on federally protected ecological resources in accordance with Federal laws protecting such resources, including but not limited to, the Endangered Species Act, the Magnuson-Stevens Fishery Conservation and Management Act, and the National Marine Sanctuaries Act. 10 CFR Part 51.41 requires that licensees submit information that may be useful in aiding the Commission in complying with section 102(2) of NEPA with information in an environmental report that should contain sufficient data to aid the Commission in its development of an independent analysis (10 CFR 51.41(c)).

ISSUE: The USFWS published a proposed rule to list the tricolored bat (Perimyotis subflavus) as endangered under the ESA on September 14, 2022 (87 FR 56381). This species range includes Grundy County and may occur in the action area. The ER does not provide an analysis of the potential impacts on this species.

REQUEST: Please provide an analysis of the potential impacts of the proposed license renewal on the tricolored bat. Please provide an analysis of the potential impacts of the proposed license renewal on tricolored bat. This analysis should address (1) mortality or injury from collisions with plant structures and vehicles; (2) habitat loss, degradation, disturbance, or fragmentation, and associated effects; and (3) behavioral changes resulting from refurbishment or other site activities, among other impacts relevant to this species that CEG may identify.

CEG Response:

Impact Assessment for the Tricolored Bat (Perimyotis subflavus)

The U.S. Fish and Wildlife Service (USFWS) published a proposed rule to list the tricolored bat (Perimyotis subflavus) as endangered under the Endangered Species Act (ESA) in September 2022. The current known range for the tricolored bat spans across much of the central and eastern continental U.S. and overlaps with the DNPS action area (USFWS 2024).

During the spring, summer and fall, tricolored bats primarily roost among live and dead leaf clusters of live or recently dead deciduous hardwood trees. In the southern and northern portions of the range, tricolored bats will also roost in Spanish moss (Tillandsia usneoides) and Usnea trichodea lichen, respectively. In addition, tricolored bats have been observed roosting during summer among pine needles, within artificial roosts like barns, beneath porch roofs, bridges, concrete bunkers, and rarely within caves. During the winter, tricolored bats hibernate in caves and mines. Tricolored bats exhibit high site fidelity with many individuals returning year after year to the same hibernaculum. (USFWS 2024)

Tricolored bats have not been recorded as occurring at DNPS or at any of the installed bat boxes at the DNPS site. Further, there have been no bat incidents, including mortality or injury from collisions with plant structures and vehicles, that have occurred at DNPS. However, given the general habitat requirements of this species, it can be conservatively assumed that suitable habitat to varying degrees is present within the forested areas of the site as well as man-made structures at the site.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 102 of 113 Potential impacts to the tricolored bat from the operations of DNPS are discussed below:

Mortality or injury from collisions with plant structures: Bat collisions with plant structures at nuclear power plants are not well documented but are likely to be rare. There have been no documented bat incidents at the DNPS site from 2013 through 2024.

Loss, degradation, or disturbance of habitat: No construction, land clearing, or other ground-disturbing activities are proposed for the proposed SLR term. Additionally, all plant operations are located in disturbed areas, and no tree clearing is proposed during the SLR term that would potentially impact the habitat for the tricolored bat.

Behavioral changes from refurbishment and/or construction activities: No construction, ground-disturbing activities, or license-related refurbishment activities have been identified or proposed at the DNPS site during the SLR term. Any bat species, if present on the DNPS site, has likely already acclimated to the noise, vibration, and general human disturbances associated with site maintenance, infrastructure repairs, and other site activities. Moreover, the undisturbed, forested areas surrounding the structures likely provide more suitable habitat; hence, it is unlikely that tricolored bats would establish a colony in the man-made structures at DNPS. As such, behavioral changes from refurbishment and/or construction activities to tricolored bats during the SLR term are unlikely.

DNPS relies on administrative controls and other regulatory programs to ensure habitats and wildlife are protected from changes in station operations or prior to activities that break ground.

The administrative controls involve reviewing the change, identifying effects, if any, on the environmental resource area (i.e., habitat and wildlife), establishing BMPs, modifying existing permits, or acquiring new permits to minimize impacts. Existing regulations required at the site, also ensure habitats and wildlife are protected. These are related to programs such as the following: stormwater management for controlling the runoff of pollution sources such as sediment, metals, or chemicals; spill prevention with BMPs and structural controls to minimize the potential for a chemical release to the environment; bird nest management due to immediate safety or reliability concerns; and herbicide management to ensure their use will not adversely affect the environment.

If necessary, CEG would consult with USFWS to ensure compliance with the ESA with regard to the tricolored bat. As such, the continued operation of the DNPS site for the proposed operating term MAY AFFECT BUT IS NOT LIKELY TO ADVERSELY AFFECT the tricolored bat.

References:

U.S. Fish and Wildlife Service. 2024. Tricolored Bat. Retrieved from

<https://www.fws.gov/species/tricolored-bat-perimyotis-subflavus> (Accessed on August 27, 2024).

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 103 of 113 Topic: Federally Protected Ecological Resources NRC RAI Number: FPE-05 REQUIREMENT: 10 CFR 51.53(c)(3)(ii)(E) requires the following: all license renewal applicants shall assess the impact of refurbishment, continued operations, and other license-renewal-related construction activities on important plant and animal habitats. Additionally, the applicant shall assess the impact of the proposed action on federally protected ecological resources in accordance with Federal laws protecting such resources, including but not limited to, the Endangered Species Act, the Magnuson-Stevens Fishery Conservation and Management Act, and the National Marine Sanctuaries Act. 10 CFR Part 51.41 requires that licensees submit information that may be useful in aiding the Commission in complying with section 102(2) of NEPA with information in an environmental report that should contain sufficient data to aid the Commission in its development of an independent analysis (10 CFR 51.41(c)).

ISSUE: The USFWS published a proposed rule to list the salamander mussel (Simpsonaias ambigua) as endangered under the ESA and to designate critical habitat for this species on August 22, 2023 (88 FR 57223). This species range includes Grundy County and may occur in the action area. The ER does not provide an analysis of the potential impacts on this species.

REQUEST: Please discuss whether any aquatic surveys have detected this species (including individuals not identified to the species level that may have been salamander mussels) and provide an analysis of the potential impacts of the proposed license renewal on the salamander mussel. This analysis should address (1) impingement of fish species that early life stages of salamander mussels use as hosts; (2) impacts related to water quality, including chemical and thermal effluents; and (3) dredging, among other impacts relevant to this species that CEG may identify.

CEG Response:

Impacts Analysis for the Salamander Mussel (Simpsonaias ambigua)

The U.S. Fish and Wildlife Service (USFWS) published a proposed rule to list the salamander mussel (Simpsonaias ambigua) as endangered under the ESA and to designate critical habitat for this species on August 22, 2023 (88 FR 57223). The current known range of the species includes Grundy County and overlaps with the DNPS action area. However, the proposed critical habitat for the salamander mussel does not overlap with the DNPS action area. (USFWS 2024)

The salamander mussel (Simpsonaias ambigua) is a species of freshwater mussel currently found in scattered populations across 14 states from New York southwest to Arkansas. The salamander mussel is a small, thin-shelled mussel that inhabits swift-flowing rivers and streams with areas of shelter under rocks or in crevices. The mussel is found in Arkansas, Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, West Virginia, Wisconsin and Ontario, Canada. The salamander mussel lives for approximately 10 years. (USFWS 2024)

Similar to other freshwater mussels, the salamander mussel has a unique life cycle that relies on a host for successful reproduction, but the salamander mussel is the only freshwater mussel in North America to use a non-fish host. The mudpuppy (Necturus maculosus), the only known

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 104 of 113 host for salamander mussel, is a fully aquatic salamander species that tends to be present within the same habitat preferred by the salamander mussel during the summer and fall when female mudpuppies are guarding their nests under large flat rocks. The salamander mussels larvae (called glochidia) develop on the gills of the mudpuppy before falling off into the stream substrate. (USFWS 2024)

Salamander mussels have not been recorded as occurring at DNPS in any of the aquatic DNPS aquatic surveys, including the freshwater mussel survey provided as part of the CWA 316(a) demonstration report (AQU-06, Enclosure 2).

Potential impacts to the salamander mussel from the operations of DNPS are discussed below:

Impingement of fish species that early life stages of salamander mussels use as hosts:

The salamander mussel is a unique species that uses an amphibian (mudpuppy), and not a fish species, as its host. Though the range of mudpuppy overlaps with Grundy County, there have been no observations of the species in any surveys or entrainment and impingement studies conducted at DNPS. In the reported absence of this species-specific host, it is unlikely that the salamander mussel is present at DNPS. The DNPS facility has operated under a NPDES permit without any identified problems with respect to impingement or entrainment. DNPS will ensure that it continues to utilize the BTA to minimize entrainment and impingement to the fullest extent practicable to maintain compliance with the NPDES permit. Based on previous impingement and entrainment studies, ecological monitoring, and compliance with NPDES permit conditions, CEG concludes that impacts from impingement and entrainment would have NO EFFECT on the salamander mussel during the proposed SLR term.

Impacts related to water quality, including chemical and thermal effluents: Chemical additives approved by the IEPA are used to control pH, scale, and corrosion in the circulating water system, and to control biofouling of station equipment. There have been no notices of violations, fish kills or spills related to the NPDES permit in the past seven years (2018-2024). DNPS is operating in conformance with its NPDES permit, and therefore is in compliance with CWA requirements. Through continued compliance with the NPDES permit conditions, and because there are no planned operational changes during the proposed SLR term that would increase the temperature of DNPSs existing thermal discharge, CEG concludes that water quality and thermal impacts due to continued operation would have NO EFFECT on the salamander mussel during proposed SLR term.

Dredging and other potential impacts: Periodic maintenance dredging of the Units 2 and 3 intake and/or discharge canal may be required during the SLR term. DNPS maintains procedures related to excavation, trenching, and shoring, and determining regulatory requirements, such as a permit from the USACE, prior to any dredging operations. In addition, DNPS follows a solid waste management procedure for managing dredge spoils. For DNPS activities that could require a construction stormwater permit, CEG would obtain the required permit and comply with the stormwater management and BMP requirements. As such, CEG concludes that dredging associated with the continued operation of DNPS during the SLR term would have NO EFFECT on the salamander mussel.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 105 of 113 If necessary, CEG would consult with USFWS to ensure compliance with the ESA with regard to the salamander mussel. The continued operation of the DNPS site for the proposed operating term will have NO EFFECT on the salamander mussel.

References:

U.S. Fish and Wildlife Service. 2024. Salamander mussel. Retrieved from

<https://www.fws.gov/species/salamander-mussel-simpsonaias-ambigua> (Accessed on September 10, 2024)

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 106 of 113 Topic: Federally Protected Ecological Resources NRC RAI Number: FPE-06 REQUIREMENT: 10 CFR 51.53(c)(3)(ii)(E) requires the following: all license renewal applicants shall assess the impact of refurbishment, continued operations, and other license-renewal-related construction activities on important plant and animal habitats. Additionally, the applicant shall assess the impact of the proposed action on federally protected ecological resources in accordance with Federal laws protecting such resources, including but not limited to, the Endangered Species Act, the Magnuson-Stevens Fishery Conservation and Management Act, and the National Marine Sanctuaries Act. 10 CFR Part 51.41 requires that licensees submit information that may be useful in aiding the Commission in complying with section 102(2) of NEPA with information in an environmental report that should contain sufficient data to aid the Commission in its development of an independent analysis (10 CFR 51.41(c)).

ISSUE: The USFWSs Information for Planning and Conservation database (https://ipac.ecosphere.fws.gov/) indicates that the whooping crane (Grus americanus) may occur in the action area. The ER does not address this species.

REQUEST: Please provide an analysis of the potential impacts of the proposed license renewal on whooping crane (Grus americanus). This analysis should address (1) a description of whooping crane use of DNPS site and vicinity, (2) mortality or injury from collisions with plant structures and vehicles; (3) habitat loss, degradation, disturbance, or fragmentation, and associated effects; and (4) behavioral changes resulting from refurbishment or other site activities, among other impacts relevant to this species that CEG may identify.

CEG Response:

Impact Analysis for the Whooping Crane (Grus americana)

The U.S. Fish and Wildlife Service (USFWS) lists the population of whooping crane (Grus americana) that occurs in Illinois, and that overlaps the DNPS action area, as an experimental, non-essential population not necessary for the continued existence of the species. However, for the purposes of consultation, non-essential experimental populations are treated as a proposed species on private land and federal actions cannot jeopardize their existence (USFWS 2024a).

The whooping crane breeds, migrates, winters and forages in a variety of habitats, including coastal marshes and estuaries, inland marshes, lakes, open ponds, shallow bays,salt marshand sand or tidal flats, upland swales, wet meadows and rivers, pastures, and agricultural fields (USFWS 2024b). Whooping cranes have not been recorded as occurring on the DNPS site. Further, DNPS does not currently have specific requirements to track whooping cranes onsite, and no specific assessment has been made of the extent or quality of whooping crane habitat at the DNPS site. However, several areas of the DNPS site and vicinity including Dresden Cooling Lake as well as rivers, freshwater ponds, and surrounding wetland areas present suitable habitat for this species. Given the habitat requirements of this species, it can be conservatively assumed that suitable habitat to varying degrees is present within areas of the site.

Potential impacts to the whooping crane from the operations of DNPS are discussed below:

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 107 of 113 Mortality or injury from collisions with plant structures: The risk of collision with in-scope transmission lines poses a potential threat to all avian species including migrating whooping cranes. CEG maintains an Avian and Wildlife Management Plan developed to avoid and minimize bird mortalities and injuries through a range of proactive and reactive approaches, improve compliance with federal avian protection laws (i.e., Endangered Species Act, Migratory Bird Treaty Act), and improve system reliability. DNPS does not have specific requirements to track whooping cranes at the DNPS site or vicinity.

However, there have been no documented incidents or encounters with whooping cranes at the site based on DNPS records from 2018-2024.

Loss, degradation, or disturbance of habitat: Loss of wetlands and degradation of riverine migration habitat from decreases in river flows have significant negative impacts to the migratory corridor used by whooping cranes. No land clearing, or specific ground-disturbing activities are proposed for the proposed SLR term that would impact wetland and marsh areas. All plant operations are located in disturbed areas, and no vegetation clearing is proposed during the SLR term that would potentially impact the habitat for the whooping crane. Any potential ground-disturbing activities associated with general operations and maintenance will undergo an environmental review, including an evaluation of potential impacts to protected species, prior to the activity occurring.

Further, DNPS continues to operate in compliance with its NPDES permit, and no changes in river flows are anticipated during the SLR term that would result in degradation of riverine migration habitat for whooping cranes.

Behavioral changes from refurbishment and/or construction activities: No construction, ground-disturbing activities, or license-related refurbishment activities have been identified or proposed at the DNPS site during the SLR term. Any whooping cranes, if present around the DNPS site, have likely already acclimated to the noise, vibration, and general human disturbances associated with site maintenance, infrastructure repairs, and other site activities. As such, behavioral changes from refurbishment and/or construction activities to whooping crane during the SLR term are unlikely.

If necessary, CEG would consult with USFWS to ensure compliance with the ESA regarding the whooping crane. Thus, CEG has concluded that the continued operation of the DNPS site for the proposed operating term will have NO EFFECT on the whooping crane.

References:

USFWS. 2024a. IPaC Listing Status. Retrieved from <https://ipac.ecosphere.fws.gov/status/list>

(accessed September 10, 2024).

USFWS. 2024b. Whooping Crane (Grus americana). Retrieved from

<https://ecos.fws.gov/ecp/species/758> (accessed September 10, 2024).

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 108 of 113 Topic: Federally Protected Ecological Resources NRC RAI Number: FPE-11 REQUIREMENT: 10 CFR 51.53(c)(3)(ii)(E) requires the following: all license renewal applicants shall assess the impact of refurbishment, continued operations, and other license-renewal-related construction activities on important plant and animal habitats. Additionally, the applicant shall assess the impact of the proposed action on federally protected ecological resources in accordance with Federal laws protecting such resources, including but not limited to, the Endangered Species Act, the Magnuson-Stevens Fishery Conservation and Management Act, and the National Marine Sanctuaries Act. 10 CFR Part 51.41 requires that licensees submit information that may be useful in aiding the Commission in complying with section 102(2) of NEPA with information in an environmental report that should contain sufficient data to aid the Commission in its development of an independent analysis (10 CFR 51.41(c)).

ISSUE: The USFWS published a proposed rule to list the Western regal fritillary (Argynnis idalia occidentalis) as threatened under the ESA on August 6, 2024 (89 FR 63888). This species range includes Will and Grundy counties. The ER does not address this species.

REQUEST: Please provide an analysis of the potential impacts of the proposed license renewal on the Western regal fritillary (Argynnis idalia occidentalis). This analysis should address: (1) a description of DNPS site habitat suitability for this species; (2) habitat loss, degradation, disturbance, or fragmentation, and associated effects to include mowing; (3) herbicide application and management; and (4) behavioral changes resulting from refurbishment or other site activities, among other impacts relevant to this species that CEG may identify.

CEG Response:

Impacts Analysis for the Western Regal Fritillary Butterfly (Argynnis idalia occidentalis)

The regal fritillary (Argynnis idalia) is a brush-footed butterfly with large, orange and black wings. Historically, it was found from Maine to Montana and south to Oklahoma and North Carolina. Habitat alteration, including loss of specific food plants and places to live and grow during critical stages of its life cycle has, over the past 30 years, reduced the species range and abundance. The regal fritillary now occurs only in local colonies of remnant prairie in Pennsylvania and Virginia in the east, from southern Wisconsin west to Montana, and south to northeast Oklahoma in the west. (USDA-NRCS 2020)

Regal fritillary butterflies have four life history stages: eggs, six larval instars, pupae, and adults.

Male adults emerge in late spring with females appearing in early summer. Adults mate in the mid to late summer, yet the female does not lay the eggs until fall. The extended period of time between mating and egg laying is known as reproductive diapause and is rare in other North American Lepidoptera. This behavior appears to be an adaptation to the life cycle of the larval food source - violets. The reproductive diapause during the heat of the summer and the overwintering of larvae allows the larvae to emerge in the spring when violet hostplants are young. (USDA-NRCS 2020)

Regal fritillary butterflies live in tallgrass prairie and other open and sunny locations such as damp meadows, marshes, wet fields, and mountain pastures. These early successional stage habitats were maintained through periodic, natural disturbance regimes. Regal fritillary habitat

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 109 of 113 has been identified as large grassland areas with prairie remnants or lightly grazed pasture lands containing prairie vegetation where topography often includes hills and valleys. Regal fritillary butterflies depend on three main habitat components: violet host plants for larvae, nectar plants for adults, and native warm season bunch grasses that provide protective sites for all life stages. Adults are encountered in both upland prairies and wet prairies, although larval development may be restricted to upland prairie where violet species grow. Wet prairies provide critical nectar sources under drought conditions. (USDA-NRCS 2020)

Adults are rarely encountered away from native prairies, and they appear to have a strong tendency to remain within the boundaries of these habitats. A viable (self-sustaining population needs about 120 to 240 acres. However, adults are frequently observed in remnant habitats that may be too small to support a self-sustaining population, suggesting that dispersal among remnants is common and that the butterflies will use somewhat degraded prairie habitats. These butterflies are strong flyers and occasionally disperse over tens of kilometers. However, they tend to remain in the bounds of their natal prairie, especially if it is surrounded by trees, croplands, or roads. (USDA-NRCS 2020)

Violets are the sole larval host plant for the regal fritillary, though the species of violets used varies. The butterfly might use any species of violet in its habitat, but they have been observed on the arrow-leaved violet (Viola sagittata; V. fimbriatula), birdfoot violet (V. pedata), prairie violet (V. pedatifida) and lance-leaved violet (V. lanceolata). Viable populations require a large number of violet plants. (USDA-NRCS 2020)

On August 8, 2024, the U.S. Fish and Wildlife Service (USWFS) proposed to list the western regal fritillary (A. idalia occidentalis) as threatened at the federal level in accordance with the Endangered Species Act (ESA). States in the current range of this subspecies include Arkansas, Colorado, Illinois, Indiana, Iowa, Kansas, Minnesota, Missouri, Montana, Nebraska, North Dakota, Oklahoma, South Dakota, Wisconsin, and Wyoming. (USFWS 2024)

Suitable habitat for the western regal fritillary butterfly is likely present in undeveloped portions of the Dresden Nuclear Power Station (DNPS) site that are not maintained by mowing, in areas planted by the station as pollinator gardens, as well as in the vicinity of the DNPS site. As mentioned above, the larval stage of this butterfly species relies solely on violets as host plants.

A grassland inventory was completed in 2018 with the Wildlife Habitat Council as part of the Invasive Plant Management Plan and did not identify any species of violets in the surveyed areas at DNPS. All plant operations are in disturbed areas, and no vegetation clearing, construction, ground-disturbing activities, or license-related refurbishment activities are proposed during the license renewal term that would potentially impact habitat for the western regal fritillary butterfly. Any western regal fritillary butterflies, if present around the DNPS site, have likely already acclimated to the noise, vibration, and general human disturbances associated with site maintenance, infrastructure repairs, and other site activities. As such, behavioral changes from refurbishment and/or construction activities to western regal fritillary butterfly during the SLR term are unlikely. Further, any potential ground-disturbing activities associated with general operations and maintenance would undergo an environmental review that includes an evaluation of potential impacts to protected species prior to the activity occurring. Existing regulatory programs for which the site is subject to, including management of herbicide applications, ensure that terrestrial habitat is protected. Finally, DNPS continues to actively restore grassland habitats in ROW areas onsite to attract pollinator species and allow native pollinators to create additional habitat over time. This grasslands restoration effort could potentially enhance and expand habitat for vulnerable species such as the western regal fritillary butterfly. As such, the continued operation of the DNPS site during the proposed license renewal term would have NO EFFECT on the western regal fritillary butterfly.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 110 of 113

References:

U.S. Department of Agriculture Natural Resource Conservation Service (USDA-NRCS). 2020.

Regal Fritillary (Speyeria idalia) Field Guide. Retrieved from

<https://www.fws.gov/sites/default/files/documents/Regal%20Fritillary%20Field%20Version-

%20Final_0.pdf> (Accessed on September 27, 2024).

U.S. Fish and Wildlife Service. 2024b. Western regal fritillary (Argynnis idalia occidentalis).

Retrieved from <https://ecos.fws.gov/ecp/species/12017> (Accessed on September 27, 2024).

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 111 of 113 Topic: Historic and Cultural Resources NRC RAI Number: HCR-07 REQUIREMENT: Section 106 of the National Historic Preservation Act (NHPA [54 USC

§306108]) directs Federal agencies to take into account the effect of the undertaking on any district, site, building, structure, or object that is included in or eligible for the National Register of Historic Places within the area of potential effect (APE). NHPAs implementing regulations 36 CFR § 800.4(1) directs Federal agencies to identify historic properties, including background research, consultation, oral history interviews, sample field investigation, and field survey. In 36 CFR § 800.1(c), federal agencies must complete the Section 106 process prior to the issuance of any license. NRC regulations at 10 CFR 51.53(c)(3)(ii)(K) state that NRC may request that applicants provide information to the NRC to identify any potentially affected historic and cultural resources and historic properties to support the environmental review and associated NHPA Section 106 consultation.

ISSUE: ER Section 3.8.3 mentions that the structures within the DNPS property have not been surveyed, although many of them are over 50 years old. The buildings were not evaluated for potential listing on the National Register of Historic Places as required under 36 CFR 800.4.

NRC staff, in consultation with the Illinois State Historic Preservation Office, has determined that an architectural survey is necessary.

REQUEST: The NRC is requesting that CEG conduct an architectural survey of above-ground resources on the DNPS site (i.e., area of potential effect) 45 years or older that meet the standards set forth in 36 CFR 800.4(b), identify historic properties, and apply the National Register criteria as required in 36 CFR 800.4(c). Preliminary determination of eligibility for the site and/or facilities would need to be known prior to the publication of NRCs Final SEIS, currently planned for October 2025 publication, to support NRCs determination of effects from the proposed undertaking. Per 36 CFR 800.1(c), the NRC must complete the NHPA Section 106 process prior to the issuance of any license. The NRC requests that CEG provide an estimated timeframe for when this survey could be completed. If a preliminary determination is not completed by publication of the Final SEIS, a Section 106 agreement document or equivalent would need to be executed.

CEG Response:

CEG will complete the draft architectural survey of above-ground resources on the DNPS site prior to NRC issuance of the Final Environmental Impact Statement (EIS), currently scheduled for October 2025. CEG will submit the draft architectural survey to the SHPO prior to October 2025, and potentially prior to issuance of the draft EIS in June 2025, to obtain a final determination of eligibility.

References:

None.

Associated Documents:

None.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 112 of 113 Topic: Greenhouse Gas and Climate Change NRC RAI Number: GHG-CC-04 REQUIREMENT: 10 CFR 51.53(c)(3)(ii)(Q) states that applicants shall include an assessment of the effects of any observed and projected changes in climate on environmental resource areas that are affected by license renewal.

ISSUE: Figure 3.6-4 and Figure 3.6-5 of the ER present average monthly discharge temperatures and average monthly intake temperatures for 2018-2022. However, the ER does not discuss if a warming trend has been observed at these locations on the long-term available period of record.

REQUEST: As provided in response to audit information need GHG-CC-4, provide time series figures of:

monthly average intake cooling water temperatures; average monthly seasonal intake temperatures; monthly average of discharge water temperatures; and average monthly seasonal discharge temperatures.

As part of the response, explain:

the gaps in data for the intake temperatures in 2015 and 2021, and why discharge temperatures for 2010 through 2013 are higher than discharge temperatures for 2014 through 2023 and identify the location of temperature probes used to measure discharge temperatures.

CEG Response:

Time series figures of the monthly average intake cooling water temperatures; average monthly seasonal intake temperatures; monthly average discharge temperatures; and average monthly seasonal temperatures for 2010 through 2023 are listed in Associated Documents below and provided in Enclosure 3.

Temperature probe issues were identified that caused the gaps in intake temperature data for both 2015 and 2021. In 2015, the issues included a temperature probe not reading accurately and the temperature readings not updating in the computer. In 2021, one of the probes failed and another probe was offline.

The discharge temperatures for 2010 through 2013 were recorded from probes in a different location on the river than those discharge temperatures for 2014 through 2023. As such, the temperature values for 2010 through 2013 are not comparable to the temperature values for 2014 through 2023. The 2010 to 2013 temperature data was recorded from the discharge canal of the reactor while the 2014 through 2023 temperature data was recorded from the Dresden Lock and Dam downstream on the Illinois River.

Dresden Nuclear Power Station, Units 2 and 3 Response to NRC RAI/RCI Environmental Review Page 113 of 113

References:

None.

Associated Documents:

Average Monthly Intake Cooling Water Temperatures 2010 through 2023 Average Monthly Seasonal Intake Temperatures Average Monthly Discharge Temperatures 2010 through 2023 Average Monthly Seasonal Discharge Temperatures