Status of the multi-detector analysis system (MDAS) and the fork detector research programs

During the past 10 years, the Electric Power Research Institute (EPRI) has supported several projects aimed at obtaining regulatory acceptance of the burnup credit concept in the design of commercial spent-fuel storage and transportation systems. Among others, these projects have included documentation of spent-fuel burnup measurements with the Fork system and development of the Fork+ system, a more advanced instrument capable of measuring burnup independently of utility records. Another EPRI project is a study estimating the maximum uncertainties in utility burnup records. Based on the latter study, it is evident that in many cases reactor records are sufficiently reliable to eliminate the need for at-reactor burnup measurements. Independent of the EPRI research, the U.S. Department of Energy (DOE) is funding the Idaho National Engineering and Environmental Laboratory (INEEL) to research and prototype a nondestructive assay system for characterization of DOE spent nuclear fuel (SNF) and remote-handled transuranic waste (RH-TRU) in preparation for transportation and long-term storage of the fuel and waste. The Multi-Detector Analysis System (MDAS) is intended to provide some understanding of the fissile mass, radiation source term, and fissile isotopic content information from recorded energy spectra, without reliance on initial fuel composition or historic plant operating records. It can verify burnup calculations or be used directly for DOE fuel and waste characterization. The work is conducted under DOE Contract No. DE-AC07-94ID 13223. Patent pending. (author)