Operational dosimetry solves the problem of implementing the principle of optimizing radiation safety, which is closely related to regulation and justification and implies a realistic achievable reduction in the dose load on a person when using ionizing radiation sources by reducing operating time, increasing the distance to radioactive material and shielding for attenuation of ionization flux. The article describes two ways of determining the thickness of shielding under necessity of making operational decision to protect a person from radionuclide source of known activity or the dose rate created by it. Based on the required multiplicity of its attenuation, which allows determining the number of half attenuation layers in the shield or its thickness, is also dependent on the energy of radiation, emitted by the source.
The purpose of the research is to develop an integrated technique for determining the effective dose (E) of external and internal exposure by different sources of ionizing radiation. The proposing technique for determining the total effective dose is based on three methods of calculation. The first one is multiplying the value of the individual dose equivalent H-p(10) by the factor of 0.642 to account for radiation shielding by various organs and tissues and its backscattering. The second method is multiplying H-p(10) by the conversion factor of air kerma in free air in a plate phantom, depending on the photon energy. The third method is multiplying H-p(10) by the sum of the radiosensitivity coefficients of various organs and tissues. As a result of research, a complex method was developed for determining the total effective dose, composed of doses of cosmic radiation, external gamma-, beta- and neutron radiation, internal exposure from radionuclides, including CDP of radon and thoron, entering the body through the organs of digestion and respiration. The proposed technique for determining the total effective dose allows one to take into account the comprehensive effect of ionizing radiation sources on a person and to obtain a more accurate measure of radiation risk than the existing methods provide.
Background: The main goal of experiments is to compare various operational and technical characteristics of D-Shuttle semiconductor personal dosimeters of the Japanese company âChiyoda Technol Corporationâ and Harshaw thermoluminescent dosimeters (TLD) manufactured by âThermo Fisher Scientificâ and DTL-02 of the Russian Research and Production Enterprise (RPE) âDozaâ by their occupational and calibration exposure at various dose equivalents from 0.5 to 20 mSv of gamma-radiation. Materials and Methods: Besides dosimeters DTL-02, D-Shuttle and Harshaw TLD, there were also used: (1) the primary reference radionuclide source Hopewell Designs IAEA: G10-1-12 with 137Cs isotope (an error is not more than 6% and activity is 20 Ci), and (2) the verification device UPGD-2M of RPE âDozaâ and installed in the National Center for Expertise and Certification of the Republic of Kazakhstan (Kapchagai, the National Center for Expertise and Certification). Results and Discussion: The main results of researches are the following: (1) TLDs for Harshaw 6600 and DVG-02TM have an approximately equal measurement accuracy of the individual dose equivalents in the range from 0.5 to 20 mSv of gamma-radiation. (2) Advantages of dosimeters for Harshaw 6600 are due to the high measurement productivity and opportunity to indicate the dose on the skin Hp(0.07). Advantages of DVG-02TM consist of operation simplicity and lower cost than of Harshaw 6600. (3) D-Shuttles are convenient for use in the current and the operational monitoring of ionizing radiation. Measurement accuracy and 10% linearity of measurements are ensured when D-Shuttle is irradiated with dose equivalents below 1 mSv at the equivalent dose rate not higher than 3 mSvâ hr-1. This allows using D-Shuttle at a routine technological activity. Conclusion: The obtained results of experiments demonstrate advantages and disadvantages of D-Shuttle semiconductor dosimeters in comparison with two TLD systems of DVG-02TM and Harshaw 6600. Keywords: Ionizing radiation, External irradiation, Dosimetry, Personal monitoring, Radiation protection, Thermoluminescent dosimeter, Semiconductor dosimeter, D-Shuttle, Harshaw 6600, DVG-02TM
The article describes the results of experiments conducted on pigs to determine the effect of plutonium, which is the most radiotoxic and highly active element in the range of mixed fuel (U0.8Pu0.2)O2 fission products, on living organisms. The results will allow empirical prediction of the emergency plutonium radiation dose for various organs and tissues of humans in case of an accident in a reactor running on mixed fuel (U0.8Pu0.2)O2.
Purpose: The purpose of this work is to describe the spectrometric analysis of gaseous cloud formation over reactor mixed uranium-and-plutonium (UP) fuel (U0.8Pu0.2)O-2 samples heated to a temperature > 2,000 degrees C, and thus forecast and evaluate radiation hazards threatening humans who cope with the consequences of any accident at a fission reactor loaded by UP mixed oxide (U0.8Pu0.2)O-2, such as a mixture of 80% U and 20% Pu in weight.Materials and methods: The UP nuclear fuel samples were heated up to a temperature of over 2,000 degrees C in a suitable assembly (apparatus) at out-of-pile experiments' implementation, the experimental in-depth study of metabolism of active materials in living organisms by means of artificial irradiation of pigs by plutonium. Spectrometric measurements were carried out on the different exposed organs and tissues of pigs for the further estimation of human internal exposure by nuclear materials released from the core of a fission reactor fueled with UP mixed oxide.Results: The main results of the research described are the following: (1) following the research on the influence of mixed fuel fission products (radioactive isotopes being formed during reactor operation as a result of nuclear decay of elements included into the fuel composition) on living organisms, the authors determined the quantities of plutonium dioxide (PuO2) that penetrated into blood and lay in the pulmonary region, liver, skeleton and other tissues; and (2) experiments confirmed that the output speed of plutonium out of the basic precipitation locations is very small. On the strength of the experimental evidence, the authors suggest that the biological output of plutonium can be disregarded in the process of evaluation of the internal irradiation doses.Conclusion: The main results of the research are useful for further evaluation of human accidental irradiation in the case of breakdown at fission reactors working on mixed nuclear fuel, and designing medical protection measures for persons irradiated by plutonium isotopes. Copyright (C) 2015, Published by Elsevier Korea LLC on behalf of Korean Nuclear Society.
International experience in nuclear energy safety issues shows that the in-pile tests of samples of various kinds of fuels (mixed, low-enriched, regenerated, etc.) involve considerable expenditure and present a higher radiation risk than out-of-pile experiments. The paper describes a facility that allows the out-of-pile investigation of nuclear fuels.
