Noise Method for Monitoring the Sub - Criticality in Accelerator Driven Systems

In this paper, an absolute measurements technique for the sub-criticality determination is presented. The development of ADS, requires of methods to monitor and control the sub-criticality of this kind of systems, without interfering it’s normal operation mode. This method is based on the Stochastic Neutron and Photon Transport Theory developed by Muñoz-Cobo et al. [1], 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 spallation collisions and the high-energy transport are simulated with LAHET. The neutrons transports with energies less than 20 MeV and the estimation of the count statistics for neutron and/or gamma ray counters in fissile systems, is simulated with MCNP-DSP. It is possible to get the kinetics parameters and the keff value of the sub-critical system through the analysis of the counter detectors.