Optimizing the performance of cold-neutron tomography for investigating annular flows and functional spacers in fuel rod bundles

In a previous study we used cold-neutron imaging to examine annular flows and the influence of functional spacers on such flows in a fuel bundle model. Investigating adiabatic, air–water annular flows in a scaled-up model of two neighboring subchannels of a BWR fuel assembly, we have shown that cold-neutron tomography is a promising tool to study such flows in nuclear fuel bundles. Here we try to optimize the performance of the method and examine the influence of certain parameters and modalities of the imaging on the quality and accuracy of the results.