EQ6 Calculation for Chemical Degradation of Enrico Fermi Codisposal Waste Packages: Effects of Updated Design and Rates
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| CAL-EDC-MD-000015_MOL.20020102.0190.pdf (5.55 MB) | 5.55 MB |
The Monitored Geologic Repository (MGR) Waste Package Project of the BSC Management and Operating Contractor for the Department of Energy's Office of Civilian Radioactive Waste Management performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the Enrico Fermi Reactor owned by the DOE (Ref. 9). The Fermi SNF has been considered for disposal at the proposed Yucca Mountain site. Because of the high content of fissile materials in the SNF, the waste package (WP) design required special consideration of the amount and placement of neutron absorbers, and the possible transport of absorbers and fissile materials over geologic time. If there is a breach in the WP, water will enter and infiltrate the WP. This water would be able to moderate neutrons, increasing the likelihood of a criticality event within the WP. Also, infiltrating water may in time gradually leach the fissile components from the WP and separate them from the neutron absorbers. Such phenomena would affect the neutronics of the system.
This study presents calculations of the long-term geochemical behavior of WPs containing one DOE disposal container and five high-level waste (HLW) glass pour canisters (GPCs) arranged according to the codisposal concept (Ref. 14). The specific study objectives were to determine:
• The extent to which criticality control material suggested for this WP design will remain in the WP after corrosion/dissolution of the initial WP configuration (such that it can be effective in preventing criticality).
• The extent to which fissile uranium (U) will be carried out of the degraded WP by infiltrating water (such that internal criticality is no longer possible, but the possibility of external criticality may be enhanced).
• The nominal chemical composition and amounts of minerals and other solids left in the WP. These may be used for the criticality evaluations of the WP design, and to suggest the range of parametric variations for additional evaluations.
