Comparison of Photon and Neutron Radiation Dosimetric Systems Used in Organizations of Rosatom State Corporation for Control in A Planned Exposure Situation

Purpose: Using the example of reviewing and discussing the results of comparison tests of dosimetric systems of gamma and neutron radiation used in organizations of the State Corporation “Rosatom”, to assess the current state of reliability of monitoring the planned exposure of workers in fields of mixed gamma-neutron radiation using the considered dosimetric systems in order to produce recommendations for corrective actions to ensure a unified approach to conduct individual dosimetric control of external exposure.

Results: All measuring instruments for individual dose equivalent of photon and neutron radiation, presented in comparison tests, comply with up-to-date requirements for individual dosimetric control systems. All measuring instruments confirmed their measuring capabilities, showed satisfactory quality of measurement results and the absence of a systematic bias in the measurement results. Analysis of the results of measuring the individual dose equivalent of neutron radiation showed that problems affecting the quality of the results obtained were identified in the considered instruments of measuring personal dose equivalent. The following factors might be the sources of problems:

lack of knowledge about the real characteristics of radiation fields (spectral characteristics, radiation direction, etc.) at workplaces;

insufficient research of the method used for measuring neutron radiation under real conditions (technical and metrological characteristics and features of the individual dosimeters used);

failure to take into account the weighing coefficients for neutrons of various energies when measuring instruments are calibrated and when real measurements are conducted.

Conclusion: It is necessary to organize and conduct investigations of the metrological characteristics of the measuring instrument that are used under conditions typical for a specific radiation object. After finishing these experimental studies, it is recommended to test the methodology with an analysis of the compliance of the accuracy indicators with the requirements of the relevant guidelines. In order to solve the problem of a lack of knowledge about the real characteristics of radiation fields, radiation safety services of organizations are recommended to organize and conduct research aimed at studying such characteristics using radiometric and spectrometric methods, experimental modeling of the process of personnel exposure using anthropomorphic phantoms and determining correction factors for the individual dosimeters used.