Enhancing the NCSU PULSTAR reactor excess reactivity utilizing beryllium

Separate experiments were performed to measure the reactivity worth of a beryllium reflector block on one side of the core of the PULSTAR reactor, and the excess reactivity gain from loading eight fresh fuel assemblies. In addition, assembly flux measurements were performed. The experimental results and estimates show that a 3.0%{Delta}k/k increase in excess reactivity is realizable with a combination of reflected core 5 x 5 No. 4 and five beryllium reflector blocks. An excess reactivity increase of this magnitude would extend the PULSTAR core life by {approximately} 13500 MWh or an additional 10 yr of operation at current utilization levels.