Noise Method for Monitoring the Subcriticality in Accelerator-Driven Systems

In this paper, an absolute measurement technique for the subcriticality determination is presented. The development of A.D.S., requires of methods to monitor and control the subcriticality of this kind of systems, without interfering its normal operation mode. This method is based on the Stochastic Neutron and Photon Transport Theory developed by Munoz-Cobo et al, and which can be implemented in presently available neutron transport codes. As a by-product of the methodology a monitoring measurement technique has been developed and verified using two coupled Monte Carlo programs. The first one LAHET simulates the spallation collisions and the high energy transport and the other MCNP-DSP is used to estimate the counting statistics from neutron ray counter in fissile system, and the transport for neutrons with energies less than 20 MeV. With the coupling LAHET-MCNP-DSP has been checked that a subcriticality monitoring system, is feasible. Through the analysis of the counter detectors is possible to get the kinetics parameters and the Keff value.