Thermal-hydraulics and neutronics overview of the DISECT experiment

Metallic fuel was developed in the 1960s and tested through the late 1980s where it was realized that there was more potential for the fuel system than historically realized[1–3]. With modern advanced reactors, such as the Versatile Test Reactor, re-approaching the use of metallic fuels, these require significant testing that provides fundamental understanding of fuel performance and validation of models for more rapid future development[4]. Investigations into of the fundamental phenomena that impacts bulk fuel behavior are critical to this development. Separate effects testing is an avenue that can aid in this understanding with a single irradiation campaign of relatively short duration. The Disc Irradiation for Separate Effects Testing with Control of Temperature (DISECT) project intends to establish a viable route for separate effects testing of nuclear fuels systems using a uniquely instrumented in-pile vehicle. DISECT is a US DOE Office of Nuclear Energy Nuclear Science User Facilities (NSUF) and Belgian Nuclear Research Centre (Studiecentrum voor Kernenergie (SCK CEN)) collaborative project executed by Idaho National Laboratory (INL) for design fabrication and characterization, the SCK CEN for irradiation and post irradiation examination, and Purdue University for technical guidance and characterization/post irradiation examination support. The test vehicle is comprised of an outer capsule that serves as the housing for individual fuel samples and instrumentation such as thermocouples. The individual samples are isolated from one another in sealed and insulated pucks allowing for in-pile conditions to vary between samples in a single device. Metallic fuels, specifically low-enriched (19-20% 235U) uranium molybdenum (U-Mo) and uranium zirconium (U-Zr) alloys, have been chosen as the pilot project for this vehicle due to their relevance in future test and research reactors. This paper serves to convey the experiment’s in-pile conditions and vehicle design.