The Transport and Dry Storage of Used Nuclear Fuel from America's Nuclear Power Stations: What are Optimal Canister Sizes and Methods to Fill Them?

摘要

The Report of the Blue Ribbon Commission on America's Nuclear Future [1 ] recommended that the United States (US) should follow a consent based approach to establish both a deep geologic repository for the US's stocks of used nuclear fuel (UNF) and one or more UNF Consolidated Interim Storage Facilities (CISF). The US's UNF is stored in pools and dry casks at all the nuclear power plant (NPP) sites across the country and, in January of 2013, the US Department of Energy (DOE) released the Administration's Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste [2] in response to the recommendations of the Blue Ribbon Commission (BRC). Consistent with this Strategy, DOE's Office of Nuclear Energy (DOE-NE) is conducting planning activities to lay the groundwork for implementing interim storage, including associated transportation, and make progress on this important national issue, within existing legislative and budgetary authorizations. A team led by Energy Solutions including NAC International, Exelon, Booz Allen Hamilton, Talisman International, and Petersen Inc. ("the Team"), has worked under contract to DOE-NE to support the DOE's work on several design studies providing their assessments on (ⅰ) transport casks for "bare" UNF taken from NPP pools, (ⅱ) standardized transportation, aging and disposal canisters (STADs) that would be suitable for all stages of UNF handling, including disposal in a geologic repository and (iii) a study on how STADs can be most efficiently loaded at the NPP sites. The pools at most NPP sites in the US are full, so new discharges of UNF from the reactors displace equal amounts of older UNF into dry storage. The NPP Utilities are currently placing this UNF into increasingly large dual purpose (storage and transportation) canisters (DPCs) because this reduces loading times and associated worker dose uptake. However, whether large DPCs may be able to be directly disposed is not known at this time, and will depend in part on future geologic disposal concepts and the DPC heat content. The use of STADs at the NPP sites and/or at a Consolidated Interim Storage Facility (CISF) could avoid a potential need to repackage UNF from DPCs but, to make STADs attractive for use, ways need to be found to fill and seal them efficiently from an operational perspective. This paper describes the Team's designs for STADs, the methods we have devised to fill them most efficiently at the NPP sites and the alternate, for pool-stored UNF, of transporting it "bare" in suitable casks, for possible placement into STAD canisters at the CISF. The work explores technical concepts that could support future decision-making by DOE.