Development of a Remote Canister Monitoring System for Aluminum Clad Spent Nuclear Fuel - Recent Activities - 21140

The U.S. Department of Energy (DOE) manages over 300 different types of spent nuclear fuel (SNF). Over 250 of those different SNF types are located at the Idaho National Laboratory (INL) Site. Included amongst these are several types of aluminum clad SNF (ASNF), including the advanced test reactor (ATR) SNF. A large portion of this ASNF is currently being stored in vented, dry storage canisters at the CPP-603 Irradiated Fuel Storage Facility (IFSF), though the environment of the individual canisters is currently not being monitored. Since 2017, the DOE Office of Environmental Management (DOE-EM) has supported investigations into the technical issues associated with extended dry storage (50+ years) of ASNF [1]. By mid-2019, investigations were initiated regarding the potential for in-canister monitoring in the CPP-603 facility to support this extended storage. These investigations included efforts to develop a remote canister-monitoring system (RCMS) for determining and monitoring environmental conditions within dry fuel storage canisters containing ASNF at INL. A successful RCMS would greatly improve the current understanding of how ASNF behaves during extended dry storage and would support a technical basis for the continued storage of this material. The capability to establish and monitor the performance of ASNF in situ provides the opportunity to (1) evaluate the appropriate technologies for monitoring, (2) collect canister environment conditions as soon as possible, (3) verify and validate current laboratory-based study results and analytic modeling approaches, and (4) potentially identify additional dry storage options for ASNF at the INL Site. The improved understanding of ASNF behavior gained by performing this work would also contribute to the safety basis for extended dry storage in current and future configurations as well as to provide information for future transportation, conditioning, and disposal of ASNF. The parameters to be monitored by the RCMS include temperature, relative humidity, hydrogen gas concentration, and radiation environment (dose). To date, three approaches have been identified for investigation. The first approach is to perform a technology update on an existing prototype developed in the early 2000's. This first approach would acquire point estimate data by measuring the air volume at the top of the canister. The second approach is to develop a wired system that requires the threading of wired sensors into the canister geometry. This approach would allow the acquisition of spatial information for the parameters of interest. The third approach is a passive system that would also acquire spatial information without the need for a wired system, which could have benefits in terms of maintenance and operation within the storage facilities. This paper provides an overview of the recent activities to develop an RCMS for ASNF. (author)