The nuclear industry wants to ensure the Department of Energy completes an ongoing research project on dry storage of high-burnup reactor fuel.
The Nuclear Energy Institute, the trade association for the industry, on June 25 submitted its sixth update to the Energy Department regarding research and development priorities for the long-term storage and transportation of used nuclear fuel.
The 11 priorities cited by NEI would contribute data to applications for renewal of licenses for dry-storage pads at nuclear power plants around the country, Rod McCullum, the organization’s senior director for fuel and decommissioning, told RadWaste Monitor. “The more data we have the easier it’s going to be for us to get through these license renewals.”
The research and development data bolster the case for renewal of licenses for independent spent fuel storage installations (ISFSIs), he said. The NRC currently is reviewing five applications for 40-year license renewals, with 33 more applications due by the end of 2020.
The NEI priorities are divided into three tiers: research and development connecting to existing aging management commitments and providing risk-informed means for long-term safety; research and development in support of current aging management programs; and research and development that could aid current or future aging management programs or associated industry goals.
Topping the list is full completion of the High Burnup Dry Storage Cask Research and Development Project, which DOE contracted to the nongovernmental Electric Power Research Institute (EPRI). That covers all phases of the project, “up to and including opening of the full size cask,” McCullum wrote in a letter attached to the list, addressed to William Boyle, acting deputy assistant secretary in DOE’s Office of Spent Fuel and Waste Disposition.
Burnup, per the Nuclear Regulatory Commission, is the amount of energy generated by uranium that powers a nuclear reactor. Anything above 45 gigawatt days per metric ton of uranium is considered high burnup, with radioactivity, temperature, and physical consistency that must be considered for long-term storage in dry casks after the fuel is removed from power plant cooling ponds.
Roughly 1,200 dry-storage casks today hold at least one high-burnup fuel assembly, according to McCullum. The Energy Department says “almost all” spent fuel going into dry storage is high-burnup.
Under a 10-year contract with DOE, EPRI is carrying out a test plan it developed to glean data on high-burnup fuel in dry storage. This involves collecting information by monitoring a cask at Dominion Energy’s North Anna Power Station in Louisa County, Va., and studying differences in the fuel before and after storage.
“The high burnup demo project has provided substantial benefit early on. We already gained substantial data that has helped better understand the thermal behavior of the used fuel in drying and storage,” Aladar Csontos, an EPRI technical executive for fuel reliability and high-level waste, said in a statement to RadWaste Monitor. “Furthermore, the high burnup demo project will continue to provide valuable data during the remaining storage period and when the DOE opens and examines the high burnup fuel assemblies 10 or more years from the loading date.”
The decade-long study period will allow time for readying the follow-on phase of work, according to EPRI: opening the cask at a location to be determined to examine the fuel.
“The importance of cask opening and stored rod examination is not in any way lessened by recent data obtained from the project indicating fuel temperatures are lower than expected,” according to the NEI priorities list. “This work is vital irrespective of these results – i.e. improved understanding of thermal conditions is not a substitute for direct and thorough visual examination of the fuel.”
Among the other priorities:
- Preparing mitigation, repair, and other measures to address degradation of stainless-steel canisters after they have been deployed to storage sites.
- “Analysis of the potential consequences of corrosion and cracking” of such canisters in storage.
- “Broad scope transportation activities” to ensure used fuel can be removed from reactor facilities starting in 2023, the schedule under which consolidated interim storage sites in Texas and New Mexico are assumed to be ready to take the waste.
- Collecting more data and performance analyses for degradation of bolts, seals, and cask body materials in bolted systems.
