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Thermal neutron multiplicity measurements using the pyrochemical multiplicity counter at Lawrence Livermore National Laboratory

Conference ·
OSTI ID:10179312
;  [1]; ;  [2]
  1. Los Alamos National Lab., NM (United States)
  2. Lawrence Livermore National Lab., CA (United States)
+ Show Author Affiliations
The pyrochemical multiplicity counter designed and built at Los Alamos has been undergoing tests and evaluation at Lawrence Livermore National Laboratory (LLNL). Measurements have been performed using a variety of plutonium oxide and metal materials. The pyrochemical multiplicity counter uses the information contained in the higher moments of the neutron multiplicity distribution to deduce the three unknowns in the assay problem: {sup 240}Pu-effective mass, ({alpha},n) neutron rate, and self-multiplication. This is an improvement over conventional neutron coincidence counting, which must rely on some estimate of the ({alpha},n) neutron rate or self-multiplication to deduce an assay result. Such conventional techniques are generally unsatisfactory for impure materials for which these quantities are unknown. We present the assay results obtained with the pyro-chemical multiplicity counter and discuss the procedures necessary to produce good assay results. Using these procedures, we have obtained assay accuracies of 1%--2% for oxide materials in 1/2 hour measurement times. We also compare these results to those that would have been obtained using conventional neutron assay techniques and discuss the correlations we have observed between assay results and the ratio of total neutron counts in the different rings of the pyrochemical counter.
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:
10179312
Report Number(s):
LA-UR--93-2610; CONF-930749--45; ON: DE93018538
Country of Publication:
United States
Language:
English

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Related Subjects

055001
440100
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL PROTECTION
COINCIDENCE METHODS
MULTIPLICITY
NEUTRON DETECTION
NEUTRON DETECTORS
NUCLEAR MATERIALS MANAGEMENT
RADIATION INSTRUMENTATION
TECHNICAL ASPECTS
TESTING
THERMAL NEUTRONS