Monitoring of Subcriticality Level in Accelerator Driven Systems Harmonic Modulated Source - Spatial Source Jerk Intercomparison

Two subcriticality level measurement techniques for the Accelerator Driven Systems (ADS) are discussed. A spatial source-jerk approach is derived, and results are compared with those relative to the modulated source method. A numerical simulation of both methods is performed, and results indicate an evident analogy between the two methods, although the modulated source method allows on line reactivity measurement without the cut-off of the accelerator current. In addition, some indications may be derived about the most appropriate positions in the system, in order to obtain the absolute (in dollar units) fundamental reactivity value. (author)