ORALLOY (93.15 235U) METAL ANNULI WITH BERYLLIUM CORE

Technical Report · Wed Sep 01 04:00:00 EDT 2010

DOI:https://doi.org/10.2172/1004261· OSTI ID:1004261

Bess, John D.; Montierth, Leland M.; Reed, Raymond L.; Mihalczo, John T.

A variety of critical experiments were constructed of enriched uranium metal during the 1960s and 1970s at the Oak Ridge Critical Experiments Facility (ORCEF) in support of criticality safety operations at the Y-12 Plant. The purposes of these experiments included the evaluation of storage, casting, and handling limits for the Y-12 Plant and providing data for verification of calculation methods and cross-sections for nuclear criticality safety applications. These included solid cylinders of various diameters, annuli of various inner and outer diameters, two and three interacting cylinders of various diameters, and graphite and polyethylene reflected cylinders and annuli. Of the hundreds of delayed critical experiments, two were performed that consisted of uranium metal annuli with a solid beryllium metal core. The outer diameter of the annuli was approximately 13 or 15 inches with an inner diameter of 7 inches. The diameter of the core was approximately 7 inches. The critical height of the configurations was approximately 5 and 4 inches, respectively. The uranium annuli consisted of multiple stacked rings with diametral thicknesses of approximately 2 inches apiece and varying heights. The 15-inch experiment was performed on June 4, 1963, and the 13-inch experiment on July 12, 1963 by J. T. Mihalczo and R. G. Taylor (Ref. 1) with accompanying logbook. Both detailed and simplified model specifications are provided in this evaluation. Both of these fast-spectra experiments were determined to represent acceptable benchmarks. The calculated eigenvalues for both the detailed and simple models are within approximately 0.6% of the benchmark values, but significantly greater than 3s from the benchmark value because the uncertainty in the benchmark is very small: <±0.0004 (1s). There is significant variability between results using different neutron cross section libraries, the greatest being a ?keff of ~0.67%. Unreflected and unmoderated experiments with the same highly enriched uranium metal parts were performed at the Oak Ridge Critical Experiments Facility in the 1960s and are evaluated in HEU MET FAST 051. Thin graphite reflected (2 inches or less) experiments also using the same highly enriched uranium metal parts are evaluated in HEU MET FAST 071. Polyethylene-reflected configurations are evaluated in HEU-MET-FAST-076. A stack of highly enriched metal discs with a thick beryllium reflector is evaluated in HEU-MET-FAST-069.

• Research Organization: Idaho National Laboratory (INL)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: AC07-05ID14517
• OSTI ID: 1004261
• Report Number(s): INL/EXT-10-18065
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
97 MATHEMATICS AND COMPUTING
BENCHMARKS
BERYLLIUM
CALCULATION METHODS
CASTING
CRITICALITY
CROSS SECTIONS
EIGENVALUES
ENRICHED URANIUM
GRAPHITE
HIGHLY ENRICHED URANIUM
ICSBEP
NEUTRONS
Nuclear Criticality Safety Program (NCSP)
OR-CEF REACTOR
POLYETHYLENES
SAFETY
SPECIFICATIONS
STORAGE
URANIUM
VERIFICATION
Y-12 PLANT
benchmark
beryllium
critical experiments
highly enriched uranium
oralloy