[en] In a process where the output of a radiation counting-rate meter actuates a relay, if the counting rate increases or decreases at a constant speed, the time when the output of the rate meter arrives at the relay threshold fluctuates and shifts from that expected from the mean output owing to the random radiation. From simulations of the process with a digital computer, it was found that the distribution of the time seemed to be of the Gaussian form, the mean value of which shifted to an earlier time than expected. The mean value and the standard deviation could be expressed as functions of the product of the increasing or decreasing velocity of the mean counting rate and the time constant of the rate meter. (author)