This analysis is prepared by the Mined Geologic Disposal System (MGDS) Waste Package Development (WPD) department to provide a probabilistic evaluation of the potential for criticality of fissile material which has been transported from a geologic repository containing breached waste packages of commercial spent nuclear fuel (SNF). This analysis is part of a continuing investigation of the probability of criticality resulting from the emplacement of spent nuclear fuel in a geologic repository.

The purpose of this report is to document and validate the external accumulation model that predicts accumulation of fissile materials in the invert, fractures and lithophysae in the rock beneath a degrading waste package containing spent nuclear fuel (SNF) in the monitored geologic repository at Yucca Mountain. (Lithophysae are hollow, bubblelike structures in the rock composed of concentric shells of finely crystalline alkali feldspar, quartz, and other materials (Bates and Jackson 1984 [DIRS 128109], p.

At the request of the staff to the Blue Ribbon Commission on America’s Nuclear Future (“BRC”), we have reviewed whether certain recommendations in the BRC’s July 29, 2011 Draft Report respecting near-term actions by the Department of Energy (“DOE”) or other officers or agencies in the Executive Branch can be implemented under existing law. These recommendations relate to:
(1) Initial steps to site, license and construct consolidated interim storage facilities for spent nuclear fuel (“spent fuel”);

In this study, the long-term geochemical behavior of waste package (WP), containing Pu-ceramic, was modeled. The ceramic under consideration contains Ti, U, Pu, Gd and Hf in a pyrochlore structure; the Gd and Hf stabilize the mineral structure, but are also intended to provide criticality control. The specific study objectives were to determine:
1) the extent to which criticality control material, suggested for this WP design, will remain in the WP after corrosion/dissolution of the initial package configuration (such that it can be effective in preventing criticality), and

The Disposal Criticality Analysis Methodology Topical Report (Reference 1) states that the accuracy of the criticality analysis methodology (MCNP Monte Carlo code and cross-section data) designated to assess the potential for criticality of various configurations in the Yucca Mountain proposed repository is established by evaluating appropriately selected benchmark critical experiments.

This Memorandum analyzes issues related to the Standard Contract between the U.S. Department of Energy (“DOE”) and the “utilities.” Beginning with a discussion of specific provisions of the Standard Contract, this Memorandum then analyzes the status of lawsuits involving the Standard Contract, reviews issues related to on-site storage of spent fuel and HLW, and assesses the prospects for modifying the current waste-disposal regime through Federal legislation or amendments to the Standard Contract.

This study is prepared by the Mined Geologic Disposal System (MODS) Waste Package Development Department (WPDD) to provide input to a separate evaluation on the probablility of criticality in the far- field environment. These calculations are performed in sufficient detail to provide conservatively bounding configurations to support separate probabilistic analyses.

This memo sets forth the Office of Standard Contract Management's current estimate of the US Government's liability in connection with the Government's partial breach of the "standard contracts" that it executed pursuant to the NWPA of 1982. The Office of Standard Contract Management estimates that liability, as of today and based on the analysis and qualifications set forth below, to be $15.4 billion.
...

This report presents the analyses and results for the potential occurrence of external criticality events which could result from plutonium waste forms emplaced in a geologic repository similar to the one being developed at Yucca Mountain. The analyses evaluate both the MOX spent fuel and the immobilized plutonium waste forms in a repository if the waste package has degraded and if the fissile material has migrated to the invert and out into the far-field.