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Objective:To confirm the transportation and evaporation efficiency of micro droplets sprayed by high-pressure nozzles from purified tritium-containing wastewater with carrier gas in the horizontal evaporation chamber.Methods:A scale test bench with a single high-pressure nozzle had been built based on design conditions and similarity criteria to explore the designed evaporation characteristics of generated micro droplets in the horizontal evaporation chamber. At the same time, combined with experimental data, a suitable evaporation model was constructed using the Discrete Phase Model (DPM) in Ansys Fluent. On this basis, further simulation and analysis were conducted on the evaporation process and efficiency under the condition of multiple nozzles in the desighed horizontal evaporation chamber.Results:For single nozzle tests, the particle size of micro droplets along the nozzle centerline was between 12-50 μm and the particle size distribution was similar to the Rosin-Rammler distribution. Besides, the relative light intensity decreased exponentially with distance, indicating that the particle size and concentration of micro droplets both decreased rapidly, which means the evaporation rate of micro droplets was rapid. For the simulation of multiple nozzles injection in the desighed horizontal evaporation chamber, even for the hardest design condition, the evaporation percentage reached up to 99%, and small amount of the escaping micro droplets continued to evaporate during the process of mixing with other process exhaust until complete evaporation in the vertical chimney section.Conclusions:Under the conditions of desighed sprayed particle size distribution, typical operating conditions and the incoming flow similar to the supposed area, the complete evaporation of the micro droplets can be basically achieved in the horizontal evaporation chamber, so as to ensure the complete evaporation of purified tritium-containing wastewater from the outlet of the chimney.
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Objective To establish a method for quantitative analysis of tiny amounts of tritium in hydrogen below the detection limit of isotope ratio mass spectrometer. Methods Hydrogen was oxidized to produce water in a self-developed catalytic oxidation device filled with platinum hydrophobic catalyst. The effects of different experimental conditions on hydrogen conversion rate were investigated. The tritium concentration in the synthetic water was measured using a liquid scintillation counter. The tritium concentration in hydrogen was calculated according to the measurement of the synthetic water. Results When the flow rate of hydrogen was fixed, the conversion rate of hydrogen increased with the increase of the reaction temperature but increased and then decreased with the increase of the flow rate of oxygen. Hydrogen could be completely converted under optimal experimental conditions. The hydrogen samples with volumetric tritium concentrations in the range of 1 × 10−7 to 2 × 10−14 were converted to water at the reaction temperature of 110 ℃ and hydrogen/oxygen flow rate of 100 mL/min. The resulting water was measured using a liquid scintillation counter. The measurement accuracy was better than 2%. Conclusion This method can be used to measure hydrogen samples with tiny amounts of tritium below the detection limit of isotope ratio mass spectrometer. Our results provide data support for the calculation of the separation capacity of cryogenic distillation process.
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Objective To explore the method for measurement of tritium in nuclear power plant liquid effluent purified by a mixed ion-exchange resin, to verify the feasibility of the method by experiments, and to provide technical support for the development of standard methods for the measurement of tritium in liquid effluent of nuclear power plants. Methods The purification effect of the mixed ion-exchange resin was determined by measuring the quenching factor, conductivity, and β-nuclide adsorption efficiency of the samples purified using the resin. A comparison was made between the ion-exchange resin method and the atmospheric distillation method for tritium determination. The precision and accuracy of the method were verified by calculating the relative standard deviation and the recovery in repeated measurement of samples with different activity concentrations and spiked samples. Results There were no significant differences in quenching factor, conductivity, and tritium activity concentration between the two methods. The adsorption efficiencies of EC20MB resin for common β-nuclides such as carbon, iron, nickel, strontium, yttrium, and cesium ranged from 99.28% to 99.88%. Repeated measurement of the same sample showed relative standard deviations of 5.2%-9.4% and recoveries of 86.8%-107%. Conclusion There were no significant differences between the results of the ion-exchange resin purification method and the atmospheric distillation method. The precision and accuracy of the method met the requirements of the ecological and environmental management authorities for monitoring tritium in liquid effluent from nuclear power plants. This method can be widely used in daily monitoring work.
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@#<b>Objective</b> To make the preparation method for coatings more convenient in the field where the requirements for tritium permeation resistance are not high, this paper proposes a method for preparing Al-Al<sub>2</sub>O<sub>3</sub> tritium permeation barriers by thermal spraying technology and conducts a performance analysis. <b>Methods</b> The tritium permeation resistance and adhesion of Al-Al<sub>2</sub>O<sub>3</sub> coatings prepared by thermal spraying were verified by experiments. <b>Results</b> The tritium permeability was reduced by one order of magnitude after a 0.2-mm Al-Al<sub>2</sub>O<sub>3</sub> coating was sprayed on the stainless steel surface, and the tritium permeation resistance had no significant improvement with the increase in coating thickness; the adhesion of the coating was determined in the range of 5-10 N by scratch tests. <b>Conclusion</b> In this paper, a simple preparation method for tritium permeation barrier is proposed, and the tritium permeation resistance performance of Al-Al<sub>2</sub>O<sub>3</sub> coatings prepared by thermal spraying technology is determined, which provides a reference for the selection of tritium permeation barrier in the field of tritium-containing solid waste storage.
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Objective:To explore the optimization of tritium internal exposure monitoring and dose estimation for radiation workers at pressurized heavy water reactor nuclear power plants (PHWR NPPs).Methods:A total of 92 radiation workers at Candu-6 PHWR NPPs were observed to calculate the distribution of quenching index (tSIE). Ten samples with tSIE values ranging from 160 to 460 were selected to make the blank urine quenching curve. By comparing with the quenching curve accompined with the equipment, the optimization of correlationship of urine tritium measurement system was carried out. In estimating tritium internal radiation dose, the dose coefficient was optimized and adjusted by comparing the Canadian algorithm with the national standard algorithm. Dead time correction curve was drawn by means of heavy water simulation experiment diluting main heat transfer system.Results:Through the analysis and optimization of tritium internal dose estimation, the optimal dose coefficient was determined to be 4.8 and the quenching curve of blank urine sample was made. By comparison, it was found that the deviation was larger when tSIE<200, which confirmed the necessity of blank curve. When the tritium concentration in urine was higher than 2.4×10 4 Bq/ml, the urine sample needed to be diluted and then measured to correct the effect of death time. Conclusions:By optimizing both tritium internal exposure monitoring and dose estimation, not only the collective dose management can be improved, but also the unplanned tritium intake can be detected and treated in time, which plays an important role in ensuring the protection and safety of the radiation workers at PHWR NPPs.
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@#<b>Objective</b> To discuss the selection of dose estimation methods for internal exposure to tritium, their applicable working scenarios, and accurate dose estimation. <b>Methods</b> We compared the process and formula of two methods of urine tritium concentration monitoring in estimating the committed effective dose, explained the limitations of the atmospheric tritium concentration monitoring method, and compared the three methods from the aspects of the application scope and measurement methods. <b>Results</b> The atmospheric tritium concentration monitoring and urine tritium concentration monitoring methods provided opposite results of the magnitude of the committed effective doses for persons 3 and 10. The mean of the absolute values of the percentages by which <i>E</i>(<i>τ</i>)<sub>1 </sub>values were higher than <i>E</i>(<i>τ</i>)<sub>3 </sub>values was 29.6%, and that of <i>E</i>(<i>τ</i>)<sub>2</sub> higher than <i>E</i>(<i>τ</i>)<sub>3 </sub>was 72.4%. The consistency between the reference man-based tritium dose estimation method and the atmospheric tritium concentration monitoring method was better. The atmospheric tritium concentration monitoring method tended to underestimate the committed effective dose of tritium. <b>Conclusion</b> We suggest urine tritium concentration monitoring for estimating the committed effective dose, rather than atmospheric tritium concentration monitoring. The use of the reference man-based tritium dose estimation method or urine tritium activity concentration integration method should be based on individual metabolic conditions, working environment, and intake time, and urine sampling should be on time and repeated for monitoring..
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The fusion neutron source based on Gas Dynamic Trap (GDT) device has the advantages of high neutron flux, large testing space and low construction cost, so it is an ideal solution for high-flux fusion volumetric neutron source. As a new type of radioactive facility, how to carry out radiation safety management under the current nuclear safety regulatory laws and regulations in China is an important issue that must be addressed before the construction of this facility. In this paper, the radiation safety characteristics of GDT fusion neutron source was analyzed and the main radiation terms of GDT fusion neutron source were expounded. Combined with the existing nuclear safety regulatory laws and regulations in China, the key points of radiation protection and safety management in the process of construction and application of GDT fusion neutron source were put forward. It is recommended that the GDT neutron source should be managed as a class I radiological device. Prior to operation, radiation safety permit and nuclear material permit should be obtained, and special attention should be paid to the safety protection of radioactive tritium. This study will pay the way for the radiation safety management of the international high flux fusion neutron source ALIANCE project, and also provide the reference for the related nuclear and radiation safety management departments in China.
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Tritium (3H) is an isotope of hydrogen. The main sources in the environment are natural tritium and artificial tritium.Artificially produced tritium appears as a by-product or a key fuel in the development of nuclear energy, and its release rate far exceeds that of natural tritium. The public's exposure to tritium in the environment is very low. Strategically speaking, the protection of tritium should focus on occupational exposure workers. This article briefly summarizes the nature, source, hazards, protection and pollution treatment of tritium, so that the public and radiation workers can understand relevant knowledge and do personal protection.
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OBJECTIVE To synthesize[3H]labelled trantinterol and determine the mass balance in rats and the profile of trantinterol and its metabolites in excreta. METHODS [3H]Trantinterol was synthesised from the intermediate1-(4-amino-3-chloro-5-trifluoromethyl-phenyl)-2-bromo-ethanone through reduction by sodium borotritide and aminolysis by t-butylamine. Following an oral dose of[3H] trantinterol(45.5 MBq·kg-1)to bile duct cannulated(BDC)rats and normal rats. Bile,urine and faeces were collected individually before and after dosing at different times. Liquid scintillation counter(LSC) was used to detect total radioactivity recovery and HPLC/radio-detector for metabolite profiling in urine and bile. RESULTS The majority(73.6%)of the administered radioactivity was recovered in the first 24 h postdose with 48.3%in urine and 25.4%in faeces. It was cumulated to(84.7±6.8)%till 168 h. In BDC rats,29.3%of the dose was recovered in the bile 3 d post-dose. According to the peak area ratio determined by HPLC/radio-detector,only 4.7%and 9.5%of the radioactive dose were excreted as the parent drug in urine and bile,respectively,while the majority of the remaining radioactivity was excreted in the form of various metabolites. CONCLUSION Following oral administration in rats,trantinterol is completely absorbed,extensively metabolized and rapidly excreted mainly in urine as various metabolites.
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Objective To design a new pre-treatment device and to evaluate its efficiency in order to monitor the tritium levels in biological samples.Methods The detection efficiency of tritium was determined with standard tritiated water.Recovery of tritiated water and organically bound tritium (OBT) were detected with high, medium and low activities of standard tritiated water and 3H-TdR (tritiated thymidine), respectively.Comparison of three kinds of biological samples using different pre-treatment devices was shown.Results The standard curve can be used in environmental tritium measurement and the detection efficiency for tritium was 23.3%.When 40.0 g rice with standard HTO or 3H-TdR was pretreated with this device, the average recovery of HTO and OBT was about 95.4% , which showed good reproducibility.The comparison results were similar.Conclusions The pre-treatment device can be used to survey the OBT in environmental biological samples.
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AIM To study the effects of vitamin E succinate (VES) on the cell growth and the DNA synthesis of human gastric carcinoma cell (SGC 7901). METHODS The growth curve was determined with counting viable cell numbers. The colony formations were counted with Giemsa dye staining. The cell cycle was analyzed using flow cytometry (FCM) and the DNA synthesis was observed with the 3H TdR incorporation method. RESULTS VES could inhibit the growth and colony formation of SGC 7901 cells. Growth curve display:after SGC 7901 cells were treated with 5 mg?L -1 、10 mg?L -1 and 20 mg?L -1 VES for seven days, the inhibition rate are 41 2%、98 3% and 100%, respectively. The colony formation of SGC 7901 cell at 24 h was inhibited 6 7%、50 4%、87 2%, and at 48 h was 24 7%、73 4%、100%, respectively. FCM analysis revealed that VES could decrease the percentage of cells in G 2 M phase after treated 48 h in a dose dependent manner, while increase the percentage of cells in S pheise. The assays of 3H TdR incorporation into DNA showed obvious inhibition dose dependently after exposure to VES for 48 h. CONCLUSION VES could inhibit gastric carcinoma cell growth by arresting DNA synthesis in vitro .