I ABSTRACTObjectives: To examine the pattern of nontrauma cranial CT use in an urban ED, to identify the rate of significant CT abnormalities in this setting, and to develop criteria for restricting the ordering of CT scans. Methods: A prospective, observational study of a case series of adults who underwent cranial CT scanning for nontraumatic cases was performed at the EDs of an urban teaching hospital and an affiliated community hospital with a combined annual census of 110,000. Clinically significant CT scans were defined as: 1) acute stroke, 2) CNS malignancy, 3 ) acute hydrocephalus, 4) intracranial bleeding, or 5) intracranial infection. x2recursive partitioning was used to derive a decision rule to restrict ordering of CT scans. Results: Only 61 (8%) of 806 CT scans revealed clinically significant abnormalities. The presence of any of the following: age 260 years, focal neurologic deficit, headache with vomiting, or altered mental status, was 100% sensitive (95% CI: 94-100%) and 31% specific (95% CI: 28-33%) in detecting clinically significant CT scans. This set of features had positive and negative predictive values of 11% (95% CI: 8-13%) and 100% (95% C1: 98-loo%), respectively. If these criteria had been used to restrict cranial CT use, 229 fewer patients (28%) would have had CT scans obtained and no clinically significant abnormalities would have been missed. Conclusion: Clinically significant CT abnormalities were uncommon in this study population, suggesting that current criteria for ordering nontrauma cranial CT scans may be too liberal. In this study, a set of clinical criteria was derived that may be useful at separating patients into high-and low-risk categories for clinically significant cranial CT abnormalities. Before these results are applied clinically, these criteria should be validated in larger, prospective studies.

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Preliminary studies of used fuel generated in the US Department of Energy's Advanced Fuel Cycle Initiative have indicated that current used fuel transport casks may be insufficient for the transportation of said fuel. This work considers transport of three 5-year-cooled oxide advanced burner reactor used fuel assemblies with a burn-up of 160 MWD kg 21 . A transport cask designed to carry these assemblies is proposed. This design employs a 7-cm-thick lead gamma shield and a 20-cm-thick NS-4-FR composite neutron shield. The temperature profile within the cask, from its centre to its exterior surface, is determined by two-dimensional computational fluid dynamics simulations of conduction, convection and radiation within the cask. Simulations are performed for a cask with a smooth external surface and various neutron shield thicknesses. Separate simulations are performed for a cask with a corrugated external surface and a neutron shield thickness that satisfies shielding constraints. Resulting temperature profiles indicate that a threeassembly cask with a smooth external surface will meet fuel cladding temperature requirements but will cause outer surface temperatures to exceed the regulatory limit. A cask with a corrugated external surface will not exceed the limits for both the fuel cladding and outer surface temperatures.

Industry and safety standards demand the knowledge of the thermal behavior of systems subjected to fire, particularly for the transportation of radioactive materials for spent nuclear fuel disposal and reprocessing. Experimentally benchmarked fire test data from Container Analysis Fire Environment (CAFE) are used to calibrate the Sandia One Dimensional Direct and Inverse Thermal (SODDIT) code by optimizing number of future times (NFT) at 11 and identifying a linear correlation and uncertainty range between the SODDIT input and output. The calibration is then used to predict the heat flux to a large pipe calorimeter in a jet fuel fire, for which the result is an 11 second window average of the actual heat flux. The maximum heat flux occurred at the beginning of the fire and was found to be 195 ± 37.3 kW/m2 at a 95% confidence level.

Preliminary studies of used fuel generated in the US Department of Energy’s Advanced Fuel Cycle Initiative have indicated that current used fuel transport casks may be insufficient for the transportation of said fuel. This work considers transport of three 5-year-cooled oxide Advanced Burner Reactor used fuel assemblies with a burn-up of 160 MWD/kg. A transport cask designed to carry these assemblies is proposed. This design employs a 7-cm-thick lead gamma shield and a 20-cm-thick NS-4-FR composite neutron shield. The temperature profile within the cask, from its center to its exterior surface, is determined by two dimensional computational fluid dynamics simulations of conduction, convection, and radiation within the cask. Simulations are performed for a cask with a smooth external surface and various neutron shield thicknesses. Separate simulations are performed for a cask with a corrugated external surface and a neutron shield thickness that satisfies shielding constraints. Resulting temperature profiles indicate that a three-assembly cask with a smooth external surface will meet fuel cladding temperature requirements but will cause outer surface temperatures to exceed the regulatory limit. A cask with a corrugated external surface will not exceed the limits for both the fuel cladding and outer surface temperatures.