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 develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips.

Fuel from the Fast Flux Test Facility ' (FFTF) has been considered for disposal at the proposed

The criticality consequence analysis for pressurized water reactor (PWR) waste packages (WP) (Civilian Radioactive Waste Management System [CRWMS] Management and Operating Contractor [M&O] 1997) focused on results obtained by maximizing postulated rates of reactivity insertion to assure no synergistic reactions could occur among waste packages from hypothetical criticality events. Other variables potentially influencing the criticality consequences were held constant during the above referenced analysis.

The purpose of this calculation is to estimate the probability of criticality in a pressurized water reactor (PWR) uncanistered fuel waste package during the postclosure phase of the repository as a function of various waste package material, loading, and environmental parameters. Parameterization on the upper subcritical limit that is used to define the threshold for criticality will also be performed. The possibility of waste package misload due to human or equipment error during preclosure is also considered in estimating the postclosure criticality probability.

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:

This analysis documents the screening analysis for postclosure criticality features, events, and
processes (FEPs). It addresses the probability of criticality events resulting from degradation
processes as well as disruptive events (i.e., seismic, igneous, and rockfall). Probability
evaluations are performed utilizing the configuration generator model described in Configuration
Generator Model for In-Package Criticality1, a component of the methodology from Disposal

The Monitored Geologic Repository (MGR) Waste Package Operations (WPO) of the Civilian Radioactive Waste Management System Management & Operating Contractor (CRWMS M&O) performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the Emico Fermi Atomic Power Plant (Ref. 1). The Fermi fuel has been considered for disposal at the potential Yucca Mountain site.

The Monitored Geologic Repository Waste Package Operations of the Civilian Radioactive Waste Management System Management & Operating Contractor (CRWMS M&O) performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the Training, Research, Isotopes, General Atomics (TRIGA) reactor (Ref. 1). The TRIGA SNF has been considered for disposal at the potential Yucca Mountain site.

The Disposal Criticality Analysis Methodology Topical Report (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, Models, in that they are procedural, rather than mathematical.