Matrix effects corrections in DDT assay of {sup 239}Pu with the CTEN instrument

Conference · Sat Nov 01 04:00:00 EST 1997

OSTI ID:539241

Hollas, C L; Brunson, G; Coop, K ^[1]

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1. Los Alamos National Lab., NM (United States)

The accuracy of transuranic (TRU) waste assay using the differential die-away technique depends upon significant corrections to compensate for the effects of the matrix material in which the TRU waste is located. We have used a new instrument, the combined thermal/epithermal neutron (CTEN) instrument for the assay of TRU waste, to develop methods to improve the accuracy of these corrections. Neutrons from a pulsed 14-MeV neutron generator are moderated in the walls of the CTEN cavity and induce fission in the TRU material. The prompt neutrons from these fission events are detected in cadmium-wrapped {sup 3}He neutron detectors. We have developed methods of data acquisition and analysis to extract correlation in the neutron signals resulting from fission during active interrogation. This correlation information, in conjunction with the total number of neutrons detected, is used to determine the fraction of fission neutrons transmitted through the matrix material into the {sup 3}He detectors. This determination allows us to cleanly separate the matrix effects into two processes: matrix modification upon the neutron interrogating flux and matrix modification upon the fraction of fission neutrons transmitted to the neutron detectors. Recent results indicate that for some matrix systems, corrections for position dependent effects within the matrix are possible. 7 refs., 7 figs., 1 tab.

• Research Organization: Lockheed Idaho Technologies Co., Idaho Falls, ID (United States)
• OSTI ID: 539241
• Report Number(s): CONF-970126--; ON: DE97052960
• Country of Publication: United States
• Language: English

Related Subjects

05 NUCLEAR FUELS
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
ACCURACY
ALPHA-BEARING WASTES
HE-3 COUNTERS
NEUTRON DETECTION
PLUTONIUM 239
RADIOASSAY