Approbation of algorithms for a risk-based approach to the control of professional internal exposure to plutonium compounds

The relevance of the work is due to the need to improve the methods of control of professional internal exposure due to incorporated radionuclides with a long biological half-life. The aim of the work was to test a methodical document regulating the organization of internal exposure control due to plutonium based on a risk-based approach to limiting radiation exposure to personnel. The task of the work was a practical application of the method of interpretation of the results of individual dosimetric control in monitoring the annual increment of the lifetime excess risk of death from radiation-induced cancer. Materials and Methods : The control system is based on the principle of limiting the doses of radiation to plutonium storage organs, depending on the age at which the exposure occurred, and the permissible levels of plutonium exposure make it possible not to exceed the acceptable level of the radiation-related risk throughout the work experience. Based on an array of data from individual dosimetric monitoring of 44 employees of the Mayak production association, calculations of annual equivalent doses to critical organs were performed, and the radiation effect on personnel was estimated based on the expected effective dose. Results and Discussion : In most cases, during the control periods, admissions were recorded that led to the formation of internal radiation doses above the registration level. The registered values of the expected effective doses for fifty years, as well as the values of equivalent doses for critical organs, did not exceed the established limits. In seven cases, the equivalent doses to critical organs were higher than 60 mSv, while the annual excess risk for the year of control did not exceed 1 ×10 -3 . For all employees of the controlled group, no excess of the acceptable annual risk was recorded in any of the control periods. Conclusion : The completed test operation of the methodological guidelines showed the practical applicability of the methods described in the document, made it possible to identify the shortcomings of the tested approach and formulate proposals for improving the calculation algorithms.