2006 Vol. 23, No. 2
The 2nd Symposium on Reactor Physics & Nuclear Materials
Display Method:
2006, 23(2): 89-95.
doi: 10.11804/NuclPhysRev.23.02.089
Abstract:
The uhimate goal of the fusion program is to develop large scale power plants for the production of electricity. At present, there are many representative designs of magnetic confinement fusion reactors in the world,e.g. ARIES and APEX in USA, PPCS in EU, SSTR in Japan, FDS in China, and International Thermonuclear Experimental Reactor （ITER）. These studies cover many aspects on fusion experimental reactors, DEMO reactors, and commercial fusion power plants, including plasma physics, blanket technologies, material behavior, and technologies required to construct and operate such complex plants. The study status and development strategy in various countries are summarized and reviewed.
The uhimate goal of the fusion program is to develop large scale power plants for the production of electricity. At present, there are many representative designs of magnetic confinement fusion reactors in the world,e.g. ARIES and APEX in USA, PPCS in EU, SSTR in Japan, FDS in China, and International Thermonuclear Experimental Reactor （ITER）. These studies cover many aspects on fusion experimental reactors, DEMO reactors, and commercial fusion power plants, including plasma physics, blanket technologies, material behavior, and technologies required to construct and operate such complex plants. The study status and development strategy in various countries are summarized and reviewed.
2006, 23(2): 96-100.
doi: 10.11804/NuclPhysRev.23.02.096
Abstract:
Preliminary design and analysis for China helium-cooled solid breeder （CH HC-SB） test blanket module （TBM） for testing in ITER（ International Thermonuclear Experimental Reactor） device have been carried out recently. In this paper, the design description, the performance analysis and the related ancillary systems for CH TBM are introduced. The key features of the design are based upon the breederoutside-tube （BOT） concept, on the use of solid breeder ceramic material, of helium as coolant and tritium purge gas, of ferrite-martensite steel as structural material, and of beryllium as neutron multiplier. Results show that the proposed TBM concept has the advantages of higher tritium breeding ratio （TBR）, simple structure design and engineering feasibility.
Preliminary design and analysis for China helium-cooled solid breeder （CH HC-SB） test blanket module （TBM） for testing in ITER（ International Thermonuclear Experimental Reactor） device have been carried out recently. In this paper, the design description, the performance analysis and the related ancillary systems for CH TBM are introduced. The key features of the design are based upon the breederoutside-tube （BOT） concept, on the use of solid breeder ceramic material, of helium as coolant and tritium purge gas, of ferrite-martensite steel as structural material, and of beryllium as neutron multiplier. Results show that the proposed TBM concept has the advantages of higher tritium breeding ratio （TBR）, simple structure design and engineering feasibility.
2006, 23(2): 101-104.
doi: 10.11804/NuclPhysRev.23.02.101
Abstract:
Nuclear energy is a preferred option for electric power generation. The disadvantages of the current uranium-dioxide （UO2 ） fuel in nuclear power were presented and the reactor using the mixed thorium dioxide and uranium dioxide fuel （ ThO2-UO2 ） in the near future was foretold. A proposal to strengthen the research cooperation on the use of the thorium mineral resources in china was put forward.
Nuclear energy is a preferred option for electric power generation. The disadvantages of the current uranium-dioxide （UO2 ） fuel in nuclear power were presented and the reactor using the mixed thorium dioxide and uranium dioxide fuel （ ThO2-UO2 ） in the near future was foretold. A proposal to strengthen the research cooperation on the use of the thorium mineral resources in china was put forward.
2006, 23(2): 105-110.
doi: 10.11804/NuclPhysRev.23.02.105
Abstract:
Accelerator driven coupled fast/thermal subcritical system is conceptually designed. In the system, the inner/fast blanket and the outer/thermal blanket are separated each other by large vacuum and B4C coating for on edirection coupling. The metal type fuel （MA ＋ Pu）Zr is loaded into the fast blanket. The oxide type fuels （Th ＋ Pu） O2 and （Th ＋ ^233U ＋ Pu）O2 are loaded into the thermal blanket during the initial cycle and the equilibrium cycle, respectively. ^99Tc, ^129I and ^135Cs are loaded respectively in the form of pure technetium metal, sodium iodide and cesium chlorine into the thermal blanket. The system has good transmutation efficiency, high energy amplification factor and good fuel conversion ability： the energy amplification factor is above 320; the transmutation support ratios of MA and FP are about 1.0 and 2.0 PWRs respectively; the fuel conversion ratio in the thermal blanket is about 0. 715.
Accelerator driven coupled fast/thermal subcritical system is conceptually designed. In the system, the inner/fast blanket and the outer/thermal blanket are separated each other by large vacuum and B4C coating for on edirection coupling. The metal type fuel （MA ＋ Pu）Zr is loaded into the fast blanket. The oxide type fuels （Th ＋ Pu） O2 and （Th ＋ ^233U ＋ Pu）O2 are loaded into the thermal blanket during the initial cycle and the equilibrium cycle, respectively. ^99Tc, ^129I and ^135Cs are loaded respectively in the form of pure technetium metal, sodium iodide and cesium chlorine into the thermal blanket. The system has good transmutation efficiency, high energy amplification factor and good fuel conversion ability： the energy amplification factor is above 320; the transmutation support ratios of MA and FP are about 1.0 and 2.0 PWRs respectively; the fuel conversion ratio in the thermal blanket is about 0. 715.
2006, 23(2): 111-114.
doi: 10.11804/NuclPhysRev.23.02.111
Abstract:
Due to the advantage of geometry simulation and nuclear data, the code MCNP is now widely used in the reactor analysis. Based on our calculation of the fuel temperature reactivity coefficient benchmark, it is quantificationally proved that MCNP with its own cross section library can＇ t be used to simulate the reactor accurately and to calculate the temperature reactivity coefficient. Furthermore, we use MCNP- 4C with a database that contains temperature dependent nuclear cross sections to calculate the benchmark. The results are well agreement with benchmark results. This means that, with the temperature dependent nuclear cross sections library, MCNP can calculate the temperature reactivity coefficient and reactor multiplication factor accurately. So the temperature dependent nuclear cross section library should be processed to meet the requirement of reactor calculation.
Due to the advantage of geometry simulation and nuclear data, the code MCNP is now widely used in the reactor analysis. Based on our calculation of the fuel temperature reactivity coefficient benchmark, it is quantificationally proved that MCNP with its own cross section library can＇ t be used to simulate the reactor accurately and to calculate the temperature reactivity coefficient. Furthermore, we use MCNP- 4C with a database that contains temperature dependent nuclear cross sections to calculate the benchmark. The results are well agreement with benchmark results. This means that, with the temperature dependent nuclear cross sections library, MCNP can calculate the temperature reactivity coefficient and reactor multiplication factor accurately. So the temperature dependent nuclear cross section library should be processed to meet the requirement of reactor calculation.
2006, 23(2): 115-118.
doi: 10.11804/NuclPhysRev.23.02.115
Abstract:
The solution methods for the higher order oped yet in the nuclear reactor engineering. Based on harmonics and higher order eigenvalues are not well develthe analysis of the convergence process of power iteration, a new approach for setting the starting values of higher order harmonic flux has been proposed. The results of numerical tests demonstrate that the proposed method could effectively improve the efficiency of calculations of higher order harmonics. In addition, a new type of criterion that judges the convergence of higher order harmonics dynamically has been proposed, it has been verified that the new convergence criterion could effectively prevent the buildup of numerical errors introduced in the solution of lower order harmonics in the solution of higher order harmonics.
The solution methods for the higher order oped yet in the nuclear reactor engineering. Based on harmonics and higher order eigenvalues are not well develthe analysis of the convergence process of power iteration, a new approach for setting the starting values of higher order harmonic flux has been proposed. The results of numerical tests demonstrate that the proposed method could effectively improve the efficiency of calculations of higher order harmonics. In addition, a new type of criterion that judges the convergence of higher order harmonics dynamically has been proposed, it has been verified that the new convergence criterion could effectively prevent the buildup of numerical errors introduced in the solution of lower order harmonics in the solution of higher order harmonics.
2006, 23(2): 119-122.
doi: 10.11804/NuclPhysRev.23.02.119
Abstract:
By using three-dimension MCNP code and FENDL2.0 data library, the neutronics calculation for a HCSB （Helium Cooling Solid Breeder） TBM （Test Blanket Module） with 3 × 3 sub-modules has been performed. Under neutron wall loading of 0.78 MW/m^2 and duty factor of 22%, it is given for the tritium breeding ratio （TBR） of 0. 907, total tritium generation rate of 0.0175 g/d, peak power density of 9.27 MW/m^3 and total power deposiit of 0.422MW/m^3.
By using three-dimension MCNP code and FENDL2.0 data library, the neutronics calculation for a HCSB （Helium Cooling Solid Breeder） TBM （Test Blanket Module） with 3 × 3 sub-modules has been performed. Under neutron wall loading of 0.78 MW/m^2 and duty factor of 22%, it is given for the tritium breeding ratio （TBR） of 0. 907, total tritium generation rate of 0.0175 g/d, peak power density of 9.27 MW/m^3 and total power deposiit of 0.422MW/m^3.
2006, 23(2): 123-126.
doi: 10.11804/NuclPhysRev.23.02.123
Abstract:
A new code package of alpha-neutron coupled transportation is developed. It can be used to simulate the transportation of alpha particle in media, to compute the neutron yield in media contains oxygen and to track the history of the secondary neutrons. The secondary neutrons are simulated efficiently by tracking lots of neutrons with small weight, which is determined by the alpha-neutron yield. The stopping power and range of alpha particle in media are given by SRIM code, the alpha-neutron cross section is from charged particle library in JENDL, and the neutrons are treated by MCNP code.
A new code package of alpha-neutron coupled transportation is developed. It can be used to simulate the transportation of alpha particle in media, to compute the neutron yield in media contains oxygen and to track the history of the secondary neutrons. The secondary neutrons are simulated efficiently by tracking lots of neutrons with small weight, which is determined by the alpha-neutron yield. The stopping power and range of alpha particle in media are given by SRIM code, the alpha-neutron cross section is from charged particle library in JENDL, and the neutrons are treated by MCNP code.
2006, 23(2): 127-129.
doi: 10.11804/NuclPhysRev.23.02.127
Abstract:
Cross section for （n, 2n） reaction on Yttrium have been measured at energy of 14 MeV neutrons from H（d, n）He by using activation technique. The ^93Nb（n, 2n）^92mNb reaction was used to monitor the neutron fluence, HPGe detector was used to detect the γ-rays. The cross section of ^89Y （n, 2n）^88Y reaction are 759 ± 42, 835 ±42, 958 ±53 mb for neutron energy 13.5 ±0.3, 14.1±0.2, 14.6 ±0.3 MeV, respectively.
Cross section for （n, 2n） reaction on Yttrium have been measured at energy of 14 MeV neutrons from H（d, n）He by using activation technique. The ^93Nb（n, 2n）^92mNb reaction was used to monitor the neutron fluence, HPGe detector was used to detect the γ-rays. The cross section of ^89Y （n, 2n）^88Y reaction are 759 ± 42, 835 ±42, 958 ±53 mb for neutron energy 13.5 ±0.3, 14.1±0.2, 14.6 ±0.3 MeV, respectively.
2006, 23(2): 130-133.
doi: 10.11804/NuclPhysRev.23.02.130
Abstract:
MCAM is a software used for MCNP automatic modeling and visualization. This article presents the principle, approach and the implementation of MCNP neutronics model visualization. Analysis on the relationship between the text description of MCNP neutronics model and the CSG shows that the conversion from CSG to CAD model is the key issue of the visualization.
MCAM is a software used for MCNP automatic modeling and visualization. This article presents the principle, approach and the implementation of MCNP neutronics model visualization. Analysis on the relationship between the text description of MCNP neutronics model and the CSG shows that the conversion from CSG to CAD model is the key issue of the visualization.
2006, 23(2): 134-137.
doi: 10.11804/NuclPhysRev.23.02.134
Abstract:
This paper presents two approaches to enhance the geometry modeling ability of SN particle transport simulation codes and focus on the key issues that lie in the processing from CAD model to SN code geometry model, e.g. CAD file format support, void modeling, mesh generation and model-editing. SNAM （SN Automatic Modeling system） has been developed as an interface code between commercial CAD software and SN particle transport simmulation codes. The testing results have shown that the algorithm and implementation used in SNAM are efficient and capable of all the necessary processing from CAD model to SN geometry model.
This paper presents two approaches to enhance the geometry modeling ability of SN particle transport simulation codes and focus on the key issues that lie in the processing from CAD model to SN code geometry model, e.g. CAD file format support, void modeling, mesh generation and model-editing. SNAM （SN Automatic Modeling system） has been developed as an interface code between commercial CAD software and SN particle transport simmulation codes. The testing results have shown that the algorithm and implementation used in SNAM are efficient and capable of all the necessary processing from CAD model to SN geometry model.
2006, 23(2): 138-141.
doi: 10.11804/NuclPhysRev.23.02.138
Abstract:
In order to conduct nuclear analyses on neutronics issues for ITER （International Thermonuclear Experimental Reactor）, a standard three-dimensional model of the ITER reactor is being developed. The complex nuclear
analyses are conducted by MCNP/4C in three dimensions. MCAM （MCNP Auto-Modeling system） , as an implementation of the interface code between modern CAD system and MCNP, is a modeling and visualization tool which can convert a CAD model to neutronics model for MCNP and vice versa. This paper presents the application of MCAM to modify ITER 3-D neutronics model, which include blanket segmentation update, incorporation of fine structures of inboard blanket and the model extension from 20° to 40° in toroidal direction
In order to conduct nuclear analyses on neutronics issues for ITER （International Thermonuclear Experimental Reactor）, a standard three-dimensional model of the ITER reactor is being developed. The complex nuclear
analyses are conducted by MCNP/4C in three dimensions. MCAM （MCNP Auto-Modeling system） , as an implementation of the interface code between modern CAD system and MCNP, is a modeling and visualization tool which can convert a CAD model to neutronics model for MCNP and vice versa. This paper presents the application of MCAM to modify ITER 3-D neutronics model, which include blanket segmentation update, incorporation of fine structures of inboard blanket and the model extension from 20° to 40° in toroidal direction
2006, 23(2): 142-145.
doi: 10.11804/NuclPhysRev.23.02.142
Abstract:
The evaluated critical safety benchmark experiments including some major elements of fission materials, such as ^233U, ^235U, ^239pu and ^237Np, ^241Am, ^244Cm, were simulated using the home-developed one-dimensional
trasportation/burnup/optimization code system VisualBUS1.0 and HENDL1.1/MG, a multi-group working library of fusion-fission Hybrid Evaluated Nuclear Data Library, by FDS team. By the comparison with the measured resuits and the calculated values given in the International Handbook of Evaluated Criticality Safety Benchmark Experiments, HENDL1.1/MG data library and VisualBUS1.0 code are validated and qualified to be reliable.
The evaluated critical safety benchmark experiments including some major elements of fission materials, such as ^233U, ^235U, ^239pu and ^237Np, ^241Am, ^244Cm, were simulated using the home-developed one-dimensional
trasportation/burnup/optimization code system VisualBUS1.0 and HENDL1.1/MG, a multi-group working library of fusion-fission Hybrid Evaluated Nuclear Data Library, by FDS team. By the comparison with the measured resuits and the calculated values given in the International Handbook of Evaluated Criticality Safety Benchmark Experiments, HENDL1.1/MG data library and VisualBUS1.0 code are validated and qualified to be reliable.
2006, 23(2): 146-150.
doi: 10.11804/NuclPhysRev.23.02.146
Abstract:
With the increasing development of accelerator technology and the growing requirements from scientific and technical researches as well as applications, high intensity and high performance become the most important characters of the new accelerator facilities. Currently, many large-scale scientific experimental facilities such as the heavy-ion driven inertial confined fusion facility, the collider, the neutrino and muon factories, the spallation neutron source and so on all need the high intensity accelerators. In this paper, the material issues relevant to the high intensity accelerators and the applications of high intensity accelerators are introduced.
With the increasing development of accelerator technology and the growing requirements from scientific and technical researches as well as applications, high intensity and high performance become the most important characters of the new accelerator facilities. Currently, many large-scale scientific experimental facilities such as the heavy-ion driven inertial confined fusion facility, the collider, the neutrino and muon factories, the spallation neutron source and so on all need the high intensity accelerators. In this paper, the material issues relevant to the high intensity accelerators and the applications of high intensity accelerators are introduced.
2006, 23(2): 151-154.
doi: 10.11804/NuclPhysRev.23.02.151
Abstract:
The impact and tensile tests were carried out on the China Low Activation Martensitic steels （CLAM）. The results show： the Ductile-Brittle Transition Temperature （DBTY） is about - 100 ℃, which is lower than those of some other RAFMs; The ultimate strength are 668 MPa at room temperature and 334 MPa at 600℃, which are comparable to those of EUROFER97. The finer grain size of about 8 μm was considered as one of reasons for the superior mechanical properties of CLAM.
The impact and tensile tests were carried out on the China Low Activation Martensitic steels （CLAM）. The results show： the Ductile-Brittle Transition Temperature （DBTY） is about - 100 ℃, which is lower than those of some other RAFMs; The ultimate strength are 668 MPa at room temperature and 334 MPa at 600℃, which are comparable to those of EUROFER97. The finer grain size of about 8 μm was considered as one of reasons for the superior mechanical properties of CLAM.
2006, 23(2): 155-160.
doi: 10.11804/NuclPhysRev.23.02.155
Abstract:
Radiation damage in structural materials of fission/fusion reactors is mainly attributed to the evolution of intensive atom displacement damage induced by energetic particles （ n, α and/or fission fragments） and highrate helium doping by direct α particle bombardments and/or （n, α） reactions. It can cause severe degradation of reactor structural materials such as surface blistering, bulk void swelling, deformation, fatigue, embrittlement, stress erosion corrosion and so on that will significantly affect the operation safety of reactors. However, up to now, behavior of structural materials at the end of their service can hardly be fully tested in a real reactor. In the present paper, damage process in reactor structural materials is briefly introduced, then the advantages of energetic ion implantation/irradiation especially high-energy heavy ion irradiation are discussed, and several typical examples on simulation of radiation effects in reactor candidate structural materials using high-energy heavy ion irradiations are introduced. Experimental results and theoretical analysis suggested that irradiation with energetic particles especially high-energy heavy ions is a very useful technique for simulating the evolution of microstructures and macro-properties of reactor structural materials.
Radiation damage in structural materials of fission/fusion reactors is mainly attributed to the evolution of intensive atom displacement damage induced by energetic particles （ n, α and/or fission fragments） and highrate helium doping by direct α particle bombardments and/or （n, α） reactions. It can cause severe degradation of reactor structural materials such as surface blistering, bulk void swelling, deformation, fatigue, embrittlement, stress erosion corrosion and so on that will significantly affect the operation safety of reactors. However, up to now, behavior of structural materials at the end of their service can hardly be fully tested in a real reactor. In the present paper, damage process in reactor structural materials is briefly introduced, then the advantages of energetic ion implantation/irradiation especially high-energy heavy ion irradiation are discussed, and several typical examples on simulation of radiation effects in reactor candidate structural materials using high-energy heavy ion irradiations are introduced. Experimental results and theoretical analysis suggested that irradiation with energetic particles especially high-energy heavy ions is a very useful technique for simulating the evolution of microstructures and macro-properties of reactor structural materials.
2006, 23(2): 161-163.
doi: 10.11804/NuclPhysRev.23.02.161
Abstract:
The change of microstructure and mechanical property in neutron irradiated aluminum was studied. It is found that neutron irradiation increased the hardness of the aluminum and caused the formation of many small dislocation loops in the aluminum.
The change of microstructure and mechanical property in neutron irradiated aluminum was studied. It is found that neutron irradiation increased the hardness of the aluminum and caused the formation of many small dislocation loops in the aluminum.
2006, 23(2): 164-166.
doi: 10.11804/NuclPhysRev.23.02.164
Abstract:
The bubble production and evolution in the home-made modified 316L stainless steel have been investigated by the proton irradiation simulation technique and the positron annihilation lifetime measurement. The experimental results of 5 × 10^12, 5 × 10^13 and 5 × 10^14/cm^2 proton irradiations show that the produced bubble size increases, while the bubble concentration decreases, with the increasing of the irradiation proton flueence. At the proton irradiation fluence of 5 × 10^14/cm^2 the bubble size reaches 0.62 nm.
The bubble production and evolution in the home-made modified 316L stainless steel have been investigated by the proton irradiation simulation technique and the positron annihilation lifetime measurement. The experimental results of 5 × 10^12, 5 × 10^13 and 5 × 10^14/cm^2 proton irradiations show that the produced bubble size increases, while the bubble concentration decreases, with the increasing of the irradiation proton flueence. At the proton irradiation fluence of 5 × 10^14/cm^2 the bubble size reaches 0.62 nm.
2006, 23(2): 167-169.
doi: 10.11804/NuclPhysRev.23.02.167
Abstract:
This paper gives a review of our recent studies on the irradiation damage induced by energetic inert-gasions in metallic materials candidate to fusion reactors. The work includes the study of helium diffusion and helium bubble formation in 316L stainless steels, the study of void formation and swelling in the low-activation Fe-Cr-Mn alloy irradiated with high-energy Ar ions, the study of irradiation damage in some low-activation Fe-based steels and ODS alloys by high-energy Ne ions.
This paper gives a review of our recent studies on the irradiation damage induced by energetic inert-gasions in metallic materials candidate to fusion reactors. The work includes the study of helium diffusion and helium bubble formation in 316L stainless steels, the study of void formation and swelling in the low-activation Fe-Cr-Mn alloy irradiated with high-energy Ar ions, the study of irradiation damage in some low-activation Fe-based steels and ODS alloys by high-energy Ne ions.
2006, 23(2): 170-173.
doi: 10.11804/NuclPhysRev.23.02.170
Abstract:
The International Fusion Materials Irradiation Materials Irradiation Facility （IFMIF） is a joint project within the framework of the Fusion Materials Implementing Agreement of the International Energy Agency （IEA）. Shielding is one of the key issues of the IFMIF engineering design. Due to the complex geometry and large size of the shields, it is difficult to make accurate shielding design using the conventional computational tools. To handle this problem, a coupled 3-D computational scheme has been developed under the cooperation of the Institute of Plasma Physics of Chinese Academy of Sciences and Forschungszentrum Karlsruhe Germany. This paper presents the newly-developed 3-D coupled computational scheme and its application to the IFMIF shielding design.
The International Fusion Materials Irradiation Materials Irradiation Facility （IFMIF） is a joint project within the framework of the Fusion Materials Implementing Agreement of the International Energy Agency （IEA）. Shielding is one of the key issues of the IFMIF engineering design. Due to the complex geometry and large size of the shields, it is difficult to make accurate shielding design using the conventional computational tools. To handle this problem, a coupled 3-D computational scheme has been developed under the cooperation of the Institute of Plasma Physics of Chinese Academy of Sciences and Forschungszentrum Karlsruhe Germany. This paper presents the newly-developed 3-D coupled computational scheme and its application to the IFMIF shielding design.
2006, 23(2): 174-179.
doi: 10.11804/NuclPhysRev.23.02.174
Abstract:
In this paper the outline of intense electronic excitation effects in solid materials induced by swift heavy ions and international research status were briefly reviewed. Few examples of experimental results obtained on HIRFL were presented. And also the developing tendency in the field was looked into the future.
In this paper the outline of intense electronic excitation effects in solid materials induced by swift heavy ions and international research status were briefly reviewed. Few examples of experimental results obtained on HIRFL were presented. And also the developing tendency in the field was looked into the future.
2006, 23(2): 180-184.
doi: 10.11804/NuclPhysRev.23.02.180
Abstract:
The radiation effect of polytetrafluoroethylene used as a kind of sealing material in the tritium system was studied by using electron beam. The superficial configuration and state were analyzed by SEM and XPS respectively, and the crystal degree and thermal stability were determined by XRD and DSC. At the same time the composition of gas products after radiation ,was measured by GC/MS, and the yield of CO2 with the dose increasing was analyzed. The free radicals produced in the process of radiation were studied by ESR, and the content of free volume of PTFE is analyzed by positron annihilation lifetime spectroscopy. The result is that the crystal structure of the sample irradiated at the dose of 1 × 10^5 Gy is of an obvious damage while the structure of the unirradiated sample is crystal band. The transformation of the sample which has high crystal degree amorphous one. The melting point and thermal ecomposition temperature trend sample＇s thermal stability drops. The radiation decomposition of the sample is is remarkable from crystal state to to decline, which indiccates that the mainly the rupture of C--C bond, and less is the rupture of C--F bond. The Intensity I3 of the third lifetime fails with increasing the absorbed dose, which demonstrates the reduction of free volume cave content. Compared with I3, the rule of τ3 is reverse.
The radiation effect of polytetrafluoroethylene used as a kind of sealing material in the tritium system was studied by using electron beam. The superficial configuration and state were analyzed by SEM and XPS respectively, and the crystal degree and thermal stability were determined by XRD and DSC. At the same time the composition of gas products after radiation ,was measured by GC/MS, and the yield of CO2 with the dose increasing was analyzed. The free radicals produced in the process of radiation were studied by ESR, and the content of free volume of PTFE is analyzed by positron annihilation lifetime spectroscopy. The result is that the crystal structure of the sample irradiated at the dose of 1 × 10^5 Gy is of an obvious damage while the structure of the unirradiated sample is crystal band. The transformation of the sample which has high crystal degree amorphous one. The melting point and thermal ecomposition temperature trend sample＇s thermal stability drops. The radiation decomposition of the sample is is remarkable from crystal state to to decline, which indiccates that the mainly the rupture of C--C bond, and less is the rupture of C--F bond. The Intensity I3 of the third lifetime fails with increasing the absorbed dose, which demonstrates the reduction of free volume cave content. Compared with I3, the rule of τ3 is reverse.
2006, 23(2): 185-188.
doi: 10.11804/NuclPhysRev.23.02.185
Abstract:
This paper gives a review of our recent studies on the defect production in silicon carbide induced by energetic inert-gas-ion irradiation. The work includes the study of the dose threshold for helium bubble formation by combining TEM, RBS-channeling and PAS, the theoretical analysis of the dose threshold for bubble formation based on the Frozen-Matrix assumption, two types of bubble arrangement at different dose regions and the study of damage um-ion production behavior in the case of irradiation with heavier inert-gas-ions （ Ne, Xe） as a comparison to heliirradiation.
This paper gives a review of our recent studies on the defect production in silicon carbide induced by energetic inert-gas-ion irradiation. The work includes the study of the dose threshold for helium bubble formation by combining TEM, RBS-channeling and PAS, the theoretical analysis of the dose threshold for bubble formation based on the Frozen-Matrix assumption, two types of bubble arrangement at different dose regions and the study of damage um-ion production behavior in the case of irradiation with heavier inert-gas-ions （ Ne, Xe） as a comparison to heliirradiation.
2006, 23(2): 189-193.
doi: 10.11804/NuclPhysRev.23.02.189
Abstract:
Amorphous silicon-dioxide （a：SiO2） films were firstly implanted at room temperature （RT） with 120 keV C-ions to doses ranging from 5.0 × 10^16 to 8.6 × 10^17 ion/cm^2, and then the C-doped a：SiO2 films were irradiated at RT with 1 754 MeV Xe ions to 1.0 × 10^11 and 5.0 × 10^11 ion/cm^2, respectively. The information of new tex- ture formation in the C-doped SiO2 films after high-energy Xe ion irradiation was investigated using micro-FTIR measurements. The obtained results showed that Si--C, C--C, Si--O--C bonds as well as CO and CO2 molecules were formed in the C-doped a-SiO2 films after Xe ion irradiation. Furthermore, Xe-ion irradiation induced a plenteous formation of Si--C bonds in the high dose C-ion implanted a：SiO2 films. Compared with the C-implanted sampies without Xe-ion irradiation and the low dose C-implanted samples with Xe-ion irraddiation, the enhanced and plenty of Si--C bond formation implied that the phase of SiC structures may be produced by Xe-ion irradiation in the high dose C-ion implanted a：SiO2 films.
Amorphous silicon-dioxide （a：SiO2） films were firstly implanted at room temperature （RT） with 120 keV C-ions to doses ranging from 5.0 × 10^16 to 8.6 × 10^17 ion/cm^2, and then the C-doped a：SiO2 films were irradiated at RT with 1 754 MeV Xe ions to 1.0 × 10^11 and 5.0 × 10^11 ion/cm^2, respectively. The information of new tex- ture formation in the C-doped SiO2 films after high-energy Xe ion irradiation was investigated using micro-FTIR measurements. The obtained results showed that Si--C, C--C, Si--O--C bonds as well as CO and CO2 molecules were formed in the C-doped a-SiO2 films after Xe ion irradiation. Furthermore, Xe-ion irradiation induced a plenteous formation of Si--C bonds in the high dose C-ion implanted a：SiO2 films. Compared with the C-implanted sampies without Xe-ion irradiation and the low dose C-implanted samples with Xe-ion irraddiation, the enhanced and plenty of Si--C bond formation implied that the phase of SiC structures may be produced by Xe-ion irradiation in the high dose C-ion implanted a：SiO2 films.
2006, 23(2): 194-197.
doi: 10.11804/NuclPhysRev.23.02.194
Abstract:
After being radiated by neutron, the glass microspheres, which used in ICF research, have greatly increased the ability of Ar diffusion in it because of the radiation-enhanced diffusion. Such results cannot be achieved by means of thermal diffusion. But after being radiated by charged particles, the ability of Ar diffusion in glass has not increased very much. The differences of the radiation-enhanced diffusion caused by neutron and ions are presented.
After being radiated by neutron, the glass microspheres, which used in ICF research, have greatly increased the ability of Ar diffusion in it because of the radiation-enhanced diffusion. Such results cannot be achieved by means of thermal diffusion. But after being radiated by charged particles, the ability of Ar diffusion in glass has not increased very much. The differences of the radiation-enhanced diffusion caused by neutron and ions are presented.
2006, 23(2): 198-201.
doi: 10.11804/NuclPhysRev.23.02.198
Abstract:
Single crystal sapphire （Al2O3 ） samples were implanted at 600 K by He, Ne and Ar ions with energy of 110 keV to doses ranging from 5 × 10^16 to 2× 10^17 ion/cm^2 or irradiated at 320 K by ^208Pb^27＋ ion with energy of 1.1 MeV/u to the fluences ranging from 1 × 10^12 to 5 × 10^14 ion/cm^2. The modification of structure and optical properties induced by ion implantation or irradiation were analyzed by using photoluminescence（PL） and Fourier transformation infrared spectrum（FIR） spectra and transmission electron microscopy（ TEM ） measurements. The PL measurements showed that absorption peaks located at 375,413 and 450 nm appeared in all the implanted or irradiated samples, the PL intensities reached up to the maximum for the 5 × 10^16 ion/cm^2 implanted samples. After Pb-ion irradiation, a new peak located at 390 nm formed. TEM analyses showed that small size voids,（1--2 nm） with high density were formed in the region from the surface till to about 100 nm in depth and also large size Nebubble formed in the Ne-doped region. From the obtained FTIR spectra, it was found that Pb-ion irradiation induced broadening of the absorption band in 460-510 cm^-1 and position shift of the absorption band in 1 000- 1 300 cm^- 1 towards to high wavenumber. The possible damage mechanism in single crystal sapphire induced by energetic ion implantation or irradiation was briefly discussed.
Single crystal sapphire （Al2O3 ） samples were implanted at 600 K by He, Ne and Ar ions with energy of 110 keV to doses ranging from 5 × 10^16 to 2× 10^17 ion/cm^2 or irradiated at 320 K by ^208Pb^27＋ ion with energy of 1.1 MeV/u to the fluences ranging from 1 × 10^12 to 5 × 10^14 ion/cm^2. The modification of structure and optical properties induced by ion implantation or irradiation were analyzed by using photoluminescence（PL） and Fourier transformation infrared spectrum（FIR） spectra and transmission electron microscopy（ TEM ） measurements. The PL measurements showed that absorption peaks located at 375,413 and 450 nm appeared in all the implanted or irradiated samples, the PL intensities reached up to the maximum for the 5 × 10^16 ion/cm^2 implanted samples. After Pb-ion irradiation, a new peak located at 390 nm formed. TEM analyses showed that small size voids,（1--2 nm） with high density were formed in the region from the surface till to about 100 nm in depth and also large size Nebubble formed in the Ne-doped region. From the obtained FTIR spectra, it was found that Pb-ion irradiation induced broadening of the absorption band in 460-510 cm^-1 and position shift of the absorption band in 1 000- 1 300 cm^- 1 towards to high wavenumber. The possible damage mechanism in single crystal sapphire induced by energetic ion implantation or irradiation was briefly discussed.
2006, 23(2): 202-206.
doi: 10.11804/NuclPhysRev.23.02.202
Abstract:
In the present investigation, fully annealed Ti-Al-Zr plates were implanted with different nitrogen fluences. The corrosion resistance was examined by the electrochemical methods in a solution with pH value of 10 at room temperature in order to determine the optimum fluenee that can give good corrosion resistance in a simulated nuclear reactor condition. The results show ε-Ti2N phase formed initially and then transformed into σ-TIN with increasing of nitrogen fluences, which was confirmed by the results of X-ray photoelectron spectroscopy （XPS）. In addition, it can be found the increase of the corrosion resistance depends on the nitrogen fluence employed and the maximum improvement of the corrosion resistance was observed with a fluence of 8 × 10^16 N^＋ ion/cm^2. The mechanism of the corrosion resistance is attributed to defect accumulation, formatio on of amorphous phase and nanocrystallization in the implanted layer.
In the present investigation, fully annealed Ti-Al-Zr plates were implanted with different nitrogen fluences. The corrosion resistance was examined by the electrochemical methods in a solution with pH value of 10 at room temperature in order to determine the optimum fluenee that can give good corrosion resistance in a simulated nuclear reactor condition. The results show ε-Ti2N phase formed initially and then transformed into σ-TIN with increasing of nitrogen fluences, which was confirmed by the results of X-ray photoelectron spectroscopy （XPS）. In addition, it can be found the increase of the corrosion resistance depends on the nitrogen fluence employed and the maximum improvement of the corrosion resistance was observed with a fluence of 8 × 10^16 N^＋ ion/cm^2. The mechanism of the corrosion resistance is attributed to defect accumulation, formatio on of amorphous phase and nanocrystallization in the implanted layer.
2006, 23(2): 207-209.
doi: 10.11804/NuclPhysRev.23.02.207
Abstract:
Radiation damage in W has been studied as a function of irradiation dose by heavy ion simulation and positron annihilation lifetime measurement. The experimental results of 20, 60 and 90 dpa irradiations illustrate that the mono-and di-vacancies, dislocations and vacancy clusters are produced by the irradiation. The concentrations of the mono-and di-vacancies and dislocations and both the concentration and size of the vacancy clusters or voids all increase with the increasing of the irradiation dose.
Radiation damage in W has been studied as a function of irradiation dose by heavy ion simulation and positron annihilation lifetime measurement. The experimental results of 20, 60 and 90 dpa irradiations illustrate that the mono-and di-vacancies, dislocations and vacancy clusters are produced by the irradiation. The concentrations of the mono-and di-vacancies and dislocations and both the concentration and size of the vacancy clusters or voids all increase with the increasing of the irradiation dose.
2006, 23(2): 210-214.
doi: 10.11804/NuclPhysRev.23.02.210
Abstract:
When penetrating an interface between two kind of solids, energetic ions can induce atomic diffusion at both sides of the interface and then result in intermixing, atom re-distribution or composition change, as well as phase transformation. Main progress on the study of intermixing and phase change at metal/insulator interface induced by energetic ion irradiations, the difference of phenomena occurred at metal/insulator interfaces induced by high-and low-energy ions were briefly reviewed. Furthermore, the possible mechanisms related to intermixing and phase change at metal/insulator interface produced by energetic ion irradiations were also discussed in short words.
When penetrating an interface between two kind of solids, energetic ions can induce atomic diffusion at both sides of the interface and then result in intermixing, atom re-distribution or composition change, as well as phase transformation. Main progress on the study of intermixing and phase change at metal/insulator interface induced by energetic ion irradiations, the difference of phenomena occurred at metal/insulator interfaces induced by high-and low-energy ions were briefly reviewed. Furthermore, the possible mechanisms related to intermixing and phase change at metal/insulator interface produced by energetic ion irradiations were also discussed in short words.
2006, 23(2): 215-220.
doi: 10.11804/NuclPhysRev.23.02.215
Abstract:
Atom diffusion at metal/metal interfaces is very important for property of reactor structural materials, which can be simulated by using energetic ion irradiations. The present situation of experimental studies on atom diffusion at metal/metal interfaces induced by energetic ion irradiations is reviewed. The influence of experimental parameters such as the irradiation dose, irradiation temperature, electronic energy loss, nuclear energy loss and the interface structure on the intermixing is emphatically introduced. In addition, the possible mechanisms of metal/ metal intermixing are also briefly described.
Atom diffusion at metal/metal interfaces is very important for property of reactor structural materials, which can be simulated by using energetic ion irradiations. The present situation of experimental studies on atom diffusion at metal/metal interfaces induced by energetic ion irradiations is reviewed. The influence of experimental parameters such as the irradiation dose, irradiation temperature, electronic energy loss, nuclear energy loss and the interface structure on the intermixing is emphatically introduced. In addition, the possible mechanisms of metal/ metal intermixing are also briefly described.
2006, 23(2): 221-223.
doi: 10.11804/NuclPhysRev.23.02.221
Abstract:
4H-SiC specimens were implanted with C-ions and then irradiated with Pb-ions, and subsequently annealed at three different temperatures. The samples were investigated by using Fourier transformation infrared spectrum（FTIR） and Rutherford backward scattering（RBS）. The obtained FTIR spectra showed that there is a buried amorphous layer close to the ion-incident surface and there are several interference fringes in the range from 960 to 1 450 cm ^-1. The intensity of fringes decreases with the increase of annealing temperature. The obtained RBS spectra showed that the yield of Si atoms in 4H-SiC crystal decreases in a well-defined depth region after annealing at 1 373 K.
4H-SiC specimens were implanted with C-ions and then irradiated with Pb-ions, and subsequently annealed at three different temperatures. The samples were investigated by using Fourier transformation infrared spectrum（FTIR） and Rutherford backward scattering（RBS）. The obtained FTIR spectra showed that there is a buried amorphous layer close to the ion-incident surface and there are several interference fringes in the range from 960 to 1 450 cm ^-1. The intensity of fringes decreases with the increase of annealing temperature. The obtained RBS spectra showed that the yield of Si atoms in 4H-SiC crystal decreases in a well-defined depth region after annealing at 1 373 K.
2006, 23(2): 224-228.
doi: 10.11804/NuclPhysRev.23.02.224
Abstract:
The measurement accuracy of electron beam by using semiconductor detector is easily affected by beam energy, dose rate, beam incidence direction, environment temperature etc. Furthermore, the presence of the detectors on the patient surface perturbs the distribution of the radiation field. In the paper, the dose characteristics of semiconductor detector are quantitatively discussed. The perturbation of the symmetrical radiation field is investigated based on the measured results of P-type electron beam detector under different clinical conditions.
The measurement accuracy of electron beam by using semiconductor detector is easily affected by beam energy, dose rate, beam incidence direction, environment temperature etc. Furthermore, the presence of the detectors on the patient surface perturbs the distribution of the radiation field. In the paper, the dose characteristics of semiconductor detector are quantitatively discussed. The perturbation of the symmetrical radiation field is investigated based on the measured results of P-type electron beam detector under different clinical conditions.
2006, 23(2): 229-232.
doi: 10.11804/NuclPhysRev.23.02.229
Abstract:
After a brief review concerning the advantages of heavy ions in radiotherapy, more interests are concentrated on treatment planning system （TPS） for heavy ion radiotherapy. Compared to the hardware devices such as accelerator and beam delivery system, the TPS is a set of software system, and different therapy facilities require their corresponding TPSs. Based on the specialities of the Heavy Ion Research Facility in Lanzhou （HIIRFL）, some suggestions on the TPS for tumor therapy at HIRFL finally are given.
After a brief review concerning the advantages of heavy ions in radiotherapy, more interests are concentrated on treatment planning system （TPS） for heavy ion radiotherapy. Compared to the hardware devices such as accelerator and beam delivery system, the TPS is a set of software system, and different therapy facilities require their corresponding TPSs. Based on the specialities of the Heavy Ion Research Facility in Lanzhou （HIIRFL）, some suggestions on the TPS for tumor therapy at HIRFL finally are given.
2006, 23(2): 233-236.
doi: 10.11804/NuclPhysRev.23.02.233
Abstract:
There are two kinds of objective functions in radiotherapy inverse planning： dose distribution-based and Dose-Volume Histogram （DVH）-based functions. The treatment planning in our days is still a trial and error process because the multi-objective problem is solved by transforming it into a single objective problem using a specific set of weights for each object. This work investigates the problem of objective function setting based on Pareto multi-optimization theory, and compares the effect on multi-objective inverse planning of those two kinds of objective functions including calculation time, converge speed, etc. The basis of objective function setting on inverse planning is discussed.
There are two kinds of objective functions in radiotherapy inverse planning： dose distribution-based and Dose-Volume Histogram （DVH）-based functions. The treatment planning in our days is still a trial and error process because the multi-objective problem is solved by transforming it into a single objective problem using a specific set of weights for each object. This work investigates the problem of objective function setting based on Pareto multi-optimization theory, and compares the effect on multi-objective inverse planning of those two kinds of objective functions including calculation time, converge speed, etc. The basis of objective function setting on inverse planning is discussed.
2006, 23(2): 237-241.
doi: 10.11804/NuclPhysRev.23.02.237
Abstract:
Monte its long simulation and photons, and investigated based Carlo method is regarded as the most accurate method for dose calculation at present, whereas time hinders its clinic application. The effects of the tally method, the cut-off energy of electrons the secondary electron number parameter ENUM on precision and speed of MCNP4c have been on a clinical case to seek for a relatively optimum calculation mode.
Monte its long simulation and photons, and investigated based Carlo method is regarded as the most accurate method for dose calculation at present, whereas time hinders its clinic application. The effects of the tally method, the cut-off energy of electrons the secondary electron number parameter ENUM on precision and speed of MCNP4c have been on a clinical case to seek for a relatively optimum calculation mode.
2006, 23(2): 242-245.
doi: 10.11804/NuclPhysRev.23.02.242
Abstract:
Based on the survival data of human hepatoma SMMC-7721 and normal liver L02 cells irradiated with γ-rays at 0.3 Gy and 2 Gy, the possibility of uhra-fractionated radiotherapy is discussed in this paper. According to calculations, it is found that if the difference in cell survival between target tumor and adjacent normal tissue is up to 3%, radiotherapy using HRS would be realized through uhra-fractionation. Furthermore, the low-dose response is time-dependent. After analyzing this phenomenon, it was pointed that there would be a correlation between fractionation interval and the duration of cell G2 phase.
Based on the survival data of human hepatoma SMMC-7721 and normal liver L02 cells irradiated with γ-rays at 0.3 Gy and 2 Gy, the possibility of uhra-fractionated radiotherapy is discussed in this paper. According to calculations, it is found that if the difference in cell survival between target tumor and adjacent normal tissue is up to 3%, radiotherapy using HRS would be realized through uhra-fractionation. Furthermore, the low-dose response is time-dependent. After analyzing this phenomenon, it was pointed that there would be a correlation between fractionation interval and the duration of cell G2 phase.
2006, 23(2): 246-249.
doi: 10.11804/NuclPhysRev.23.02.246
Abstract:
The dose distribution can be calculated by the Regular Beam Model （RBM） dose engine based on the accelerator parameters and the inhomogeneity data of the patient for the radiotherapy planning. In this paper, the newly-developed mixed Batho correction based RBM is introduced, and then the calculation results are compared with the measured ones using the head phantom. The results demonstrate that the RBM dose engine can be used as a kind of reliable fast dose calculation tool in the clinical treatment planning system.
The dose distribution can be calculated by the Regular Beam Model （RBM） dose engine based on the accelerator parameters and the inhomogeneity data of the patient for the radiotherapy planning. In this paper, the newly-developed mixed Batho correction based RBM is introduced, and then the calculation results are compared with the measured ones using the head phantom. The results demonstrate that the RBM dose engine can be used as a kind of reliable fast dose calculation tool in the clinical treatment planning system.
2006, 23(2): 250-253.
doi: 10.11804/NuclPhysRev.23.02.250
Abstract:
This paper introduces the newest research production on patient positioning method in accurate radiotherapy brought by Accurate Radiotherapy Treating System （ARTS） research team of Institute of Plasma Physics of Chinese Academy of Sciences, such as the positioning system based on binocular vision, the position-measuring system based on contour matching and the breath gate controlling system for positioning. Their basic principle, the application occasion and the prospects are briefly depicted.
This paper introduces the newest research production on patient positioning method in accurate radiotherapy brought by Accurate Radiotherapy Treating System （ARTS） research team of Institute of Plasma Physics of Chinese Academy of Sciences, such as the positioning system based on binocular vision, the position-measuring system based on contour matching and the breath gate controlling system for positioning. Their basic principle, the application occasion and the prospects are briefly depicted.
2006, 23(2): 254-257.
doi: 10.11804/NuclPhysRev.23.02.254
Abstract:
Dosimetric characteristics of L-α-alanine dosemeter used for dosimetry of ^12C ion radiation have been studied. The experimental results indicate that the alanine dosemeter can be used to measure the ^12C ion radiation. In addition, dose effects of chromosome aberration dicentrics and cenric rings were studied after human peripheral blood being irradiated by ^12C ions; the best regression equation, Y = 0. 858 503D ＋ 0. 361 5 ×10^-2D^2, was obtained within 8.0 Gy.
Dosimetric characteristics of L-α-alanine dosemeter used for dosimetry of ^12C ion radiation have been studied. The experimental results indicate that the alanine dosemeter can be used to measure the ^12C ion radiation. In addition, dose effects of chromosome aberration dicentrics and cenric rings were studied after human peripheral blood being irradiated by ^12C ions; the best regression equation, Y = 0. 858 503D ＋ 0. 361 5 ×10^-2D^2, was obtained within 8.0 Gy.
2006, 23(2): 258-262.
doi: 10.11804/NuclPhysRev.23.02.258
Abstract:
The key problem for the application of the Monte Carlo particle transport code MCNP/MCNPX in radiotherapy is the creation of complex geometrical model. To handle this problem, a software has been developed to automatically create MCNP/MCNPX geometrical model based on the CT images, and three geometric cell treatment schemes were proposed and implemented in this software. In this work, three MCNP models are created, and calculations are performed to investigate the effect of those cell treatment schemes and repeated structure technique on the calculation results.
The key problem for the application of the Monte Carlo particle transport code MCNP/MCNPX in radiotherapy is the creation of complex geometrical model. To handle this problem, a software has been developed to automatically create MCNP/MCNPX geometrical model based on the CT images, and three geometric cell treatment schemes were proposed and implemented in this software. In this work, three MCNP models are created, and calculations are performed to investigate the effect of those cell treatment schemes and repeated structure technique on the calculation results.
甘公网安备 62010202000723号