Prompt Neutron Decay Constant in Esfahan Light Water Subcritical Reactor (ELWSCR): Comparison of Rossi-α Experiment and Monte Carlo Simulation

Rossi-α method is one of the useful techniques for diagnosis of subcritical nuclear reactors. In the present work, Rossi- α method was used to measure the prompt neutron decay constant of the reactor core of the Esfahan Light Water Subcritical Reactor (ELWSCR), and to drive the neutron chain reactions, a 252Cf neutron source was used. The experimental data in the form of the arrival time of the stochastic pulses were collected by a dedicated data acquisition system, and the required data were stored in a PC. Offline processing of the data was performed by the MATLAB software engineering tool, and Rossi distribution was extracted. Finally, by the curve fitting of Rossi distribution function to the processed data, the prompt neutron decay constant of the core was determined. Based on MCNPX code simulation, the reactor core was also studied. A comparison of the results obtained by the two methods shows a fairly good agreement.