Fuel density, uranium enrichment, and performance studies for the Advanced Neutron Source reactor

Consistent with the words of the budget request for the Advanced Neutron Source (ANS), DOE commissioned a study of the impact on performance of using medium- or low-enriched uranium (MEU or LEU) in the fuel of the reactor that generates the neutrons. In the course of the study, performance calculations for 19 different combinations of reactor core volume, fuel density and enrichment, power level, and other relevant parameters were carried out. Since then, another 14 cases have been analyzed at Oak Ridge to explore some of the more interesting and important configurations and to gain further insights into the tradeoffs between performance and enrichment. Furthermore, with the aid of the data from these additional cases, we have been able to correlate the most important performance parameters (peak thermal neutron flux in the reflector and core life) with reactor power, fuel density, and fuel enrichment. This enables us to investigate intermediate cases, or alternative cases that might be proposed by people within or outside the project, without the time and expense of doing completely new neutronics calculations for each new example. The main drivers of construction and operating costs are the reactor power level and the number of fuel plates tomore » be fabricated each year; these quantities can be calculated from the correlations. The results show that the baseline two-element core design cannot be adapted to any practical fuel of greatly reduced enrichment without great performance penalties, but that a modification of the design, in which one additional fuel element is incorporated to provide extra volume for lower enrichment fuels, has the capability of using existing, or more advanced, fuel types to lower the uranium enrichment.« less