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 calculation is to apply the process described in the TDR-DS0-NU-000001 Rev. 02, Preclosure Criticality Analysis Process Report (Ref. 2.2.25) to aid in establishing design and operational criteria important to criticality safety and to identify potential control parameters and their limits important to the criticality safety of commercial spent nuclear fuel (CSNF) handling operations in the Wet Handling Facility (WHF)

The Disposal Criticality Analysis Methodology Topical Report (YMP 2003) presents the methodology for evaluating potential criticality situations in the monitored geologic repository. As stated in the referenced Topical Report, the detailed methodology for performing the disposal criticality analyses will be documented in model reports. Many of the models developed in support of the Topical Report differ from the definition of models as given in the Office of Civilian Radioactive Waste Management procedure AP-SIII.10Q, Models, in that they are procedural, rather than mathematical.

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.

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

This new report from the National Research Council’s Nuclear and Radiation Studies Board (NRSB) and the Transportation Research Board reviews the risks and technical and societal concerns for the transport of spent nuclear fuel and high-level radioactive waste in the United States. Shipments are expected to increase as the U.S. Department of Energy opens a repository for spent fuel and high-level waste at Yucca Mountain, and the commercial nuclear industry considers constructing a facility in Utah for temporary storage of spent fuel from some of its nuclear waste plants.

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

The purpose of this report is to develop and analyze the Engineered Barrier System (EBS) Radionuclide Transport Abstraction Model, consistent with Level I and Level II model validation, as identified in Technical Work Plan for: Near-Field Environment: Engineered Barrier System: Radionuclide Transport Abstraction Model Report (BSC 2006 [DIRS 177739]). The EBS Radionuclide Transport Abstraction (or RTA) is the conceptual model used in the Total System Performance Assessment (TSPA) to determine the rate of radionuclide releases from the EBS to the unsaturated zone (UZ).

This model report documents the drift scale coupled thermal-hydrological-mechanical (THM) processes model development and presents simulations of the THM behavior in fractured rock close to emplacement drifts. The modeling and analyses are used to evaluate the impact of THM processes on permeability and flow in the near-field of the emplacement drifts.