Quasi - Differential Neutron Scattering Measurements of 238 U

Uranium-238 is used extensively in nuclear reactor cores. Its nuclear properties have a significant effect on many aspects of the entire fuel cycle process from enrichment facilities and power production to nuclear waste storage facilities. In order to safely design such systems, an accurate evaluation of neutron interactions with U is required. This paper describes a process of quantifying differences between evaluations through the energy-angle distribution of neutrons from scattering and fission of U using the Rensselaer Polytechnic Institute (RPI) neutron scattering system. Differential neutron scattering data are available in evaluated nuclear data libraries such as ENDF/B-VI.8 and VII.0 [1], JEFF-3.1 [2], and JENDL-4.0 [3] which often contain discrepancies. In order to compare the different evaluations, a benchmarking process was performed comparing experimental data to models. With this experiment, there are several factors that differentiate it from a typical double differential neutron scattering experiment [4]. The main factor was the use of a white neutron source that was incident onto the sample. In addition, multiple scattered elastic and inelastic interactions along with fission neutrons are produced by the U sample and recorded by the detectors. This increased the signal-to-background ratio, which reduced the statistical errors and accentuated library differences due to multiple interactions. This led to the terminology describing the experiment as quasi-differential neutron scattering [5].