[en] A statistical method for determining safety margin of nuclear power plants has been developed. Each nuclear plant has a number of characteristic parameters, defining nuclear safety, for example, neutron life time, reactivity margin or dropping time of scram system rods. For the parameters determined were their characteristic limiting values. To determine the nuclear safety dependence on characteristic parameters the distribution density was calculated. The results obtained were compared to the data on 60 safety parameters and on 15 characteristic parameters of approximately 400 research reactors. A possibility of calculated estimation of reactor safety is proved on the basis of statistical treatement of literature data. The method developed permits to formulate the recommendations for substantiation many parameters of reactor nuclear safety, which are more cancrete and objective as compared to the ones at present. It is noted, that because of insufficient statistics its general application is limited