[en] In a reprocessing facility or a part of uranium fuel manufacturing facility where nuclear fuel solution is processed, one could frequently observe a series of power peaks with the first highest right after a criticality accident. The criticality alarm system (CAS) is designed to detect the first power peak and immediately warn workers around the reacting material by any means such as sounding alarms. Consequently, exposure of the workers could be minimized by an immediate and effective evacuation. Therefore in the design and installation of CAS, it is necessary to estimate the magnitude of the first power peak and to set up the threshold point for CAS initiating alarm. Furthermore, it is necessary to estimate the potential level of accidental exposure of workers so as to decide whether or not it is appropriate to install CAS for any compartment. In this report, simplified evaluation models to estimate the minimum scale of the first power peak and the released energy during a criticality accident are derived only by theoretical consideration for use in the design of CAS to set up the threshold point triggering the alarm signal. Other simplified evaluation models are in the same way derived to estimate the maximum scale of the first power peak and the released energy and to predict possible exposure level of workers to be used to judge the appropriateness of CAS installation. These evaluation models are shown to have adequate margin in predicting the minimum and maximum scale of criticality accidents by comparing their results with French CRAC experiment data. Furthermore, comparison of the maximum scale of the first power peak simplified evaluation, has been made with simulated results by the TRACE code based on the extrapolated conditions predicted by the CRAC experiment data to verify the effectiveness of the derived evaluation models