Advanced neutron source reactor dynamics calculations: Comparison with SPERT-II experimental results

This paper documents a series of benchmark calculations that compare the results of a dynamic model of the advanced neutron source (ANS) reactor against experimental data. The current ANS design employs a small, high-power density, split-core concept that will serve as a powerful neutron source for physics experiments and irradiation studies. To achieve these high neutron fluxes, the ANS core is cooled, moderated, and reflected by heavy water. A lumped-parameter dynamics model of the ANS system has been developed to assist in the design of the control and protection systems and to scope safety-related transients. The model is composed of three major modules: the core region, the reflector region, and the main cooling circuits. The purpose of this paper is to present results that compare model calculations with experimental results, specifically, the short period excursion reactor transient (SPERT) experiments. The SPERT tests, which most closely approximate conditions for the ANS reactor (i.e., closely packed fuel cooled and reflected by heavy water) are the SPERT-II experiments. The agreement between the present ANS model and the SPERT-II experiments is quite reasonable considering the single-phase flow limitation of the present model. Extending the validity of the present model via implementation of a simple,more » two-phase flow model is currently under consideration.« less