Experience on statistical analyses of occupational dose distributions in NPP EBO Jaslovske Bohunice

Our experience with the statistical analyses of occupational doses in NPP EBO confirmed that: 1) The assessment of annual individual and collective doses by using three methods of dose distributions shows small differences. The average values of annual effective doses for monitored persons are in the range of 1.4 to 2.0 mSv. LN distribution show lower values. 2) The LN distribution method gives significantly lower values of NRE and SRE. 3) Direct method and HLN distribution model provides practically the same results. According to Basic Safety Standards we suppose that 5 mSv could be an investigation level (instead of until now used three tenths of the basic limit, that is 15 mSv). This value is exceeded by less than ten percent of workers. The fraction of collective doses due to the effective doses higher than 5 mSv, reaches the value of about 50%. In the light of the given results one can see that the introduction of the reduced basic annual limits of effective dose (20 mSv/a), will not create a serious problem by organizing the work in NPP EBO. The fraction of the 'lost' collective effective doses, with respect to the chosen recording level of 0.1 mSv, does not exceed 2%. (author)