Criticality study of various highly enriched uranium samples measured in an active well coincidence counter
A criticality study has been conducted for the measurement of highly enriched uranium (HEU) samples using the Active Well Coincidence Counter (AWCC). Computer calculations were performed to estimate the k{sub eff} of large samples inside the AWCC in the form of metal, UF{sub 4}, and UO{sub 2}. The discrete ordinates transport code TWODANT was used for all computations. In performing the study, the authors varied the AQCC in the following ways: (a) with and without the cadmium sample-cavity liner, (b) with and without the nickel reflector, and (c) with a water-filled sample cavity. Metal samples consisted of right-circular cylinders containing masses of up to 20 kg of uranium (18.6 kg of {sup 235}U) with a 12-cm diam. The samples of UF{sub 4} and UO{sub 2} contained up to 10 kg of {sup 235}U, had a height-to-diameter ratio of unity, and were modeled as both dry and having a moisture content of up to 40% by weight. The most reactive configuration resulted when they removed the cadmium liner and nickel reflector and flooded the sample cavity with water (case 3). Results of the study indicate a maximum k{sub eff} of 0.96 for the water-filled cavity containing a 20-kg uranium-metal cylinder. Dry samples composed of 10 kg of {sup 235}U in the form of UF{sub 4} and UO{sub 2} resulted in a maximum k{sub eff} of 0.64 and 0.71 respectively. Samples of UF{sub 4} and UO{sub 2}, also containing 10 kg of {sup 235}U, with 10% moisture by weight resulted in a maximum k{sub eff} of 0.81 and 0.83 respectively. The subcritical limit for a water-flooded chamber without the nickel and cadmium in place is somewhat greater than 20% moisture by weight for a homogeneous fissile-water mixture containing 10 kg of {sup 235}U.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 10194481
- Report Number(s):
- LA-12837-MS; ISPO-365; ON: DE95003015; TRN: 94:024020
- Resource Relation:
- Other Information: PBD: Sep 1994
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HIGHLY ENRICHED URANIUM
CRITICALITY
RADIOASSAY
NEUTRON DETECTORS
SAFETY ANALYSIS
COINCIDENCE METHODS
URANIUM DIOXIDE
URANIUM FLUORIDES
T CODES
NEUTRON REFLECTORS
URANIUM 235
NEUTRON SOURCES
SAMPLE PREPARATION
DESIGN
420203
440101
400101
HANDLING EQUIPMENT AND PROCEDURES
GENERAL DETECTORS OR MONITORS AND RADIOMETRIC INSTRUMENTS
ACTIVATION, NUCLEAR REACTION, RADIOMETRIC, AND RADIOCHEMICAL PROCEDURES