The impregnation behavior of molten 2LiF–BeF_2(FLiBe) salt into a graphite matrix of fuel elements for a solid fuel thorium molten salt reactor(TMSR-SF) at pressures varying from 0.4 to 1.0 MPa was studied by mercury...The impregnation behavior of molten 2LiF–BeF_2(FLiBe) salt into a graphite matrix of fuel elements for a solid fuel thorium molten salt reactor(TMSR-SF) at pressures varying from 0.4 to 1.0 MPa was studied by mercury intrusion, molten salt impregnation, X-ray diffraction, and scanning electron microscopy techniques.It was found that the entrance pore diameter of the graphite matrix is less than 1.0 μm and the contact angle is about 135°. The threshold impregnation pressure was found to be around 0.6 MPa experimentally, consistent with the predicted value of 0.57 MPa by the Washburn equation. With the increase of pressure from 0.6 to 1.0 MPa, the average weight gain of the matrix increased from 3.05 to 10.48%,corresponding to an impregnation volume increase from 2.74 to 9.40%. The diffraction patterns of FLiBe are found in matrices with high impregnation pressures(0.8 MPa and1.0 MPa). The FLiBe with sizes varying from tens of nanometers to a micrometer mainly occupies the open pores in the graphite matrix. The graphite matrix could inhibit the impregnation of the molten salt in the TMSR-SF with a maximum operation pressure of less than 0.5 MPa.展开更多
Molten salt reactor, with good economics and inherent reliability, is one of the six types of Generation IV candidate reactors. The Basket-Fuel-Assembly Molten Salt Reactor(BFAMSR) is a new concept design based on fue...Molten salt reactor, with good economics and inherent reliability, is one of the six types of Generation IV candidate reactors. The Basket-Fuel-Assembly Molten Salt Reactor(BFAMSR) is a new concept design based on fuel assemblies composed of fuel pebbles made of TRISOcoated particles. Four refueling patterns, similar to the fuel management strategy for water reactors, are designed and analyzed for BFAMSR in terms of economy and security.The MCNPX is employed to calculate the parameters, such as the total duration time, cycle length, discharge burnup,total discharge quantity of ^(235)U, total discharge quantity of ^(239)Pu, neutron flux distribution and power distribution. The in–out loading pattern has the highest burnup and duration time, the worst neutron flux and power distribution and the lowest neutron leakage. The out–in pattern possesses the most uniform neutron flux distribution, the lowest burnup and total duration time, and the highest neutron leakage.The out–in partition alternate pattern has slightly higher burnup, longer total duration time and smaller neutron leakage than that of the out–in loading pattern at the cost of sacrificing some neutron flux distribution and power distribution. However, its alternative distribution of fuelelements cut down the refueling time. The low-leakage pattern is the second highest in burnup, and total duration time, and its neutron flux and power distributions are the second most uniform.展开更多
To fabricate thorium-based fuel kernel for solid fuel molten salt reactor,a component of tri-structural isotropic fuel particles is mostly based on sol-gel method.The preparation of thorium sol is an important step fo...To fabricate thorium-based fuel kernel for solid fuel molten salt reactor,a component of tri-structural isotropic fuel particles is mostly based on sol-gel method.The preparation of thorium sol is an important step for fabrication of thorium-based fuel kernels,such as thorium carbide and thorium oxide.The gel quality affects the gel particle dispersion and the final products.In this work,thorium sols were prepared using Th(NO_3)_4 and NH_3·H_2O by sol-gel method.The effects of thorium concentration,mole ratio of NH_4^+/NO_3^- and reaction temperature on the pH,viscosity,turbidity,particle size and the thorium sol distribution were investigated.The results show that the viscosity and turbidity increased with the NH_4^+/NO_3^- ratio;the turbidity and colloidal particle size increased with the reaction temperature,which affected little the sol viscosity;the sol viscosity increased with the thorium concentration,which virtually did not change the turbidity;and the particle size decreased and the size distribution narrowed with increasing thorium concentration.The sol could be stored at room temperature for one day without significant property changes.Thorium gel spheres of good quality were prepared at 60℃ with the NH_4^+/NO_3^- ratio of 75-85% and the thorium concentration of 1.2-1.4 mol/L.展开更多
Based on the analysis of element geochemistry and total organic carbon(TOC),this study investigates the main factors controlling organic matter(OM)enrichment,reconstructs the evolution process of the sedimentary envir...Based on the analysis of element geochemistry and total organic carbon(TOC),this study investigates the main factors controlling organic matter(OM)enrichment,reconstructs the evolution process of the sedimentary environment,and proposes a dynamic OM enrichment model of the Jurassic Da’anzhai(D)Formation,Sichuan Basin.The results indicate that the Sichuan Basin was generally dominated by a warm and oxidizing sedimentary environment,but with some peculiarities,such as a hotter climate in the D1 member and more anoxic lake water in the D2a member.The sedimentary evolution of the Da’anzhai Formation can be divided into a fluctuating sedimentary stage,a stable sedimentary stage and a reef-building stage.The D2a member showed the strongest hypoxia,the weakest weathering,the largest amount of terrestrial inputs,and the highest TOC content.The TOC is positively correlated with reducing conditions and terrestrial inputs,negatively correlated with weathering.Based on these findings,it is suggested that the global climate in the Early Jurassic period had a complex regional effect and the global oceanic anoxic events of the Toarcian did not spread to the Sichuan Basin.Thus,the anoxic deep water,high terrestrial inputs,and weak weathering were conducive to rapid deposition and preservation of lacustrine OM.展开更多
基金supported by the Thorium Molten Salt Reactor Nuclear Energy System under the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA02030000)the Frontier Science Key Program of the Chinese Academy of Sciences(No.QYZDY-SSW-JSC016)the State Key Laboratory of Particle Detection and Electronics(No.SKLPDE-KF-201811)
文摘The impregnation behavior of molten 2LiF–BeF_2(FLiBe) salt into a graphite matrix of fuel elements for a solid fuel thorium molten salt reactor(TMSR-SF) at pressures varying from 0.4 to 1.0 MPa was studied by mercury intrusion, molten salt impregnation, X-ray diffraction, and scanning electron microscopy techniques.It was found that the entrance pore diameter of the graphite matrix is less than 1.0 μm and the contact angle is about 135°. The threshold impregnation pressure was found to be around 0.6 MPa experimentally, consistent with the predicted value of 0.57 MPa by the Washburn equation. With the increase of pressure from 0.6 to 1.0 MPa, the average weight gain of the matrix increased from 3.05 to 10.48%,corresponding to an impregnation volume increase from 2.74 to 9.40%. The diffraction patterns of FLiBe are found in matrices with high impregnation pressures(0.8 MPa and1.0 MPa). The FLiBe with sizes varying from tens of nanometers to a micrometer mainly occupies the open pores in the graphite matrix. The graphite matrix could inhibit the impregnation of the molten salt in the TMSR-SF with a maximum operation pressure of less than 0.5 MPa.
基金supported by the Strategic Priority Program of Chinese Academy of Sciences(No.XDA02030200)
文摘Molten salt reactor, with good economics and inherent reliability, is one of the six types of Generation IV candidate reactors. The Basket-Fuel-Assembly Molten Salt Reactor(BFAMSR) is a new concept design based on fuel assemblies composed of fuel pebbles made of TRISOcoated particles. Four refueling patterns, similar to the fuel management strategy for water reactors, are designed and analyzed for BFAMSR in terms of economy and security.The MCNPX is employed to calculate the parameters, such as the total duration time, cycle length, discharge burnup,total discharge quantity of ^(235)U, total discharge quantity of ^(239)Pu, neutron flux distribution and power distribution. The in–out loading pattern has the highest burnup and duration time, the worst neutron flux and power distribution and the lowest neutron leakage. The out–in pattern possesses the most uniform neutron flux distribution, the lowest burnup and total duration time, and the highest neutron leakage.The out–in partition alternate pattern has slightly higher burnup, longer total duration time and smaller neutron leakage than that of the out–in loading pattern at the cost of sacrificing some neutron flux distribution and power distribution. However, its alternative distribution of fuelelements cut down the refueling time. The low-leakage pattern is the second highest in burnup, and total duration time, and its neutron flux and power distributions are the second most uniform.
基金supported by the Strategic Priority Program of the Chinese Academy of Sciences(Nos.XDA 02030000 and XDA02030200)the Frontier Science Key Program of the Chinese Academy of Sciences(No.QYZDY-SSW-JSC016)
文摘To fabricate thorium-based fuel kernel for solid fuel molten salt reactor,a component of tri-structural isotropic fuel particles is mostly based on sol-gel method.The preparation of thorium sol is an important step for fabrication of thorium-based fuel kernels,such as thorium carbide and thorium oxide.The gel quality affects the gel particle dispersion and the final products.In this work,thorium sols were prepared using Th(NO_3)_4 and NH_3·H_2O by sol-gel method.The effects of thorium concentration,mole ratio of NH_4^+/NO_3^- and reaction temperature on the pH,viscosity,turbidity,particle size and the thorium sol distribution were investigated.The results show that the viscosity and turbidity increased with the NH_4^+/NO_3^- ratio;the turbidity and colloidal particle size increased with the reaction temperature,which affected little the sol viscosity;the sol viscosity increased with the thorium concentration,which virtually did not change the turbidity;and the particle size decreased and the size distribution narrowed with increasing thorium concentration.The sol could be stored at room temperature for one day without significant property changes.Thorium gel spheres of good quality were prepared at 60℃ with the NH_4^+/NO_3^- ratio of 75-85% and the thorium concentration of 1.2-1.4 mol/L.
基金he Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance(NO.2020CX050000)the Research and Innovation Fund for Graduate Students of Southwest Petroleum University(NO.2019cxyb005)。
文摘Based on the analysis of element geochemistry and total organic carbon(TOC),this study investigates the main factors controlling organic matter(OM)enrichment,reconstructs the evolution process of the sedimentary environment,and proposes a dynamic OM enrichment model of the Jurassic Da’anzhai(D)Formation,Sichuan Basin.The results indicate that the Sichuan Basin was generally dominated by a warm and oxidizing sedimentary environment,but with some peculiarities,such as a hotter climate in the D1 member and more anoxic lake water in the D2a member.The sedimentary evolution of the Da’anzhai Formation can be divided into a fluctuating sedimentary stage,a stable sedimentary stage and a reef-building stage.The D2a member showed the strongest hypoxia,the weakest weathering,the largest amount of terrestrial inputs,and the highest TOC content.The TOC is positively correlated with reducing conditions and terrestrial inputs,negatively correlated with weathering.Based on these findings,it is suggested that the global climate in the Early Jurassic period had a complex regional effect and the global oceanic anoxic events of the Toarcian did not spread to the Sichuan Basin.Thus,the anoxic deep water,high terrestrial inputs,and weak weathering were conducive to rapid deposition and preservation of lacustrine OM.
