Advantage of the area-ratio pulsed neutron source technique for ADS reactivity calibration

In this work, one shows the area-ratio pulsed neutron source (PNS) technique is as good candidate for reactivity calibration of accelerator-driven systems (ADS). Some properties of that method are discussed. One starts with a newly developed point-kinetics model that is able to simulate the PNS histogram experimentally obtained. The question of the convergence rate of the estimator based on that method is addressed. Some simulations that are in good agreements with experimental data reveal the convergence time is clearly longer than the flux stabilization time due to the delayed neutron. The sensitivity of the area-ratio estimator to the pulse width, the time discretization and the source strength variation is then explored. Finally, the initial model is extended to a reflected neutronic system. It is thus shown that the area-ratio reactivity estimator still provides satisfactory results in the core and reflector region.