Year
2018
Abstract
The last several years of the Spent Fuel NDA project focused on fabricating and deploying two large NDA instruments: Differential Die-away Self-Interrogation (DDSI), and Differential Die-Away (DDA). These instruments take advantage of complex data acquisition software to obtain neutron list-mode data, both passive and active respectively, during fuel measurements. Analysis of time-correlated neutron captures in an array of detectors provide more detailed insight than state-of-the-practice NDA tools for system parameters including how much fissile material is present, estimates of initial enrichment, burnup, and cooling time, and detection of missing pins. Instruments designed through the spent fuel NDA project to assess die-away time are large, complex, and technologically advanced. We will discuss 1) design lessons learned as part of this project (such as types of conduit, enhancements in electronics and detectors, and data acquisition for list mode counts from multiple detectors), and 2) the broad range of fuel assemblies measured and instrumentation field tested at the Clab interim storage facility in Sweden. The permanent nature of NDA deployment at the Clink Swedish Encapsulation and Repository Facilities and additional needs to determine multiplication and decay heat in spent fuel assemblies provide an opportunity for improvements for NDA to be applied. The overall effort of the project displays significant technological advancements, demonstration of novel instrumentation, and opportunities in data analysis for many years to come.