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 calculation is to evaluate the probability of flooding a waste package with seepage water. Disruptive events can affect the Engineered Barrier System (EBS) components and have the potential to allow an advective flow of seepage water to reach the waste package. The advective and diffusive flow paths into the waste package have the potential to result in water accumulation inside the waste package, which in turn can lead to a potentially critical configuration. This calculation will evaluate the following:

The purpose of this analysis is to document the Commercial Reactor Critical (CRC) benchmark evaluation performed for the Quad Cities Unit 1 boiling water reactor (BWR). The CRC benchmark is performed at a beginning of life (BOL) statepoint representing reactor start-up critical conditions. The objective of this CRC benchmark analysis is to provide a validation benchmark for the MCNP 4A analytic tool for use in the disposal criticality analysis methodology.

In this study, the long-term geochemical behavior of waste package (WP), containing Pu-ceramic, was modeled. The ceramic under consideration contains Ti, U, Pu, Gd and Hf in a pyrochlore structure; the Gd and Hf stabilize the mineral structure, but are also intended to provide criticality control. The specific study objectives were to determine:
1) the extent to which criticality control material, suggested for this WP design, will remain in the WP after corrosion/dissolution of the initial package configuration (such that it can be effective in preventing criticality), and

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 emplacement of nuclear waste in the proposed geologic repository must satisfy relevant regulatory requirements with respect to criticality, 10CFR60. I31 (h) (Ref. 25). The waste packages for the various waste forms will be designed to preclude criticality (typically by the inclusion of neutron absorbers) even if the waste package becomes filled with water. Criticality may, however, be possible if the contents of the waste package become degraded in such a way that the fissile material can be separated from the neutron absorbers, while sufficient moderator is retained.

The purpose ofthis engineering calculation is to estimate the frequency of misloading spent nuclear fuel (SNF) assemblies that would result in exceeding the criticality design basis of a waste package (WP). This type of misload - a reactivity misload - results from the incorrect placement of one or more fuel assemblies into a waste package such that the criticality controls do not match the required controls for the fuel assemblies.

This technical report provides an updated summary of the waste package (WP) external criticalityrelated
risk of the plutonium disposition ceramic waste form, which is being developed and
evaluated by the Office of Fissile Materials Disposition of the U.S. Department of Energy (DOE).
The ceramic waste form consists of Pu immobilized in ceramic disks, which would be embedded
in High-Level Waste (HLW) glass in the HLW glass disposal canisters, known as the "can-incanister"