Estimation with Monte Carlo of thermal neutrons in the FANT, using 252Cf and 241Am/9Be neutron source.

The thermal neutron irradiation device (FANT), developed at the Neutron Measurements Laboratory of the Energy Engineering Department at Universidad Politécnica de Madrid, is a high-density polyethylene regular parallelepiped, with a rather uniform neutron fluence inside its irradiation chamber. It uses a A m 95 241 / B e 4 9 neutron source aiming to provide thermal neutron fluence rates. Neutron spectra and neutron fluences were estimated with Monte Carlo methods in the FANT irradiation chamber when a C f 98 252 neutron source is used and were compared with the results obtained with the A m 95 241 / B e 4 9 source. Regardless of the neutron source, the largest contribution is due to thermal neutrons, producing also epithermal and fast neutrons. Per neutron emitted by the source, the use of C f 98 252 produces a larger amount of neutrons. • 241Am/9Be neutron source. • Neutrons sources 241Am/9Be and 252Cf are moderated and scattered in the system. • 252Cf neutron source. • MCNP6.2 [ABSTRACT FROM AUTHOR]