Electrochemical Safeguards Measurement Technology Development at LANL

摘要

As part of the U. S. Department of Energy Office of NuclearEnergy MPACT campaign Virtual Facility Distributed Test Bed,Los Alamos National Laboratory has developed advanced nondestructiveassay (NDA) technologies based on gamma ray andneutron signatures. This paper focuses on the development ofultra-high resolution microcalorimeter gamma spectroscopyand the High Dose Neutron Detector (HDND) and their performanceevaluation in relation to key measurement points withinthe Virtual Facility Distributed Test Bed flowsheet. Gamma rayspectroscopy and correlated neutron counting are cornerstonesof nuclear material assay for safeguards and security. Advancednuclear fuel cycles that utilize technologies such as electrochemicalseparation of spent nuclear fuel (SNF) present new measurementchallenges and call for the development of new solutions.The development of microcalorimeter gamma spectroscopy isintended to provide nondestructive isotopic analysis capabilitieswith sufficient precision and accuracy to reduce the needfor sampling and destructive analysis (DA) to meet safeguardsand security goals. With nearly 10 times better energy resolutionthan high-purity germanium detectors, ultra-high-resolutionmicrocalorimeter gamma ray spectrometers have been shown toovercome important uncertainty limits for nondestructive isotopicanalysis. Recent development has led to the first microcalorimeterspectrometers designed for use in nuclear facilities andanalytical laboratories, including SOFIA (Spectrometer Optimizedfor Facility Integrated Applications). Implemented in an on-siteanalytical laboratory, SOFIA could enable precise measurementof the isotopic composition of process samples in a much morerapid and cost-effective manner than destructive analysis. Dailynondestructive measurements to determine changes in key isotopicratios with 1% 1-sigma precision for input fuel, ER salt, andU/TRU product are feasible with the current instrument. Relativeto planar HPGe detectors, SOFIA can significantly improve confidencein results and reduce potential measurement bias byresolving closely spaced gamma ray peaks. The developmentof the HDND enables the capability to perform neutron countingand NDA in high gamma backgrounds and high count rate applicationssuch as measurements of U/TRU products. The HDNDis shown to be capable of tolerating increases in gamma doserate by almost two orders of magnitude (up to 800 R/hr) withonly ~30% reduction in neutron detection efficiency. To demonstratethe HDND performance for U/TRU product accountancy,the instrument was tested with high-mass Pu-bearing U/TRUsurrogate materials and demonstrated the capability to measuremultiplication using correlated neutron counting. Additionally, theHDND provides a dual capability of neutron and gamma detectionfor simultaneous neutron counting and gamma-dose measurementsand is shown to be a versatile tool for process monitoringapplications. By leveraging these and other advanced measurementtechnologies for electrochemical facilities, development ofa robust and economic safeguards approach will be an importantenabling capability for the next generation of nuclear energy.