Neutron tomography of nuclear fuel bundles

The ANL-W neutron radiography reactor offers a unique capability for the inspection of highly irradiated reactor fuels. Combined with the EGandG data processing capabilities, it has been demonstrated that useful images of 91-pin EBR-II fuel bundles can be obtained from 36 penetrating neutron radiographs. Neutron tomography of irradiated fuel bundles is an expensive form of nondestructive testing, and it would probably not find general application for examination of routine fuel bundles. However, there are safety tests being conducted on fuel bundles in which there is a very large capital investment, and the expected results warrant the cost of tomography. In these instances, the irradiation effects on the fuel under the deliberately induced severe operating conditions have caused very gross displacement of the internal components. These features would obviously be lost or disturbed during disassembly of the bundle. Neutron tomography thus becomes a valuable and effective way to study the relationship of these internal components prior to disassembly.