Los Alamos second-generation system for passive and active neutron assays of drum-size containers

Technical Report · Mon Sep 01 00:00:00 EDT 1986

DOI:https://doi.org/10.2172/5093966· OSTI ID:5093966

Caldwell, J T; Hastings, R D; Herrera, G C; Kunz, W E; Shunk, E R

We describe in a comprehensive fashion the Los Alamos second-generation system for passive and active neutron assays of drum-size containers. The developmental history of this 7-year project is presented with emphasis on the pulsed active neutron technique (differential dieaway), which has achieved milligram levels of assay sensitivity for both plutonium and uranium wastes. We describe in detail the matrix effects for both passive and active neutron assays. We present in a thorough fashion our novel approach to achieving comprehensive corrections for these matrix effects using measurements made during the assays. We develop a matrix correction formalism based on separate neutron absorption and moderator indices determined from these measurements. These are presented as a series of analytic functions fitted to the data. Absolute calibrations and calibration standards are discussed, as is a practical means (pink drum measurements) of achieving routine calibration verification at all implementation sites. We present our overall assay algorithm, integrating absolute calibrations with matrix corrections. We also present a systematic error formalism that is based on the matrix response data. Finally, we outline a strategy for the verification of our entire assay formalism. This is based on measurements with a set of salted waste matrix drums combined with systematic assay intercomparisons of well-characterized transuranic wastes.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5093966
• Report Number(s): LA-10774-MS; ON: DE87002230
• Country of Publication: United States
• Language: English

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