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Evaluation of in-plant neutron coincidence counters for the measurement of molten salt extraction residues

Conference ·
OSTI ID:10180435
; ;
Americium is extracted from plutonium by a molten salt extraction (MSE) process. The residual americium-laden salts are a significant waste stream in this pyrochemical purification process. Rapid assay of MSE residues is desirable to minimize the exposure of personnel to these often high-level emissions. However, the quantitative assay of plutonium in MSE residues is difficult. Variable, unknown (a,n) rates and variable emitted-neutron energy spectra preclude the use of standard neutron coincidence counting techniques with old-generation neutron coincidence counters. Gamma-ray assay methods have not been successful with some residues because of random lumps of plutonium metal. In this paper, we present measurements of MSE residues with two state-of-the-art neutron coincidence counters at the Los Alamos Plutonium Processing Facility: an in-line counter built for the assay of bulk waste material and the pyrochemical multiplicity counter that underwent test and evaluation at that facility. Both of these counters were designed to minimize the effects on measurements of variations in the sample geometry and variable energy spectra of emitted neutrons. These results are compared to measurements made with an HLNCII and with a 20-yr-old in-line well counter. The latter two counters are not optimized in ft sense. We conclude that the newer counters provide significantly improved assay results. The pyrochemical multiplicity counter operated in the conventional coincidence mode provided the best assays overall.
Research Organization:
Los Alamos National Lab., NM (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
10180435
Report Number(s):
LA-UR--93-2579; CONF-930749--29; ON: DE93018552
Country of Publication:
United States
Language:
English

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Related Subjects

052001
055001
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
440101
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION
ALPHA REACTIONS
AMERICIUM
COINCIDENCE METHODS
EVALUATION
GENERAL DETECTORS OR MONITORS AND RADIOMETRIC INSTRUMENTS
MOLTEN SALTS
NEUTRON DETECTORS
NEUTRONS
NUCLEAR MATERIALS MANAGEMENT
PLUTONIUM
PLUTONIUM 240
RADIOACTIVE WASTES
RADIOASSAY
TECHNICAL ASPECTS
THERMAL NEUTRONS
WASTE PROCESSING