Commonwealth Edison Company, Dresden Nuclear Power Station, Unit 1; Issuance of Environmental Assessment and Finding of No Significant Impact Regarding the Proposed Exemption From Certain Requirements of 10 CFR Part 72

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 Commonwealth Edison Company (ComEd). The requested exemption would allow ComEd to deviate from the requirements of Certificate of Compliance 1008 (the Certificate), Appendix B, Items 1.4.6.b and 1.4.6.c and place HI-STAR 100 Cask Systems, loaded with spent nuclear fuel, on a concrete storage pad with a concrete compressive strength of less than or equal to 4,200 psi at 28 days and concrete reinforcement of 60 ksi yield strength ASTM material at the Dresden Nuclear Power Station (Dresden) Independent Spent Fuel Storage Installation (ISFSI).

Environmental Assessment (EA)

Identification of Proposed Action: By letter dated April 24, 2000, ComEd 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.b and 1.4.6.c. ComEd is a general licensee, authorized by NRC to use spent fuel storage casks approved under 10 CFR Part 72, Subpart K.

ComEd plans to use the HI-STAR 100 Cask System to store spent nuclear fuel, generated at Dresden Unit 1, 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 ComEd from 10 CFR 72.212(a)(2), 72.212(b)(2)(i), and 72.214, ComEd will be authorized to place loaded HI-STAR 100 Casks Systems on cask storage pads that include the following characteristics:

(1) Compressive Strength: ≤ 4,200 psi at 28 days.

(2) Reinforcement top and bottom (both directions): Reinforcement area and spacing determined by analysis Reinforcement shall be 60 ksi yield strength ASTM material.

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

On November 24, 1999, as supplemented February 4, 18 and 28, and March 2, 16 and 31, 2000, the cask designer, Holtec International (Holtec), submitted to NRC an application to amend Certificate of Compliance 1008. The requested amendment includes revisions to the storage pad specifications in Items 1.4.6.b and 1.4.6.c in Appendix B to the Certificate. Item 1.4.6.b requires a concrete compressive strength of less than or equal to 4,200 psi; Holtec is requesting that this requirement be revised to specify a concrete compressive strength of less than or equal to 4,200 psi at 28 days. Item 1.4.6.c includes the requirement that the reinforcement yield strength be less than or equal to 60,000 psi; Holtec is requesting that this requirement be revised to specify that reinforcement shall be 60 ksi yield strength ASTM material. 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 for the Fall 2001 refueling outage, ComEd needs to begin loading Dresden Unit 1 spent fuel into storage casks in June 2000. 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 ComEd 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 ComEd 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 proposed exemption and Certificate amendment request authorization to use storage pads with a concrete compressive strength of less than or equal to 4,200 psi at 28 days. This is a deviation from the pad requirement currently given in Certificate of Compliance 1008, Appendix B, Item 1.4.6.b, which does not specify a time frame for when the concrete compressive strength is to be measured. A time frame is necessary because concrete typically gets stronger as it ages. Measuring the concrete compressive strength at 28 days is standard practice. Thus, specifying a time frame of 28 days provides clarification and ensures that full compliance with the Certificate can be achieved.

The proposed exemption and Certificate amendment also request authorization to use storage pads with concrete reinforcement made of 60 ksi yield strength ASTM material. This is a deviation from the storage pad requirements currently given in Certificate of Compliance 1008, Appendix B, Item 1.4.6.c, which specifies a reinforcement yield strength of less than or equal to 60,000 psi. The standard practice for reinforcing bar specification and procurement is by the grade of the material. Reinforcing bar specified as Grade 60 has a nominal yield strength of 60 ksi and may in fact exceed 60 ksi. Thus, specifying the concrete reinforcement as “60 ksi yield strength ASTM material” takes into account that the yield strength is a nominal value and ensures that full compliance with the certificate can be achieved.

The staff found that the proposed exemption and Certificate amendment are consistent with the cask drop and tipover analyses presented in the 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 concrete compressive strength of less than or equal to 4,200 psi at 28 days and concrete reinforcement of 60 ksi yield strength ASTM material 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 compressive strength of less than or equal to 4,200 psi at 28 days and concrete reinforcement of 60 ksi yield strength ASTM material.

Alternative to the Proposed Action: Since there is no significant environmental impact associated with the proposed action, any 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 May 19, 2000, 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 ComEd may place loaded HI-STAR 100 Cask Systems on concrete storage pads with a concrete compressive strength of less than or equal to 4,200 psi at 28 days and concrete reinforcement of 60 ksi yield strength ASTM material 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.

For further details with respect to this exemption request, see the ComEd exemption request dated April 24, 2000, which is docketed under 10 CFR Part 72, Docket No. 72-37.

The exemption request is available for public inspection at the Commission's Public Document Room, 2120 L Street, NW, Washington, DC, 20555.