Criticality of a Neptunium-237 sphere surrounded with highly enriched uranium shells and an iron reflector

Conference · Thu Jan 01 04:00:00 EST 2004

OSTI ID:977401

Sanchez, R G ^[1]; Loaiza, D J ^[2]; Hayes, D K ^[3]; Kimpland, R H ^[4]

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1. Rene G.
2. David J.
3. David K.
4. Robert H.

An additional experiment has been performed using the recently cast 6-kg {sup 237}Np sphere. The experiment consisted of surrounding the neptunium sphere with highly enriched uranium and an iron reflector. The purpose of the critical experiment is to provide additional criticality data that can be used to validate criticality safety evaluations involving the deposition of neptunium. It is well known that {sup 237}Np is primarily produced by successive neutron capture events in {sup 235}U or through the (n, 2n) reaction in {sup 238}U. These nuclear reactions lead to the production of {sup 237}U, which decays by beta emission into {sup 237}Np. In addition, in the spent fuel, {sup 241}Am decays by alpha emission into {sup 237}Np. Because {sup 237}Np is a threshold fissioner, the best reflectors for critical systems containing neptunium are those materials that exhibit good neutron scattering properties such as low carbon steel (99 wt % Fe). In this experiment, the iron reflector reduced the amount of uranium used in the critical experiment and increased the importance of the neptunium sphere.

• Research Organization: Los Alamos National Laboratory
• Sponsoring Organization: DOE
• OSTI ID: 977401
• Report Number(s): LA-UR-04-0216; LA-UR-04-216
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
36 MATERIALS SCIENCE
CAPTURE
CARBON STEELS
CRITICALITY
DEPOSITION
HIGHLY ENRICHED URANIUM
IRON
NEPTUNIUM
NEPTUNIUM 237
NEUTRON REACTIONS
NEUTRONS
NUCLEAR REACTIONS
PRODUCTION
SAFETY
SCATTERING
SPENT FUELS
URANIUM