Analysis of correspondence between the current individual monitoring system of internal exposure caused by plutonium intake and the relevant ICRP recommendations

Abstract

Individual dosimetry monitoring of occupational internal exposure due to plutonium intake is performed by the bioassay method which measures the plutonium isotopes in daily urine samples. Then, to estimate normalized values (committed effective dose and intake), biokinetic and dosimetry models are used. The currently valid major instruments of radiation safety in the Russian Federation are based on the requirements and approaches outlined in Publications 68 and 78 of the International Commission on Radiobiological Protection. In implementing the requirements of Publication 130 there will be a need for updating the Russian guidance documents to the new requirements. The purpose of this study was the analysis of correspondence of the current system of individual monitoring of internal exposure caused by plutonium intake to the relevant recommendations of the International Commission on Radiobiological Protection outlined in Publication 130 by the example of the FSUE “Mayak PA” production conditions. As a result of the study, the values of annual limit of plutonium intake were determined based on new biokitetic and dosimetry models, and the measured values were calculated during the current dosimetry monitoring corresponding to the value of committed effective dose limit for Category A, B personnel and women under 45 years of age. It was found that following the introduction of new requirements of the International Commission on Radiobiological Protection for Type M compounds, an intake of more than 1/4 of annual limit of plutonium intake could be determined within a year after intake using the method of alpha spectrometry. To determine an intake of 1/20 of annual limit of intake at the recommended interval of 180 days between measurements, it is necessary to use inductively-coupled plasma mass spectrometry. For the personnel working with insoluble compounds of plutonium, an intake of one annual limit of intake and 1/4 of annual limit of intake can be determined using mass spectrometry, and 1/20 of annual limit of intake can be determined using only a more sensitive method.