Complete release from regulatory control via the density of radioactive contamination of soil of the Chornobyl exclusion zone

Full text: In this work a general procedure of establishment the criterion of complete release from regulatory control via the density of radioactive contamination of soil of alone areas of the Chornobyl exclusion zone is represented by the following three stages, namely: 1) Justification of the dose criterion of complete release by applying the fundamental approaches of regulating the prolonged exposure of the public on a basement of ICRP Publication No. 82; 2) Justification of a procedure for establishment of dose constraint through evaluation of the statistical distribution of a controlled radiation value through determination of the high boundary of the confidence interval; 3) Generalization of conversion coefficients (via the density of radioactive contamination of soil) and coverage coefficients for the dose forming factors of the public (inhalation intake of transuranium radionuclides both at natural and technogenic dust resuspension, peroral intake of 137Cs and 90Sr via food stuff, external exposure from 137Cs); on a basis of these coefficients average doses and dose constraint of a critical group of the public are calculated. As it is shown in the work, the generalized criterion of complete release from regulatory control via the density of radioactive contamination of soil of the Chornobyl exclusion zone can be defined by dividing the recommended ICRP dose clearance level for situation of the post-accidental prolonged exposure of a critical group of the public, namely, 0.3 mSv·year-1 to the dose conversion coefficient (i.e. transfer from the superficial soil contamination of radioactivity to the dose constraint for the Chornobyl exclusion zone), namely, 12.9 μSv·year-1/((kBq·M-2). Thus, a level of the density of radioactive contamination of soil, that provides the complete release from regulatory control makes 23.3 kBq·M-2. For completion of the work on justification of the criterion of complete territory release in the conditions of prolonged post-accidental exposure it is actually needed to conduct additional calculations for more careful validation of constructing the total conversion coefficient, as well as its dynamics and the area of territories which do not meet this criterion. It is also necessary to develop and apply a certified method for monitoring of compliance of the territory to the established remediation criteria. (author)