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.

There are more than 250 forms of U.S. Department of Energy (DOE)­owned spent nuclear fuel (SNF). Due to the variety of the spent nuclear fuel, the National Spent Nuclear Fuel Program (NSNFP) has designated nine representative fuel groups for disposal criticality analyses based on fuel matrix, primary fissile isotope, and enrichment. For each fuel group, a fuel type that represents the characteristics of all fuels in that group has been selected for detailed analysis.

The American Nuclear Society (ANS) supports (1) the development and use of geological
repositories for disposal of high-level radioactive wastes and (2) expeditious processing of the
Yucca Mountain license application in an open, technically sound manner. Geological disposal
means placing the wastes hundreds of feet underground and far from the biosphere. The U.S.
Nuclear Regulatory Commission (NRC) is following a legislatively well-defined regulatory
process to evaluate the safety of the proposed Yucca Mountain Site to meet both the scientific

The purpose of this report is to document the thermal-hydrologic-chemical (THC) seepage model and model simulations. The simulations predict the composition of fracture water that could potentially seep into repository emplacement drifts and the composition of the associated gas phase. The THC seepage model is not used to feed the total system performance assessment (TSPA) for the license application (LA).

The purpose of this report is to <,locument the sensitivity of the drift-scale thermal-hydrologic- chemical (THC) seepage model (SNL 2007 [DIRS 177404]) to heterogeneities in permeability and capillarity, which could affect predicted fluxes and chemistries of water and gases seeping into the emplacement drifts. This report has been developed following Technical Work Plan for: Revision of Model Reports for Near-Field and In-Drift Water Chemistry (SNL 2007 [DIRS 179287]).

The "Summary Report of Commercial Reactor Criticality Data for Crystal River Unit 3" contains the detailed information necessary to perform commercial reactor criticality (CRC) analyses for the Crystal River Unit 3 (CR3) reactor.

The objective of this calculation is to perform additional degraded mode criticality evaluations of the Department of Energy's (DOE) Fast Flux Test Facility (FFTF) Spent Nuclear Fuel (SNF) codisposed in a 5-Defense High-Level Waste (5-DHLW) Waste Package (WP). The scope of this calculation is limited to the most reactive degraded configurations of the codisposal WP with an almost intact Ident-69 container (breached and flooded but otherwise non-degraded) containing intact FFTF SNF pins.

The purpose of this document is to present the methodology to be used for development of the Subcritical Limit (SL) for post closure conditions for the Yucca Mountain repository. The SL is a value based on a set of benchmark criticality multiplier, keff> results that are outputs of the MCNP calculation method. This SL accounts for calculational biases and associated uncertainties resulting from the use of MCNP as the method of assessing kerr·

This report summarizes the results of EPA's review of the AEC
draft environmental statement, "Management of Commercial High-Level
and Transuranium-Contaminated Radioactive Waste" (WASH-1539). The
means by which high-level and long-lived radioactive wastes are
managed constitutes one of the most important questions upon which
the public acceptability of nuclear power, with its social and economic
benefits, will be determined. While the generation of power by
nuclear means offers certain benefits from the environmental viewpoint,