Loose Parts Monitoring signals in the control room of the nuclear power plant come in through multiple channels and are presented as graphs on the display devices. It involves a lengthy and complicated process to determine the size, mass, speed, and impact location of the loose part when the signals are collected and processed. In this work, a simple and efficient model for determining the impact location of the loose part using the Least-Sum-of-Square-Errors (LSSEs) method combined with iteration has been developed based on the phase distortion of the impact signal envelopes. The signal peak point shifts to the right on the time axis when the sensor is located farther away from the impact location. This method provides a good estimation of the impact location and can be used as an alternative to existing calculations based on other attributes of the impacting signal. To automate the backend portion of the LPMS algorithm, interpolation was used for compensating the impact attenuation effect and log-log regression was also employed to determine the impacting part size and impact velocity, and the result turned out to be well in line with the manual calculations. The automated algorithm will improve the efficiency of the LPMS software. (C) 2003 Published by Elsevier B.V.