Evaluation of Criticality Criteria for Fissile Class II Packages in Transportation

Conference · Mon Aug 23 04:00:00 EDT 1976

OSTI ID:7267241

Thomas, J. T. ^[1]

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1. Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

The nuclear criticality safety of packages in transportation is explored systematically by a surface density representation of reflected array criticality of air-spaced units. Typical perturbations to arrays are shown to be related analytically to the corresponding reactivity changes they produce. The reactivity change associated with the removal of three reflecting surfaces from a totally water reflected array is shown to depend upon the fissile material loading of the packages. For U (93.2) metal, the expected reactivity loss can range from 2 to 21 percent. Replacement of a three-sided reflector of water on a critical array by one of concrete results in a reactivity increase ranging from 0 to 6 percent. Mass limits established by criticality data for reflected arrays of air-spaced units can provide a minimum, uniform margin of safety, expressible in terms of reactivity, to more reliably specify subcriticality in transport. Mass limits less than those defined by air-spaced units in water-reflected arrays are unnecessary for Fissile Class II packages.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 7267241
• Report Number(s): IAEA-SR-10/10(Draft); CONF-760813-2
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
42 ENGINEERING
420203* -- Engineering-- Handling Equipment & Procedures
ACTINIDES
Air-Spaced Units
CRITICALITY
Criticality Data
ELEMENTS
ENRICHED URANIUM
FISSILE MATERIALS
FISSIONABLE MATERIALS
HIGHLY ENRICHED URANIUM
ISOTOPE ENRICHED MATERIALS
METALS
Mass Limits
Nuclear Criticality Safety Program (NCSP)
Package Transportation Safety
Reactivity Loss
SAFETY
TRANSPORT
U(93.2) Metal
URANIUM