Consideration of Nuclear Criticality When Directly Disposing Highly Enriched Spent Nuclear Fuel in Unsaturated Tuff - I: Nuclear Criticality Constraints

Journal Article · Sat Nov 15 00:00:00 EST 2003 · Nuclear Technology

OSTI ID:20837808

Rechard, Rob P; Sanchez, Lawrence C; Trellue, Holly R ^[1]

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1. Sandia National Laboratories (United States)

This paper presents the mass, concentration, and volume required for a critical event to occur in homogeneous mixtures of fissile material and various other geologic materials. The fissile material considered is primarily highly enriched uranium spent fuel; however, {sup 239}Pu is considered in some cases. The non-fissile materials examined are those found in the proposed repository area at Yucca Mountain, Nevada: volcanic tuff, iron rust, concrete, and naturally occurring water. For {sup 235}U, the minimum critical solid concentration for tuff was 5 kg/m{sup 3} (similar to sandstone), and in goethite, 45 kg/m{sup 3}. The critical mass of uranium was sensitive to a number of factors, such as moisture content and fissile enrichment, but had a minimum, assuming almost 100% saturation and >20% enrichment, of 18 kg in tuff as Soddyite (or 9.5 kg as UO{sub 2}) and 7 kg in goethite. For {sup 239}Pu, the minimum critical solid concentration for tuff was 3 kg/m{sup 3} (similar to sandstone); in goethite, 20 kg/m{sup 3}. The critical mass of plutonium was also sensitive to a number of factors, but had a minimum, assuming 100% saturation and 80-90% enrichment, of 5 kg in tuff and 6 kg in goethite.

• OSTI ID: 20837808
• Journal Information: Nuclear Technology, Vol. 144, Issue 2; Other Information: Copyright (c) 2006 American Nuclear Society (ANS), United States, All rights reserved. http://epubs.ans.org/; Country of input: International Atomic Energy Agency (IAEA); ISSN 0029-5450
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
CONCRETES
CRITICAL MASS
CRITICALITY
ENRICHMENT
FISSILE MATERIALS
GOETHITE
HIGHLY ENRICHED URANIUM
HOMOGENEOUS MIXTURES
IRON
MOISTURE
PLUTONIUM
PLUTONIUM 239
SANDSTONES
SATURATION
SODDYITE
SOLIDS
SPENT FUELS
TUFF
URANIUM 235
URANIUM DIOXIDE
WATER
YUCCA MOUNTAIN