Exelon Generation Company, LLC Dresden Independent Spent Fuel Storage Installation Issuance of Environmental Assessment and Finding of No Significant Impact

The U.S. Nuclear Regulatory Commission (NRC or Commission) is considering issuance of an exemption, pursuant to 10 CFR 72.7, from the provisions of 10 CFR 72.212(a)(2), 72.212(b)(2)(i), and 72.214 to Exelon Generation Company, LLC (EGC). The requested exemption would allow EGC to deviate from the requirements of Certificate of Compliance 1008 (the Certificate), Appendix B, Items 1.4.6.a, 1.4.6.b and 1.4.6.d and place HI-STAR 100 Cask Systems, loaded with spent nuclear fuel, on a concrete storage pad with a concrete thickness of less than or equal to 28 inches, concrete compressive strength of less than or equal to 6,000 psi at 28 days, and soil effective modulus of elasticity of less than or equal to 16,000 psi at the Dresden Nuclear Power Station (Dresden) Independent Spent Fuel Storage Installation (ISFSI).

Environmental Assessment (EA)

Identification of Proposed Action

By letter dated January 11, 2001, EGC requested an exemption from the requirements of 10 CFR 72.212(a)(2), 72.212(b)(2)(i), and 72.214 to deviate from the requirements of Certificate of Compliance 1008, Appendix B, Items 1.4.6.a, 1.4.6.b and 1.4.6.d. EGC is a general licensee, authorized by NRC to use spent fuel storage casks approved under 10 CFR Part 72, Subpart K.

EGC plans to use the HI-STAR 100 Cask System to store spent nuclear fuel, generated at the Dresden Nuclear Power Station, at an ISFSI located in Morris, Illinois, on the Dresden Nuclear Power Station site. The Dresden ISFSI has been constructed for interim dry storage of spent nuclear fuel.

By exempting EGC from 10 CFR 72.212(a)(2), 72.212(b)(2)(i), and 72.214, EGC will be authorized to place loaded HI-STAR 100 Casks Systems on cask storage pads that include the following characteristics:

(1) Concrete Thickness: ≤ 28 inches

(2) Concrete Compressive Strength: ≤ 6,000 psi at 28 days

(3) Soil Effective Modulus of Elasticity: ≤ 16,000 psi

The storage pad characteristics specified above would be in lieu of those specified in Certificate of Compliance 1008, Appendix B, Items 1.4.6.a, 1.4.6.b, and 1.4.6.d, respectively. The proposed action before the Commission is whether to grant this exemption under 10 CFR 72.7.

On August 4, 2000, the cask designer, Holtec International (Holtec), submitted to NRC an application to amend Certificate of Compliance 1008. The requested amendment includes revision to the storage pad specifications in Item1.4.6 in Appendix B to the Certificate and requests approval of a second set of cask pad parameters. Item 1.4.6.a requires a concrete thickness of less than or equal to 36 inches; the analysis performed by Holtec demonstrates that this requirement can be revised to specify a concrete thickness of less than or equal to 28 inches. Item 1.4.6.b requires a concrete compressive strength of less than or equal to 4,200 psi at 28 days; the analysis performed by Holtec demonstrates that this requirement can be revised to specify a concrete compressive strength of less than or equal to 6,000 psi at 28 days. Item 1.4.6.d includes the requirement that the soil effective modulus of elasticity be less than or equal to 28,000 psi; the analysis performed by Holtec demonstrates that this requirement can be revised to specify that the soil effective modulus of elasticity be less than or equal to 16,000 psi. The NRC staff has reviewed the application and determined that placement of HI-STAR 100 Cask Systems on storage pads with the revised characteristics would have minimal impact on the design basis and would not be inimical to public health and safety.

Need for the Proposed Action

There are a number of Dresden Unit 1 spent fuel assemblies in the Dresden Unit 2 spent fuel pool. To maintain full core offload capability in the Dresden Unit 2 spent fuel pool once new fuel arrives in the Summer of 2001, EGC needs to begin loading spent fuel into storage casks in Spring of 2001. Unless the exemption is granted or the Certificate is amended, the storage pads at the Dresden ISFSI will not be in full conformance with the Certificate. Because the 10 CFR part 72 rulemaking to amend the Certificate will not be completed prior to the date that EGC plans to begin loading HI-STAR 100 Cask Systems, the NRC is granting this exemption based on the staff's technical review of information submitted by EGC and Holtec.

Environmental Impacts of the Proposed Action

The potential environmental impact of using the HI-STAR 100 Cask System was initially presented in the Environmental Assessment (EA) for the Final Rule to add the HI-STAR 100 Cask System to the list of approved spent fuel storage casks in 10 CFR 72.214 (64 FR 171, 09/03/99). Furthermore, each general licensee must assess the environmental impacts of the specific ISFSI in accordance with the requirements of 10 CFR 72.212(b)(2). This section also requires the general licensee to perform written evaluations to demonstrate compliance with the environmental requirements of 10 CFR 72.104, “Criteria for radioactive materials in effluents and direct radiation from an ISFSI or MRS [Monitored Retrievable Storage Installation].”

The HI-STAR 100 Cask System is designed to mitigate the effects of design basis accidents that could occur during storage. Design basis accidents account for human-induced events and the most severe natural phenomena reported for the site and surrounding area. Postulated accidents analyzed for an ISFSI include tornado winds and tornado generated missiles, design basis earthquake, design basis flood, accidental cask drop, lightning effects, fire, explosions, and other incidents.

The HI-STAR 100 Cask System consists of a stainless steel multi-purpose canister and a steel overpack. The welded MPC provides confinement and criticality control for the storage and transfer of spent nuclear fuel. The overpack provides radiation shielding and structural protection of the MPC during storage and handling operations. Special design feature requirements for the cask and for the site are specified in Certificate of Compliance 1008, Appendix B. These include the storage pad design characteristics.

Considering the specific cask and site design requirements for each accident condition, the design of the cask would prevent loss of containment, shielding, and criticality control. Without the loss of either containment, shielding, or criticality control, the risk to public health and safety is not compromised.

The staff performed a safety evaluation of the proposed exemption and the Certificate amendment. The HI-STAR amendment requests a revision to Item 1.4.6 of Appendix B to the Certificate of Compliance (CoC), which defines some of the design requirements for cask pad. The CoC amendment requests specific approval for an additional set of cask pad parameters. The exemption requests authorization to utilize the additional set of cask pad parameters presented in the CoC amendment.

The staff found that the proposed exemption is consistent with the cask drop and tipover analyses presented in the revised Safety Analyses Report for the HI-STAR 100 Cask System and do not reduce the safety margin. In addition, the staff has determined that placement of loaded HI-STAR 100 Cask Systems on storage pads with a (1) concrete thickness of less than or equal to 28 inches, (2) concrete compressive strength of less than or equal to 6,000 psi at 28 days, and (3) soil effective modulus of elasticity less than or equal to 16,000 psi does not pose any increased risk to public health and safety. Furthermore, the proposed action now under consideration would not change the potential environmental effects assessed in the initial rulemaking (64 FR 171, 09/03/99).

Therefore, the staff has determined that there is no reduction in the safety margin nor significant environmental impacts as a result of placing loaded HI-STAR 100 Cask Systems on storage pads with a concrete thickness of less than or equal to 28 inches, concrete compressive strength of less than or equal to 6,000 psi at 28 days, and soil effective modulus of elasticity less than or equal to 16,000 psi.

Alternative to the Proposed Action

Since there is no significant environmental impact associated with the proposed action, alternatives with equal or greater environmental impact are not evaluated. The alternative to the proposed action would be to deny approval of the exemption. Denial of the exemption request will have the same environmental impact.

Agencies and Persons Consulted

On February 9, 2001, Mr. F. Niziolek, Reactor Safety Section Head, Illinois Department of Nuclear Safety, was contacted about the Environmental Assessment for the proposed action and had no comments.

Finding of No Significant Impact

The environmental impacts of the proposed action have been reviewed in accordance with the requirements set forth in 10 CFR part 51. Based upon the foregoing EA, the Commission finds that the proposed action of granting an exemption from 10 CFR 72.212(a)(2), 72.212(b)(2)(i), and 72.214 so that EGC may place loaded HI-STAR 100 Cask Systems on concrete storage pads with a concrete thickness of less than or equal to 28 inches, concrete compressive strength of less than or equal to 6,000 psi at 28 days, and soil effective modulus of elasticity less than or equal to 16,000 psi at the Dresden ISFSI will not significantly impact the quality of the human environment. Accordingly, the Commission has determined not to prepare an environmental impact statement for the proposed exemption.

The request for exemption was docketed under 10 CFR part 72, Docket 72-37. For further details with respect to this action, see the exemption request dated January 11, 2001, which is available for public inspection at the Commission's Public Document Room, One White Flint North Building, 11555 Rockville Pike, Rockville, Maryland 20852, or from the publicly available records component of NRC's Agencywide Document Access and Management System (ADAMS). ADAMS is accessible from the NRC web site at http://www.nrc.gov/NRC/ADAMS/index.html (the Public Electronic Reading Room).