Intact and Degraded Mode Criticality Calculations for the Codisposal of Fort Saint Vrain HTGR Spent Nuclear Fuel in a Waste Package

The objective of these calculations is to perform intact and degraded mode criticality evaluations of the Department of Energy's (DOE) Fort Saint Vrain (FSV) commercial High Temperature Gas Reactor (HTGR) spent nuclear fuel. This analysis evaluates codisposal in a 5-Defense High-Level Waste (5-DHLW/DOE SNF) Long Waste Package (WP)(CRWMS M&O 2000c, Attachment V), which is to be placed in a potential monitored geologic repository (MGR). The scope of this calculation is limited to the determination of the effective neutron multiplication factor (k-eff) for both intact and degraded mode internal configurations of the codisposal waste package. These calculations will support the analysis that will be performed to demonstrate the technical viability for disposing of graphite based (FSV) spent nuclear fuel in the potential MGR. The calculations are associated with the waste package design and is performed in accordance with the "Technical Work Plan For: Department of Energy Spent Nuclear Fuel Work Packages (Civilian Radioactive Waste Management System Management and Operating Contractor (CRWMS M&O 2000a]).