This report presents a best-estimate probabilistic risk assessment (PRA) to quantify the frequency of criticality accidents during railroad transportation of spent nuclear fuel casks. The assessment is of sufficient detail to enable full scrutiny of the model logic and the basis for each quantitative parameter contributing to criticality accident scenario frequencies. The report takes into account the results of a 2007 peer review of the initial version of this probabilistic risk assessment, which was published as EPRI Technical Report 1013449 in December 2006.

The U.S. Nuclear Regulatory Commission (NRC) is evaluating the safety and security of spent nuclear fuel (SNF) stored in dry casks for extended time periods before transportation to a location where the SNF is further processed or permanently disposed.

Several hundred distinct types of DOE-owned spent nuclear fuel (DSNF) may potentially be disposed in the Yucca Mountain repository. These fuel types represent many more types than can be viably individually examined for their effect on the Total System Performance Assessment for the License Application (TSPA-LA). Additionally, for most of these fuel types, there is no known direct experimental test data for the degradation and dissolution of the waste form in repository groundwaters.

There have been roughly 2,600 shipments of commercial spent fuel in this country over the past three decades or so. Although this is not an enormous volume by European standards, it is nevertheless significant. These shipments fall into two general categories: individual and "campaign."
There have been a number of individual shipments where lead test assembly fuel was shipped from a reactor to a laboratory for examination. This is an important part of reactor fuel development.

With the Department of Energy’s (DOE) recent submittal of a license application to the U.S. Nuclear Regulatory Commission, the development of Yucca Mountain, Nevada, as a national nuclear waste repository moves one step closer to reality. An operating site at Yucca Mountain could receive between 38-106 rail shipments and 53-89 truck shipments annually over a period of 50 years.