The article provides outcomes of efforts taken by the specialists of radiation safety departments of Ukrainian Nuclear Power Plants （NPPs） to optimize and decrease exposure doses of personnel performing works during...The article provides outcomes of efforts taken by the specialists of radiation safety departments of Ukrainian Nuclear Power Plants （NPPs） to optimize and decrease exposure doses of personnel performing works during outages at NPP units. The article is written based on many years＇ experience and analysis of radiation hazardous works performed during scheduled maintenance of NPP equipment. It highlights significance of planning radiation doses （dose quotas） and organization of pending works during outages based on lessons learned. The results of works allowed to give due consideration to training of NPP maintenance personnel, improvement of labour conditions, workplace setup and enhancement of radiation protection means.展开更多
The paper presents a brief summary of the introduction of the term “practical elimination” as prevention of the conditions that could lead to early or large radioactive releases. The concept of “practical eliminat...The paper presents a brief summary of the introduction of the term “practical elimination” as prevention of the conditions that could lead to early or large radioactive releases. The concept of “practical elimination” is defined as part of the Defence in Depth (DiD) of Nuclear Power Plant (NPP) in the International Atomic Energy Agency (IAEA) document INSAG-12 in 1999. But, the special attention to it was paid after the accident in Fukushima NPP in 2011. The mechanisms of the containment failure of reactor WWER-1000/V320 are presented. As an example, the summarized design features and preventing and mitigation measures already implemented at Kozloduy NPP to extend the design basis and beyond design basis envelop are presented. Issues related to external steam explosion are underlined for further study.展开更多
This study aims to produce 229Th using an innovative nuclear reactor concept,i.e.,accelerator-driven system(ADS)reactor.Herein,we investigated the feasibility of producing 229Th from neutron transmutation of 226Ra to ...This study aims to produce 229Th using an innovative nuclear reactor concept,i.e.,accelerator-driven system(ADS)reactor.Herein,we investigated the feasibility of producing 229Th from neutron transmutation of 226Ra to expand the availability of 225Ac and 213Bi in a simple model of ADS reactor.ADS reactor comprises two zones,i.e.,an inner zone with a fast neutron spectrum and outer zone with thermal neutron spectrum,which is a subcritical core coupled with an external neutron source.Transmutation behavior,activity,and mass ratio of the obtained isotopes were investigated using the Monte-Carlo tool.In addition with offering the capability,flexibility,and safety of radioactive waste transmutation,the proposed ADS model provides high 229Th yield and requires less time than a critical reactor with the same neutron flux and irradiated quantity of 226Ra.展开更多
Critical submergence in pumping systems can be determined using a number of calculations, all of which result from heterogeneous geometries based on water. The most widely spread critical submergence formula is that o...Critical submergence in pumping systems can be determined using a number of calculations, all of which result from heterogeneous geometries based on water. The most widely spread critical submergence formula is that of the Hydraulic Institute. A study, carried out in Germany, looked at eight different formulations used to calculate critical submergence, comparing their results with those of a hydraulic model test. The conclusion is that the simplest models, overestimate the critical submergence. Similarly, a study of submergence in water intake structures concluded that predicted values were much higher than real values. A detailed analysis has been done to detect the origin of the off-set between the measured submergence and the calculated value. The main aspects selected from the analysis were the fluid properties involved in the surface deformation and the dynamic behavior outlet flow, so two a-dimensional numbers have been selected, Weber and Reynolds. To build an equation, to calculate the critical submergence, based on the mentioned a-dimensional numbers, a mixed technique (numerical and testing) has been used. The first step was driving a test in a hydraulic model to verify the critical submergence level. Then, a numerical model was built to simulate the same phenomenon and calibrate it, to be used in the future. After that, the second step is to simulate and calculate the critical submergence with other boundary condition (fluid, flow rate, pipe diameter). Once the critical submergence is calculated, a non-linear least squared approach has been developed to build the equation to calculate the critical submergence based on the Reynolds and Weber number. The numerical method used in this paper is a finite element model with a fluid volume scheme, used normally in the fluid simulation activities.展开更多
Based on fundamental research, we developed the basic scheme of a decontamination setup to remove acid gases (HCl, SO2, NOx) from steam-air flows with simultaneous localization of radioactive aerosols, including aeros...Based on fundamental research, we developed the basic scheme of a decontamination setup to remove acid gases (HCl, SO2, NOx) from steam-air flows with simultaneous localization of radioactive aerosols, including aerosols with a particle size of less than 0.1 μm and volatile radioactive iodine compounds. The decontamination process is based on the method of the agglomeration cocrystallization of finely dispersed and other aerosols in the gas phase by including the aerosols in the inner structure of large-particle non-radioactive aerosols of ammonium salts, for example, NH4Cl or (NH4)2SO3. For 137Cs, the most ecologically dangerous long-lived radionuclide, the setup ensures a decontamination factor of 102 to 103 in one decontamination stage. Because the setup consists of three consecutive stages of the same type, the cumulative decontamination factor can reach to 106 - 107. To localize radioactive iodine as I2, HI, HOI, HIO3, and CH3I from vapor-air flows, the setup uses a unit containing special granulated sorbents based on inorganic compounds. Developed at the Institute of Physical Chemistry, Russian Academy of Sciences, these sorbents effectively remove various radioactive iodine species (inorganic species and methyl iodide) from steam-air flows, ensuring decontamination factors of at least 104. The proposed technological scheme will allow vapor-gas flows to be cleaned of radioaerosols and all volatile radioactive iodine species at decontamination factors of not less than 104.展开更多
The Cydia pomonella granulovirus (CpGV) has been used for many years as biological agent for codling moth control in apple orchards. Resistance to the Mexican strain of CpGV was detected in orchards in Germany, France...The Cydia pomonella granulovirus (CpGV) has been used for many years as biological agent for codling moth control in apple orchards. Resistance to the Mexican strain of CpGV was detected in orchards in Germany, France and Italy. A laboratory insect colony was started from insects collected in a French resistant orchard. It was named RGV. Various virus isolates were identified as active against this resistant insect colony. Field tests were carried out in 2007 to test if the two virus isolates CpGV-I12 and NPP-R1 were effective in the field. Although these virus isolates were not able to reduce insect caused fruit damages, they significantly reduced the overwintering insect populations. NPP-R1 was subjected to eight passages on RGV larvae (NPP-R1.8) that improved its biological activity on RGV larvae. 2008 field trials were set up to test this improved virus strain, compared to CpGV-I12 and Madex plus active on RGV. These tests confirmed the ability to control both in susceptible and resistant insect populations.展开更多
Evaluation of radionuclide concentrations in foodstuffs is of great concern owing to the potential radiological hazards to human health. This study was carried out to assess the radionuclide concentrations of ^40K, ^1...Evaluation of radionuclide concentrations in foodstuffs is of great concern owing to the potential radiological hazards to human health. This study was carried out to assess the radionuclide concentrations of ^40K, ^134Cs, ^137Cs, ^131I, ^90Sr, ^239pu, in selected foodstuffs, in order to assess the effects of the elevated levels of radionuclides concentration in environmental media after the FDNPS （Fukushima Daiichi Nuclear Power Station） accident on imported food. HPGe （high purity germanium） detector based spectrometry system coupled with multi-channel analyzer was used for the assessment. The mean concentrations of ^40K, ^134Cs, ^137Cs, ^131I, ^90Sr, ^239pu, were found to be 50.1 ± 2.44 Bq/Kg, 109.6 ± 0.141 Bq/Kg, 134.2 ± 0.027 Bq/Kg, 2.57 ± 0.019 Bq/Kg, 0.59 ± 0.03 Bq/Kg, 0.160 ± 0.033 Bq/Kg, and 0.227 ± 0.021 Bq/Kg respectively. The analysis showed that the radioactivity levels of ^241Am, ^134Cs and ^137Cs were found to be relatively low and within the acceptable levels.展开更多
文摘The article provides outcomes of efforts taken by the specialists of radiation safety departments of Ukrainian Nuclear Power Plants （NPPs） to optimize and decrease exposure doses of personnel performing works during outages at NPP units. The article is written based on many years＇ experience and analysis of radiation hazardous works performed during scheduled maintenance of NPP equipment. It highlights significance of planning radiation doses （dose quotas） and organization of pending works during outages based on lessons learned. The results of works allowed to give due consideration to training of NPP maintenance personnel, improvement of labour conditions, workplace setup and enhancement of radiation protection means.
文摘The paper presents a brief summary of the introduction of the term “practical elimination” as prevention of the conditions that could lead to early or large radioactive releases. The concept of “practical elimination” is defined as part of the Defence in Depth (DiD) of Nuclear Power Plant (NPP) in the International Atomic Energy Agency (IAEA) document INSAG-12 in 1999. But, the special attention to it was paid after the accident in Fukushima NPP in 2011. The mechanisms of the containment failure of reactor WWER-1000/V320 are presented. As an example, the summarized design features and preventing and mitigation measures already implemented at Kozloduy NPP to extend the design basis and beyond design basis envelop are presented. Issues related to external steam explosion are underlined for further study.
基金supported by the International Center for Theoretical Physics and the Institute of International Education’s Scholar Rescue Fund.
文摘This study aims to produce 229Th using an innovative nuclear reactor concept,i.e.,accelerator-driven system(ADS)reactor.Herein,we investigated the feasibility of producing 229Th from neutron transmutation of 226Ra to expand the availability of 225Ac and 213Bi in a simple model of ADS reactor.ADS reactor comprises two zones,i.e.,an inner zone with a fast neutron spectrum and outer zone with thermal neutron spectrum,which is a subcritical core coupled with an external neutron source.Transmutation behavior,activity,and mass ratio of the obtained isotopes were investigated using the Monte-Carlo tool.In addition with offering the capability,flexibility,and safety of radioactive waste transmutation,the proposed ADS model provides high 229Th yield and requires less time than a critical reactor with the same neutron flux and irradiated quantity of 226Ra.
文摘Critical submergence in pumping systems can be determined using a number of calculations, all of which result from heterogeneous geometries based on water. The most widely spread critical submergence formula is that of the Hydraulic Institute. A study, carried out in Germany, looked at eight different formulations used to calculate critical submergence, comparing their results with those of a hydraulic model test. The conclusion is that the simplest models, overestimate the critical submergence. Similarly, a study of submergence in water intake structures concluded that predicted values were much higher than real values. A detailed analysis has been done to detect the origin of the off-set between the measured submergence and the calculated value. The main aspects selected from the analysis were the fluid properties involved in the surface deformation and the dynamic behavior outlet flow, so two a-dimensional numbers have been selected, Weber and Reynolds. To build an equation, to calculate the critical submergence, based on the mentioned a-dimensional numbers, a mixed technique (numerical and testing) has been used. The first step was driving a test in a hydraulic model to verify the critical submergence level. Then, a numerical model was built to simulate the same phenomenon and calibrate it, to be used in the future. After that, the second step is to simulate and calculate the critical submergence with other boundary condition (fluid, flow rate, pipe diameter). Once the critical submergence is calculated, a non-linear least squared approach has been developed to build the equation to calculate the critical submergence based on the Reynolds and Weber number. The numerical method used in this paper is a finite element model with a fluid volume scheme, used normally in the fluid simulation activities.
文摘Based on fundamental research, we developed the basic scheme of a decontamination setup to remove acid gases (HCl, SO2, NOx) from steam-air flows with simultaneous localization of radioactive aerosols, including aerosols with a particle size of less than 0.1 μm and volatile radioactive iodine compounds. The decontamination process is based on the method of the agglomeration cocrystallization of finely dispersed and other aerosols in the gas phase by including the aerosols in the inner structure of large-particle non-radioactive aerosols of ammonium salts, for example, NH4Cl or (NH4)2SO3. For 137Cs, the most ecologically dangerous long-lived radionuclide, the setup ensures a decontamination factor of 102 to 103 in one decontamination stage. Because the setup consists of three consecutive stages of the same type, the cumulative decontamination factor can reach to 106 - 107. To localize radioactive iodine as I2, HI, HOI, HIO3, and CH3I from vapor-air flows, the setup uses a unit containing special granulated sorbents based on inorganic compounds. Developed at the Institute of Physical Chemistry, Russian Academy of Sciences, these sorbents effectively remove various radioactive iodine species (inorganic species and methyl iodide) from steam-air flows, ensuring decontamination factors of at least 104. The proposed technological scheme will allow vapor-gas flows to be cleaned of radioaerosols and all volatile radioactive iodine species at decontamination factors of not less than 104.
基金supported by the French Research Agency (ANR-06-RIB-003-02) and by NPP
文摘The Cydia pomonella granulovirus (CpGV) has been used for many years as biological agent for codling moth control in apple orchards. Resistance to the Mexican strain of CpGV was detected in orchards in Germany, France and Italy. A laboratory insect colony was started from insects collected in a French resistant orchard. It was named RGV. Various virus isolates were identified as active against this resistant insect colony. Field tests were carried out in 2007 to test if the two virus isolates CpGV-I12 and NPP-R1 were effective in the field. Although these virus isolates were not able to reduce insect caused fruit damages, they significantly reduced the overwintering insect populations. NPP-R1 was subjected to eight passages on RGV larvae (NPP-R1.8) that improved its biological activity on RGV larvae. 2008 field trials were set up to test this improved virus strain, compared to CpGV-I12 and Madex plus active on RGV. These tests confirmed the ability to control both in susceptible and resistant insect populations.
文摘Evaluation of radionuclide concentrations in foodstuffs is of great concern owing to the potential radiological hazards to human health. This study was carried out to assess the radionuclide concentrations of ^40K, ^134Cs, ^137Cs, ^131I, ^90Sr, ^239pu, in selected foodstuffs, in order to assess the effects of the elevated levels of radionuclides concentration in environmental media after the FDNPS （Fukushima Daiichi Nuclear Power Station） accident on imported food. HPGe （high purity germanium） detector based spectrometry system coupled with multi-channel analyzer was used for the assessment. The mean concentrations of ^40K, ^134Cs, ^137Cs, ^131I, ^90Sr, ^239pu, were found to be 50.1 ± 2.44 Bq/Kg, 109.6 ± 0.141 Bq/Kg, 134.2 ± 0.027 Bq/Kg, 2.57 ± 0.019 Bq/Kg, 0.59 ± 0.03 Bq/Kg, 0.160 ± 0.033 Bq/Kg, and 0.227 ± 0.021 Bq/Kg respectively. The analysis showed that the radioactivity levels of ^241Am, ^134Cs and ^137Cs were found to be relatively low and within the acceptable levels.
