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DOE OSTI2019

Delayed Gamma-ray Assay for Nuclear Materials Safeguards: Additional Tasks

This report documents the activities and findings completed under the extended task scope in FY17-18. This work was performed as a follow-up to the original effort that investigated the delayed gamma-ray signatures of nuclear materials and was a collaborative effort between Lawrence Livermore, Lawrence Berkeley, Los Alamos National Laboratories and the Idaho Accelerator Center. The original project was focused on the delayed gamma-ray (DG) assay application for spent nuclear fuel safeguards, as a methodology to directly quantify the content and composition of U and Pu isotopes in irradiated assemblies in storage or before transfer to a difficult-to-access repository.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2018

Stilbene Scintillator Detector Array and Data-Acquisition System for Active Interrogation

A large area Stilbene crystal detector array has been assembled and calibrated for use in active interrogation measurements. The array consists of 10 high-efficiency 4”x2” stilbene cells. The cells were grown by Inrad Optics using LLNL developed technology. The array can be used to detect multiple signatures of SNM items, both actively and passively. Prompt and delayed gamma rays as well as prompt and delay neutrons can be detected and counted separately. The array is coupled to the Mesytec MDPP-16 VME-based digitizer module for data acquisition. This module performs on-board pulse-shape discrimination of signals from the Stilbene crystal detectors. This data-acquisition module allows separation of neutron and gamma-ray events with a low demand on data transfer rates. In addition, the high-resolution timing (<100 ps) is suitable for correlated gamma-ray and neutron multiplicity counting. This report describes the construction and calibration of the system. We also discuss applications of the system as well as how the system is currently being utilized by end users.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗