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.

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

As part of the Mined Geologic Disposal System Waste Package Development design activities, it has been determined that it may be beneficial to add material to fill the otherwise free spaces remaining in waste package after loading high-level nuclear waste. The use of filler material will benefit criticality control in spent nuclear fuel waste packages, by the moderator displacement method.

The Monitored Geologic Repository Waste Package Operations of the Civilian Radioactive Waste Management System Management & Operating Contractor (CRWMS M&O) performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the Training, Research, Isotopes, General Atomics (TRIGA) reactor (Ref. 1). The TRIGA SNF has been considered for disposal at the potential Yucca Mountain site.

This report evaluates the radiological impacts during postulated accidents associated with the
transportation of spent nuclear fuel to the proposed Yucca Mountain repository, using the
RADTRAN 5.5 computer code developed by Sandia National Laboratories. RADTRAN 5.5 can
be applied to estimate the risks associated both with incident-free transportation of radioactive
materials as well as with accidents that may be assumed to occur during transportation. Incidentfree
transportation risks for transport of spent nuclear fuel to Yucca Mountain were evaluated in

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 effects of radiation on the corrosion of various metals and alloys, particularly with respect to in-reactor processes, has been discussed by a number of authors (Shoesmith and King 1998, p.2). Shoesmith and King (1998) additionally discuss the effects of radiation of the proposed Monitored Geologic Repository (MGR) Waste Package (WP) materials. Radiation effects on the corrosion of metals and alloys include, among other things, radiolysis of local gaseous and aqueous environments lead to the fixation of nitrogen as NO, NO2, and especially HN03 (Reed and Van Konynenburg 1988, pp.

The success of the Civilian Radioactive Waste Management Program of the U.S.
Department of Energy (DOE) is critical to U.S. ability to manage and dispose of
nuclear waste safely--and to the reestablishment of confidence in the nuclear energy
option in the United States. The program must conform with all applicable standards
and, in fact, set the example for a national policy on the safe disposal of radioactive
waste.
The Secretary of Energy has recently completed an extensive review of the

This report was developed in accordance with the requirements in Technical Work Plan for Postclosure Waste Form Modeling (BSC 2005 [DIRS 173246]). The purpose of the in-package chemistry model is to predict the bulk chemistry inside of a breached waste package and to provide simplified expressions of that chemistry as a function of time after breach to Total Systems Performance Assessment for the License Application (TSPA-LA).

The purpose of this calculation is to estimate the probability of criticality in a pressurized water reactor (PWR) uncanistered fuel waste package during the postclosure phase of the repository as a function of various waste package material, loading, and environmental parameters. Parameterization on the upper subcritical limit that is used to define the threshold for criticality will also be performed. The possibility of waste package misload due to human or equipment error during preclosure is also considered in estimating the postclosure criticality probability.