ENVIRONMENTAL ASSESSMENT FOR PROPOSED RULE ENTITLED, “STORAGE OF SPENT NUCLEAR FUEL USING THE HOLTEC HI-STORM 100U VERTICAL VENTILATED MODULE SYSTEM AT NUCLEAR POWER REACTOR SITES” DOCKET NO. 72-1014 HOLTEC INTERNATIONAL U.S. Nuclear Regulatory Commission Office of Federal and State Materials and Environmental Management Programs Division of Waste Management and Environmental Protection June 2009 1 TABLE OF CONTENTS 1.0 INTRODUCTION……………………………………………………………………………… 5 1.1 Background……………………………………………………………………………………. 5 1.2 Need for the Proposed Action…………………………………………………….….……… 6 1.3 Scope………………………………………………………………………………................. 6 1.4 Previous Environmental Assessments and Supporting Document……………….….…. 6 2.0 THE PROPOSED ACTION………………………………………………….……………..... 6 2.1 Locations of the Proposed Action…………………………………………………….…….. 7 2.2 Description of Proposed Underground Dry Cask Storage System……………………… 7 2.3 Planned Activities…………..……………………….……………………………….……… 10 2.3.1 Site Preparation….……………………………………………………….………. 10 2.3.2 Operation………………………………………………………………………….. 11 2.3.3 Decommissioning……………………………………………………………....... 12 2.4 Duration of the Proposed Action…………………………………………………..………. 13 3.0 ALTERNATIVES TO THE PROPOSED ACTION……………………………………..… 13 3.1 No Action Alternative……………………………………………………………………….. 13 4.0 AFFECTED ENVIRONMENT…………………………………………………………..….. 13 4.1 Licensed Commercial Nuclear Reactor Sites…………………………………………….. 14 4.2 Background and Reactor Site Radiological Characteristics….………………………….14 5.0 ENVIRONMENTAL IMPACTS OF THE PROPOSED ACTION………………………... 15 5.1 Non-radiological Impacts…………………………………………………………………….15 5.1.1 Construction Impacts……………………………………………………............. 15 5.1.2 Operational Impacts……………………………………………………………… 16 5.2 Radiological Impacts…………………………………………………………………………17 5.2.1 Normal Operations……………………………………………………………….. 17 5.2.2 Accidents………………………………………………………………………….. 17 5.3 Impacts of Decommissioning…………………………………………………....... 18 5.4 Cumulative Impacts……………………………………………………………………........ 18 6.0 MONITORING AND MITIGATION………………………………………………….……... 19 7.0 AGENCIES AND PERSONS CONSULTED………………………………………….….. 19 8.0 CONCLUSION……………………………………………………………………………..... 19 9.0 LIST OF PREPARERS……………………………………….…………………………….. 20 10.0 LIST OF REFERENCES………………………………………………………………….. 20 2 FIGURES Figure 1: Cut-Away View of the HI-STORM 100U VVM……………………………………… 8 Figure 2: Cut-Away View of HI-STORM 100U VVM loaded with MPC……………………... 9 Figure 3: HI-STORM 100U VVM ISFSI Array for 25 casks…………….…………………….10 3 ACRONYMS ALARA: As low as reasonably achievable CFR: Code of Federal Regulations EA: Environmental Assessment (prepared by the NRC) ER: Environmental Report (submitted by Holtec International) FONSI: Finding of No Significant Impact GTCC: Greater than Class C waste HI-STORM 100U: Holtec International’s subsurface HI-STORM100U vertical ventilated module system for spent nuclear fuel storage ISFSI: Independent Spent Fuel Storage Installation MPC: multi-purpose canister NCRP: National Council on Radiation Protection and Measurements NRC: U.S. Nuclear Regulatory Commission REMP: Radiological and Environmental Monitoring Program RFB: refueling building SAR: Safety Analysis Report (submitted by Holtec International) SER: Safety Evaluation Report (prepared by the NRC) 4 1.0 INTRODUCTION By letter dated April 27, 2007, as supplemented June 12 and July 14, 2008, January 16, 21, February 6, and April 6, 22, 2009, Holtec International (Holtec) submitted an application to the U.S. Nuclear Regulatory Commission (NRC) to amend Certificate of Compliance (CoC) No. 1014 for the HI-STORM 100 Dry Cask Storage System (License Amendment Request 1014-6, Revision 0). The amendment proposes to add an underground storage overpack that provides an alternative Vertical Ventilated Module (VVM) design to be used with the Holtec multi-purpose canisters (MPC) and the Hi-Trac transfer cask. This proposed design is the seventh in a series of HI-STORM 100 Dry Cask Storage Systems, for which specific safety and environmental reviews are required prior to the addition of a design to the list of approved spent fuel storage casks in 10 CFR 72.214. Under the requirements of 10 CFR 51.41, Holtec submitted an environmental report to NRC on June 2, 2008 as a reference document for evaluating the potential environmental impacts of this subsurface design. Holtec also provided supplemental information on December 19, 2008 in response to questions requesting additional information from the NRC staff. A holder of an NRC license for a power reactor under 10 CFR Part 50 or 10 CFR 52 may construct and operate an independent spent fuel storage installation (ISFSI) at that power reactor site under the general license provisions of 10 CFR Part 72. Once CoC 1014, Amendment 7 system is approved for listing under 10 CFR 72.214, holders of NRC licenses under 10 CFR 50 and 10 CFR 52 will have the option of deploying the system at a general license ISFSI. 1.1 Background The NRC licenses and regulates the interim storage of civilian spent nuclear fuel (SNF) in dry cask storage under 10 CFR 72. Interim dry storage of SNF by nuclear power plant operators is authorized by the Nuclear Waste Policy Act of 1982, as amended, until the issue of a disposition pathway (e.g., the siting, construction and operation of a permanent, deep geologic repository) is resolved and a plan implemented by the Federal Government. There are currently 55 licensed and operating ISFSIs at 51 sites around the United States. The footprint of most ISFSI storage pads at civilian nuclear reactors ranges from one-half acre to three acres in size, and requires additional land for buffer zones and security fencing; typically an additional one to two acres. Regarding the duration of interim storage, the Commission has determined that spent fuel can be stored safely and without significant environmental impact, in either wet storage or in wet storage followed by dry storage, for at least 100 years (55 FR 38511). The environmental impacts of interim storage of civilian SNF at ISFSIs have been evaluated in several previous NRC environmental reviews. These include NUREG-0575, “Final Generic Environmental Impact Statement (FGEIS) on Handling and Storage of Light Water Power Reactor Fuel” (US NRC, 1979); NUREG-1092, “Environmental Assessment for 10 CFR 72 Licensing Requirements for the Independent Storage of Spent Fuel and High-Level Radioactive Waste” (US NRC, 1984); and an environmental assessment (EA) for the proposed rule entitled “Storage of Spent Nuclear Fuel in NRC-Approved Storage Casks and Nuclear Power Reactor Sites” (US NRC, 1989). The latter EA provided the basis for allowing deployment of ISFSIs under general licenses at nuclear power reactor sites without the need for additional site- specific approvals, but it did not consider subsurface designs. As such, this EA is being done to evaluate the potential impacts of construction, operation and decommissioning of subsurface cask arrays installed at a reactor site under the 10 CFR Part 72 general license. 5 1.2 Need for the Proposed Action Holtec developed the subsurface HI-STORM 100U system to fill a potential market niche for nuclear power plant operators interested in utilizing a low-profile and more physically-hardened system for the interim storage of SNF. Utilities wishing to increase public confidence or address intervenor concerns regarding the security of interim on-site storage of SNF, would benefit from the availability of an underground system deployable under the general license provisions of 10 CFR Part 72. 1.3 Scope The NRC staff is reviewing Holtec’s request in accordance with the requirements under 10 CFR Part 72 for spent nuclear fuel cask storage systems and under the environmental protection regulations in 10 CFR Part 51. This document provides the results of the NRC staff’s environmental review; the staff’s technical and radiological review is documented separately in a Safety Evaluation Report. The NRC staff has prepared this Environmental Assessment (EA) in accordance with NRC requirements in 10 CFR 51.21 and 51.30, and with the associated guidance in NRC report NUREG-1748, “Environmental Review Guidance for Licensing Actions Associated with NMSS Programs” (NRC, 2003). The NRC regulation, 10 CFR 51.14, defines an EA as “a concise public document” that briefly provides “sufficient evidence and analysis for determining whether to prepare an environmental impact statement or a finding of no significant impact.” 1.4 Previous Environmental Assessments and Supporting Documents Among the documents evaluated in the preparation of this EA were: Draft Safety Evaluation Report of the Holtec International HI-STORM 100U Cask System. (USNRC, 2007) NRC ADAMS accession number: ML070250251 HI-STORM 100U Final Safety Analysis Report submittal “License Amendment Request #6 to HI-STORM CoC”. (Holtec International, 2007) NRC ADAMS accession number ML071280377 Environmental Report on the HI-STORM 100U VVM in the HI-STORM 100 MPC based storage system” (Holtec International, 2008) NRC ADAMS accession number: ML081910244 Additional references may be found in Section 10.0 of this EA. 2.0 THE PROPOSED ACTION The proposed action is the approval of the Holtec HI-STORM 100U underground spent fuel storage system design for use under the general license authorized by 10 CFR 72.210 and, adding the system to the “List of Approved Spent Fuel Storage Casks” in 10 CFR 72.214. If approved, this cask design will be the first system to provide the option of below-ground, interim dry storage for SNF that has been stored in reactor facility spent fuel pools for five or more years. The proposed casks would be deployed in an in-ground array. General licensees would be subject to the conditions of the general license set forth in 10 CFR 72.212, however, the use of an approved cask system under the general license requires no site-specific approval from the NRC. 6 2.1 Locations of the Proposed Action The Holtec HI-STORM 100U cask system could potentially be deployed at any licensed commercial reactor site meeting the attendant site parameters listed in 10 CFR 72.212 (the regulation setting forth the conditions of the general license) and the CoC 1014 requirements for the cask system. 2.2 Description of Proposed Underground Dry Cask Storage System The HI-STORM 100U is a subsurface dry cask storage system designed to accommodate all NRC-approved Holtec multi-purpose canisters (MPCs). MPCs are sealed stainless steel vessels that may contain spent light water reactor fuel and “greater than Class C” (GTCC) waste. The subsurface cask, referred to as the vertically ventilated module (VVM), consists of a below-grade cylindrical vertical storage cavity and closure lid (Figure 1), provides radiation shielding and structural protection of the MPC during storage (Figure 2). The fixed structure of the vertical storage cavity, identified by Holtec as the “Cavity Enclosure Container” (CEC), is made of a cylindrical container shell integrally welded to both a bottom plate and upper container flange. A continuous weld between the container shell and bottom plate is done to ensure that the CEC is completely sealed at its base. The constituent parts of the CEC are fabricated out of ~2.54 cm (~1 in.) thick low-carbon steel plate, and are coated with epoxy paint following fabrication. During mounting of the CEC on the below grade support foundation, the cylinder is equipped with zinc cathodic protection to further mitigate the effects of subsurface corrosion. For installation in highly corrosive soils, the subsurface outer shell of the VVM would be encased in concrete for additional protection against corrosion. As installed in the subsurface, an individual VVM extends approximately 5.8 m (19 ft) below ground surface and rests in a recess in a concrete support foundation of requisite thickness (0.61 – 0.91m) (2 to 3 feet). Engineered backfill surrounds the VVM for most of its subsurface interface, but the VVM is encircled by a two-foot-thick reinforced concrete top surface pad at its uppermost portion (Figure 1). The VVM is capped by a massive steel and concrete ventilated closure lid that extends about a foot and a half into the CEC, thereby minimizing the lid’s height above ground surface to about 0.74 m (~ 29 in.), and preventing its horizontal shifting during design basis events. Internally, the CEC is equipped with a removable insulated divider shell and MPC bearing pads to help meet cask thermal performance requirements. The divider shell and closure lid are configured to allow outside ambient air to flow through the outer openings of the VVM, down the outer annulus of the CEC and into inner annulus surrounding the MPC. Circulation is driven as air heated by the MPC rises the through lower divider shell openings, up the inner annulus and out through the center of the closure lid. All ventilation openings in the VVM are covered with stainless steel wire mesh to preclude the entry of small birds and mammals. The stainless steel bearing pads at the base of the CEC create a bottom plenum underneath the MPC for additional access to coolant air and prevent direct contact between the MPC and the base of the cylinder. The CEC internals are also engineered to allow the easy placement and removal of MPCs; either for maintenance of the CEC or eventual offsite disposition of the MPCs. 7 Figure 1: Cut-Away View of the HI-STORM 100U VVM (Holtec, 2008) For deployment of multiple HI-STORM 100U VVMs at a general license ISFSI, the modules can be placed in a rectangular gridded array with a minimum pitch or spacing of 3.67 m (12 ft) (center to center). Twelve-foot spacing can be used to achieve a reduced footprint, if space considerations merit, while allowing bi-directional orthogonal access to each unit by all commercially available cask transporters. Figure 3 shows the layout of 5 x 5 canister array with 3.67 m (12 ft) spacing. A typically-sized array of 64 casks with such spacing would occupy less than 0.1 ha (0.25 ac), while more typical 4.89 m (16 ft) spacing would increase the area to just under 0.2 ha (0.5 ac). Regarding the life-of-plant SNF storage needs, a potential 80-year operational life for a nuclear power reactor is considered to estimate the maximum footprints of vertical cask arrays at reactor sites. A review of reactors with long operating histories (NRC, 2005a; NRC 2009) shows that per 1000 MWe, approximately one MPC of SNF has been generated per year over a 35-year period. With increasingly higher fuel burnup rates allowed by NRC regulations, now up to 62,000 MWD/MTU from an earlier limit of 35,000 MWD/MTU, there has been a marked decrease in the generation of SNF per unit of power produced. 8 Figure 2: Cut-Away View of HI-STORM 100U VVM loaded with MPC (Holtec, 2008) As such, the rate of SNF accumulation per MWe generated is expected to decrease compared to previous generation levels. Nonetheless, historical data is used for a conservative estimate of maximum SNF storage needs at reactor sites. For a multi-reactor site with 4000 MWe capacity, the total number of MPCs anticipated to be filled over an 80-year period is 320; requiring four 80-cask arrays or five 64-cask arrays. The total pad areas needed for the aforementioned multiple arrays (at 16 foot cask spacing) would be under two and a half acres, and just over two acres, respectively. Requisite ISFSI buffer zones, spoils storage areas and security fencing would involve an additional four to five acres of land, totaling a potential maximum land area of under seven and a half acres dedicated to a plant’s ISFSI to meet individual reactor site life of plant SNF storage needs. 9 Figure 3: HI-STORM 100U VVM ISFSI Array for 25 casks (Holtec, 2008) 2.3 Planned Activities The activities associated with deployment of a HI-STORM 100U cask system include the following three phases: site preparation, operation, and decommissioning. While life of plant SNF storage needs could require up to five 64-unit arrays, total storage capacity is not required initially and cost considerations drive reactor operators to favor incremental cask deployment. As such the phases of 64-unit cask deployment are described below. The effects of multiple arrays of 64-unit arrays are addressed under cumulative impacts in Section 5.4. 2.3.1 Site Preparation The major site preparation elements of associated with deploying a HI-STORM 100U cask system would be (1) the installation of the subsurface vertical ventilated module array, (2) construction of an associated security building and installation of fencing (if not already existing), and (3) construction of a transport route from the reactor to the cask array. The site preparation of a 64 unit array is expected to take approximately six months to a year, with activity occurring generally during daylight hours. Activities would be confined to the area within the owner controlled area, with the construction limited to the vicinity of the array site and the nearby onsite excavation spoils storage area. Construction of the vertical ventilated module array would require the removal of site vegetation, soil excavation, spoils disposal, forming and pouring the concrete slab support for the vertical ventilated module array, and excavation of appropriate backfill (if available on site). A 64 unit array would require a 6.72 m (22 ft) deep excavation of an area measuring approximately 45.8 10