RECENT ASSESSMENTS IN THE U.S. OF TYPE B PACKAGES TO IMPACTS BEYOND THE REGULATORY PACKAGE TEST STANDARDS

The regulatory-driven design of radioactive material transportation packages leads package vendors to perform analyses that demonstrate the package’s ability to meet the regulatory requirements. However, for risk assessment and communication, the response of packages to impacts that are more severe than the regulatory impact is required. Traditionally, the task of performing assessments of package response to impacts more severe than the regulatory ones has been performed in the U.S. by the Department of Energy national laboratories. These assessments have been both experimental and analytical. This paper will provide a brief history of extra-regulatory package impacts and then focus on recent analyses performed by Sandia National Laboratories for the U.S. NRC and the U.S. DOE. The analyses have been primarily in support of two large studies; “Reexamination of Spent Fuel Shipment Risk Estimates” and “Package Performance Study”. The first of these examined the response of four generic spent fuel casks to impacts onto rigid targets at speeds up to 53.6 m/s [120 mph]. The second examined the response of two certified spent fuel cask designs to impacts up to 33.5 m/s [75 mph]. Analyses have been performed for closure-end impacts, closure-end CG-over-corner impacts, and side impacts. The analyses and testing of packages to beyond regulatory impact standards has shown that the packages have a considerable margin of safety against release of radioactive material. This fact reinforces the adequacy of the packaging requirements of the U.S. NRC and IAEA and the methods currently used to certify that spent fuel casks meet these requirements. Of increasing concern to the transportation community is the response of the fuel assemblies themselves in both regulatory and extra-regulatory impacts. In risk assessments this information is needed to calculate the source term available for release.