2024-29564. Tennessee Valley Authority; Clinch River Nuclear Site; Exemption

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Nuclear Regulatory Commission

1. [Docket No. 99902056; NRC-2024-0146]

AGENCY:

Nuclear Regulatory Commission.

ACTION:

Notice; issuance.

SUMMARY:

The U.S. Nuclear Regulatory Commission (NRC) has issued an exemption in response to a request dated November 30, 2023, from Tennessee Valley Authority for approval to conduct certain excavation support activities prior to the issuance of a construction permit application for the Clinch River Nuclear Site.

DATES:

The exemption was issued on December 10, 2024.

ADDRESSES:

Please refer to Docket ID NRC-2024-0146 when contacting the NRC about the availability of information regarding this document. You may obtain publicly available information related to this document using any of the following methods:

• Federal Rulemaking website: Go to https://www.regulations.gov and search for Docket ID NRC-2024-0146. Address questions about Docket IDs in Regulations.gov to Stacy Schumann; telephone: [phone]; email: [e-mail]. For technical questions, contact the individual listed in the FOR FURTHER INFORMATION CONTACT section of this document.
• NRC's Agencywide Documents Access and Management System (ADAMS): You may obtain publicly available documents online in the ADAMS Public Documents collection at https://www.nrc.gov/​reading-rm/​adams.html. To begin the search, select “Begin Web-based ADAMS Search.” For problems with ADAMS, please contact the NRC's Public Document Room (PDR) reference staff at 1-800-397-4209, at 301-415-4737, or by email to [e-mail]. The ADAMS accession number for each document referenced (if it is available in ADAMS) is provided the first time that it is mentioned in this document.
• NRC's PDR: The PDR, where you may examine and order copies of publicly available documents, is open by appointment. To make an appointment to visit the PDR, please send an email to [e-mail] or call 1-800-397-4209 or 301-415-4737, between 8 a.m. and 4 p.m. eastern time (ET), Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Allen Fetter, Office of Nuclear Reactor Regulation, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, telephone: [phone]; email: [e-mail].

SUPPLEMENTARY INFORMATION:

The text of the exemption is attached.

Dated: December 11, 2024.

( print page 101644)

For the Nuclear Regulatory Commission.

Allen Fetter,

Senior Project Manager, Licensing and Regulatory Infrastructure Branch, Division of New and Renewed Licenses, Office of Nuclear Reactor Regulation.

Attachment—Exemption

NUCLEAR REGULATORY COMMISSION

[Docket No. 99902056; NRC-2024-0146]

Tennessee Valley Authority Clinch River Nuclear Site; Exemption

1.0 Background

By letter dated November 30, 2023 (Agency wide Documents Access and Management System (ADAMS) Accession Number ML23335A100), Tennessee Valley Authority (TVA) submitted a request for an exemption from Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Section 50.10(c). The U.S. Nuclear Regulatory Commission (NRC or the NRC staff) has reviewed this request for an exemption, pursuant to 10 CFR 50.12, as it relates to TVA's request to conduct certain excavation support activities that are otherwise prohibited by 10 CFR 50.10(c) prior to the issuance of a construction permit (CP) application for the Clinch River Nuclear (CRN) Site, which is expected to be submitted for NRC review in 2025. This exemption would authorize TVA to conduct certain excavation activities at the CRN Site and to abandon in place the initial ground support system, which may include rock bolts, wire mesh, horizontal gravity drains, and pressurized grout.

Granting this exemption does not obviate the need for the applicant to meet the Permit Conditions or Action Items in the Early Site Permit for the CRN Site. Granting this exemption would also not constitute a commitment by the NRC to issue a CP for the CRN Site. TVA would conduct these excavation activities assuming the risk that its CP application may later be denied.

2.0 Request/action

The proposed action, as described in TVA's request for an exemption from 10 CFR 50.10(c), would allow TVA to conduct certain excavation activities which would otherwise be prohibited prior to issuance of a CP. This exemption would authorize TVA to abandon in place the initial ground support system for conducting certain excavation activities at the CRN Site. According to TVA, the initial ground support system for the reactor will serve no function in the completed reactor building (RB). As such, TVA's interpretation of NRC regulations is that this proposed construction does not have a reasonable nexus to nuclear safety or security and therefore does not meet the definition of “construction,” as defined in 10 CFR 50.10(a). However, NRC regulations clearly require that the activities described by TVA that involve the placement/installation of permanent parts of the overall facility are considered “construction” as defined in 10 CFR 50.10(a) (see 72 FR 57416, pp. 57416-57447). Therefore, an exemption from the requirements of 10 CFR 50.10(c) is needed for TVA's request.

TVA states that the initial ground support system includes the following activities:

• rock bolts to secure unstable rock blocks, as required;
• wire mesh and a non-structural sprayed-gunite lining to stabilize and protect exposed rock walls;
• horizontal gravity drains to manage groundwater, as required;
• pressurized grout to seal any notable areas of water entry, as required.

TVA also states that additional components of the initial ground support system, depending on the excavation method selected, may include items such as the following or similar:

• steel soldier beams with timber lagging through the soil overburden and weathered rock;
• rock bolts to secure soldier beams; and
• reinforced concrete compression rings to provide lateral support for the soldier beams.

As construction of the permanent plant structures proceeds, TVA states that the initial ground support system is infeasible to remove and would be abandoned in place. After abandonment, the initial ground support system would have no function in the completed RB construction.

In its exemption request, TVA stated that the proposed exemption is needed to allow excavation to proceed in advance of the issuance of the CP for the CRN Site. The initial ground support system would allow TVA to complete certain on-site activities in parallel with the licensing process, so that it can begin construction promptly upon issuance of the CP. The on-site activities will ensure worker safety as the excavation activities proceed.

3.0 Discussion

Pursuant to 10 CFR 50.12(a), the Commission may, upon application by any interested person or upon its own initiative, grant exemptions from the requirements of 10 CFR part 50 when (1) the exemption is authorized by law, will not present an undue risk to public health or safety, and is consistent with the common defense and security; and

(2) when special circumstances are present.

Under 10 CFR 50.12(b), to issue an exemption from 10 CFR 50.10 that would allow for the conduct of activities prior to the issuance of a construction permit, the Commission may grant such an exemption upon considering and balancing the following factors: (1) whether conduct of the proposed activities will give rise to a significant adverse impact on the environment and the nature and extent of such impact, if any; (2) whether redress of any adverse environment impact from conduct of the proposed activities can reasonably be effected should such redress be necessary; (3) whether conduct of the proposed activities would foreclose subsequent adoption of alternatives; and (4) the effect of delay in conducting such activities on the public interest, including the power needs to be used by the proposed facility, the availability of alternative sources, if any, to meet those needs on a timely basis and delay costs to the applicant and to consumers.

10 CFR 50.12(a)(1): Authorized by Law

This exemption would authorize the applicant to abandon in place the initial ground support system prior to issuance of a CP for the CRN Site. Granting of the applicant's proposed exemption will not otherwise result in a violation of the Atomic Energy Act of 1954, as amended, or the Commission's regulations. Therefore, the NRC staff finds that the exemption is authorized by law.

10 CFR 50.12(a)(1): No Undue Risk to Public Health and Safety

In determining that the proposed exemption would not pose an undue risk to public health and safety and that the applicant could be exempted from the prohibition on construction for the limited purpose of the installation and subsequent abandonment of the initial ground support system to ensure worker safety during the onsite excavation activities, the NRC staff evaluated the safety aspects of the exemption in the areas of Geology and Geotechnical Engineering because the excavation activities described by TVA are specific to those technical review areas.

Geology

The NRC staff reviewed geologic information in the CRN Site exemption request using the criteria in NUREG-0800, Standard Review Plan (SRP), Chapter 2.5.1, “Geological Characterization Information” and Chapter 2.5.3, “Surface Deformation.” ( print page 101645) The related excavation support activities requested in the exemption request would result in covering the excavation floor and walls; therefore, the purpose of staff's review was to determine whether the proposed activities to be completed under the exemption request would affect TVA's ability to meet the terms of the Clinch River Site early site permit (ESP-006), issued on December 19, 2019 (ML19352D868), with respect to geologic mapping of the foundation-bearing rock unit, to include the floor and walls of the open excavation. ESP-006 included permit condition #3, which requires TVA to perform detailed geologic mapping of excavations for safety-related engineered structures, examine and evaluate geologic features discovered in those excavations, and notify the staff once excavations for safety related structures are open for examination. The geologic mapping of the foundation-bearing unit in the open excavation required under permit condition #3 would not be implementable once the excavations support activities proposed in this exemption request are complete. Therefore, the staff considered how this permit condition can be met under this exemption request.

For this exemption request, staff planned and conducted a virtual regulatory audit between March 5, 2024, and May 3, 2024. Audit information needs were provided to TVA in an audit plan (ML24060A069) and through a supplemental additional information request from the NRC staff (ML24075A322).

During the virtual audit (see NRC Audit Summary Report, ML24145A107), the applicant summarized how it would perform the geologic mapping of the excavation as required in permit condition #3 of ESP-006 (Early Site Permit for the Clinch River Nuclear Site, ML1935D868). The applicant clarified that during the excavation activities requested in the exemption, geologic mapping will be conducted for each lift before the excavation walls are covered by any stabilization methods and the subsequent lift commences. The applicant further clarified that the data obtained from mapping each lift will be available as it is recovered during the excavation activities.

The staff reviewed the applicant's response to audit questions about how the applicant intends to perform the necessary geologic mapping to obtain the required information to address permit condition #3 in ESP-006 related to geologic mapping of the excavation. The staff concludes that because the applicant will perform the geologic mapping as the requested early excavation activities proceed and that information will be made available before the subsequent lifts commence, these early excavation activities will not affect the satisfactory addressing of permit condition #3 in ESP-006. Because the applicant will obtain the information necessary to meet the terms of the geologic mapping permit condition to ensure the foundation-bearing geologic unit meets the criteria reviewed and approved in the ESP, the staff concludes that there is no undue risk to public health and safety in approving this exemption request.

Geotechnical Engineering

The NRC staff evaluated geotechnical engineering information in the CRN Site exemption request using the criteria in NUREG-0800, Standard Review Plan (SRP), Chapter 2.5.4, “Stability of Subsurface Materials and Foundations”. The guidance that applies to aspects of the early excavation exemption request includes specific criteria from:

1. RG 1.132, “Site Investigations for Foundations of Nuclear Power Plants.”

2. RG 1.138 “Laboratory Investigations of Soils and Rocks for Engineering Analysis and Design of Nuclear Power Plants.”

For this exemption request, staff conducted a virtual regulatory audit between March 5, 2024, and May 3, 2024. Audit information needs were provided to TVA in an audit plan (ML24060A069) and through a supplemental additional information request from the NRC staff (ML24075A322). In response to the staff's information needs, the applicant provided a summary of disposition regarding Early Site Permit (ESP) permit condition #4 that relate to geotechnical engineering (Audit Summary Report ML24145A107).

ESP-006 permit condition #4 requires TVA to remove the material above El. 225.9 m (741 ft) NAVD88 in the areas where safety-related structures will be located to minimize adverse effects of discontinuities, weathered and shear-fracture sones, and karst features on the stability of the subsurface materials and foundations. Permit condition #4 also requires TVA to perform additional investigations at the excavation level to identify any potential geologic features that may adversely impact the stability of subsurface materials and foundations. The staff considered how this permit condition can be met under this exemption request.

The applicant intends to address the ESP-006 permit condition #4 to ensure that compliance with relevant terms and conditions of the early site permit will not be affected by the excavation performed pursuant to the exemption request. Specifically, the applicant stated that the proposed BWRX-300 RB foundation elevation is located below the required permit condition excavation elevation and the applicant will remove the material above Elevation 225.9m (741 ft) NAVD 88 in the RB area as part of the early excavation. In addition, the applicant stated that it will provide details of its supplemental site investigation program at the center and perimeter of the RB shaft as part of a future CP application. The applicant will perform additional investigations in accordance with RG 1.132 at the foundation level if any significant anomalous issues are discovered while performing the excavation and geologic mapping of the RB shaft. In addition, the applicant stated that the activities related to this early excavation exemption request should not affect addressing the permit conditions and CP or COL action items in a future application.

The staff reviewed the applicant's summary of dispositions clarifying how the applicant intends to address permit condition #4. Given that the applicant will gather all necessary data during the activities that involve this early excavation exemption request and will utilize it to address regulatory requirements in a subsequent application, the staff finds that this early excavation activities would not pose an undue risk to public health and safety and would not affect addressing permit condition #4 in ESP-006.

The applicant states that it plans to use a combination of stabilization methods as the initial ground support system for erosion control to ensure the safety of their employees and to facilitate construction activities. The applicant stated that the initial ground support system serves no function in the completed RB construction, but that its components are not feasible to remove and will remain in place. The applicant indicated that the initial ground support system is expected to be composed of rock bolts, wire mesh and non-structural sprayed-gunite, horizontal gravity drains, and pressurized grout. Depending on the final excavation method, the applicant stated that the initial ground support system could also include steel soldier beams and reinforced concrete compression rings. In addition, the applicant stated that no part of the RB walls or foundations will be installed before a CP is approved.

During the virtual audit, the applicant provided a conceptual excavation plan describing its planning efforts for the excavation, such as site preparation ( print page 101646) activities, installation of field instrumentation, methods of excavation, construction of temporary crane pads, temporary dewatering systems, a finite element model to assess the impact of dewatering and construction stages on excavation support and foundation, geologic mapping, and stabilization methods. In a CP application, the applicant plans to quantify and incorporate the impacts of rock excavation on the mechanical properties in a numerical simulation for the assessment of the foundations. The applicant stated that it will also develop an instrumentation and monitoring program consistent with Chapter 3.4 of the approved Licensing Topical Report (LTR) NEDO-33914-A to meet regulatory requirements. The applicant stated that it plans to monitor lateral and vertical displacement during excavation and construction. In addition, during the excavation the applicant plans to monitor slope movement, heave, changes in pore pressures and dewatering, and settlement.

During the virtual audit, the applicant clarified that neither the annulus filled with lean concrete nor the steel plate composite RB walls, as shown in Figure 1 “Conceptual Layout of Excavation utilizing Soldier Beams and Compression Rings” of the exemption request, are considered part of this early excavation exemption request. Furthermore, the applicant stated that the emplacement of the annulus will occur after CP issuance and that it will be approximately 5 feet wide around the RB shaft, thus separating the RB from the excavation and any abandoned initial ground support system.

The staff reviewed the description of the design methodology for the BWRX-300 as approved in the LTR NEDO-33914-A Section 5.0, Revision 1, and notes that the BWRX-300 design does not rely on the resistance provided by initial ground support system. However, the staff noted that in accordance with the design methodology, the applicant must consider the effects of the initial ground support system in its seismic sensitivity analysis for a future application. Therefore, in the event that, during early excavation, the applicant needs additional retaining measures as part of the initial ground support system, the potential effects of all retaining measures on the RB structure shall be included as part of the SSI sensitivity analysis in a future CP licensing application.

Based on the foregoing and in accordance with 10 CFR 50.12(a)(1), the staff finds that the proposed exemption that would permit the installation of an initial ground support system for erosion control measures and subsequently abandon it in place prior to the issuance of a CP, would not pose an undue risk to public health and safety because (1) the applicant will gather all necessary data during the activities that involve this early excavation exemption request and will utilize it to address regulatory requirements and relevant ESP-006 permit conditions; (2) the applicant will include demonstration of the structural integrity of the RB prior to the presence or use of radiological materials on the CRN Site to provide adequate protection of the public health and safety; (3) the initial ground support system will not perform a support function of the RB since the BWRX-300 design does not rely on the resistance provided by initial ground support system; (4) the annulus filled with lean concrete will separate the RB from the excavation and any abandoned initial ground support system, and (5) the applicant will consider the potential effects of all retaining measures (including the initial ground support system) on the RB structure as part of the Soil-Structure Interaction (SSI) sensitivity analysis in a future licensing application.

10 CFR 50.12(a): Consistent With Common Defense and Security

The proposed exemption would allow the applicant to pursue excavation of the CRN Site and install the initial ground support system to ensure worker safety during excavation activities. Because the exemption would allow for early excavation and excavation wall support only, the exemption has no relation to defense and security issues. Therefore, the common defense and security is not impacted by this exemption.

10 CFR 50.12(a)(2): Special Circumstances

Special circumstances, in accordance with 10 CFR 50.12(a)(2)(iii), are present whenever “compliance [with a regulation] would result in undue hardship or other costs that are significantly in excess of those contemplated when the regulation was adopted, or that are significantly in excess of those incurred by others similarly situated”. The applicant cited undue hardship or other costs as a special circumstance that would warrant granting this exemption. The applicant stated that removal of the initial ground support system, which would make the system temporary and therefore not “construction,” as defined in 10 CFR 50.10(a), is infeasible because the initial ground support system is necessary for personnel safety and removal of these items could potentially destabilize the rock walls. The applicant stated that the delay in excavation for the RB at the CRN Site until receipt of the CP will result in substantial costs due to delays to the construction schedule and commercial operation of CRN Unit 1, hence delaying the deployment of carbon-free electricity generation.

10 CFR 50.12(b): Environmental Considerations

The applicant has also provided information on this proposed action pursuant to 10 CFR 50.12(b) which states any person may request an exemption permitting the conduct of activities prior to the issuance of the construction permit prohibited by 10 CFR 50.10. The NRC staff considered the balancing factors for granting such an exemption and its evaluation is documented in the environmental assessment (EA) that is attached to this package. The ADAMS Accession number for this associated EA is ML24310A024. The staff made a finding of no significant impact.

4.0 Conclusion

Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12(a) and 10 CFR 50.12 (b), the exemption is authorized by law, will not present an undue risk to the public health and safety, and is consistent with the common defense and security. Also, special circumstances are present.

Therefore, the Commission hereby grants Tennessee Valley Authority an exemption from the requirements in 10 CFR 50.10(c) for the installation of initial ground support system prior to and during excavation activities.

Pursuant to 10 CFR 51.32, the Commission has determined that the granting of this exemption will not have a significant effect on the quality of the human environment (89 FR 90319).

This exemption is effective upon issuance.

Dated at Rockville, Maryland, this 10th day of December 2024.

For the Commission

/RA/

Michele Sampson,

Director Division of New and Renewed Licenses Office of New Reactors.