From 1998 to 2004, a series of critical experiments referred to as the fission product (FP) experimental program was performed at the Commissariat à l'Energie Atomique Valduc research facility. The experiments were designed by Institut de Radioprotection et de Sûreté Nucléaire (IRSN) and funded by AREVA NC and IRSN within the French program supporting development of a technical basis for burnup credit validation.

A methodology for performing and applying nuclear criticality safety calculations, for PWR spent nuclear fuel (SNF) packages with actinide-only burnup credit, is described. The changes in the U-234, U-235, U-236, U-238, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, and Am-241 concentration with burnup are used in burnup credit criticality analyses. No credit for fission product neutron absorbers is taken. The methodology consists of five major steps. (1) Validate a computer code system to calculate isotopic concentrations of SNF created during burnup in the reactor core and subsequent decay.

In the 1980s a series of the Haut Taux de Combustion (HTC) critical experiments with fuel pins in a water-moderated lattice was conducted at the Apparatus B experimental facility in Valduc (Commissariat à l'Energie Atomique, France) with the support of the Institut de Radioprotection et de Sûreté Nucléaire and AREVA NC. Four series of experiments were designed to assess profit associated with actinide-only burnup credit in the criticality safety evaluation for fuel handling, pool storage, and spent-fuel cask conditions.

The characteristics of spent nuclear fuel and high-level waste are described, and options for permanent disposal that have been considered are described. These include:
•disposal in a mined geological formation,
•disposal in a multinational repository, perhaps on an unoccupied island,
•by in situ melting, perhaps in underground nuclear test cavities,
•sub-seabed disposal,
•disposal in deep boreholes,
•disposal by melting through ice sheets or permafrost,
•disposal by sending the wastes into space, and

In the 1980s, a series of critical experiments referred to as the Haut Taux de Combustion (HTC)
experiments was conducted by the Institut de Radioprotection et de Sûreté Nucléaire (IRSN) at the
experimental criticality facility in Valduc, France. The plutonium-to- uranium ratio and the isotopic
compositions of both the uranium and plutonium used in the simulated fuel rods were designed to be
similar to what would be found in a typical pressurized-water reactor fuel assembly that initially had an

The purpose of this engineering calculation is to document the benchmark range, over a variety of parameters, for the validation of the criticality calculations supporting the Monitored Geologic Repository (MGR). This engineering calculation accomplishes this by characterizing the Laboratory Critical Experiments (LCE) and the Pressurized Water Reactor (PWR) Commercial Reactor Criticals (CRC), and summarizing the significant parameters. This engineering calculation supports the Disposal Criticality Analysis Methodology program.

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"

The objective of this analysis is to characterize the criticality safety aspects of a degraded Department of Energy spent nuclear fuel (DOE-SNF) canister containing Massachusetts Institute of Technology (MIT) or Oak Ridge Research (ORR) fuel in the Five-Pack Defense High-Level Waste (DHLW) waste package to demonstrate concept viability related to use in the Mined Geologic Disposal System (MGDS) environment for the postclosure time frame.

The purpose of this design analysis is to determine the accuracy of the SAS2H module of SCALE 4.3 in predicting isotopic concentrations of spent fuel assemblies. The objective is to develop a methodology for modeling assemblies similar to those evaluated within this analysis and to establish the consistency of SAS2H predictions. The results of this analysis may then be applied to future depletion calculations using SAS2H in which no measurements are available. The analytical model employed for this analysis was the SAS2H module of the SCALE sequence.