The purpose of this document is to summarize the degraded waste package disposal criticality evaluations which were performed in fiscal years I995 and I996. These evaluations were described in detail in 4 previous documents (Refs. I through 4). The initial version of this summary has been described in the I996 Disposal Criticality Analysis Methodology Technical Report (Ref. 5). A topical report planned for 1998 will present the methodology in its final form for approval by the US Nuclear Regulatory Commission.

The objective of this calculation is to evaluate the required minimum burnup as a function of initial boiling water reactor (BWR) assembly enrichment that would permit loading of spent nuclear fuel into the 44 BWR waste package configuration as provided in Attachment IV. This calculation is an application of the methodology presented in ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2003). The scope of this calculation covers a range of enrichments from 0 through 5.0 weight percent (wt%) U-235, and a burnup range of 0 through 40 GWd/MTU.

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

The table is based on historical costs through 2006, which are shaded, and projected costs in the 2008 TSLCC. To convert to 2010$, multiply by 1.0586. The 2008 TSLCC assumes a single repository system capable of accepting and disposing of SNF and HLW equivalent to 122,100 Metric Tons of Heavy Metal (MTHM). This estimate includes all defense wastes currently destined for disposal at Yucca Mountain and projected discharges of SNF from commercial utilities, including the 47 nuclear power reactors that had received license extensions from the NRC as of January 2007.

The purpose of this calculation is to characterize the criticality aspect of the codisposal of TRIGA (Training, Research, Isotopes, General Atomic) reactor spent nuclear fuel (SNF) with Savannah River Site (SRS) high-level waste (HLW). The TRIGA SNF is loaded into a Department of Energy (DOE) standardized SNF canister which is centrally positioned inside five-canister defense SRS HLW waste package (WP). The objective of the calculation is to investigate the criticality issues for the WP containing the five SRS HLW and DOE SNF canisters in various stages of degradation.

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 purpose of this scientific analysis report, CSNF Loading Curve Sensitivity Analysis, is to establish the required minimum burnup as a function of initial enrichment for both pressurized water reactor (PWR) and boiling water reactor (BWR) commercial spent nuclear fuel (CSNF) that would allow permanent disposal of these waste forms in the geologic repository at Yucca Mountain. The relationship between the required minimum burnup and fuel assembly initial enrichment forms a loading curve.

Disposal Criticality Analysis Methodology Topical Report describes a methodology for performing postclosure criticality analyses within the repository at Yucca Mountain, Nevada. An important component of the postclosure criticality analysis is the calculation of conservative isotopic concentrations for spent nuclear fuel. This report documents the isotopic calculation methodology. The isotopic calculation methodology is shown to be conservative based upon current data for pressurized water reactor and boiling water reactor spent nuclear fuel.

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 preclosure criticality analysis process described in this technical report provides a systematic approach for determining the need for criticality controls and for evaluating their effectiveness during the preclosure period of the Monitored Geologic Repository at Yucca Mountain, Nevada.