The purpose of this scientific analysis report, Commercial Spent Nuclear Fuel Igneous Scenario Criticality Evaluation, is to investigate the effects of an igneous intrusion event occurring in the repository on commercial spent nuclear fuel (CSNF) stored in waste packages. This activity supports the Postclosure Criticality Department's development of bounding (design-basis) configurations for loading specifications and the evaluation of features, events, and processes (FEPs) that could lead to waste package criticality.

This report presents the analysis and conclusions with respect to disposal criticality for canisters containing aluminum-based fuels from research reactors. The analysis has been divided into three phases. Phase I, dealt with breached and flooded waste packages containing relatively intact canisters and intact internal (basket) structures; Phase II, the subject of this report, covers the degradation of the spent nuclear fuel (SNF) and structures internal to the codisposal waste package including high level waste (HLW), canisters, and criticality control material.

Thep purpose of this calculation is to perform degraded mode criticality evaluations of plutonium disposed in a ceramic waste form and emplaced in a Monitored geologic Repository (MGR). A 5 Defense High-Level Waste (DHLW) Canister Waste Package (WP) design, incorporating the can-in-canister concept for plutonium immobilization is considered in this calculation. Each HLW glass pour canister contains 7 tubes. Each tube contains 4 cans, with 20 ceramic disks (immobilized plutonium) in each.

The first objective of this calculation is the identification of the degraded configurations of the Enhanced Design Alternatives (EDA) II design that have some possibility of criticality and that can occur within 10,000 years of placement in the repository. The next objective is to evaluate the criticality of these configurations and to estimate the probability of occurrence for those configurations that could support criticality.

The purpose of this calculation is to perform waste-form specific nuclear criticality safety calculations to aid in establishing criticality safety design criteria, and to identify design and process parameters that are potentially important to the criticality safety of the transportation, aging and disposal (TAD) canister-based systems.

This design calculation is a revision of the previous criticality evaluation of the operations and
processes that are performed in the Aging Facility. It will also demonstrate and assure that the
storage and aging operations to be performed in the Aging Facility meet the criticality safety
design criteria in the Project Design Criteria Document (BSC 2005i, Section 4.9.2.2), and the
nuclear criticality safety requirements described in the SNF Aging System Description Document

The purpose of this methods report is to document: (1) the origin, and the methods used in the development of a comprehensive list of features, events, and/or processes (FEPs) that could potentially affect the postclosure performance of the Yucca Mountain disposal system; (2) the methodology and guidance used to screen FEPs for inclusion or exclusion from Total System Performance Assessment for the License Application (TSPA-LA) analysis; (3) the methodology and guidance used to create scenario classes; and (4) compliance with NUREG-1804 (NRC 2003.

The means to prevent and control criticality must be addressed as part of the Preclosure Safety Analysis (PCSA) required for compliance with 10 CFR Part 63 [DIRS 180319], where the preclosure period covers the time prior to permanent closure activities. This technical report presents the nuclear criticality safety evaluation that documents the achievement of this objective.

This analysis is prepared by the Mined Geologic Disposal System (MGDS) Waste Package Development Department (WPDD) in response to a request received via a QAP-3-12 Design Input Data Request (Reference 5.1) from Waste Acceptance, Storage, & Transportation (WAST) Design (formerly MRSMPC Design). This design analysis is an answer to the Design Input Data Request to provide: Specific requirements for long-term criticality control.

The objective of this calculation is to characterize the criticality aspect of a Department of Energy Spent Nuclear Fuel (DOE SNF) canister containing 5 Fast Flux Test Facility (FFTF) assemblies in a Five-Pack Defense High-Level Waste (HLW) waste package(WP). The purpose of this calculation is to investigate the criticality issues for the WP containg HLW and DOE SNF canisters in various stages of degradation. The calculational method used to perform the criticality calculations consisted of using the MNCP Version 4B2 (Ref.