ML25259A216

Project Long Mott Docs - Long Mott Generating Station Environmental Information Needs Revision 5

ML25259A216
Person / Time
Site:	05000614
Issue date:	09/16/2025
From:	NRC
To:	NRC/NMSS/DREFS
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Download: ML25259A216 (19)

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From:

Joe OHara Sent:

Tuesday, September 16, 2025 1:29 PM To:

Milton Gorden; ext_Mark_Feltner; ProjectLongMott-EnvPUBLICem Resource Cc:

Robert Hoffman; ext_Dave_Goodman; ext_Hayley_McClendon

Subject:

Long Mott Generating Station Environmental Information Needs Revision 5 Attachments:

Long Mott Generating Station Environmental Information Needs Revision 5.pdf Good afternoon, Attached please find the revised Information Needs document which is updated to reflect the addition of SW-14. Based upon our discussion at the site audit held on September 8th and 9th, we have revised the Information Needs document to reflect the current status of each item as Resolved, RCI, or RAI.

If you have any questions whatsoever, please contact me.

R/

Joe OHara Environmental Project Manager U.S. Nuclear Regulatory Commission Environmental Review Project Management Branch

Hearing Identifier:

XeDOW_ProjectLongMott_EnvPublic Email Number:

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Subject:

Long Mott Generating Station Environmental Information Needs Revision 5 Sent Date:

9/16/2025 1:29:18 PM Received Date:

9/16/2025 1:29:23 PM From:

Joe OHara Created By:

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Long Mott Information Needs Revision 5 Resolved Unresolved Info Need #

Information Need ER Section SME Status (i.e., applicants response is sufficient or RAI/RCI needed)

Accidents ACC-1 The calculated bounding dose values for postulated accidents is supplied for the time period of 0-720 hours.

Please provide an SME to discuss the dose value for the worst 2-hour period requested in guidance (see RG 4.2 Revision 3 Section 5.11.1, Design-Basis Accidents) with respect to the 0-720 hour dose values associated with this calculation and access to related calculational files.

This information need and any related access to calculational files should be coordinated with the NRC Safety Staff.

5.13 Jon Napier/Don Palmrose RESOLVED ACC-2 Please provide access to the MACCS calculations (input and output files in the ERR), any additional relevant calculational files or explanations, and an SME to discuss the calculations.

5.13 Jon Napier/Don Palmrose RESOLVED ACC-3 Step 1 of the SAMA analysis has been described as being complete. Please provide an SME to discuss the analysis from step 1 and why the maximum benefit value (step 2) from items identified in step 1 of the analysis was not performed, and what will be addressed at the OL stage.

5.13 Jon Napier/Don Palmrose RESOLVED ACC-4 SecPop version 4.3.0 is based on the 2010 census data and 2007 county data. Please confirm that the population land use data used as an input to the accident analysis has been adjusted for potential changes in use over the time period analyzed (e.g., adjustment based on 2020 census data and years beyond along with recent county data). The staff observed population data in Section 2.5.1 and Section 5.13.2.2, however it is unclear if the population projections discussed in both sections are the same. Please provide any additional relevant calculational files or explanations (in the ERR) and an SME to discuss the calculations.

5.13 Jon Napier/Don Palmrose RCI to confirm that this information is correct and that the demographic information in Chapter 2 links to the analysis in Chapter 5.13

2 ACC-5 The last row in ER Table 5.13.101, Design Basis Accidents, is for seismic DBA sequences with N/A as initiating event along with the remarks statement As discussed in PSAR Section 2.5, a seismic event is not a credible initiating event for the LMGS site. However, PSAR Section 3.6.12 is entitled Seismic DBA and results of the seismic DBA analysis is an overall dose at the EAB of less than 15 rem (TEDE), satisfying the 25-rem limit (see the end of PSAR Section 3.6.12.4, Dose Consequence, at the top of PSAR page 3.5-72). Please provide an SME(s) to discuss the apparent difference between ER Table 5.13.1-1 and PSAR Section 3.6.12.

5.13 Don Palmrose RCI to confirm that the value provided in the PSAR tables are reduced corresponding to information in the ER.

Air Quality AQ-1 Please provide regional NAAQS measurements, or links to publications with these measurements (ESRP-2.7) 2.7 Brad Fritz RESOLVED AQ-2 Please provide monthly dewpoint and monthly average temperatures (ESRP-2.7) 2.7 Brad Fritz Possible RCI depending on how data was pulled/manipulated. May need to be an RAI if we cant replicate the averaging.

AQ-3 Please provide a summary of monthly stability class (ESRP-2.7) 2.7 Brad Fritz Possible RCI depending on how data was pulled/manipulated. May need to be an RAI if we cant replicate the averaging.

AQ-4 Please provide information on emissions during pre-construction and construction. While emission factors by vehicle type were provided, no data on total use of these was provided. Some mechanism to determine the total emissions during construction and pre-construction should be added. (10 CFR 51.45(c) and ESRPs 4.4.1, 5.3.2.1, and 5.3.3.1) 7.2.7 Brad Fritz Tentative RAI for scaling information.

Alternatives ALT-1 Dow's corporate decarbonization goals are cited as one of the project needs for the installation of Xe-100 reactor.

It would be beneficial to comprehend the significance of these objectives in relation to the anticipated reduction in CO2 emissions (ESRP 9.2).

9.2 Dave Goodman RESOLVED

3 ALT-2 As outlined in ER Section 9.2.2, it appears that several energy alternatives may not fully align with the project's dual goals of 1) demonstrating the Xe-100 reactor and 2) supplying the power needs of the SDO while also reducing the carbon footprint from the current natural gas cogeneration plant, leading to their preliminary exclusion.

Nonetheless, Section 9.3.1 suggests that the new power plant's main aim is to supply electricity and steam directly to SDO, which may be achievable through various energy alternatives. Could you clarify whether the primary focus is on the demonstration of the Xe-100 reactor, the generation of electricity and steam, or both? (ESRP 9.2.2).

9.2.2 Dave Goodman RESOLVED ALT-3 The proposed action is to authorize the construction of four Xe-100 modules; if the objective is demonstration rather than generation, why is construction and operation of four modules necessary? (ESRP 9.2.2) 9.2.2 Dave Goodman RESOLVED ALT-4 Please provide the Site Feasibility Study and Alternative Site Study, particularly to support the requirement that the reactors be located within 1.5 miles of SDO. (ESRP 9.3) 9.3.1 Dave Goodman RESOLVED ALT-5 Please clarify the comparative acreages of Sites A, B, C, and D. If Site A is the Proposed Site, then according to Sec 4.3.1 it is 1537 acres, of which appr. 721 acres would be disturbed. Site B is reported as 235 acres, Site C as 166 acres, and Site D as 193 acres. Yet in Figure 9.3-1, Site A does not appear to be several times bigger than Sites B, C, or D.

9.3.2 Dave Goodman RAI - sites were evaluated early during feasibility, which did not account for additional footprint that was added as project went on (e.g, adding laydown yards and other extras). RAI for acreage clarifications.

Aquatic Ecology AE-1 Please provide any report(s) and data from the macroinvertebrate and fish surveys conducted in 2023 and 2024 that supported development of Tables 2.4-9 and 2.4-10. (ESRP 2.4.2) 2.4.2.2 Peyton Doub/Caitlin Wessel Response sufficient; referenced information (Document in TE-12) will need to be made publicly available.

RAI for SL-XEN-2024-135_PLM_Ecological_Resources_Tech_Report_Rev_1.pdf AE-2 Please provide shapefiles OR digital, zoomable map depicting benthic macroinvertebrate sampling locations in West Coloma Creek. (ESRP 2.4.2) 2.4.2.2 Peyton Doub/Caitlin Wessel RESOLVED AE-3 Please provide information on which organisms listed in Table 2.4-9 are key indicator organisms that are particularly vulnerable to impacts from plant construction or operation. (ESRP 2.4.2)

Table 2.4-9 Peyton Doub/Caitlin Wessel RESOLVED

4 AE-4 Please provide additional information (e.g. flow rates, grates and spacing, trash racks and spacing, temperature data, etc.) on the existing intake and discharge structures for the Seadrift Plant, the new pump station and water intake structure on the GBRA Calhoun Canal to provide water via Basin #5, digital, zoomable maps showing location of each structure, and copies of the current TPDES permit and SWPPP. (ESRP 2.4.2) 2.4.2, 3.3, 3.4.2.6, 4.2.1, 5.10.2.1, 5.10.2.2, Figure 3.1-3 Peyton Doub/Caitlin Wessel RAI for the TPDES permit AE-5 Please provide a digital, zoomable map OR shapefile layers for the information displayed in Figure 4.3-1.

(ESRP 4.3.2)

Figure 4.3-1 Peyton Doub/Caitlin Wessel RESOLVED AE-6 Please provide a proposed construction schedule, including expected timing and duration of specific construction activities. Potential activities that should be included are but are not limited to: placement of intake and discharge structures, channel modifications for navigation or flow control, placement and removal of cofferdams, construction of bulkheads, piers, jetties, basins, and storm sewers, direct dredging, including the area that may be affected by resulting siltation and turbidity, percent (or the width and depth) of the waterbody cross section that might be obstructed by construction activity at any time, time and duration of such obstruction, potential changes to water quality caused by exposure of substrate to contaminants during construction (e.g., dredging for intake channels, cofferdam construction). (ESRP 4.3.2)

Table 1.3-1 (just says construction start Oct 2028),

4.3.2.2 Peyton Doub/Caitlin Wessel RESOLVED AE-7 Please provide information on the existing intake structure for the Seadrift Plant on GBRA Calhoun Canal.

Including information on location, depth, size, intake flow velocity, any racks or grate systems, impingement and entrainment rates, etc. (ESRP 4.3.2 and 5.3.1.2, 40 CFR 125.84(b)(2))

Figure 3.1-3, Section 3.3, Section 3.4.2.6, 4.3.2.2 Peyton Doub/Caitlin Wessel RESOLVED AE-8 Please provide additional information, at least at a conceptual level, about mitigation needed to offset impacts to the West Coloma Creek (per USACE). (ESRP 4.3.2) 4.3.2 Peyton Doub/Caitlin Wessel RESOLVED AE-9 Does the Section 10 permit currently held by the applicant for maintenance dredging apply to dredging done as part of the LMGS? If yes, please provide a copy of the permit.

(ESRP 4.3.2)

Table 1.4-1 Peyton Doub/Caitlin Wessel Potential RCI - coordinating with Shannon Healy. Is a Section 10 permit anticipated to be required? Verify that no work being done within the Victoria Barge Canal or any other Section 10 water.

5 AE-10 Please provide copies of any responses and other related communications from USFWS, NOAA National Marine Fisheries Service (NMFS), and TPWD concerning aquatic species that have been received since writing the ER.

(ESRP 2.4.2 and 4.3.2) 2.4.2.3, Appendix 1A Peyton Doub/Caitlin Wessel/Shannon Healy RESOLVED AE-11 Please provide additional information on the proposed locations of pile driving activities and any anticipated impacts to aquatic resources. (ESRP 4.3.2) 4.4.1.4 Peyton Doub/Caitlin Wessel Potential RCI - coordinating with Shannon Healy about LME's answer about pile driving in water bodies.

AE-12 What material(s) are/ will the condenser tubes be made of? (ESRP 4.3.2) n/a Peyton Doub/Caitlin Wessel RESOLVED AE-13 Please provide the through-screen design intake velocity.

(ESRP 5.3.1.2, 40 CFR 125.84(b)(2))

Table 3.3-1, 5.10.2.1 Peyton Doub/Caitlin Wessel RESOLVED AE-14 Please provide information on the original source of water (natural waterbody) that will supply the LMGS, beyond GBRA Calhoun Canal, to where the Canal gets its water from. Please include a figure(s) depicting the flow path, any relevant diversion structures, and the alternate intake location mentioned in ER Section 5.2.1.1.1 that draws from canal water downstream (east). Please clarify the scenario in which the alternate intake will be utilized and the expected frequency of utilization. (ESRP 5.3.1.2, 40 CFR 125.84(b)(2))

Peyton Doub/Caitlin Wessel/Shannon Healy RCI LME response: Freshwater from the Guadalupe River is diverted near Tivoli east into the GBRA Diversion Canal and flows into Goff Bayou. Just above Goff Bayou Salt Barrier two 96 pipelines convey water underneath the Victoria Barge Canal to the GBRA/Dow pump station (owned by GBRA and operated by Dow SDO at GBRA direction). The pump station is equipped with seven submersible pumps of varying capacity and conveys water into the Calhoun Canal network. The canal runs south along HWY 185 and then turns towards Port Lavaca and runs along the southside of the SDO facility where it is pulled from the canal into the operating basins, currently via the GBRA Relift 1 Pump Station. A new LMGS intake will be constructed along this same segment of the canal nearby and downstream of the existing (ER pg 3.4-5) to serve Basin #5 for LMGS. It is assumed that the new intake structure would be similar to the existing pump station.

AE-15 Please provide, if available, data about impingement and entrainment of aquatic species at the other intake structures on the GBRA Calhoun Canal and at the pump station for GBRA. (ESRP 5.3.1.2) 5.10.2.1 Peyton Doub/Caitlin Wessel RESOLVED AE-16 Please provide a description detailing the existing discharge structure (ex. Where it reenters the waterway, info. about current flow rate and temperature, anticipated change in discharge flow rate and variations with season once LMGS goes online, and impacts to biota downstream; ESRP 5.3.2.2) 1.2.4, 2.4.2.1 Peyton Doub/Caitlin Wessel/Shannon Healy RCI: Nonradiological effluent from LMGS would be 3rd party wastewater to the existing TPDES permitting the SDO combined outfall at the Victoria Barge canal and would be treated to meet their existing acceptance criteria thereby causing no additional impact at the discharge location.

6 AE-17 Please provide a copy of TDOT, 2016-Essential Fish Habitat Assessment, Neches River Bridge Study, CSJ:7220-01-001, Texas Department of Transportation.

2.4.2, 2.11 Peyton Doub/Caitlin Wessel/Shannon Healy RESOLVED AE-18 ER Section 4.3.2 mentions avoidance of building activities during ecologically sensitive times (i.e., spawning), please provide the dates during which building activities will be avoided and any supporting information for the avoided dates.

4.3.2 Shannon Healy RESOLVED AE-19 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. Please provide a description of the ESA action area, including all potential direct and indirect impacts of construction and operation.

In the description, address:

1. transportation activities, including the mode of transportation, route of transportation, material to be transported, the frequency and timing of the transportation, and any associated impacts;

2. the extent of impacts associated with diverting water from the Guadalupe River, including the downstream limit where flow and salinity impacts may be experienced;

3. the extent of impacts associated with the withdrawal of water from the GBRA Calhoun Canal; and

4. any other potential direct or indirect impacts associated with this action.

Shannon Healy RCI: Construction materials for LMGS are expected to be transported by road, there are no plans to barge in materials.

Benefit-Cost No issues related to benefit-cost identified 10.6 Jeff Rikhoff Climate Change CC-1 Has X-Energy conducted thermal discharge studies that account for potential increases in water temperature in the Guadalupe River due to climate change? If so, please provide a copy.

Lloyd Desotell RESOLVED Cumulative Impacts No issues related to cumulative impacts identified Chapter 7 Jeff Rikhoff

7 Decommissioning No issues related to decommissioning were identified.

Jon Napier Fuel Cycle No issues related to the uranium cycle were identified.

Jon Napier Historic and Cultural Resources HCR-1 Provide ArcGIS shapefiles of the archaeological APE, the architectural APE, and for the polygons in Figure 3.1-3.

Lindsey Renaud Cleve Davis RESOLVED HCR-2 Provide a discussion on pre-construction activities covered under DOEs NEPA process and the construction activities expected to be covered under NRCs NEPA analysis, including estimated areas of disturbance and depth of excavation.

Lindsey Renaud Cleve Davis RESOLVED

8 HCR-3 Section 2.5.3.1 and 2.5.3.2 mention archaeological and architectural surveys conducted but do not include any information on the purpose of the surveys, who conducted the surveys, who sponsored the surveys, or how they are connected to NRCs licensing action (issuance of a construction permit). Section 2.5.3.2.1 identified consultation that occurred through the Department of Energy for ground-disturbing site characterization and environmental monitoring activities at the LMGS site, but it is unclear how it is connected to NRCs licensing action. To support NRCs NHPA Section 106 review and avoid duplication of efforts, provide the following:

1. Provide copies of (a) the scope of work (SOW) for the July 2023 survey, and (b) correspondence from May and June 2023 regarding WSPs submission of the SOW to the Texas Historical Commission (THC) and THCs concurrence on the SOW.

2. If not described in the SOW or THCs concurrence on the SOW, provide summary descriptions of the methodologies used for both archaeological and architectural surveys. This should include a) explanation of the justification for differing APEs between archaeological and architectural surveys, b) specifics about the shovel test intervals and placement strategies, and c) criteria used for assessing architectural significance and any specific techniques applied during the surveys.

2.5.3.1 2.5.3.2 Lindsey Renaud Cleve Davis RCI for the inclusion of the SOW information (but we do not need the SOW on the docket).

9 HCR-4 Confirm that the Phase I archaeological survey results are documented in two separate reports: (1) August 1, 2023 Hunter and Cantrell, Xe-100 Dow Seadrift Site Phase I Intensive Archaeological Survey, Calhoun County, Texas Negative Finding Short Report, and (2) February 19, 2024 Hunter and Cantrell, Phase I Intensive Archaeological Survey for the Proposed Project Long Mott, Calhoun County, Texas - Negative Finding Report (provided in Enclosure 6 of the ER).

1. Please provide a copy of the August 1, 2023, Hunter and Cantrell report.

2. For both reports, describe the undertaking and activities associated with the undertaking that were considered when determining there would be no effect on historic properties. Please clarify why the reports do not address the proposed construction of a small modular reactor and nor include details on pre-construction and construction activities.

3. For both reports, please provide copies of correspondence that submitted the reports to the THC for their concurrence. (This could include correspondence from DOE to THC in August 2023, or from WSP to THC in January or February of 2024.)

4. Pages 74 and 76 in Appendix A of the ER are letters from THC concurring on the reports. Is there any other correspondence related to THCs concurrence on the reports? If so, please provide copies. It is unclear what undertaking THC was considering in its concurrence letter dated February 16, 2024.

5. In the August 1, 2023, Hunter and Cantrell report, the Management Summary states that from July 10-19, 2023, WSP conducted a Phase I intensive archaeological survey of 1,277 acres in support of the ER for the Xe-100 Dow Seadrift Site in Calhoun County, Texas. That report covered a 617.4-acre portion of the 1,277-acre survey. The February 19, 2024, report covers a 930.6-acre portion portion of the Long Mott project that has not been previously submitted for consultation.

This totals 1,548 acres, which is total survey acreage cited in the ER. Please explain the discrepancy between the 1,277-acreage cited in the August 1, 2023, report and 1,548-acreage cited in the ER.

Part VI Supplemental Information Lindsey Renaud Cleve Davis RAI for August 2023 report. RCI will be submitted to confirm responses provided by applicant to parts 3, 4, and 5 of this info need.

10 HCR-5 Based on the information provided in the ER, there is no clear indication that Traditional Cultural Places (TCPs) were considered or that efforts were made to identify them as part of the cultural resources review. Provide documentation and/or summary that demonstrates the level of effort to identify potential TCPs.

2.5.3 Lindsey Renaud Cleve Davis RCI to confirm response HCR-6 Section 4.1.3.4 of the ER mentions the development of an Inadvertent Discovery Plan with a description to provide three provisions for human burials or human remains. However, it is limited to human remains only and only supports consultation with THC and not the Tribes.

Provide the Inadvertent Discovery Plan, or provide additional details about how inadvertent discoveries of cultural resources will be managed, such as: 1) immediate steps to halt work and secure the area; 2) contact details for archaeological personnel who will be involved in the evaluation of any discoveries; 3) protocols for notifying local enforcement, the coroners office, federal agencies, Tribes, and the Texas Historical Commission; and 4) projected timeline outlining how investigations and evaluations will occur after a discovery to minimize project delays and ensure effective preservation.

4.1.3.4 Lindsey Renaud Cleve Davis RCI to confirm response HCR-7 Provide any other company policies, procedures, and/or best management practices that address the protection of cultural resources.

Lindsey Renaud Cleve Davis RESOLVED Human Health -

Radiological HHR-1 Please provide the version number of NRCDose used to complete the GASPAR II modelling and population dose assessment for effluent releases.

If NRCDose3 was used, were the generic representative biota used for the analysis. If not, what biota were modelled?

Please provide any additional relevant calculational files or explanations (in the ERR) and an SME to discuss the results of the analysis discussed in Section 5.4.4 and results provided in Table 5.4-26.

This information need should be coordinated with the NRC Safety Staff.

5.4.1.2 Jon Napier/Rao Tammara RESOLVED Human Health -

Non-Radiological

11 HHN-1 Per Regulatory Guide 4.2, Revision 3, Section 4.4.1, please provide a statement on blasting activities, what those noise levels would attenuate to at the nearest resident, and any mitigation that would be put in place due to blasting activities.

4.4.1 Kim Leigh/Hayley McClendon RCI to include statement in EA about blasting activities not planned during construction.

Hydrology -

Groundwater GW-1 ESRP 2.3.1 and 2.3.2 require maps of sufficient detail to show the relationship of the site to major hydrological systems that could affect or be affected by plant construction or operation. In conformance, the following figures are requested in higher resolution to ensure the readability of labels and descriptions - Figure 2.3.2-19, Figure 2.3.2-27, Figure 2.3.2-29, Figure 2.3.2-32, Figure 2.3.2-33, Figure 2.3.2-34, Figure 2.3.2-35.

2.3 Swasti Saxena/Rebecka Iveson/Phil Meyer/Gerry Stirewalt RESOLVED GW-2 Section 6.6.3.2 of the ER describes operational monitoring of groundwater quality. The ER states, Following the first annual monitoring interval, the list of parameters is reviewed and revised to focus on specific indicators for the long-term monitoring program. ESRP 6.3 requires an operational monitoring program be established to identify the impacts of operation of the plant and to detect any unexpected impacts arising from plant operation. Describe in detail how the long-term monitoring program will be assessed and executed, including detail on anticipated indicator species and adherence to industry standards for groundwater protection (i.e. NEI 07-07).

6.6.3.2 Swasti Saxena/Rebecka Iveson/Phil Meyer/Gerry Stirewalt RESOLVED GW-3 ESRP 4.2.1 requires identification of hydrologic alterations expected to result from the project related to construction activities. ESRP 5.2.1 requires a description of operational activities expected to result in hydrologic alterations within the site and vicinity. A temporary sediment basin and permanent stormwater basin are described in section 4.2.1.1.1 of the ER. These basins may also hold construction dewatering water and may interact with groundwater. Provide additional details about the design of the basins, including depth, lining material, and anticipated inflow and outflow rates.

4.2.1.1.1 Swasti Saxena/Rebecka Iveson/Phil Meyer/Gerry Stirewalt RESOLVED Hydrology -

Surface Water

12 SW-1 10 CFR 51.45(c) and (d). Please describe any floodplains at or near the LMGS site located in areas for construction operations or locations of new permanent structures. If applicable, please specify if any approvals (local, state, federal) are needed to work in or develop floodplain areas and describe the timeline of operations.

1.4, 2.3.1.1.2, 4.1.1.1, and 4.2.1.1.1 Stephen Ferencz RESOLVED SW-2 10 CFR 51.45(c). Please provide higher-resolution ER Figures 3.4-1 and 3.4-2 for the staffs review.

3.4 Stephen Ferencz RESOLVED SW-3 REMOVE N/A Stephen Ferencz SW-4 10 CFR 51.45(c). Please provide a knowledgeable person(s) to describe LMGS cooling systems water use and consumptive water use associated with process steam and electricity generation. Specifically, the different sources of consumptive water use for LMGS and their relative magnitudes and whether the frequency of steam generation expected to influence seasonal water demands from the Guadalupe River via the GBRA diversion.

3.3 Stephen Ferencz RCIs to confirm response SW-5 10 CFR 51.45(c). Please provide a knowledgeable person(s) to discuss peak water demand under future operation of LMGS and how the magnitude relates to diversion rights on the Guadalupe River and the conveyance capacity of the GBRA Calhoun Canal.

3.3 Stephen Ferencz RESOLVED SW-6 10 CFR 51.45(c). Please provide a knowledgeable person(s) to discuss the existing SDO wastewater discharge system. Are there any anticipated changes to SDO facility effluent (temperature, volume, solute/constituent loading) due to the shift from the current power plant to the LMGS? If so, are the changes substantial enough to require changes to the existing SDO TPDES permit? If there is an increase to the volume of discharge, are any structural modifications to the existing outfall required to accommodate the increased outfall discharge?

3.6, 5.3.2, 5.5.1.2 Stephen Ferencz RCI for the status of the 401 permit (see discussion in SW-13).

SW-7 10 CFR 51.45(c). Are there any naturally occurring materials in the ambient surface waters that influence TPDES permit limits or monitoring requirements related to LMGS - SDO operation?

3.6, 5.5.1.2 Stephen Ferencz RESOLVED SW-8 10 CFR 51.45(c). Please provide a knowledgeable person(s) to discuss LMGS plant water use in relation to other surface water uses in the GBRA Calhoun Canal.

5.2.1 Stephen Ferencz RCI needed to confirm interpretation of water rights table.

13 SW-9 10 CFR 51.45(c). Please provide a knowledgeable person(s) to discuss downstream water rights in the Guadalupe River and GBRA Calhoun Canal and their relation to SDO and LMGS maximum water demand.

Would anticipated water use for LMGS influence downstream water supply for users in either the Calhoun Canal or the Guadalupe River? I.e., is the change in water use from the current generating station to the LMGS substantive enough to affect water supply to downstream users?

5.2.1 and 2.3.1 Stephen Ferencz RESOLVED; pending RCI for SW-8.

SW-10 REMOVE N/A Stephen Ferencz SW-11 REMOVE N/A Stephen Ferencz SW-12 10 CFR 51.45(c). Please provide a knowledgeable person(s) to discuss alternative water treatment systems.

This discussion is to include costs (capital, maintenance, operating, and site adaptation costs) associated with the alternative water treatment systems.

9.4 Stephen Ferencz RESOLVED SW-13 10 CFR 51.45(c). Please provide a knowledgeable person(s) to discuss the development and the associated timeline of the Spill Prevention, Control and Countermeasure (SPCC) Plan.

4.2.1 Stephen Ferencz RESOLVED SW-14 (NEW)

Regarding estimated reliable surface volume for the GBRA/Dow water rights, ER page 2.3-3 reports a TCEQ estimated firm water supply of 8,870 acre-feet per year while ER Table 2.3.1-10 lists 159,719 acre-feet per year as reliable. Additionally, ER Table 2.3.1-10 lists the minimum annual supply for the GBRA/Dow rights at

~33,700 acre-feet/year, of which ~12,000 acre-feet per year are associated with permitted industrial uses. Please clarify the difference between firm, reliable, and minimum annual supply for the GBRA/Dow water rights. Also, please explain the distinction between authorized diversion and annual diversion values in ER Table 2.3.1-

10.

2.3 Stephen Ferencz NOTE: New info need Land Use LU-1 Clarify technical basis used to identify prime farmland on the site. What about Unique Farmland or Farmland of Statewide or Local Importance? Provide NRCS 2022 reference.

2.2.1 Peyton Doub This information is publicly available. RESOLVED LU-2 Provide NRCS Form AD-1006 completed for the site.

Explain key assumptions used in completing the form.

Provide copies of key correspondence with the NRCS, if any.

4.1.1 Peyton Doub Potential RAI of NRCS correspondence unless publicly available.

14 LU-3 Please provide any information from the CZM Certification Package that submitted March 2025 that was not included in the letter to Texas GLO requesting consistency certification with the TX Coastal Management Program goals and policies and any response that have been received by the Texas GLO.

4.1.1.1 Peyton Doub RESOLVED Need for Power No issues related to need for power were identified.

Chapter 8 Jeff Rikhoff Site and Technical Overview STO-1 In the Approvals and Authorizations listed in Table 1.4-1, please provide the anticipated dates for approvals (column 6) as known.

Table 1.4-1 Dave Goodman RESOLVED Socioeconomics No issues related to socioeconomics were identified.

4.4 and 5.8 Jeff Rikhoff Terrestrial Ecology Resources TE-1 Per Regulatory Guide 4.2, Revision 3, Section 2.1.1, please provide GIS data underlying Figures 4.2-1 and 4.3-1.

4.2 and 4.3 Peyton Doub/Dana Vesty RESOLVED TE-2 Per Regulatory Guide 4.2, Revision 3, Section 4.3.1, provide 1) confirmation of the jurisdictional status of wetlands from USACE once received; 2) a breakout of wetland impacts by impact type, e.g., fill, vegetation conversion; and 3) copies of the jurisdictional determination package submitted to the USACE including relevant data sheets.

4.3.1.1.2 Peyton Doub/Dana Vesty/Shannon Healy RCI to capture the information (bottom of the table where wetlands are summarized by type) for citing within the EA.

TE-3 Per Regulatory Guide 4.2, Revision 3, Section 4.3.1, provide 1) the height of building equipment that will be 50 feet or more; and 2) the height of the proposed MET tower.

4.3.1.1.3 Peyton Doub/Dana Vesty RCI to confirm the equipment that would be used, including cranes TE-4 Per Regulatory Guide 4.2, Revision 3, Section 4.3.1, provide information on conceptual approach to meeting wetland mitigation requirements.

4.3.1.1.2 Peyton Doub/Dana Vesty RESOLVED TE-5 Per Regulatory Guide 4.2, Revision 3, Section 4.3.1 and 5.3.1, provide more information on planned vegetation maintenance under onsite transmission line and switchyard. Please include the Best Management Practices for transmission line maintenance around aquatic and wetland habitats mentioned in Section 5.6.2 of the ER.

5.6 Peyton Doub/Dana Vesty/Shannon Healy RCI to cite both parts of this question

15 TE-6 Per Regulatory Guide 4.2, Revision 3, Section 5.3.1, provide information on measures to prevent avian injury from transmission lines and meteorological tower guy wires.

4.3.1.3 Peyton Doub/Dana Vesty/Shannon Healy RCI to summarize this info need response TE-7 Per Regulatory Guide 4.2, Revision 3, Section 2.3.1 and 5.3.1, provide additional information on potential habitat on the site for the monarch butterfly and the construction and operation impacts.

4.3.1, 5.3.3.2, 5.6.1, 5.3.3.2, 5.10.1, and 7.2.3.1 Peyton Doub/Dana Vesty/Shannon Healy RCI to summarize this info need response TE-8 Per Regulatory Guide 4.2, Revision 3, Section 9.3.5, confirm that the same studies for the site would be used for the alternatives or if another study was performed.

9.3 Peyton Doub/Dana Vesty RESOLVED TE-9 Please provide copies of any responses and other related communications from USFWS, NMFS, and TPWD concerning terrestrial species that have been received since writing the ER. (ESRP 2.4.1 and 4.3.1) 2.4.1.5 Shannon Healy RESOLVED TE-10 Please provide details regarding any tree clearing activities on site. Include the number or acreage of trees (alive or dead) that will be removed and specify where on site the clearing will occur. (ESRP 4.1.1)

Shannon Healy RCI to confirm this information unless Shannon wants to use this figure in the EA, in which case an RAI would be needed TE-11 Please provide additional information on the proposed locations of pile driving activities and any anticipated impacts to terrestrial resources. (ESRP 4.3.1) 4.4.1.4 Shannon Healy RESOLVED TE-12 Please provide any report(s) and data from the terrestrial surveys conducted in 2023 that supported development of Tables 2.4-3, 2.4-4, 2.4-5, 2.4-6 and 2.4-7. (ESRP 2.4.1) 2.4.1 Shannon Healy RCI to confirm this information in the report TE-13 Per section 7(a)(2) of the Endangered Species Act, the NRC is required to examine all potential direct and indirect impacts of the Federal action on federally listed species. To fulfill this requirement, please complete the USFWS Northern Long-Eared Bat and Tricolored Bat Range-Wide Determination Key (https://ipac.ecosphere.fws.gov/) and provide a copy of the answers.

Shannon Healy RAI for DKey results.

Potential for another RAI on the culvert results.

TE-14 Please provide additional information regarding the potential non-radiological waste treatment options including whether any associated ground disturbance is anticipated and, if so, describe the potentially impacted habitats.

5.10.2.2 Shannon Healy RESOLVED

16 TE-15 Section 5.6.1 of the ER states that herbicide use around wetlands will be prohibited and Section 5.10.1.1 states that mowing and heavy equipment operation will be avoided within wetlands and streams. Please provide clarifying information including:

1. details regarding whether/how wetlands will be marked in the field to prevent mowing or herbicide use;

2. whether a riparian buffer will be maintained around the streams on site or if mowing will occur up to the bank of streams on site; and

3. whether herbicides will be used onsite during the operating period for purposes other than transmission line maintenance and targeted invasive plant management.

5.6.1, 5.10.1.1 Shannon Healy RESOLVED Transportation TR-1 Please provide the input and output files used for the transportation routing and risk analysis. Please include TRAGIS (or WebTRAGIS) and RADTRAN input and output files and provide an SME to discuss the analysis.

Jon Napier/Rao Tammara RCI: Please confirm that the radiological and nonradiological transportation accident and incident free shipping analysis will be submitted as part of the Operating License Application.

Visual Resources VIS-1 Provide copies of one or more available ground photographs depicting the area within the site where the plant would be constructed. An ideal photograph would show in the foreground the area where the plant would be constructed and the existing Seadrift industrial complex in the background.

4.4.3.1 Peyton Doub RESOLVED Waste - Non-Radiological WNR-1 Per Regulatory Guide 4.2, Revision 3, Section 3.4.3, please provide an estimate of the quantities of solid nonhazardous waste generated during construction.

4.4.5 Kim Leigh/Hayley McClendon RAI - LME should provide scaling information regarding solid non-hazardous waste WNR-2 Per Regulatory Guide 4.2, Revision 3, Section 3.4.3, please provide a statement that outlines a proposed schedule or timeline as to when the SDO TPDES Permit No. WQ0000447000 would be modified to include the sanitary waste and other liquid process wastes from the Long Mott facility, if appropriate.

3.6 Kim Leigh/Hayley McClendon RESOLVED

17 WNR-3 Per Regulatory Guide 4.2, Revision 3, Section 3.4.3, please provide a statement that clarifies whether Long Mott facility waste will be disposed of at SDOs North Landfill Expansion Cell.

3.6, 2.3.2.1.3.2 Kim Leigh/Hayley McClendon RESOLVED Waste -

Radiological WM-1 Regulatory Guide 4.2 Revision 3, Section 6.1.6 states the following should be described in the environmental report:

The annual total number of curies from low level reactor solid wastes and if it is within the bounds of the estimated total of curies of solid waste identified in Section 3.5.2 Radioactive Waste Management. (Table 3.5-2 and Table 3.5-3 provide solid waste volumes, but not activity)

Being cognizant of the analysis in NUREG-2157 Generic Environmental Impact Statement for Continued Storage of Spent Nuclear Fuel. Final Report, describe the plans for offsite storage of spent fuel.

o NUREG-2157 Section 1.8.6 states that advanced reactors (e.g., high-temperature and gas-cooled reactors) are not addressed because they are not within the scope of the review.

Please provide an SME to discuss the characteristics of expected radiological waste to be generated on an annual basis and to discuss the applicability of NUREG-2157 to the proposed reactor design.

Jon Napier/Don Palmrose RCI - would the form of the fuel kernels be similar to the Fort St. Vrain?