Giovanni Magrotti

A new diagnostic instrument to detect generalized roughness in rolling bearings for induction motors

In this paper the external stray flux around a motor has been investigated as a possible new diagnostic instrument to detect generalized roughness. This very common bearing fault has been slightly considered in the literature so far. Stray flux was measured by two probes, one commercially available and one realized in laboratory; the diagnostic content of both signals has been compared also with the measurement of the stator current. The experimental tests have been carried out on an induction motor by substituting one of its bearings with an artificially damaged one, according to three steps of progressive wear. The three measured variables have been analyzed in the frequency domain, by evaluating in particular the characteristic frequencies of the single-point bearing defects. The diagnostic content of the stray flux has been discovered as definitely higher with respect to the stator current and therefore its use to detect generalized roughness is promising.

A new model with Serpent for the first criticality benchmarks of the TRIGA Mark II reactor

Abstract We present a new model, developed with the Serpent Monte Carlo code, for neutronics simulation of the TRIGA Mark II reactor of Pavia (Italy). The complete 3D geometry of the reactor core is implemented with high accuracy and detail, exploiting all the available information about geometry and materials. The Serpent model of the reactor is validated in the fresh fuel configuration, through a benchmark analysis of the first criticality experiments and control rods calibrations. The accuracy of simulations in reproducing the reactivity difference between the low power (10 W) and full power (250 kW) reactor condition is also tested. Finally, a direct comparison between Serpent and MCNP simulations of the same reactor configurations is presented.

Study of a new Automatic Reactor Power Control for the TRIGA MARK II reactor at University of Pavia

The installation of a new Instrumentation and Control (I&C) system for the TRIGA MARK II reactor at University of Pavia has recently been completed in order to assure a safe and continuous reactor operation for the future. The intervention involved nearly the whole I&C system and required a channel-by-channel component substitution. One of the most sensitive part of the intervention concerned the Automatic Reactor Power Controller (ARPC) which permits to keep the reactor at an operator-selected power level acting on the control rod devoted to the fine regulation of system reactivity. This controller installed can be set up using different control logics: currently the system is working in relay mode. The main goal of the work presented in this paper is to set up a Proportional-Integral-Derivative (PID) configuration of the new controller installed on the TRIGA reactor of Pavia so as to optimize the response to system perturbations.