β-ray-induced X-ray spectroscopy(BIXS)is a promising technique for tritium analysis that offers several unique advantages,including substantial detection depth,nondestructive testing capabilities,and ease of operatio...β-ray-induced X-ray spectroscopy(BIXS)is a promising technique for tritium analysis that offers several unique advantages,including substantial detection depth,nondestructive testing capabilities,and ease of operation.For thin solid tritium-containing samples with substrates,the currently used BIXS analysis method can measure the tritium depth profile and content when the sample thickness is known.In this study,a backpropagation(BP)neural network algorithm was used to predict the tritium content and thickness of a thin solid tritium-containing sample with substrates and a uniformly distributed tritium profile.A semi-analytical method was used to generate datasets for training and testing the BP neural network.A dataset ofβ-decay X-ray spectra from 420 tritium-containing zirconium models with different known thicknesses and tritium-tozirconium ratios was used as the input data.The corresponding zirconium thicknesses and tritium-to-zirconium ratios served as the output for training and testing the BP neural network.The mean relative errors(MREs)of the zirconium thickness in the training and test datasets were 0.56%and 0.42%,respectively,whereas the MREs of the tritium-to-zirconium ratio were 0.59%and 0.38%,respectively.Furthermore,the trained BP neural network demonstrates excellent predictive capability across various levels of statistical uncertainty.For the experimentalβ-decay X-ray spectra of two tritium-containing samples,the predicted zirconium thicknesses and tritium-to-zirconium ratios showed good agreement with the results obtained through the elastic backscattering spectrometry(EBS).展开更多
β-ray-induced X-ray spectroscopy(BIXS)is a promising method for tritium detection in solid materials because of its unique advantages,such as large detection depth,nondestructive testing capabilities,and low requirem...β-ray-induced X-ray spectroscopy(BIXS)is a promising method for tritium detection in solid materials because of its unique advantages,such as large detection depth,nondestructive testing capabilities,and low requirements for sample preparation.However,high-accuracy reconstruction of the tritium depth profile remains a significant challenge for this technique.In this study,a novel reconstruction method based on a backpropagation(BP)neural network algorithm that demonstrates high accuracy,broad applicability,and robust noise resistance is proposed.The average reconstruction error calculated using the BP network(8.0%)was much lower than that obtained using traditional numerical methods(26.5%).In addition,the BP method can accurately reconstruct BIX spectra of samples with an unknown range of tritium and exhibits wide applicability to spectra with various tritium distributions.Furthermore,the BP network demonstrates superior accuracy and stability compared to numerical methods when reconstructing the spectra,with a relative uncertainty ranging from 0 to 10%.This study highlights the advantages of BP networks in accurately reconstructing the tritium depth profile from BIXS and promotes their further application in tritium detection.展开更多
Beryllium(^(9)Be)serves as a crucial neutron multiplier and reflection material,being extensively employed in the nuclear industry.The evaluated nuclear data are utilized in the design of the nuclear devices.Following...Beryllium(^(9)Be)serves as a crucial neutron multiplier and reflection material,being extensively employed in the nuclear industry.The evaluated nuclear data are utilized in the design of the nuclear devices.Following the interaction between neutrons and^(9)Be,all neutrons generated stem from the^(9)Be(n,2n)^(8)Be reaction channel,except for the elastic scattering reaction channel.Nevertheless,the data of the outgoing neutron double differential cross section of the reaction channel provided by the latest internationally evaluated libraries still exhibit considerable discrepancies.A shielding integral experiment based on slab^(9)Be samples with measurements of neutron spectra leaked from different angles is an effective approach to verify the double differential cross-section data.Hence,in this study,a shielding integral experiment of^(9)Be samples of different thicknesses was conducted using a nanosecond pulsed deuterium-tritium neutron source established by the China Institute of Atomic Energy.The neutron time-of-flight spectra of three thicknesses(4.4 cm,8.8 cm,and 13.2 cm)and six angles(47°,58°,73°,107°,122°,and 133°)were measured by the neutron time-of-flight method,and 18 sets of experimental data were obtained.Additionally,the MCNP-4C program was used to obtain the simulated results of the leakage neutron spectra using the evaluated nuclear data of^(9)Be from the CENDL-3.2,ENDF/B-Ⅷ.0,JENDL-5,and JEFF-3.3 libraries.The simulated results of the leakage neutron spectra were compared with the experimental results,and the results showed that in the elastic scattering energy region,the simulated results from the CENDL-3.2,ENDF/B-Ⅷ.0,and JENDL-5 libraries were slightly higher at small angles and slightly lower at large angles.In the(n,2n)energy region,the simulated results from the CENDL-3.2 library were significantly different from the experimental results in terms of spectral shape,and the simulated results from the ENDF/B-Ⅷ.0 and the JENDL-5 libraries were in good agreement with the experimental results at small angles but low at large angles.The simulated results from the JEFF-3.3 library showed serious underestimation at all angles.展开更多
An efficient procedure for the synthesis of agmatine labelled with tritium and deuterium is reported. The final tritiated product 4 was obtained with a specific activity of 40 Ci/mmol and a radiochemical purity of 95%.
Tritium concentrations in precipitation can be used as a criterion to evaluate the tritium baseline of the environment. The tritium concentration in precipitation in Shanghai during 2014-2015 was determined. Values ra...Tritium concentrations in precipitation can be used as a criterion to evaluate the tritium baseline of the environment. The tritium concentration in precipitation in Shanghai during 2014-2015 was determined. Values ranged from 0.68 ± 0.04 to 4.11 ± 0.39 Bq/L, and it showed a decreasing trend compared with historical data; however,the values were slightly higher than the natural background tritium level. Additionally, the tritium concentration shows a seasonal variation: It was higher in autumn and winter and lower in summer and spring. A comparison of concentrations in precipitation in Shanghai and around the Qinshan Nuclear Power Plant reveals no correlation,implying that the nuclear power plant operations may not affect the environment of Shanghai. Thus, the raised tritium concentrations in Shanghai might be due to the effects of monsoons, spring leak, raindrop, or other activities that generate tritium there. Those activities may include chemistry research that uses tritium as a tracer.展开更多
Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substr...Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substrate, but also changes the properties of the material. In this study,finite element analysis was used to investigate the relationship between the residual thermal stress and the mechanical properties of Al_2O_3 tritium penetration barrier systems. Moreover, the residual thermal stress influenced by factors such as different substrates, temperature, and substrate roughness was also analyzed. The calculation showed that the hardness and elastic modulus increased with increasing compressive stress. However, the hardness and elastic modulus decreased with increasing tensile stress. The systems composed of Al_2O_3 coatings and different substrates exhibited different trends in mechanical properties. As the temperature increased, the hardness and the elastic modulus increased in an Al_2O_3/316 L stainless steel system; the trend was opposite in an Al_2O_3/Si system.Apart from this, the roughness of the substrate surface in the system could magnify the change in hardness and elastic modulus of the coating. Results showed that all these factors led to variation in the mechanical properties of Al_2O_3 tritium permeation barrier systems. Thus, thedetailed reasons for the changes in mechanical properties of these materials need to be analyzed.展开更多
Tritium release is one of the most concerning topics in nuclear power plants. Here, the tritium production in a 2 MW liquid-fueled molten salt experimental reactor(TMSR-LF1) was calculated by ORIGEN-S with an updated ...Tritium release is one of the most concerning topics in nuclear power plants. Here, the tritium production in a 2 MW liquid-fueled molten salt experimental reactor(TMSR-LF1) was calculated by ORIGEN-S with an updated cross-section library generated by TRITON in SCALE 6.1.3 code system. The results show that the tritium production rate and normalized tritium production rate of TMSR-LF1 are 8.90x10^(11)Bq/day and4.45x10^(11)Bq/(MW day), respectively. The environmental impact of tritium was analyzed via PC-CREAM 08 with an assumed 36 % release rate of tritium referring to the molten salt reactor experiment. During normal operations, the maximum tritium concentration is 1.4 Bq/m^3 under normal condition, and the corresponding individual dose to the public is about 1 μSv/a; under extreme conditions, the maximum concentration and corresponding individual doses are 11.8 Bq/m^3 and 9 μSv/a, respectively.Ingestion is the main exposure pathway and accounts for62 % of the total dose. Of this, 35 % is from organically bound tritium.展开更多
A method of measuring the tritium in seawater based on electrolytic enrichment and ultra-low background liquid scintillation counting techniques was established.The different factors influencing the detection limit we...A method of measuring the tritium in seawater based on electrolytic enrichment and ultra-low background liquid scintillation counting techniques was established.The different factors influencing the detection limit were studied,including the counting time,the electrolytic volume of the seawater samples,the selection of background water,scintillation solution and their ratio.After optimizing the parameters and electrolyzing 350 mL volume of samples,the detection limit of the method was as low as 0.10 Bq/L.In order to test the optimization of system for this method,of the 84 seawater samples collected from the Arctic Ocean we measured,92%were above the detection limit(the activity of this samples ranged from 0.10 Bq/L to 1.44 Bq/L with an average of(0.30±0.24)Bq/L).In future research,if we need to accurately measure the tritium activity in samples,the volume of the electrolytic samples will be increased to further reduce the minimum detectable activity.展开更多
A series of Ti-Zr-Hf-Mo-Nb high-entropy alloys with different Mo concentrations were developed as candidate materials for hydrogen/tritium storage in solid phase.The crystal structures and hydrogenation properties of ...A series of Ti-Zr-Hf-Mo-Nb high-entropy alloys with different Mo concentrations were developed as candidate materials for hydrogen/tritium storage in solid phase.The crystal structures and hydrogenation properties of the Ti-Zr-Hf-Mo-Nb alloys were investigated by X-ray diffraction and differential scanning calorimetry techniques.All the alloys have a body-centred cubic single phase structure.The results demonstrate that the cell volume of the Ti-Zr-Hf-Mo-Nb hydride decreases with increasing Mo concentration,which reduces their thermal stability.The theoretical calculation proposes that the lower binding energy of the Ti-Zr-Hf-Mo-Nb hydride decreases the thermal stability of Ti-Zr-Hf-Mo-Nb alloys with higher Mo content.The great hydrogenation performance for all the Ti-Zr-Hf-Mo-Nb alloys is owing to their reversible single-phase transformation during the hydrogen absorption-desorption cycle,which would be bene ficial to improving the hydrogen recycling rate and preventing the disproportionation.The compositional dependence of the hydrogenation performance of the Ti-Zr-Hf-Mo-Nb alloys was established and will be useful in designing novel hydrogen/tritium storage materials to satisfy the requirements of diffe rent application fields in hydrogen,solar thermal and nuclear energy.展开更多
For a more systematic understanding of the levels of environmental tritium and its behavior in East Asia,a database on environmental tritium was established based on the literature published in the past 30 years.Subse...For a more systematic understanding of the levels of environmental tritium and its behavior in East Asia,a database on environmental tritium was established based on the literature published in the past 30 years.Subsequently,the levels and behavior of the environmental tritium were further studied by statistical analyses.The results indicate that the distribution of environmental tritium is inhomogeneous and complex.In areas without nuclear facilities,the level of environmental tritium has decreased to its background level,even though a certain number of atmospheric nuclear tests were performed before 1980.In general,the level of atmospheric tritium was marginally higher than the levels in precipitation and surface water;the levels in shallow groundwater and seawater were considerably lower.Furthermore,the levels of tritium in the atmosphere,precipitation,and inland surface water were strongly correlated with latitude and distance from the coastline.In soil and living organisms,the level of tissue-free water tritium(TFWT)was comparable to the tritium levels in local rainfall,whereas the persistence of organically bound tritium(OBT)in the majority of organisms resulted in an OBT/TFWT ratio greater than one.Conversely,extremely high levels of environmental tritium were observed near certain nuclear power plants and the Fukushima accident sites.These results highlight the requirement to know the tritium baseline level and its behavior in the environment beforehand to better assess the impact of tritium discharge.Further investigations of environmental tritium in East Asia using more efficient and adequate monitoring methods are also required.展开更多
La_((1-x))Mg_xNi_(4.25)Al_(0.75)(x = 0.0, 0.1, 0.2, 0.3)alloys for tritium storage were prepared by a method of electromagnetic induction melting. The crystal structure and hydrogen storage performance of the as-cast ...La_((1-x))Mg_xNi_(4.25)Al_(0.75)(x = 0.0, 0.1, 0.2, 0.3)alloys for tritium storage were prepared by a method of electromagnetic induction melting. The crystal structure and hydrogen storage performance of the as-cast alloys were investigated. The results showed that a single phase of La Ni_4Al was in the alloys with x = 0.0 and 0.1 and that LaNi_4Al and second phase of(La,Mg)Ni)_3 and AlNi_3 were in the alloys with x = 0.2 and 0.3. On the other hand, the plateau pressures of P–C isotherms of the alloys were increased with the rise of the x value from 0.2 to 0.3 and the hydrogen storage capacity was obviously degraded simultaneously. It was found that the alloy had faster absorption kinetics as the proportion of Mg increased from 0.1 to 0.3.展开更多
In this study,the effects of changing first wall materials and their thicknesses on a reactor were investigated to determine the displacement per atom(DPA)and gas production(helium and hydrogen)in the first wall,as we...In this study,the effects of changing first wall materials and their thicknesses on a reactor were investigated to determine the displacement per atom(DPA)and gas production(helium and hydrogen)in the first wall,as well as the tritium breeding ratio(TBR)in the coolant and tritium breeding zones.Therefore,the modeling of the magnetic fusion reactor was determined based on the blanket parameters of the International Thermonuclear Experimental Reactor(ITER).Stainless steel(SS 316 LNIG),Oxide Dispersion Strengthened Steel alloy(PM2000 ODS),and China low-activation martensitic steel(CLAM)were used as the first wall(FW)materials.Fluoride family molten salt materials(FLiBe,FLiNaBe,FLiPb)and lithium oxide(LiO_(2))were considered the coolant and tritium production material in the blanket,respectively.Neutron transport calculations were performed using the wellknown 3D code MCNP5 using the continuous-energy Monte Carlo method.The built-in continuous energy nuclear and atomic data libraries along with the Evaluated Nuclear Data file(ENDF)system(ENDF/B-V and ENDF/B-VI)were used.Additionally,the activity cross-section data library CLAW-IV was used to evaluate both the DPA values and gas production of the first wall(FW)materials.An interface computer program written in the FORTRAN 90 language to evaluate the MCNP5 outputs was developed for the fusion reactor blanket.The results indicated that the best TBR value was obtained for the use of the FLiPb coolant,whereas depending on the thickness,the first wall replacement period in terms of radiation damage to all materials was between 6 and 11 years.展开更多
The triple-to-double coincidence ratio （TDCR） method of liquid scintillation count- ing is an absolute measurement method of radioactivity. The formulation of the TDCR method and the established TDCR liquid scintill...The triple-to-double coincidence ratio （TDCR） method of liquid scintillation count- ing is an absolute measurement method of radioactivity. The formulation of the TDCR method and the established TDCR liquid scintillation counter are presented in this paper. The NIST standard reference material （SRM） of tritium water was measured to verify the performance of the TDCR liquid scintillation counter.展开更多
Tritium real-time measurement in glovebox or workplace is important to ensure safe operation of tritium. A novel tritium monitor system including an open-walled ionization chamber, an electrometer and an IPC(Industria...Tritium real-time measurement in glovebox or workplace is important to ensure safe operation of tritium. A novel tritium monitor system including an open-walled ionization chamber, an electrometer and an IPC(Industrial Personal Computer) has been developed to measure tritium in gaseous form. Using mesh walls, instead of sealed wall, the open-walled ionization chamber has less tritium absorption and lower memory effect. In addition, tritium gas can diffuse into the chamber's sensitive region without the assistant of sampling system and ion trap, which are installed at the front-end of commonly used flow-through ionization chambers. Background signal of this monitor system is about 3.7 × 105Bq/m3, and after exposed to tritium concentration at about 1011Bq/m3 for 4h, background of the monitor can recover after purging it several times with dry air. It is suitable for longtime tritium measurements in both glovebox and workplace.展开更多
Salt-resistant Bacillus strains, isolated from agricultural soils in Uzbekistan, were tested for degradation activity towards a mixture of polychlorinated biphenyls (PCBs) under aerobic conditions. The study employed ...Salt-resistant Bacillus strains, isolated from agricultural soils in Uzbekistan, were tested for degradation activity towards a mixture of polychlorinated biphenyls (PCBs) under aerobic conditions. The study employed the use of tritium labeled PCB congeners and traced the tritium label in cultures with high salt content. The experiments show that most of the selected strains were able to adsorb a part of the radioactivity, indicating transformation of the added PCBs. Gas chromatography demonstrated transformation of PCBs. The radioactive label was removed from several cultures by up to 91%, indicating also mineralization of PCBs. The study suggests that the isolated strains might be good candidates for the bioremediation of contaminated high-salt soils in Uzbekistan and other Central-Asian countries.展开更多
基金supported by the National Natural Science Foundation of China(No.12175158)the Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics(No.HG2022022)。
文摘β-ray-induced X-ray spectroscopy(BIXS)is a promising technique for tritium analysis that offers several unique advantages,including substantial detection depth,nondestructive testing capabilities,and ease of operation.For thin solid tritium-containing samples with substrates,the currently used BIXS analysis method can measure the tritium depth profile and content when the sample thickness is known.In this study,a backpropagation(BP)neural network algorithm was used to predict the tritium content and thickness of a thin solid tritium-containing sample with substrates and a uniformly distributed tritium profile.A semi-analytical method was used to generate datasets for training and testing the BP neural network.A dataset ofβ-decay X-ray spectra from 420 tritium-containing zirconium models with different known thicknesses and tritium-tozirconium ratios was used as the input data.The corresponding zirconium thicknesses and tritium-to-zirconium ratios served as the output for training and testing the BP neural network.The mean relative errors(MREs)of the zirconium thickness in the training and test datasets were 0.56%and 0.42%,respectively,whereas the MREs of the tritium-to-zirconium ratio were 0.59%and 0.38%,respectively.Furthermore,the trained BP neural network demonstrates excellent predictive capability across various levels of statistical uncertainty.For the experimentalβ-decay X-ray spectra of two tritium-containing samples,the predicted zirconium thicknesses and tritium-to-zirconium ratios showed good agreement with the results obtained through the elastic backscattering spectrometry(EBS).
基金supported by the National Key Research and Development Program of China(No.2022YFE03170003)the National Natural Science Foundation of China(Nos.12305403 and 12275243).
文摘β-ray-induced X-ray spectroscopy(BIXS)is a promising method for tritium detection in solid materials because of its unique advantages,such as large detection depth,nondestructive testing capabilities,and low requirements for sample preparation.However,high-accuracy reconstruction of the tritium depth profile remains a significant challenge for this technique.In this study,a novel reconstruction method based on a backpropagation(BP)neural network algorithm that demonstrates high accuracy,broad applicability,and robust noise resistance is proposed.The average reconstruction error calculated using the BP network(8.0%)was much lower than that obtained using traditional numerical methods(26.5%).In addition,the BP method can accurately reconstruct BIX spectra of samples with an unknown range of tritium and exhibits wide applicability to spectra with various tritium distributions.Furthermore,the BP network demonstrates superior accuracy and stability compared to numerical methods when reconstructing the spectra,with a relative uncertainty ranging from 0 to 10%.This study highlights the advantages of BP networks in accurately reconstructing the tritium depth profile from BIXS and promotes their further application in tritium detection.
基金supported by the National Natural Science Foundation of China(Nos.11775311,U2167203,U2067205 and 12075105)Research and development project of China National Nuclear Corporation(FD010241222552)+2 种基金Continuous-Support Basic Scientific Research Project(BJ010261223282)Major Science and Technology Projects of Gansu Province(22ZD6GB020)Fundamental Research Funds for the Central Universities(lzujbky-2024-jdzx10)。
文摘Beryllium(^(9)Be)serves as a crucial neutron multiplier and reflection material,being extensively employed in the nuclear industry.The evaluated nuclear data are utilized in the design of the nuclear devices.Following the interaction between neutrons and^(9)Be,all neutrons generated stem from the^(9)Be(n,2n)^(8)Be reaction channel,except for the elastic scattering reaction channel.Nevertheless,the data of the outgoing neutron double differential cross section of the reaction channel provided by the latest internationally evaluated libraries still exhibit considerable discrepancies.A shielding integral experiment based on slab^(9)Be samples with measurements of neutron spectra leaked from different angles is an effective approach to verify the double differential cross-section data.Hence,in this study,a shielding integral experiment of^(9)Be samples of different thicknesses was conducted using a nanosecond pulsed deuterium-tritium neutron source established by the China Institute of Atomic Energy.The neutron time-of-flight spectra of three thicknesses(4.4 cm,8.8 cm,and 13.2 cm)and six angles(47°,58°,73°,107°,122°,and 133°)were measured by the neutron time-of-flight method,and 18 sets of experimental data were obtained.Additionally,the MCNP-4C program was used to obtain the simulated results of the leakage neutron spectra using the evaluated nuclear data of^(9)Be from the CENDL-3.2,ENDF/B-Ⅷ.0,JENDL-5,and JEFF-3.3 libraries.The simulated results of the leakage neutron spectra were compared with the experimental results,and the results showed that in the elastic scattering energy region,the simulated results from the CENDL-3.2,ENDF/B-Ⅷ.0,and JENDL-5 libraries were slightly higher at small angles and slightly lower at large angles.In the(n,2n)energy region,the simulated results from the CENDL-3.2 library were significantly different from the experimental results in terms of spectral shape,and the simulated results from the ENDF/B-Ⅷ.0 and the JENDL-5 libraries were in good agreement with the experimental results at small angles but low at large angles.The simulated results from the JEFF-3.3 library showed serious underestimation at all angles.
文摘An efficient procedure for the synthesis of agmatine labelled with tritium and deuterium is reported. The final tritiated product 4 was obtained with a specific activity of 40 Ci/mmol and a radiochemical purity of 95%.
文摘Tritium concentrations in precipitation can be used as a criterion to evaluate the tritium baseline of the environment. The tritium concentration in precipitation in Shanghai during 2014-2015 was determined. Values ranged from 0.68 ± 0.04 to 4.11 ± 0.39 Bq/L, and it showed a decreasing trend compared with historical data; however,the values were slightly higher than the natural background tritium level. Additionally, the tritium concentration shows a seasonal variation: It was higher in autumn and winter and lower in summer and spring. A comparison of concentrations in precipitation in Shanghai and around the Qinshan Nuclear Power Plant reveals no correlation,implying that the nuclear power plant operations may not affect the environment of Shanghai. Thus, the raised tritium concentrations in Shanghai might be due to the effects of monsoons, spring leak, raindrop, or other activities that generate tritium there. Those activities may include chemistry research that uses tritium as a tracer.
文摘Residual thermal stress in the system is a serious problem that affects the application of tritium permeation barrier coatings in fusion reactors. The stress not only determines the adhesion between coating and substrate, but also changes the properties of the material. In this study,finite element analysis was used to investigate the relationship between the residual thermal stress and the mechanical properties of Al_2O_3 tritium penetration barrier systems. Moreover, the residual thermal stress influenced by factors such as different substrates, temperature, and substrate roughness was also analyzed. The calculation showed that the hardness and elastic modulus increased with increasing compressive stress. However, the hardness and elastic modulus decreased with increasing tensile stress. The systems composed of Al_2O_3 coatings and different substrates exhibited different trends in mechanical properties. As the temperature increased, the hardness and the elastic modulus increased in an Al_2O_3/316 L stainless steel system; the trend was opposite in an Al_2O_3/Si system.Apart from this, the roughness of the substrate surface in the system could magnify the change in hardness and elastic modulus of the coating. Results showed that all these factors led to variation in the mechanical properties of Al_2O_3 tritium permeation barrier systems. Thus, thedetailed reasons for the changes in mechanical properties of these materials need to be analyzed.
文摘Tritium release is one of the most concerning topics in nuclear power plants. Here, the tritium production in a 2 MW liquid-fueled molten salt experimental reactor(TMSR-LF1) was calculated by ORIGEN-S with an updated cross-section library generated by TRITON in SCALE 6.1.3 code system. The results show that the tritium production rate and normalized tritium production rate of TMSR-LF1 are 8.90x10^(11)Bq/day and4.45x10^(11)Bq/(MW day), respectively. The environmental impact of tritium was analyzed via PC-CREAM 08 with an assumed 36 % release rate of tritium referring to the molten salt reactor experiment. During normal operations, the maximum tritium concentration is 1.4 Bq/m^3 under normal condition, and the corresponding individual dose to the public is about 1 μSv/a; under extreme conditions, the maximum concentration and corresponding individual doses are 11.8 Bq/m^3 and 9 μSv/a, respectively.Ingestion is the main exposure pathway and accounts for62 % of the total dose. Of this, 35 % is from organically bound tritium.
基金The project sponsored by the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources,under contract No.2020012the Join Project of Xiamen Marine Research and Development Institute under contract No.K191301.
文摘A method of measuring the tritium in seawater based on electrolytic enrichment and ultra-low background liquid scintillation counting techniques was established.The different factors influencing the detection limit were studied,including the counting time,the electrolytic volume of the seawater samples,the selection of background water,scintillation solution and their ratio.After optimizing the parameters and electrolyzing 350 mL volume of samples,the detection limit of the method was as low as 0.10 Bq/L.In order to test the optimization of system for this method,of the 84 seawater samples collected from the Arctic Ocean we measured,92%were above the detection limit(the activity of this samples ranged from 0.10 Bq/L to 1.44 Bq/L with an average of(0.30±0.24)Bq/L).In future research,if we need to accurately measure the tritium activity in samples,the volume of the electrolytic samples will be increased to further reduce the minimum detectable activity.
基金The author, Huahai Shen is grateful for support from the President’s Foundation of the China Academy of Engineering Physics(No.YZJJLX2018003)the National Natural Science Foundation of China(No.21601168)support from the Joint Funds of the National Natural Science Foundation of China(No.U1930120)。
文摘A series of Ti-Zr-Hf-Mo-Nb high-entropy alloys with different Mo concentrations were developed as candidate materials for hydrogen/tritium storage in solid phase.The crystal structures and hydrogenation properties of the Ti-Zr-Hf-Mo-Nb alloys were investigated by X-ray diffraction and differential scanning calorimetry techniques.All the alloys have a body-centred cubic single phase structure.The results demonstrate that the cell volume of the Ti-Zr-Hf-Mo-Nb hydride decreases with increasing Mo concentration,which reduces their thermal stability.The theoretical calculation proposes that the lower binding energy of the Ti-Zr-Hf-Mo-Nb hydride decreases the thermal stability of Ti-Zr-Hf-Mo-Nb alloys with higher Mo content.The great hydrogenation performance for all the Ti-Zr-Hf-Mo-Nb alloys is owing to their reversible single-phase transformation during the hydrogen absorption-desorption cycle,which would be bene ficial to improving the hydrogen recycling rate and preventing the disproportionation.The compositional dependence of the hydrogenation performance of the Ti-Zr-Hf-Mo-Nb alloys was established and will be useful in designing novel hydrogen/tritium storage materials to satisfy the requirements of diffe rent application fields in hydrogen,solar thermal and nuclear energy.
基金supported by the National Natural Science Foundation of China(Nos.11375048 and 11775053).
文摘For a more systematic understanding of the levels of environmental tritium and its behavior in East Asia,a database on environmental tritium was established based on the literature published in the past 30 years.Subsequently,the levels and behavior of the environmental tritium were further studied by statistical analyses.The results indicate that the distribution of environmental tritium is inhomogeneous and complex.In areas without nuclear facilities,the level of environmental tritium has decreased to its background level,even though a certain number of atmospheric nuclear tests were performed before 1980.In general,the level of atmospheric tritium was marginally higher than the levels in precipitation and surface water;the levels in shallow groundwater and seawater were considerably lower.Furthermore,the levels of tritium in the atmosphere,precipitation,and inland surface water were strongly correlated with latitude and distance from the coastline.In soil and living organisms,the level of tissue-free water tritium(TFWT)was comparable to the tritium levels in local rainfall,whereas the persistence of organically bound tritium(OBT)in the majority of organisms resulted in an OBT/TFWT ratio greater than one.Conversely,extremely high levels of environmental tritium were observed near certain nuclear power plants and the Fukushima accident sites.These results highlight the requirement to know the tritium baseline level and its behavior in the environment beforehand to better assess the impact of tritium discharge.Further investigations of environmental tritium in East Asia using more efficient and adequate monitoring methods are also required.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA02020200)the National Natural Science Foundation of China (No. 11475145)the Yangzhou Foundation for Development of Science and Technology (No. YZ2014041)
文摘La_((1-x))Mg_xNi_(4.25)Al_(0.75)(x = 0.0, 0.1, 0.2, 0.3)alloys for tritium storage were prepared by a method of electromagnetic induction melting. The crystal structure and hydrogen storage performance of the as-cast alloys were investigated. The results showed that a single phase of La Ni_4Al was in the alloys with x = 0.0 and 0.1 and that LaNi_4Al and second phase of(La,Mg)Ni)_3 and AlNi_3 were in the alloys with x = 0.2 and 0.3. On the other hand, the plateau pressures of P–C isotherms of the alloys were increased with the rise of the x value from 0.2 to 0.3 and the hydrogen storage capacity was obviously degraded simultaneously. It was found that the alloy had faster absorption kinetics as the proportion of Mg increased from 0.1 to 0.3.
文摘In this study,the effects of changing first wall materials and their thicknesses on a reactor were investigated to determine the displacement per atom(DPA)and gas production(helium and hydrogen)in the first wall,as well as the tritium breeding ratio(TBR)in the coolant and tritium breeding zones.Therefore,the modeling of the magnetic fusion reactor was determined based on the blanket parameters of the International Thermonuclear Experimental Reactor(ITER).Stainless steel(SS 316 LNIG),Oxide Dispersion Strengthened Steel alloy(PM2000 ODS),and China low-activation martensitic steel(CLAM)were used as the first wall(FW)materials.Fluoride family molten salt materials(FLiBe,FLiNaBe,FLiPb)and lithium oxide(LiO_(2))were considered the coolant and tritium production material in the blanket,respectively.Neutron transport calculations were performed using the wellknown 3D code MCNP5 using the continuous-energy Monte Carlo method.The built-in continuous energy nuclear and atomic data libraries along with the Evaluated Nuclear Data file(ENDF)system(ENDF/B-V and ENDF/B-VI)were used.Additionally,the activity cross-section data library CLAW-IV was used to evaluate both the DPA values and gas production of the first wall(FW)materials.An interface computer program written in the FORTRAN 90 language to evaluate the MCNP5 outputs was developed for the fusion reactor blanket.The results indicated that the best TBR value was obtained for the use of the FLiPb coolant,whereas depending on the thickness,the first wall replacement period in terms of radiation damage to all materials was between 6 and 11 years.
文摘The triple-to-double coincidence ratio （TDCR） method of liquid scintillation count- ing is an absolute measurement method of radioactivity. The formulation of the TDCR method and the established TDCR liquid scintillation counter are presented in this paper. The NIST standard reference material （SRM） of tritium water was measured to verify the performance of the TDCR liquid scintillation counter.
基金Supported by the National magnetic confinement fusion energy research and development projects(No.2014GB112004)
文摘Tritium real-time measurement in glovebox or workplace is important to ensure safe operation of tritium. A novel tritium monitor system including an open-walled ionization chamber, an electrometer and an IPC(Industrial Personal Computer) has been developed to measure tritium in gaseous form. Using mesh walls, instead of sealed wall, the open-walled ionization chamber has less tritium absorption and lower memory effect. In addition, tritium gas can diffuse into the chamber's sensitive region without the assistant of sampling system and ion trap, which are installed at the front-end of commonly used flow-through ionization chambers. Background signal of this monitor system is about 3.7 × 105Bq/m3, and after exposed to tritium concentration at about 1011Bq/m3 for 4h, background of the monitor can recover after purging it several times with dry air. It is suitable for longtime tritium measurements in both glovebox and workplace.
文摘Salt-resistant Bacillus strains, isolated from agricultural soils in Uzbekistan, were tested for degradation activity towards a mixture of polychlorinated biphenyls (PCBs) under aerobic conditions. The study employed the use of tritium labeled PCB congeners and traced the tritium label in cultures with high salt content. The experiments show that most of the selected strains were able to adsorb a part of the radioactivity, indicating transformation of the added PCBs. Gas chromatography demonstrated transformation of PCBs. The radioactive label was removed from several cultures by up to 91%, indicating also mineralization of PCBs. The study suggests that the isolated strains might be good candidates for the bioremediation of contaminated high-salt soils in Uzbekistan and other Central-Asian countries.
