Modified Fuchs-Nordheim model for use in reactor pulse measurements

Experimental reactor physics is constantly advancing new methods to determine parameters of interest in reactor systems. The development of analytical and semi-analytical solutions to characterize complex systems relies on the ability to isolate specific phenomena that may be represented by governing equations. Two values in particular, the delayed neutron fraction, β, and the prompt neutron lifetime, l, are directly related to the performance of a pulse-type reactor during a reactor transient. A great deal of research has been performed to determine these quantities with limited success, especially at high power conditions. The Fuchs-Nordheim model is capable of qualitatively predicting reactor power during the transient, but assumptions limit its ability to determine reactor kinetics parameters during the transient. A modification to the FN model is presented and compared with the FN model along with experimental data from the Oregon State University TRIGA reactor to independently measure of the β/l ratio of the OSTR experimentally with quantifiable uncertainty.