The objective of this calculation is to perform intact and degraded mode criticality evaluations of the U.S. Department of Energy’s (DOE) Advanced Test Reactor (ATR) Spent Nuclear Fuel (SNF) placed in the DOE standardized SNF canister. This analysis evaluates the codisposal of the DOE SNF canister containing the ATR SNF in a 5-Defense High-Level Waste (5-DHLW) Short Waste Package (WP) (Bechtel SAIC Company, LLC [BSC] 2004a), which is to be placed in a monitored geologic repository (MGR).

The results of the MCNP criticality safety calculations described in this document are presented in Section 7.1. Based on the results presented attributes of the TAD canister-based systems that are important to ensuring their subcriticality are established. These attributes can be categorized according to the criticality control parameter that is impacted. Based on the categorization presented it is seen that moderation control is the underlying criticality control parameter for TAD canister-based systems containing CSNF with a maximum initial enrichment of 5 wt.% 235U/U.

The purpose of this analysis is to document the MCNP evaluations of benchmark lattice Laboratory Critical Experiments (LCE's). The objective of this analysis is to quantify the MCNP 4A (Reference 5.4) code system's ability to accurately calculate the effective neutron multiplication factor (keff) for various measured critical (i.e., keff= 1.0) configurations. This analysis quantifies the effectiveness of the MCNP criticality calculation for lattice configurations containing U02 and Pu02 fissile oxide fuel using two different cross section data libraries.

The objective of this calculation is to characterize the nuclear criticality safety concerns
associated with the codisposal of the Department of Energy’s (DOE) Enrico Fermi (EF) Spent
Nuclear Fuel (SNF) in a 5-Defense High-Level Waste (5-DHLW) Waste Package (WP) and
placed in a Monitored Geologic Repository (MGR). The scope of this calculation is limited to
the determination of the effective neutron multiplication factor (keff) for the degraded mode
internal configurations of the codisposal WP. The results of this calculation and those of Ref. 8

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 purpose of this calculation is to perform an example criticality evaluation for degraded internal configurations of a boiling water reactor (BWR) waste package (WP) containing 44 spent nuclear fuel (SNF) assemblies. The BWR assembly design considered is based on the General Electric (GE) 8x8 assembly (see section 5.1). Depletion analyses for various assembly average enrichment and burnup (expressed as gigawatt days/metric ton Uranium; GWd/MTU) combinations are performed using the SAS2H/ORIGEN-S sequence of SCALE 4.3 (CSCI:30011-2002; Ref. 7.5).

The purpose of this calculation is to perform a parametric study to determine the effects of fission product leaching, assembly collapse, and iron oxide loss on the reactivity of a waste package containing mixed oxide spent nuclear fuel. Previous calculations (CRWMS M&O 1998a) have shown that the criticality control features of the waste package are adequate to prevent criticality of a flooded WP for all the enrichment/burnup pairs expected for the MOX SNF.

This analysis is prepared by the Mined Geologic Disposal System (MGDS) Waste Package Development Department (WPDD) to determine the viability of the Defense High-Level Waste (DHLW) Glass waste package concept with respect to criticality regulatory requirements in compliance with the goals of the Waste Package Implementation Plan (Ref. 5.1) for conceptual design. These design calculations are performed in sufficient detail to provide a comprehensive comparison base with other design alternatives.

The objective of this analysis is to evaluate accumulations within the thermally altered tuff surrounding a drift. The evaluation examines accumulation of uranium minerals (soddyite), plutonium oxide (Pu01), and combinations of these materials. A hypothetical model of the tuff is used to provide insight into the factors that affect criticality for this near-field scenario. The factors examined include: the size of the accumulation, the fissile composition of the accumulation, the water or clayey material fraction in the accumulation and the water fraction in the tuff

The objective of this calculation is to document the Grand Gulf Unit 1 (GG1) reactivity calculations for sixteen critical statepoints in cycles 4 through 8. The GG1 reactor is a boiling water reactor (BWR) owned and operated by Entergy Operations Inc. The Commercial Reactor Criticality (CRC) evaluations support the development and validation of the neutronic models used for criticality analyses involving commercial spent nuclear fuel to be placed in a geologic repository. This calculation is performed as part of the evaluation in the CRC program.