ML25220A249
| ML25220A249 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 12/08/2025 |
| From: | Johnston I NRC/NMSS/DREFS/EPMB2 |
| To: | |
| References | |
| EAXX-429-00-000-1744695251 | |
| Download: ML25220A249 (37) | |
Text
Environmental Center of Expertise Division of Rulemaking, Environmental, and Financial Support Office of Nuclear Material Safety and Safeguards ML25220A249 EAXX-429-00-000-1744695251 Environmental Assessment for the License Amendment for the Fort Calhoun License Termination Plan in Washington County, Nebraska Environmental Assessment Docket Number: 50-285 Issued: December 2025
Environmental Center of Expertise Division of Rulemaking, Environmental, and Financial Support Office of Nuclear Material Safety and Safeguards
i CONTENTS CONTENTS..................................................................................................................... I LIST OF FIGURES......................................................................................................... III LIST OF TABLES.......................................................................................................... III ABBREVIATIONS AND ACRONYMS........................................................................... IV 1
INTRODUCTION................................................................................................... 1-1 1.1 Background........................................................................................................... 1-1 1.2 Proposed Action.................................................................................................... 1-1 1.2.1 Purpose and Need for the Proposed Action........................................... 1-2 1.2.2 Scope of the Environmental Analysis..................................................... 1-2 2
ALTERNATIVE..................................................................................................... 2-1 2.1 No-Action Alternative............................................................................................. 2-1 3
AFFECTED ENVIRONMENT................................................................................ 3-1 3.1 Land Use............................................................................................................... 3-1 3.1.1 Land Use - Affected Environment.......................................................... 3-1 3.1.2 Land Use - Impacts............................................................................... 3-1 3.2 Geology and Soils................................................................................................. 3-1 3.2.1 Geology and Soils - Affected Environment............................................ 3-1 3.2.2 Geology and Soils - Impacts.................................................................. 3-1 3.3 Water Resources................................................................................................... 3-4 3.3.1 Water Resources - Affected Environment............................................. 3-4 3.3.2 Surface Water Impacts........................................................................... 3-4 3.3.3 Groundwater Impacts............................................................................. 3-5 3.4 Ecology................................................................................................................. 3-7 3.4.1 Terrestrial Resources............................................................................. 3-7 3.4.2 Aquatic Resources................................................................................. 3-8 3.4.3 Threatened and Endangered Species.................................................... 3-8 3.5 Historic and Cultural Resources.......................................................................... 3-16 3.5.1 Historic and Cultural Resources - Affected Environment..................... 3-16 3.5.2 Historic and Cultural Resources - Impact............................................ 3-16 3.6 Public and Occupational Health and Safety........................................................ 3-17 3.6.1 Public and Occupational Health and Safety - Affected Environment... 3-17 3.6.2 Radiological Impact.............................................................................. 3-17 3.6.3 Non-radiological Impacts...................................................................... 3-19 4
AGENCIES AND PERSONS CONSULTED......................................................... 4-1
ii 4.1 National Historic Preservation Act......................................................................... 4-1 4.2 Endangered Species Act....................................................................................... 4-1 4.3 State Review......................................................................................................... 4-2 5
CONCLUSION AND FINDING OF NO SIGNIFICANT IMPACT........................... 5-1 6
LIST OF PREPARERS......................................................................................... 6-1 7
REFERENCES...................................................................................................... 7-1
iii LIST OF FIGURES Figure 3-1 FCS Site (Source: OPPD 2024)......................................................................... 3-3 Figure 3-2 HESCO Barrier (Source: OPPD 2024)............................................................... 3-5 LIST OF TABLES Table 3-1 Cumulative Fractional Release from Uniformly Contaminated Grout of 45 cm with 30 cm Cover.................................................................................................... 3-6 Table 3-2 Occurrences of Federally Listed and Proposed Species Under U.S. Fish and Wildlife Service Jurisdiction in the Fort Calhoun License Amendment Request Action Area............................................................................................ 3-10 Table 3-3 Effect Determinations for Federally Listed Species under U.S. Fish and Wildlife Service Jurisdiction for the Proposed License Amendment Request...... 3-12 Table 3-4 Effect Determinations for Newly Proposed for Federal Listing Species under U.S. Fish and Wildlife Service Jurisdiction for Full Site Decommissioning Activities............................................................................................................... 3-14
iv ABBREVIATIONS AND ACRONYMS ac acre(s)
ALARA as low as reasonably achievable BMPs best management practices bgs below ground surface CFR Code of Federal Regulations cm centimeter(s)
DCGLs Derived Concentration Guideline Levels EA environmental assessment EPA U.S. Environmental Protection Agency ESA U.S. Endangered Species Act FCS Fort Calhoun Station, Unit 1 FSS final status survey ft feet/foot FWS U.S. Fish and Wildlife Service GEIS generic environmental Impact Statement H-3 tritium ha hectare(s) in.
inch(es)
IPaC Information for Planning and Consultation km kilometer(s)
LAR License Amendment Request LTP License Termination Plan m
meter(s) mi mile(s) mrem millirem mSv millisievert(s)
Ne Nebraska NPDES National Pollutant Discharge Elimination System NRC U.S. Nuclear Regulatory Commission OPPD Omaha Public Power District PSDAR Post-Shutdown Decommissioning Activities Report RAI Request for Additional Information SER Safety Environmental Report SEIS Supplemental Environmental Impact Statement SHPO State Historic Preservation Officer USGS U.S. Geological Survey
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INTRODUCTION
1.1 Background
By letter dated June 18, 2024, Omaha Public Power District (OPPD) submitted an application for a license amendment request (LAR) for the Fort Calhoun Station, Unit No. 1 (FCS) License Termination Plan (LTP) to the U.S. Nuclear Regulatory Commission (NRC) (OPPD 2024).
OPPD is requesting a license amendment to incorporate revised dose calculations for the Auxiliary Building and Containment Building, requirements for remediation, and final status survey (FSS) methodologies.
In accordance with Title 10 of the Code of Federal Regulation (10 CFR) Part 51, Environmental Protection Regulations for Domestic Licensing and Related Regulatory Functions, which implements the National Environmental Policy Act of 1969, as amended, the NRC staffs environmental review of the proposed license amendment is documented in this environmental assessment (EA). The purpose of this document is to assess the potential environmental impacts of the proposed license amendment.
The NRC previously reviewed OPPDs LTP Revision 1 in 2023 (NRC 2023a). The License Amendment for the LTP added a condition to OPPDs license establishing criteria for determining when changes to the LTP require prior NRC approval. OPPD has requested changes to the methodology for dose model calculations for the Auxiliary Building and survey methodologies, which require NRC approval prior to implementation.
OPPD changed the remediation strategy for the Auxiliary Building basement floor embedded piping from decontaminate and leave in place to a strategy that includes the removal of most of the embedded piping. The majority of the radioactivity was removed along with the piping; however, there remains significant contamination in the concrete trenches (OPPD 2024).
Additionally, the concrete foundation was damaged by trench remediation and further remediation is expected to increase the damage, potentially leading to additional groundwater intrusion. OPPD determined that the tendon stressing gallery and a portion of the concrete of the 973-foot elevation west wall of the Containment Building would also be suitable for grouting.
The NRC staff prepared this EA to evaluate and document the potential environmental impacts resulting from the NRCs approval of OPPDs LAR. The NRC staff are also performing a detailed safety analysis of OPPDs LAR. The results of the safety analysis will be documented in a separate safety evaluation report. The NRC decision whether to approve the LAR will be based on the results of the NRC staffs reviews documented in this EA and the safety evaluation report.
1.2 Proposed Action The proposed action is the review and subsequent approval of FCS LTP Revision 2. Proposed LTP revisions include changes in dose calculations for the Auxiliary Building basement and Containment Building, requirements for remediation, and FSS methodologies. If the NRC approves the LTP Revision 2, approval will be issued in the form of an amendment to the FCS license that adds the requested license conditions.
1-2 1.2.1 Purpose and Need for the Proposed Action The purpose and need for the proposed action would be to allow for FCS decommissioning and termination of the operation license, and subsequent unrestricted release from FCS. The approval of the LTP Revision 2 ensures that final decommissioning activities are appropriately completed.
OPPD intends for FCS to meet the criteria for unrestricted use as defined in 10 CFR 20.1402.
OPPD proposed derived concentration guideline levels (DCGLs) to meet the 10 CFR 20.1402 criteria in the initial LTP (OPPD 2021). The proposed action includes changes to the DCGLs used for the Auxiliary Building basement and two areas of the Containment Building to demonstrate compliance with 10 CFR 20.1402. As part of the LTP review process, the NRC staff determines whether the procedures and activities planned for completing decommissioning appear sufficient as described in the LTP Revision 2.
1.2.2 Scope of the Environmental Analysis The NRC previously evaluated the potential environmental impacts of nuclear reactor decommissioning in NUREG-0586, Supplement 1, Generic Environmental Impact Statement on Decommissioning of Nuclear Facilities (GEIS) (NRC 2002). The GEIS is used by NRC staff to evaluate environmental impacts that could occur during the decommissioning of nuclear power reactors. The GElS is considered generic in that it evaluates environmental impacts from decommissioning activities common to nuclear power reactor facilities.
The NRC previously evaluated the site-specific impacts of decommissioning at the FCS site in the 2023 EA for the LTP submitted by OPPD in 2021 (OPPD 2021; NRC 2023a). In the 2023 LTP EA, the NRC staff concluded that decommissioning and unrestricted release of the FCS site would have no significant impact on any environmental resource and that decommissioning was bound by the GEIS for all resource areas where the GEIS made a generic assessment.
The proposed action involves a portion of the Auxiliary Building, Containment Building, and immediately surrounding area, which consists of previously disturbed and paved land in an industrial area. The proposed action would alter site characteristics 3 meters (m) (9.8 feet [ft])
below ground surface (bgs) and deeper and alter some conservative assumptions in the dose estimate around the Auxiliary Building and Containment Building concrete structures. The Auxiliary Building basement walls and trenches are generally 989 ft above mean sea level or deeper. The concrete wall of the 973-foot elevation floor in the Containment Building is contaminated in one area that is roughly 5.5 m x 6.1 m (18 ft x 20 ft) with an expected depth of less than 1.2 m (4 ft). The surface grade at FCS is roughly 306 m (1004 ft) above mean sea level; therefore, the Auxiliary Building basement and the contaminated wall of the Containment Building are more than 3 m (9.8 ft) bgs (OPPD 2025c). The stressing gallery is connected to and underneath the Containment Building and is therefore also more than 3 m (9.8 ft) bgs.
The proposed action does not alter site DCGLs for other buildings or soils in open land areas from those included in the previously approved LTP. The end-state grading of the site would remain unchanged, and the proposed action would not affect offsite conditions for any resource area or the number of people working on site.
The proposed action does involve use of heavy machinery, but all activity is within the scope of the potential impacts considered in the 2023 LTP EA and is bound by the conclusions therein.
The NRC staff do not expect a significant change in the potential greenhouse gas emissions
1-3 from the site due to the proposed action beyond what was considered in the 2023 LTP EA Section 3.3. The proposed action would not generate any new waste streams or significantly change any of the waste streams previously considered in the 2023 LTP EA. The NRC staff conclude that there are no expected changes to the LTP impacts on socioeconomics, aesthetics, noise, transportation, waste management, climate, meteorology, and air quality. The proposed action does not include any new action that is beyond the scope of the 2023 LTP EA for these resource areas therefore, these resource areas (socioeconomics, aesthetics, noise, transportation, waste management, climate, meteorology, and air quality) are bound by previous environmental review and are not discussed further in this EA.
Cumulative impacts of decommissioning FCS are considered in the 2023 LTP EA Section 3.14, and the NRC staff conclude that the proposed action is within the scope considered in the EA and does not require additional analysis. As discussed below, the impacts of the proposed action are narrow in focus and would not be significant.
The following documents were reviewed and considered in the development of this EA:
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ALTERNATIVE 2.1 No-Action Alternative The only alternative considered in this EA is the no-action alternative under which the NRC would deny OPPDs LAR and the decommissioning would continue under the previously approved LTP. OPPD would have to comply with currently approved DCGLs site-wide or apply for another alternative route for decommissioning and license termination.
To complete decommissioning using current DCGLs, OPPD would have to implement a plan for demonstrating compliance with the FSS requirements for the Auxiliary Building basement concrete slab and the Containment Building using the DCGLs and dose model parameters in the current LTP. Under this scenario, OPPD would continue decommissioning under the previously approved LTP, and activities at FCS would continue and the environmental impacts would neither increase nor decrease.
Alternatively, OPPD could submit a revised LTP for NRC approval that meets the requirements in 10 CFR 50.82(a)(10). Under this scenario, OPPD resubmits the LTP, activities at FCS would likely continue, and the environmental impacts would neither increase nor decrease as a result of the additional time required for the LTP resubmission. As such, the no-action alternative is not evaluated in further detail.
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AFFECTED ENVIRONMENT 3.1 Land Use 3.1.1 Land Use - Affected Environment The FCS is in an unincorporated area of Washington County approximately 31 kilometers (km)
(19 miles [mi]) north of Omaha, Nebraska (OPPD 2021). In 2019, the NRC approved a request from OPPD to release approximately 48.6 hectares (ha) (120 acres [ac]) of undeveloped land from the FCS site (NRC 2019). The plant facilities cover approximately 55 ha (135 ac).
Approximately 140 ha (345 ac) of the FCS site are cropland that OPPD leases to local farmers, with approximately 73 ha (180 ac) covered in natural vegetation or drainage courses and railroad spurs (NRC 2003). The FCS site is bordered to the northwest by an industrial facility and farm fields, to the southeast by farm fields, and to the south by a state highway and residences, and to the north by the Missouri River, farm fields, and a wildlife refuge (OPPD 2025). There are no residences within 0.80 km (0.5 mi) of the FCS site as measured from the center of the Auxiliary Building (RSCS 2020).
3.1.2 Land Use - Impacts The proposed action involves land under and immediately adjacent to the Auxiliary Building and Containment Building, all of which is paved land (Figure 3-1). Any material used to fill the Auxiliary Building basement and Containment Building would be from previously disturbed land on the FCS site (OPPD 2024). The proposed action does not include any new temporary storage or staging areas and would not increase the operational area. OPPD would implement best management practices (BMPs) to minimize the potential for sediment and erosion discharges from the proposed action. There are no new impacts to land use beyond impacts previously considered in the 2023 LTP EA Section 3.1; therefore, the NRC staff conclude the proposed action would have no significant impact on land use (NRC 2023).
3.2 Geology and Soils 3.2.1 Geology and Soils - Affected Environment The FCS is in a geologic environment made of thick beds of limestone, dolomite, shale, sandstone, and coal beds. Nebraska-Iowa-Missouri River Valley features started to develop at the end of the Permian Period with no record of fault movement in recent years (OPPD 2024).
Most of the Missouri River Valley and tributaries were formed during the Pleistocene period and during glacial movements. Soils at the site consist of upper fine-grained sandy clay with silt 6 to 15 m (20 to 50 ft) thick that is likely not continuous as it is indicative of former river deposits, layered sands with some gravels and silts 20 to 23 m (65 to 75 ft) thick, and an underlying carbonate bedrock surface.
There is infrequent seismic activity in the area, with 15 earthquakes of 4.0 or stronger within 322 km (200 mi) of the site since 1900, the most recent of which was 4.0 in 2023 near Bennington, Kansas, while the largest was 4.6 in 1935 near Elk Creek, Nebraska (USGS 2025).
3.2.2 Geology and Soils - Impacts The proposed action would not result in disturbing any previously undisturbed land as the area around the Auxiliary Building and Containment Building concrete slabs are all previously
3-2 disturbed land. Any site impacts are expected to be less than those from construction previously evaluated in the Final Environmental Statement (OPPD 1971).
The proposed license amendment includes grouting the Auxiliary Building concrete block, the stressing gallery underneath the Containment Building, and one wall of the Containment Building, which would not impact the local geology and soil. The grout in each area would not leach out and incorporate into the local soil or result in meaningful changes to the site geologic characteristics. Any fill material used would be taken from previously considered locations and the potential impacts to geology and soils were considered previously in the 2023 LTP EA Section 3.5. Any potential impacts to the site geology would be bound by the GEIS and the previous LTP environmental review for full decommissioning (NRC 2002; NRC 2023a).
Therefore, the NRC staff conclude the proposed action would have no significant impact on geology and soils.
3-3 Figure 3-1 FCS Site (Source: OPPD 2024)
3-4 3.3 Water Resources 3.3.1 Water Resources - Affected Environment The FCS site is bordered to the north by the Blair Bend of the Missouri River. Wetland and surface streams exist near the FCS, including Fish Creek, which runs along the west side of the independent spent fuel storage installation and switchyard, Long Creek, which is approximately 1.1 km (0.7 mi) southeast of the site, and DeSoto Lake which is approximately 2.9 km (1.8 mi) east of the site (NRC 2023a).
The Missouri River is an important source of municipal and domestic water for the region, with multiple potable intakes located near FCS. The closest potable water intakes are located approximately 1.6 km (1 mi) upstream of the site and 32 km (20 mi) downstream (OPPD 2025a).
The FCS has a general National Pollutant Discharge Elimination System (NPDES) permit for stormwater discharges and a general NPDES permit for dewatering discharges. OPPD is permitted to discharge non-radiological water into Fish Creek and the Missouri River (OPPD 2025a).
The FCS has experienced several floods from Missouri River overflow, most notably in 2011 when the site was flooded for approximately 3 months. To mitigate flooding during decommissioning, OPPD installed a HESCO barrier around the FCS in 2020 (see Figure 3-2)
(OPPD 2024). The barrier consists of sand and gravel-filled fabric-lined cages and ranges from 1.5-3.0 m (5-10 ft) in height and is approximately 2,438 m (8,000 ft) in length.
Groundwater gradients at the FCS are nearly flat, gently sloping toward the nearby Missouri River. Groundwater levels vary from 302.8 m (993.7 ft) to 302.5 m (992.4 ft) in elevation at the site. Groundwater levels vary with changing river levels for a system that the OPPD described as bank storage effects (OPPD 2025a). In the bank storage conceptualization, groundwater flow is generally toward the river in the late summer and winter when the Missouri River is falling, while flow is generally away from the river in the spring when the river level is rising.
There are 31 active private wells for domestic use and 13 irrigation wells within 4.0 km (2.5 mi) upstream and 7.2 km (4.5 mi) downstream from the FCS (OPPD 2025a). There are several additional wells used for public water supply for recreational areas, environmental monitoring, and commercial or industrial operations. No groundwater within 0.8 km (0.5 mi) of the FCS is used for drinking water.
3.3.2 Surface Water Impacts The proposed action involves alterations to site characteristics and final site status conditions 3 m (9.8 ft) or deeper below the surface grade at and immediately adjacent to the Auxiliary Building and Containment Building (OPPD 2025c). OPPD has committed to using BMPs to limit impacts to stormwater during decommissioning activities (OPPD 2025a). The proposed action uses significantly less surface water for operations than the site did when operating (OPPD 2024). There are no significant water discharges from the proposed action beyond stormwater runoff. The proposed action would have no significant impact on surface waters beyond the scope previously considered in Section 3.6.1 of the 2023 NRC EA (NRC 2023a). Therefore, the NRC staff conclude the proposed action would have no significant impact on surface water.
3-5 Figure 3-2 HESCO Barrier (Source: OPPD 2024) 3.3.3 Groundwater Impacts The proposed action includes changing the DCGLs for various radionuclides at the Auxiliary Building and Containment Building. The Auxiliary Building basement slab, the stressing gallery, and the 973-foot elevation west wall are all below the median depth of the groundwater as discussed in Section 3.3.1. To demonstrate compliance with regulatory limits for potential dose after unrestricted release of the site, OPPD modeled the release rate for all radionuclides from the Auxiliary Building basement slab over a 1,000-year period in the LTP Revision 2 Chapter 6 (OPPD 2025c). The release rate accounted for the grout used to fill the trenches in the slab, designed to prevent groundwater intrusion into the slab and reduce radionuclide mobility to that based on diffusional processes. Without grout, the release rate would necessarily also include advective processes.
In the LAR, OPPD stated that the trenches would be filled with grout with an additional 30 centimeters (cm) (11.8 inches [in.]) cover over the filled trenches (OPPD 2024). The cover would be 90 cm (35.4 in.) wide to ensure a 30 cm (11.8 in.) cover on each side of the trench to account for diffusion in all directions. Because the cover is 30 cm (11.8 in) on each side of the trench, the diffusion distance of all radionuclides is the same in all directions.
3-6 Table 6-22 in the LAR shows the cumulative fractional release for a suite of radionuclides at the site over the 1,000-year evaluation period (Table 1; OPPD 2024). The cumulative fractional release is a measure of how much of the total fraction of a substance has been released from a surface over a given period (e.g., a cumulative fractional release of 0.5 over 1,000 years would mean half of the material has leached out over 1,000 years). The cumulative fractional releases in Table 3-1 for a suite of radionuclides at the FCS site vary from 3e-30 to 6.15e-5 except for tritium (H-3), which has a cumulative fractional release of 1.47e-1. Thus, with the proposed grouting of the concrete slab, most of the radionuclides in the concrete slab would remain inside the slab with very little diffusion into the local groundwater.
Table 3-1 Cumulative Fractional Release from Uniformly Contaminated Grout of 45 cm (18 in.) with 30 cm (12 in.) Cover Radionuclide Cumulative Fractional Release Am-241 3.00E-30 C-14 3.00E-30 Ce-144 3.00E-30 Cm-243 3.00E-30 Cm-244 3.00E-30 Co-58 3.00E-30 Co-60 3.00E-30 Cs-134 9.33E-24 Cs-137 7.32E-08 Eu-152 3.00E-30 Eu-154 3.00E-30 Eu-155 3.00E-30 Fe-55 3.00E-30 H-3 1.47E-01 Ni-59 6.15E-05 Ni-63 1.69E-07 Np-237 3.00E-30 Pu-238 3.00E-30 Pu-239 3.00E-30 Pu-240 3.00E-30 Pu-241 3.00E-30 Sb-125 3.00E-30 Sr-90 5.34E-15 Tc-99 3.00E-05 The largest release over 1,000 year is expected to be H-3 with less than 20 percent of the total concentration released from the concrete slab over 1,000 years. Most radionuclides would release less than 1 percent of the total concentration in the slab over 1,000 years.
Therefore, it is unlikely that any release of radioactive material from the grouted concrete slab into the groundwater would result in public doses above NRC regulations in 10 CFR 20.1301 or 10 CFR 20.1402 or concentrations above U.S. Environmental Protection Agency (EPA) maximum contaminate levels, for constituents that have defined maximum contaminate levels.
3-7 The small rate of release for all radionuclides along with each radionuclides half-life ensures the concentration of all radionuclides would remain well below the regulatory limits for effluent release in 10 CFR 20 Appendix B. Grout in the Containment Building stressing gallery and 973-foot elevation west wall would similarly limit radionuclide mobility and prevent the release of radioactive contaminants into the groundwater because the walls and floors in these two areas are thicker than the 30 cm (12 in.) thickness of the cover used in the calculations of the diffusion factors for the Auxiliary Building trenches. Therefore, the diffusion factors for the Auxiliary Building basement are bounding for the Containment Building.
The proposed action would allow for more radionuclides to be left on the site after license termination; however, the grout used with the concrete would significantly reduce the residual radioactivity released into the site groundwater system. The largest cumulative fractional release over 1,000 year is H-3, with an estimated 14.7 percent of the H-3 released from the concrete slab over 1,000 years. Therefore, the NRC staff conclude that the proposed action would have no significant impact on groundwater.
3.4 Ecology There are no new significant impacts on ecology from those considered in Section 3.8 of the 2023 LTP EA. Section 3.8 of the 2023 LTP EA describes the site ecology and discusses the impacts of full site decommissioning on the local ecology. The largest change is the proposed listing of three species under the Endangered Species Act (ESA), which is discussed in more detail in Section 3.4.3.
3.4.1 Terrestrial Resources 3.4.1.1 Terrestrial Resources - Affected Environment Approximately 75 percent of the FCS site consists of agricultural land, station facilities, and other developed land with the remaining 25 percent consisting of natural vegetation such as upland forest, wetlands, and floodplain forests (NRC 2023).
The upland forest was described in the Fort Calhoun Supplemental EIS (SEIS) Section 2.2.6 as dominated by black locust (Robinia pseudoacacia), red mulberry (Morus rubra), Siberian elm (Ulmus pumila), and hackberry (Celtis occidentalis), with abundant poison ivy (Toxicodendron spp.) and stinging nettle (Urtica dioica) in the understory (NRC 2003).
According to the SEIS, the floodplain forest borders the Missouri River, North and South Sloughs, and Long Creek and is dominated by green ash (Fraxinus pennsylvanica), cottonwood (Populus spp.), box elder (Acer negundo), silver maple (Acer saccharinum), and hackberry, with an understory of false indigo (Baptisia spp.), rough dogwood (Cornus drummondii), giant ragweed (Ambrodia trifida), goldenrod (Solidago spp.), and milkweed (Ascepias spp.). Wetlands comprise less than 5 percent of the FCS land and include narrow-leaved cattail (Typha angustifolia), reed canary grass (Phalaris arundinacea), sedges (Carex spp.), rushes (Juncus spp.), spikerushes (Eleocharis spp.), milkweed, rough dogwood, and black willow (Salix nigra)
(NRC 2003).
The DeSoto National Wildlife Refuge comprises approximately 3,157 ha (7,800 ac) situated approximately 1.6 km (1 mi) east of the FCS site along the Missouri River (OPPD 2025). The refuge contains bottomland forests, tallgrass prairie, and wetlands and an oxbow lake that formed from a bend in the Missouri River. During the spring and fall the location and suitable habitats are host to a diversity of migratory birds as well as turtles and deer (FWS 2025g).
3-8 3.4.1.2 Terrestrial Resources - Impacts In its LAR, OPPD stated that it does not anticipate significant disturbances to habitats beyond the operational areas of the plant (OPPD 2025). All dismantlement, demolition, and waste staging activities would be conducted within the operational area of the site. The proposed action involves the Auxiliary Building, the Containment Building, and immediately adjoining areas, which is not on the edge of the site boundary or adjacent to previously undisturbed land. In the LAR, OPPD committed to controlling fugitive dust emissions through water spraying and to implement BMPs to prevent runoff and erosion (OPPD 2024). Wildlife could be affected by noise generated during decommissioning activities; however, the site is an established industrial site where the local wildlife has likely acclimated to the noise and human activity typical for the site. The proposed action does not involve any new activities or noise generating machinery that would impact local wildlife beyond that previously considered in the 2023 LTP EA Section 3.8 (NRC 2023). Therefore, the NRC staff conclude the proposed action would have no significant impact on terrestrial ecology.
3.4.2 Aquatic Resources 3.4.2.1 Aquatic Resources - Affected Environment The main aquatic habitat in the vicinity of the FCS is the adjoining Missouri River. The river channel is approximately 183 m (600 ft) wide and 4.5 m (15 ft) deep where it flows past the FCS site (NRC 2003). Section 2.2.5 of the SEIS for the construction of FCS summarized the results of multiple fish surveys for the reach of the Missouri River near FCS. Electroshocking data from 1982 indicated that the most abundant fish species in the Missouri River near the FCS were the gizzard shad (Dorosoma cepedianum), goldeye (Hiodon alosoides), common carp (Cyprinus carpio), western silvery minnow (Hybognathus argyritis), silver chub (Macrhybopsis storeriana), emerald shiner (Notropis atherinoides), river shiner (Notropis blennius), red shiner (Cyprinella lutrensis), river carpsucker (Carpiodes carpio), and freshwater drum (Aplodinotus grunniens) (NRC 2003).
3.4.2.2 Aquatic Resources - Impacts In its LAR, OPPD states that it would continue to maintain its existing NPDES permits and would perform all work in compliance with the permits and implement BMPs as appropriate.
The proposed action involves the Auxiliary Building, the Containment Building, and immediately surrounding area, which is near the Missouri River (Figure 31). OPPD has stated in the LAR that it will continue to implement Stormwater Pollution Prevention Plan to limit runoff water at the site (OPPD 2025c). Because no new, or significant impacts were identified from the LAR proposed action, potential impacts from the proposed action to the Missouri River are bound by potential impacts considered in Section 3.8.2.4 of the 2023 LTP EA for the site which concluded no significant impacts from site decommissioning activities on aquatic resources (NRC 2023a).
Therefore, the NRC staff conclude that the proposed action would have no significant impact on aquatic resources.
3.4.3 Threatened and Endangered Species The U.S. Fish and Wildlife Service (FWS) and the National Marine Fisheries Service (NMFS) jointly administer the ESA. The FWS manages the protection of, and recovery effort for, listed terrestrial and freshwater species, and the NMFS manages the protection of and recovery effort for listed marine and anadromous species.
3-9 Using the FWS Information for Planning and Consultation (IPaC) database, the NRC staff generated a species list dated January 2025 for an action area comprising the FCS site and immediately adjacent lands (FWS 2025a). Of the identified species, the northern long-eared bat, piping plover, and pallid sturgeon were listed species in 2023 for the LTP environmental review and the impacts of site decommissioning for each species were considered in Sections 3.8.1.4 and 3.8.2.2 of the 2023 LTP EA (NRC 2023). Three identified species were not listed at the time of the 2023 LTP EA: the monarch butterfly (Danaus plexippus), western regal fritillary (Argynnis idalia occidentalis), and the Suckleys cuckoo bumble bee (Bombus suckleyi). The impacts of the proposed action are discussed further in Section 3.4.3.1, while the impacts of the full site decommissioning on the three newly listed species are discussed further in Section 3.4.3.2. No species under NMFS jurisdiction were identified as part of this review.
3.4.3.1 Threatened and Endangered Species - Proposed Action During the Fort Calhoun LTP Federal action, the NRC consulted with the FWS regarding the northern long-eared bat, piping plover, and pallid sturgeon (NRC 2023c). On November 5, 2023, the NRC received concurrence from FWS for these species (FWS 2023). However, the monarch butterfly, western regal fritillary, and Suckleys cuckoo bumble bee are proposed to be listed under the ESA and were not analyzed under the Fort Calhoun 2023 LTP EA. Table 32 lists occurrences of federally listed and proposed species under FWS jurisdiction in the Fort Calhoun LAR action area.
Action Area 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. For the purposes of assessing the potential impacts of the FCS LAR on federally listed species, the NRC staff considers the action area to consist of the Auxiliary Building, the Containment Building, the fill material taken from the previous rail spur expansion, all roads used to transport material to/from these locations, and any immediately adjacent land (Figure 3-1).
The proposed action does not significantly alter the site-specific impacts of decommissioning on any of the previously reviewed species because the proposed action involves alterations to site conditions 3 meters (9.8 ft) or deeper around the Auxiliary Building and the Containment Building. All other potential impacts are therefore part of the environmental baseline. There are no ESA listed species at the site that burrow or rely on subsurface conditions beyond impacts to foliage for food. Because the proposed action only occurs in previously disturbed areas around buildings and on paved land, there are no significant impacts to the current site foliage.
The proposed action does not include use of heavy machinery outside of the scope of the previously considered impacts in the 2023 EA and would not involve any previously undisturbed land. There are no changes to the potential impacts due to noise or land use and no alterations to species habitats in the area.
Table 3-3 lists effect determinations for federally listed species under FWS service jurisdiction for the proposed LAR.
3-10 Table 3-2 Occurrences of Federally Listed and Proposed Species Under U.S. Fish and Wildlife Service Jurisdiction in the Fort Calhoun License Amendment Request Action Area Species or Critical Habitat Federal Status(a)
Habitat Type and Likelihood of Occurrence in Action Area northern long-eared bat (Myotis septentrionalis)
FE In non-hibernating seasons, northern long-eared bats typically roost individually or in colonies underneath bark or in cavities or crevices of both live trees and snags. Males and nonreproductive females also may roost in cooler locations, including caves and mines. Individuals may use caves and mines during fall swarming (FWS 2022).
Seasonal and occasional. The action area falls within the general range of the species but does not contain caves, mines, or other features suitable for hibernating. Therefore, bats would not be present in winter inactive season (FWS 2025e). Forested areas in the action area contain suitable habitat to support foraging, mating, and sheltering. An acoustic survey was performed in 2018, which identified 13 calls attributed to the northern long-eared bat. No bats were captured or directly observed during the survey (OPPD 2020). The NRC conservatively assumes that the northern long-eared bat could occur within the action area in the spring, summer, and fall. If present during these seasons, individuals would only occur occasionally and in low numbers.
piping plover (Charadrius melodus)
FT Shorebird, in northern Great Plains breeds and raises young on sparsely vegetated sandbars and shorelines, winters in the south on beaches and other coastal areas, populations have declined due to disturbance and degradation of breeding and wintering habitat (FWS 2016). Loss of sandbar nesting habitat caused by river channelization and flow changes from construction and operations of dams have resulted in population declines along the Missouri River (OPPD 2021).
Seasonal and occasional. Aerial photography shown in PSDAR indicates that there is no sandbar habitat along the Missouri River shoreline where it abuts the FCS-developed areas, although photographs suggest that some sandbar habitats potentially favorable for the piping plover may occur more than 304.8 m (1,000 ft) downstream (OPPD 2020). Therefore, piping plover could occur in the action area.
pallid sturgeon (Scaphirhynchus albus)
FE Pallid Sturgeon are found in large, deep turbid river channels such as the Missouri and Mississippi Rivers and some larger tributaries (FWS 2022h). Dam construction has adversely altered habitat for this long-lived fish, and many reproductively mature fish are thought to have been born before the dams were constructed (Nebraska Game and Parks 2022).
Only potentially suitable habitat on or near the FCS site is the Missouri River.
3-11 Species or Critical Habitat Federal Status(a)
Habitat Type and Likelihood of Occurrence in Action Area monarch butterfly (Danaus plexippus)
FPT The species spends spring and summer in fields, wetlands, urban gardens, or anywhere with suitable milkweed.
Populations of monarch butterflies will live and breed year-round in areas with year-round presence of milkweed and suitable temperatures. Monarch caterpillars eat only milkweed thus the species will lay eggs on milkweed plants. The adult butterflies will eat milkweed and the nectar of various flowers (FWS 2025b).
Seasonal. The floodplain forest bordering the Missouri River and Long Creek contains sufficient milkweed for monarch butterfly larvae (NRC 2003). The nearby plains and wetlands are suitable habitats for the monarch butterfly as it migrates up to 4828 km (3,000 mi) between Canada to Mexico every year (FWS 2025b).
western regal fritillary (Argynnis idalia occidentalis)
FPT Adults mate in mid-to-late summer but eggs are not laid until fall. Females lay up to 2,000 eggs each on vegetation, dead leaves, or pebbles (USDA 2025). Larvae seek hibernation sites quickly after hatching, entering diapause to overwinter without feeding on host plants. The species lives in tallgrass prairies, marshes, wet fields, or meadows.
Adults eat nectar from flowering plants however the primary food source for the young is violets.
Occasional. Western regal fritillary may pass through the area, however there are no known violets at the site and the prairie onsite is less than 10 acres (FCS 2025c). This prairie could be used by adult butterflies as a nectar source, but it is unlikely they would remain or become a reproducing population due to the small size of the prairie and the lack of violets for larvae to eat.
Suckleys cuckoo bumble bee (Bombus suckleyi)
FPE The Suckleys cuckoo bumble bee can be found in a wide range of habitats including prairies, meadows, grasslands, woodlands, agricultural fields, and urban areas. As a parasitic species, the species relies on other bumble bee species for its survival and raising its young. The female cannot produce a worker caste or make enough wax to construct a nest, thus the species is highly dependent on other bumble bee species. Because it is a parasitic species, the Suckleys cuckoo bumble bee is particularly susceptible to habitat loss and decline of other bumble bee species.
None. Suckleys cuckoo bumble bee relies on other species of bumble bee, particularly the western bumble bee (Bombus occidentalis),
which has no historical sightings in Washington County (Xerxes 2022). None of the other known host species have been sighted in the county in over 10 years. Suckleys cuckoo bumble bee has not been sighted in Washington County or any neighboring counties in the past 10 years (Xerxes 2022)
(a) Indicates protection status under the ESA. FE = Federally Endangered; FPE = Federal Proposed Endangered; FPT = Federal Proposed Threatened; FT =
Federally Threatened.
3-12 Table 3-3 Effect Determinations for Federally Listed Species under U.S. Fish and Wildlife Service Jurisdiction for the Proposed License Amendment Request Species Federal Status(a)
Potentially Present in the Action Area?
Effect Determination(b) northern long-eared bat (Myotis septentrionalis)
FE Yes NE piping plover (Charadrius melodus)
FT Yes NE pallid sturgeon (Scaphirhynchus albus)
FE Yes NE monarch butterfly (Danaus plexippus)
FPT Yes NE Western regal fritillary (Argynnis idalia occidentalis)
FPT Yes NE Suckleys cuckoo bumble bee (Bombus suckleyi)
FPE No NE FE = federally endangered; FPE = proposed for Federal listing as endangered; FPT = proposed for Federal listing as threatened; FT = federally threatened; NE = no effect; NLAA = may affect, not likely to adversely affect.
(a) Indicates protection status under the ESA.
(b) The NRC staff makes its effect determinations for federally listed species in accordance with the language and definitions specified in the FWS and NMFS Endangered Species Consultation Handbook (FWS and NMFS 1998).
Northern Long-eared Bat (FE)
The proposed action involves digging around the Auxiliary Building and Containment Building, which are surrounded by paved land and other industrial use structures. All potential effects on the northern long-eared bat resulting from the proposed action would be considered part of the environmental baseline, as defined in 50 CFR 402.02, because the proposed action would not alter any impacts previously considered in the 2023 LTP EA Section 3.8. There are no previously undisturbed areas impacted by the proposed action, and all activities involve soil and building material 3 m (9.8 ft) or deeper bgs. The proposed action does not include any alterations to wetlands or riparian forest and would not result in the removal of trees at the site.
Therefore, the NRC concludes that the proposed action would have no effect on the northern long-eared bat. As such, the NRCs obligations under Section 7 of the ESA are considered complete for this species.
Piping Plover (FT)
The shoreline of the operational area of the site is concrete and does not contain sandbars, which is the preferred nesting habitat for piping plovers. The proposed action includes the Auxiliary Building and immediately adjacent land, which is entirely paved land within the operational area. All potential effects on the piping plover resulting from the proposed action would be considered part of the environmental baseline, as defined in 50 CFR 402.02, because the proposed action would not alter any impacts previously considered in the 2023 LTP EA Section 3.8. The proposed action would not increase the amount of water taken from the Missouri River for cooling and does not increase the effluent concentration of any contaminants of concern. The proposed action would not alter the river shoreline at the site or downriver, thus it would not alter potential nesting habitats along the river. The proposed action would generate some noise, but it would be noise typical of an industrial site and is consistent with noise
3-13 considered in the 2023 LTP EA. Therefore, the NRC staff conclude the proposed action has no effect on the piping plover. As such, the NRCs obligations under Section 7 of the ESA are considered complete for this species.
Pallid Sturgeon (FE)
All potential effects on the pallid sturgeon resulting from the proposed action would be considered part of the environmental baseline, as defined in 50 CFR 402.02, because the proposed action would not alter any impacts previously considered in the 2023 LTP EA Section 3.8. OPPD committed in the LAR to implement BMPs to prevent runoff water from the proposed action and to use water to limit fugitive dust (OPPD 2021). The proposed action includes altering the DCGLs at the Auxiliary Building basement and Containment Building deeper than 3 m (9.8 ft) (OPPD 2025c). However, grouting of the Auxiliary Building basement concrete slab, the stressing gallery, and the 973-foot elevation west wall would reduce groundwater intrusion and radionuclide mobility. The estimated release into the groundwater is discussed more in Section 3.3.2 of this EA. The proposed action would not increase the concentration of radionuclides in the groundwater or increase radionuclide mobility at the site.
Stormwater runoff management at the site during decommissioning was considered in the 2023 LTP and is not expected to change due to the proposed action. Thus, the proposed action would have no impact on the quality of water in the Missouri River or in the amount of water discharged from the site into the Missouri River. Therefore, the NRC staff conclude the proposed action has no effect on the pallid sturgeon. As such, the NRCs obligations under Section 7 of the ESA are considered complete.
Monarch Butterfly (FPT)
The monarch butterfly was discussed in the 2023 LTP EA. However, the species was a candidate species at the time, and on December 12, 2024, the monarch butterfly was proposed listed as threatened (89 FR 100662) (NRC 2023). Monarch butterflies require milkweed for breeding as eggs are laid exclusively on milkweed for the caterpillar to eat after hatching.
Milkweed is unlikely to exist near the Auxiliary Building or Containment Building since they are surrounded by paved lands. Milkweed exists near the operational area in the vegetated lands along the river; however, the proposed action would not impact vegetated lands as it involves the Auxiliary Building, the Containment Building, and immediately surrounding area, which are all previously disturbed and paved land. BMPs would prevent damage to the milkweed by sedimentation, runoff, or fugitive dust. Vegetation management activities that could damage or destroy milkweed and/or nectar plants at the site would only occur when monarch butterfly is unlikely to be at the site (OPPD 2025b). Therefore, the NRC staff conclude the proposed action has no effect on the monarch butterfly. As such, the NRCs obligations under Section 7 of the ESA are considered complete.
Western Regal Fritillary (FPT)
Western regal fritillary is a brush-footed butterfly that relies on violets for larval food. There is one prairie near the entrance to the site, however it is not immediately adjacent to the Auxiliary Building or the Containment Building and is not sufficiently large enough to sustain a reproducing population of western regal fritillary (OPPD 2025b). Violets have never been observed within the FCS site, although they may exist in small patches (OPPD 2025b). The NRC staff conclude that the proposed action has no effect on the western regal fritillary. As such, the NRCs obligations under Section 7 of the ESA are considered complete.
3-14 Suckleys Cuckoo Bumble Bee (FPE)
Suckleys cuckoo bumble bee relies on other bumble bee hives as hosts for raising its young; therefore, the species is susceptible to loss of habitat for the host species, particularly Bombus occidentalis, Bombus rufocinctus and Bombus appositus (WDFW 2025). There are no known sightings of the Suckleys cuckoo bumble bee or its two host species at the FCS, or within Washington County for more than 10 years (Xerxes 2022). The NRC staff conclude that the proposed action has no effect on the Suckleys cuckoo bumble bee because the Suckleys cuckoo bumble bee is not present at the site. As such, the NRCs obligations under Section 7 of the ESA are considered complete.
3.4.3.2 Threatened and Endangered Species - Full Site Decommissioning Appendix C of the Environmental Report in the PSDAR is a report for an acoustic and mist net survey performed in 2018 that identified 13 calls attributed to the northern long-eared bat (OPPD 2020). No northern long-eared bats were captured or identified directly during the survey. However, these surveys were not included in the 2023 LTP EA (NRC 2023). The conclusion in the 2023 LTP EA assumed presence at the site for the northern long-eared bat and considered potential impacts to known habitat in the area. Although no northern long-eared bats were captured or identified directly during the survey, acoustic activity of the northern long-eared bat identified during the acoustic and mist net survey in 2018 would indicate the species is present at the site. However, decommissioning at the site is limited to industrial lands and would not involve the removal of forest cover or wetland alterations. Therefore, the NRC staff affirms the conclusion in the 2023 LTP EA for the northern long-eared bat remains true, that the site decommissioning may affect, not likely to adversely affect the northern long-eared bat.
On November 5, 2023, the FWS concurred with the NRC determinations on potential impacts from the FCS LTP for the northern long-eared bat, piping plover, and pallid sturgeon (FWS 2023).
The potential impacts of site decommissioning on the monarch butterfly, Suckleys cuckoo bumble bee, and the western regal fritillary were not considered in the 2023 EA LTP because none of the three species were ESA listed or proposed listed species at the time. Because the LTP Federal action is ongoing, these three species will require an ESA analysis regarding the initial LTP Federal action in addition to the LAR discussed in Section 3.4.3.1). Section 3.8 of the 2023 LTP EA includes additional information regarding the action area for the full site decommissioning plan (NRC 2023).Table 3-4 lists effect determinations for federally listed species under FWS service jurisdiction for the full site decommissioning that were not previously considered in the 2023 LTP EA.
Table 3-4 Effect Determinations for Newly Proposed for Federal Listing Species under U.S. Fish and Wildlife Service Jurisdiction for Full Site Decommissioning Activities Species Federal Status(a)
Potentially Present in the Action Area?
Effect Determination(b) monarch butterfly (Danaus plexippus)
FPT Yes NLAA western regal fritillary (Argynnis idalia occidentalis)
FPT Yes NLAA Suckleys cuckoo bumble bee FPE No NE
3-15 Species Federal Status(a)
Potentially Present in the Action Area?
Effect Determination(b)
(Bombus suckleyi)
FPE = proposed for Federal listing as endangered; FPT = proposed for Federal listing as threatened; NLAA = may affect, not likely to adversely affect. NE = no effect.
(a) Indicates protection status under the ESA.
(b) The NRC staff makes its effect determinations for federally listed species in accordance with the language and definitions specified in the FWS and NMFS Endangered Species Consultation Handbook (FWS and NMFS 1998).
Monarch Butterfly (FPT)
Decommissioning of the site does not include any naturally vegetated land as OPPD has stated there is sufficient space within the operational area for staging and storage so no previously undisturbed land is needed for decommissioning (OPPD 2024). Decommissioning of the FCS site could indirectly impact vegetated lands near the operational area by fugitive dust, runoff, or sedimentation. OPPD has committed to implementing BMPs to prevent such damage. Any future work at the FCS site on the prairie would include tree removal, spraying of invasive plants, and wildflower seeding, all of which would benefit the monarch butterfly by improving the health and diversity of flowering plants and milkweed (OPPD 2025b). Routine agricultural activities around the site would be on land that has been used for agricultural purposes for years and do not include any milkweed or flowering plants that could be a source of nectar for the butterfly. Most of the decommissioning effort would be centered around the removal of structures, filling in basements and foundations with soil, and grading. There is no milkweed or flowering plants in these areas as they are all paved lands. Therefore, the NRC staff conclude the full site decommissioning may affect, not likely to adversely affect the monarch butterfly.
Because the monarch butterfly is proposed for Federal listing as threatened, the ESA does not require the NRC to consult with or receive concurrence from the FWS regarding this species as long as continued existence of the species is not jeopardized.
Western Regal Fritillary (FPT)
The western regal fritillary could pass through the FCS site, but it is unlikely the butterfly would remain as the site is not suitable for a reproducing population. There are no known violets at the site, which are the only food source for western regal fritillary larvae. Additionally, the prairie on the site is too small and fragmented to sustain a sufficiently large adult population (OPPD 2025b). The western regal fritillary could use the prairie as a source of nectar as the DeSoto National Wildlife Refuge is across the Missouri River and likely would have suitable habitat for the western regal fritillary (FWS 2025g). Most of the decommissioning effort would be centered around the removal of structures, filling in basements and foundations with soil, and grading.
There are no violets or flowering plants in these areas as they are all paved lands. Therefore, the NRC staff concludes that full site decommissioning may affect, not likely to adversely affect the western regal fritillary. Because the western regal fritillary is proposed for Federal listing as threatened, the ESA does not require the NRC to consult with or receive concurrence from the FWS regarding this species as long as continued existence of the species is not jeopardized.
Suckleys Cuckoo Bumble Bee (FPE)
The Suckleys cuckoo bumble bee has not been sighted in Eastern Nebraska in over 10 years (Xerxes 2022). Its primary host species, the western bumble bee, are typically only found in
3-16 Western Nebraska. None of the three previously identified host species, Bombus occidentalis, Bombus rufocinctus and Bombus appositus are known to be present at the FCS, nor are there any known sightings of any of the three species in Washington County or any neighboring county in the last 10 years (WDFW 2025; Xerxes 2022). Therefore, the NRC staff concludes that full site decommissioning has no effect on the Suckleys cuckoo bumble bee because the species is not present at the site. Because the Suckleys cuckoo bumble bee is proposed for Federal listing as endangered, the ESA does not require the NRC to consult with or receive concurrence from the FWS regarding this species as long as continued existence of the species is not jeopardized.
3.5 Historic and Cultural Resources 3.5.1 Historic and Cultural Resources - Affected Environment The NRC reviewed the site historic characteristics in the SEIS Section 4.4.5 for license renewal of the operating reactor license and identified the section of the plant site that lies north of the rail spur and bounded on the west by U.S. Highway 75 as having a moderate-to-high potential for historic or cultural resources because it contains remnants of the former town of De Soto (NRC 2003).
The 2023 LTP EA Section 3.7.2 determined the full decommissioning of the FCS would have no effect on historic properties as there are no known historic properties at the site beyond De Soto, which would not be impacted by the decommissioning of FCS. The NRC staff sent its determination on the impacts to cultural and historic resources from the LTP to the Nebraska State Historic Preservation Officer (Nebraska SHPO) on September 29, 2022 (NRC 2022a).
The Nebraska SHPO responded on September 30, 2022, with its concurrence that no historic properties would be affected by the undertaking (Nebraska SHPO 2022).
3.5.2 Historic and Cultural Resources - Impact The proposed action involves the Auxiliary Building, the Containment Building, and immediately adjacent land, which is entirely within the operational area of the FCS site and is comprised entirely of previously disturbed and paved land. There are no activities included in the proposed action that would occur on previously undisturbed land at the FCS site or its surroundings (OPPD 2025).
The proposed action does not alter any of the NRC determinations for potential impacts to historic and cultural resources from the 2023 LTP EA. The proposed action would impact a small area of the FCS which is previously disturbed and does not include the former town of De Soto. The proposed action is altering the end-state conditions for previously disturbed land under and immediately adjacent to the Auxiliary Building and Containment Building where there are no known historic or cultural resources. OPPD confirmed with the Nebraska SHPO that the FCS is not a historic property itself; therefore, there are no impacts to historic and cultural resources from the proposed action (OPPD 2022).
NRCs approval of the proposed action does not have the potential to cause effects to historic properties, assuming such properties were present. Therefore, pursuant to 36 CFR 800.3(a)(1),
the NRC has no further National Historic Preservation Act Section 106 obligations. The proposed action is bounded by the 2023 LTP EA Section 3.7 for historic and cultural resources as all activities related to the proposed action are within the previously approved site boundary and are limited to previously disturbed soils and concrete structures deeper than 3 m (9.8 ft).
3-17 Therefore, the NRC staff conclude the proposed action has no significant impact on historic and cultural resources.
3.6 Public and Occupational Health and Safety 3.6.1 Public and Occupational Health and Safety - Affected Environment All facilities that are granted NRC licenses must adhere to the radiation protection standards in 10 CFR 20 to protect workers and the public from potential exposure to radioactive material at the site. The NRC reviewed the potential impacts to public and occupational health for the full FCS site decommissioning in the 2023 LTP EA Section 3.10. OPPD estimated that the total radioactive exposure at the FCS site during decommissioning would be 2.3 person-Sv (230 person-rem), which is less than the estimate in the decommissioning GEIS of 3.5 to 16 person-Sv (350 to 1600 person-rem) (OPPD 2021; NRC 2002).
The NRC concluded in the decommissioning GEIS that the collective dose to the public would be lower than when the facility was operating, with the maximally exposed individual estimated to receive a dose of less than 1 mrem/yr (0.01 mSv/yr) (GEIS NRC 2002).
Because of OPPDs implementation of the Radiological Groundwater Protection Plan, Radiological Environmental Monitoring Plan, and as low as reasonably achievable (ALARA) goals to ensure public protection, the NRC staff concluded in the 2023 LTP EA Section 3.10.2 that there would be no significant impact associated with public and occupational dose beyond those discussed in the GEIS for FCS site decommissioning.
3.6.2 Radiological Impact The proposed action would only alter potential impacts around the Auxiliary Building basement and the Containment Building; therefore, only impacts in this area of the site are considered here.
The proposed action involves altering the DCGLs for concrete structures of the Auxiliary Building, including (i) the reduction in radionuclide release from grouted trenches in the floor slabs, (ii) using separate DCGLs for concrete above and below 3m depths, and (iii) altering the excavation scenario by reducing the conservatism for radionuclide release rates associated with the assumption that concrete acts like soil (OPPD 2024). The alterations include switching from a Resident Farmer scenario to an Industrial Use scenario in the dose assessment for portions of the concrete structures more than 3 m (9.8 ft) bgs, which alters the potential exposure pathways based on how the land is used. NUREG-1757 Vol. 2, Revision 2, notes that residential basements are assumed to be dug to a maximum depth of 3 m (9.8 ft) bgs; therefore, the resident farmer would not be likely to interact with contaminated concrete from deeper than 3 m (9.8 ft) in an excavation of a basement (NRC 2022b). Additionally, the dose models removed some of the overly conservative assumptions involving the dose calculations for the excavation scenario (e.g., treating concrete like soil for radionuclide mobility and for root growth for the plant ingestion pathway).
The proposed action would also alter the DCGLs for concrete structures in the stressing gallery and the 973-foot elevation west wall of the Containment Building directly adjacent to the Auxiliary Building. Both areas of the Containment Building are more than 3 m (9.8 ft) bgs and would not have any impact on the resident farmer, as described for the Auxiliary Building basement. The revised DCGLs for these two areas alter the Containment Building DCGLs in the
3-18 initial LTP and consider only the Industrial Use scenario for an exposure pathway (OPPD 2025c)
DCGLs are radionuclide-specific concentration limits that are calculated based on an all-pathway dose assessment for a specific site. The DCGL represents the concentration of a radionuclide that would have a peak dose over a 1,000-year compliance period equal to the specified dose limit (e.g., 0.25 mSv/yr [25 mrem/yr] for unrestricted release) to the average member of a group of individuals reasonably expected to receive the highest dose. For the Industrial Use Scenario, OPPD instead chose to assign the DCGLs for each radionuclide based on the year with the highest relative dose. The highest relative dose is calculated using the year of the highest total dose and incorporating the mixture fractions of radionuclides from site characterization as discussed in Section 6.13.3 of the LTP LAR (OPPD 2024). The alternative DCGL methodology is evaluated in more detail by the NRC staff in the accompanying safety environmental report (SER) for this review.
The DCGL for a specific radionuclide is the concentration that radionuclide must be below during clean-up to ensure that dose from the radionuclide will not exceed regulatory limits over the next 1,000 years. DCGLs are site-specific as they are only appropriate for the specific conditions for which they are derived.
The proposed changes to the DCGLs alter the concentration of radionuclides remaining at the site after unrestricted release; however, public and occupational risk assessment is based on anticipated dose risk rather than concentration. Section 6.13.5 of the LTP details the dose modeling for the Auxiliary Building using the revised DCGLs and demonstrates that the new DCGLs would not result in a change to dose assessment for the public after unrestricted release of the site compared to the previously approved LTP as discussed in Section 3.10 of the 2023 LTP EA (NRC 2023a). Sections 6.14 and 6.15 of the LTP detail the dose modeling for the 973-foot elevation west wall and stressing gallery, respectively. The dose models in Section 6 of the LTP Revision 2 consider potential exposure pathways including residing at the site, eating crops grown at the site, using groundwater as a source of potable water, and excavation of the basement area of the Auxiliary Building and the Containment Building. OPPD demonstrated that the revised dose models result in expected dose for the average member of the critical group would remain well below the regulatory limit for unrestricted release of 0.25 mSv (25 mrem) in 10 CFR 20.1402. Additionally, the residual radioactivity in the Auxiliary Building basement and the Containment Building would be reduced to levels that are ALARA before factoring in the reduction in releases due to grouting. The NRC staff reviewed the model parameters and conclusions in more detail in the accompanying SER for this review.
The revised DCGLs are based on revised assumptions to reduce conservatism due to the challenges of meeting FSS requirements with the trenches in the Auxiliary Building basement concrete slab. The DCGLs for soil and concrete structures less than 3 m (9.8 ft) deep remain unchanged from the previously approved LTP values. For soils and concrete structures deeper than 3m (9.8 ft), the dose model parameters were changed to an Industrial Use scenario to apply a less conservative, but still reasonably bounding, scenario to calculate maximum dose after unrestricted site release. The DCGLs were calculated to result in the same final dose assessment as the initial LTP, thus resulting in no change to the potential dose to an average member of the critical group public after unrestricted release of the site.
3-19 If the final site survey measurements show that the remaining radionuclide concentrations are above the values set forth in the Memorandum of Understanding that the NRC signed with the EPA, then the NRC will engage in Level 2 consultation with the EPA to identify and resolve any remaining issues (NRC 2023a).
The NRC staff expects no impact associated with public and occupational dose beyond those discussed in the GEIS and 2023 LTP EA Section 3.10. Because of OPPDs implementation of the Radiological Groundwater Protection Plan, Radiological Environmental Monitoring Plan, and ALARA goals to ensure public protection as discussed above, the NRC staff conclude that the proposed action would have no significant impact on public and occupational radiological health and safety.
3.6.3 Non-radiological Impacts The non-radiological impacts of the proposed action include the use of heavy machinery, the generation of fugitive dust, and other hazards typical of a construction site of this size.
The proposed action does not include land outside of the site boundary and is limited to the Auxiliary Building, the Containment Building, and soil directly adjacent to the buildings. There are no new impacts on non-radiological health from the proposed action that are beyond the scope of those considered in the 2023 LTP EA and decommissioning GEIS (NRC 2023; NRC 2002). In the GEIS Section 4.3.10.4, the NRC concluded that potential impacts on occupational issues (e.g., non-radiological health and safety) are SMALL. Therefore, the NRC staff conclude the proposed action is bound by previous reviews and has no significant impact on non-radiological public or occupational health.
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AGENCIES AND PERSONS CONSULTED 4.1 National Historic Preservation Act The NRCs approval of the proposed action does not have the potential to cause effects to historic properties, assuming such properties were present. Therefore, pursuant to 36 CFR 800.3(a)(1), the NRC has no further National Historic Preservation Act Section 106 obligations.
However, on August 18, 2025, the NRC staff provided a courtesy copy of the draft EA to the Nebraska State Historic Preservation Officer (NRC 2025b). The Nebraska State Historic Society responded on August 25, 2025, concurring with the NRC staffs determination of no historic properties affected (Ne SHPO 2025) 4.2 Endangered Species Act The NRC must consider the effects of its actions on ecological resources protected under several Federal statues and must consult with the FWS or the National Oceanic and Atmospheric Administration, as appropriate, prior to acting in cases where an agency may affect those resources. The ESA of 1973, as amended (16 U.S.C. § 1531 et seq.) provides a program for the conservation of endangered and threatened plants and animals (collectively, listed species) and the habitats in which they are found. The FWS and NMFS are the lead Federal agencies for implementing the ESA, and these agencies determine species that warrant listing.
The NRC staff conducted a search of federally listed species and critical habitats that have the potential to occur in the action area by using the FWS IPaC. Three listed species and three proposed species for listing have the potential to occur within the vicinity of the action area:
northern long-eared bat, piping plover, pallid sturgeon, monarch butterfly, western regal fritillary, and the Suckleys cuckoo bumble bee.
The NRC staff found that there is no increase or decrease of stressor exposure as a result of the proposed action and that potential impacts to species are part of the environmental baseline (50 CFR 402.02) resulting from the LTP Federal action. Accordingly, the NRC staff concludes that the proposed license amendment would have no effect on federally listed and proposed species for listing.
Additionally, the NRC staff analyzed the potential impacts of the full site decommissioning activities listed in the 2023 LTP EA for three proposed species for listing (NRC 2023). The monarch butterfly, western regal fritillary, and Suckleys cuckoo bumble bee previously were not analyzed for potential impacts resulting from the LTP full site decommissioning action.
Accordingly, the NRC staff found that full site decommissioning activities may affect, not likely to adversely affect the monarch butterfly and western regal fritillary and would have no effect on the Suckleys cuckoo bumble bee. Because these three species are proposed for Federal listing, the ESA does not require the NRC to consult with or receive concurrence from the FWS regarding these species as long as continued existence of the species is not jeopardized. The NRC staff considers its obligations under ESA Section 7 to be complete. By letter dated August 7, 2025, the NRC staff requested conference concurrence on the NLAA determination for the monarch butterfly and Western regal fritillary (NRC 2025a). FWS responded by letter dated September 25, 2025, concurring with the NRC staffs determination (FWS 2025h)
4-2 4.3 State Review On August 15, 2025, the NRC submitted the draft EA to the Nebraska Department of Health and Human Services and the Nebraska Department of Water, Energy, and the Environment for their review and comment (NRC 2025c). The Nebraska Department of Water, Energy, and the Environment responded on September 22, 2025, providing additional details on the State of Nebraskas applicable regulations for air quality, stormwater, geological services, water quality, remediation, and waste management (NDWEE 2025). The state requested clarification on the grouting used at the site. The NRC staff provided additional information on the grout source and method of placement to the state on November 24, 2025 (NRC 2025d).
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CONCLUSION AND FINDING OF NO SIGNIFICANT IMPACT Based on its review of the proposed action, in accordance with the requirements of 10 CFR 51, the NRC staff has determined that the license amendment of the 10 CFR 50 License for FCS, Unit No. 1., authorizing the proposed alterations of end state conditions at FCS, will not significantly affect the quality of the human environment. No significant changes in OPPDs authorized operations for the FCS were requested as part of the license amendment application. Approval of the proposed action would not result in any new construction or expansion of the existing FCS footprint beyond that previously approved. The proposed action does not increase the expected amount of liquid or gaseous effluent previously approved in the LTP.
No significant radiological or non-radiological impacts are expected from the proposed action.
Occupational dose estimates associated with the proposed action and continued decommissioning of the FCS are expected to be at ALARA levels and within the limits of 10 CFR 20.1201 and 10 CFR 20.1402. Therefore, the NRC staff has determined that pursuant to 10 CFR 51.31, preparation of an environmental impact statement is not required for the proposed action, and pursuant to 10 CFR 51.32, a Finding of No Significant Impact is appropriate.
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LIST OF PREPARERS Isaac Johnston, PhD, Office of Nuclear Materials Safety and Safeguards, NRC Mitchell Dehmer, Office of Nuclear Materials Safety and Safeguards, NRC
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REFERENCES 10 CFR Part 20. Code of Federal Regulations, Title 10, Energy, Part 20, Standards for Protection Against Radiation.
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