Patching Holes in the Explanation of Lead Slowing-down Spectroscopy (LSDS) as Applied to the Nondestructive Assay (NDA) of Used Nuclear-fuel Assemblies

Abstract Within the past decade, several research groups around the world have investigated the application of lead slowing-down spectroscopy (LSDS) to the nondestructive assay (NDA) of used nuclear-fuel assemblies. Though their research has been good, they have largely skipped the explanation of the basics of LSDS. Furthermore, the papers that they have cited for the derivations of the fundamental LSDS equations do not actually contain the derivations, or they are obscure and difficult to obtain, or they are extremely difficult to read and understand. Also, the approaches that the various groups take to analyze LSDS data have not been compared. This INMM paper partially fills-in these gaps. The way that LSDS works is explained in an intuitive way. The main LSDS equation—i.e., the energy-time relationship—is derived and thereby revealed to be conceptually simple, in fact. Lastly, it is shown that the two popular types of data analysis—the time intervals matrix analysis promoted by the Swedish and Russian groups and the spectral deconvolution analysis promoted by the American groups—are not actually as different from each other as they appear.