In this study, the activation cross-sections were measured for ^(232)Th(n,2n)^(231)Th reactions at neutron energies of 14.1 and 14.8 MeV, which were produced by a neutron generator through a T(d,n)~4He reaction. Induc...In this study, the activation cross-sections were measured for ^(232)Th(n,2n)^(231)Th reactions at neutron energies of 14.1 and 14.8 MeV, which were produced by a neutron generator through a T(d,n)~4He reaction. Induced gamma-ray activities were measured using a low background gamma ray spectrometer equipped with a high resolution HPGe detector. In the cross-section calculations, corrections were made regarding the effects of gamma-ray attenuation, dead-time, fluctuation of the neutron flux, and low energy neutrons. The measured cross-sections were compared with the literature data, evaluation data(ENDF-B/VII.1, JENDL-4.0 and CENDL-3.1), and the results of the model calculation(TALYS1.6).展开更多
Neutron spectrum should be measured before test samples are irradiated.Neutron spectrum in an irradiation chamber of a research reactor was measured by using activation method when the reactor is in normal operation u...Neutron spectrum should be measured before test samples are irradiated.Neutron spectrum in an irradiation chamber of a research reactor was measured by using activation method when the reactor is in normal operation under 2 MW.Sixteen kinds of non-fission foils(19 reaction channels) were selected,of which 10 were sensitive to thermal and intermediate energy regions,while the others were of different threshold energy and sensitive to fast energy regions.By measuring the foil radioactivity,the neutron spectrum was unfolded with the iterative methods SAND-Ⅱ and MSIT.Finally,shielding corrections of group cross-section and main factors affecting the calculation accuracy were studied and the uncertainty of solution was analyzed using the Monte Carlo method in the process of SAND-Ⅱ.展开更多
A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculatio...A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculation and validation of the response matrix, are presented. The PFNS for ^235U in the energy range 1–12 MeV, induced by thermal neutrons, was obtained. The measured spectrum in the low-energy region was in good agreement with previous work and the ENDF/B-VII library, except for minor differences. In the high-energy region, however, the relative height of the measured spectrum was greater, and an analysis of the experiment indicated uncertainties of 13% at 10 MeV and 24% at 12 MeV. Experimental results showed that the recoil proton method could be used to measure prompt fission neutron spectra. Some directions for future work are included.展开更多
Based on a new second-order neutron transport equation, self-adjoint angular flux (SAAF) equation, the spherical harmonics (PN) method for neutron transport equation on unstructured-meshes is derived. The spherical ha...Based on a new second-order neutron transport equation, self-adjoint angular flux (SAAF) equation, the spherical harmonics (PN) method for neutron transport equation on unstructured-meshes is derived. The spherical harmonics function is used to expand the angular flux. A set of differential equations about the spatial variable, which are coupled with each other, can be obtained. They are solved iteratively by using the finite element method on un- structured-meshes. A two-dimension transport calculation program is coded according to the model. The numerical results of some benchmark problems demonstrate that this method can give high precision results and avoid the ray effect very well.展开更多
Fertile fuel, such as thorium or depleted uranium, can be bred into fissile fuel and burnt in a breed-andburn(B&B) reactor. Modeling a full core with fertile fuel can assess the performance of a B&B reactor wi...Fertile fuel, such as thorium or depleted uranium, can be bred into fissile fuel and burnt in a breed-andburn(B&B) reactor. Modeling a full core with fertile fuel can assess the performance of a B&B reactor with exact quantitative estimates, but costs too much computation time. For simplicity, performing the recently developed neutron balance method with a zero-dimensional(0-D)model can also provide a reasonable result. Based on the0-D model, the feasibility of the B&B mode for thorium fuel in a fast reactor cooled by sodium was investigated by considering the(n, 2n) and(n, 3n) reaction rates of fuel and coolant in this work, and compared with that of depleted uranium fuel. Afterward, the performance of the same thorium-based fuel core, but cooled by helium, lead-bismuth, and FLi Be, respectively, is discussed. It is found that the(n, 2n) and(n, 3n) reactions should not be neglected for the neutron balance calculation for thorium-based fuel to sustain the B&B mode of operation.展开更多
In the procedure of neutron fluence measurement in the whole energy range (10-4 eV^18 MeV), in the irra- diation chamber of a UZrH reactor, the neutron energy spectra are unfolded using the method of minimizing direct...In the procedure of neutron fluence measurement in the whole energy range (10-4 eV^18 MeV), in the irra- diation chamber of a UZrH reactor, the neutron energy spectra are unfolded using the method of minimizing directed divergence and SAND-II, which are used broadly at home and abroad. These methods belong to the iterative methods. In this article, the procedure of the spectra unfolding using the two methods is described in detail. The neutron spec- trum distribution unfolded by the two methods agree well with each other. In the end, the major differences of the two iterative methods are compared with each other, and the main factors affecting the accuracy of the spectra unfolding with the iterative method are discussed.展开更多
A new method of NAA for sediment movement study is presented in this paper. Through analyzing the natural sediment, the information about natural tracing agents has been obtained, which can show the direction of sedim...A new method of NAA for sediment movement study is presented in this paper. Through analyzing the natural sediment, the information about natural tracing agents has been obtained, which can show the direction of sediment movement and relative discharge of sediment transportation. Test results in some areas, such as Shantou Harbour and Hangzhou Bay, are in good agreement with those from normal hydrologic measurements and some results are not obtainable with the latter. The NAA is economical, practical and reliable, and should be widely used in engineering practice.展开更多
In this paper, we use the well-known Hartle’s perturbation method in order to compute models of differentially rotating neutron stars obeying realistic equations of state. In our numerical treatment, we keep terms up...In this paper, we use the well-known Hartle’s perturbation method in order to compute models of differentially rotating neutron stars obeying realistic equations of state. In our numerical treatment, we keep terms up to third order in the angular velocity. We present indicative numerical results for models satisfying a particular differential rotation law. We emphasize on computing the change in mass owing to this differential rotation law.展开更多
In this paper, a new numerical method, the coupling method of spherical harmonic function spectral and streamline diffusion finite element for unsteady Boltzmann equation in the neutron logging field, is discussed. Th...In this paper, a new numerical method, the coupling method of spherical harmonic function spectral and streamline diffusion finite element for unsteady Boltzmann equation in the neutron logging field, is discussed. The convergence and error estimations of this scheme are proved. Its applications in the field of neutron logging show its effectiveness.展开更多
Calculation results of the Monte Carlo method of the average energy of the electrostatic interaction between the quarks are presented to the neutron and proton. The proposed model of the distribution of quarks in prot...Calculation results of the Monte Carlo method of the average energy of the electrostatic interaction between the quarks are presented to the neutron and proton. The proposed model of the distribution of quarks in protons and neutrons is possible to assess the area which included a strong (gluon) interaction. Given the fact that the probability of finding a quark in the field with strong interaction is less than one, there is a good agreement between the experimental and calculated values of the mass difference between the neutron and the proton.展开更多
三维全堆芯pin-by-pin中子输运模型的高效加速方法是核反应堆高精度计算的重点和难点。本文有效融合课题组开发的并行多维离散纵坐标(S_(N))中子输运程序comeSn和Jacobian-Free Newton Krylov(JFNK)通用求解框架comeJFNK的高效并行特性...三维全堆芯pin-by-pin中子输运模型的高效加速方法是核反应堆高精度计算的重点和难点。本文有效融合课题组开发的并行多维离散纵坐标(S_(N))中子输运程序comeSn和Jacobian-Free Newton Krylov(JFNK)通用求解框架comeJFNK的高效并行特性、鲁棒性和强收敛性,开发了一套三维稳态及瞬态中子输运模型的JFNK并行求解程序comeSn_JFNK。为了提高计算效率,选择中子标通量密度(而非中子角通量密度)作为JFNK全局求解变量,并利用基于空间区域并行的KBA输运扫描方法和物理预处理方法,分别构建了稳态及瞬态模型的JFNK统一残差计算模型。计算结果表明,comeSn_JFNK相比于comeSn,计算效率具有显著优势,对于三维pin-by-pin稳态KAIST-3A算例,加速比为10倍以上;对于栅元均匀化的二维七群瞬态C5G7-TD2系列基准算例,加速比约为30倍。展开更多
基金Supported by National Natural Science Foundation of China(No.11205076)
文摘In this study, the activation cross-sections were measured for ^(232)Th(n,2n)^(231)Th reactions at neutron energies of 14.1 and 14.8 MeV, which were produced by a neutron generator through a T(d,n)~4He reaction. Induced gamma-ray activities were measured using a low background gamma ray spectrometer equipped with a high resolution HPGe detector. In the cross-section calculations, corrections were made regarding the effects of gamma-ray attenuation, dead-time, fluctuation of the neutron flux, and low energy neutrons. The measured cross-sections were compared with the literature data, evaluation data(ENDF-B/VII.1, JENDL-4.0 and CENDL-3.1), and the results of the model calculation(TALYS1.6).
基金Supported by"Strategic Priority Research Program"of the Chinese Academy of Science(No.XDA02001003)
文摘Neutron spectrum should be measured before test samples are irradiated.Neutron spectrum in an irradiation chamber of a research reactor was measured by using activation method when the reactor is in normal operation under 2 MW.Sixteen kinds of non-fission foils(19 reaction channels) were selected,of which 10 were sensitive to thermal and intermediate energy regions,while the others were of different threshold energy and sensitive to fast energy regions.By measuring the foil radioactivity,the neutron spectrum was unfolded with the iterative methods SAND-Ⅱ and MSIT.Finally,shielding corrections of group cross-section and main factors affecting the calculation accuracy were studied and the uncertainty of solution was analyzed using the Monte Carlo method in the process of SAND-Ⅱ.
基金supported by the National Natural Science Foundation of China(No.11775196)the Chinese Special Project for ITER(No.2015GB108006)
文摘A measurement of the ^235U prompt fission neutron spectrum (PFNS) by the recoil proton method was performed at the Institute of Nuclear Physics and Chemistry, China. Details of the method, which include the calculation and validation of the response matrix, are presented. The PFNS for ^235U in the energy range 1–12 MeV, induced by thermal neutrons, was obtained. The measured spectrum in the low-energy region was in good agreement with previous work and the ENDF/B-VII library, except for minor differences. In the high-energy region, however, the relative height of the measured spectrum was greater, and an analysis of the experiment indicated uncertainties of 13% at 10 MeV and 24% at 12 MeV. Experimental results showed that the recoil proton method could be used to measure prompt fission neutron spectra. Some directions for future work are included.
基金Supported by pre-research fund of State Key Laboratory (51479080201 JW0802)
文摘Based on a new second-order neutron transport equation, self-adjoint angular flux (SAAF) equation, the spherical harmonics (PN) method for neutron transport equation on unstructured-meshes is derived. The spherical harmonics function is used to expand the angular flux. A set of differential equations about the spatial variable, which are coupled with each other, can be obtained. They are solved iteratively by using the finite element method on un- structured-meshes. A two-dimension transport calculation program is coded according to the model. The numerical results of some benchmark problems demonstrate that this method can give high precision results and avoid the ray effect very well.
基金supported by the Chinese TMSR Strategic Pioneer Science and Technology Project(No.XDA02010000)
文摘Fertile fuel, such as thorium or depleted uranium, can be bred into fissile fuel and burnt in a breed-andburn(B&B) reactor. Modeling a full core with fertile fuel can assess the performance of a B&B reactor with exact quantitative estimates, but costs too much computation time. For simplicity, performing the recently developed neutron balance method with a zero-dimensional(0-D)model can also provide a reasonable result. Based on the0-D model, the feasibility of the B&B mode for thorium fuel in a fast reactor cooled by sodium was investigated by considering the(n, 2n) and(n, 3n) reaction rates of fuel and coolant in this work, and compared with that of depleted uranium fuel. Afterward, the performance of the same thorium-based fuel core, but cooled by helium, lead-bismuth, and FLi Be, respectively, is discussed. It is found that the(n, 2n) and(n, 3n) reactions should not be neglected for the neutron balance calculation for thorium-based fuel to sustain the B&B mode of operation.
文摘In the procedure of neutron fluence measurement in the whole energy range (10-4 eV^18 MeV), in the irra- diation chamber of a UZrH reactor, the neutron energy spectra are unfolded using the method of minimizing directed divergence and SAND-II, which are used broadly at home and abroad. These methods belong to the iterative methods. In this article, the procedure of the spectra unfolding using the two methods is described in detail. The neutron spec- trum distribution unfolded by the two methods agree well with each other. In the end, the major differences of the two iterative methods are compared with each other, and the main factors affecting the accuracy of the spectra unfolding with the iterative method are discussed.
文摘A new method of NAA for sediment movement study is presented in this paper. Through analyzing the natural sediment, the information about natural tracing agents has been obtained, which can show the direction of sediment movement and relative discharge of sediment transportation. Test results in some areas, such as Shantou Harbour and Hangzhou Bay, are in good agreement with those from normal hydrologic measurements and some results are not obtainable with the latter. The NAA is economical, practical and reliable, and should be widely used in engineering practice.
文摘In this paper, we use the well-known Hartle’s perturbation method in order to compute models of differentially rotating neutron stars obeying realistic equations of state. In our numerical treatment, we keep terms up to third order in the angular velocity. We present indicative numerical results for models satisfying a particular differential rotation law. We emphasize on computing the change in mass owing to this differential rotation law.
文摘In this paper, a new numerical method, the coupling method of spherical harmonic function spectral and streamline diffusion finite element for unsteady Boltzmann equation in the neutron logging field, is discussed. The convergence and error estimations of this scheme are proved. Its applications in the field of neutron logging show its effectiveness.
文摘Calculation results of the Monte Carlo method of the average energy of the electrostatic interaction between the quarks are presented to the neutron and proton. The proposed model of the distribution of quarks in protons and neutrons is possible to assess the area which included a strong (gluon) interaction. Given the fact that the probability of finding a quark in the field with strong interaction is less than one, there is a good agreement between the experimental and calculated values of the mass difference between the neutron and the proton.
文摘三维全堆芯pin-by-pin中子输运模型的高效加速方法是核反应堆高精度计算的重点和难点。本文有效融合课题组开发的并行多维离散纵坐标(S_(N))中子输运程序comeSn和Jacobian-Free Newton Krylov(JFNK)通用求解框架comeJFNK的高效并行特性、鲁棒性和强收敛性,开发了一套三维稳态及瞬态中子输运模型的JFNK并行求解程序comeSn_JFNK。为了提高计算效率,选择中子标通量密度(而非中子角通量密度)作为JFNK全局求解变量,并利用基于空间区域并行的KBA输运扫描方法和物理预处理方法,分别构建了稳态及瞬态模型的JFNK统一残差计算模型。计算结果表明,comeSn_JFNK相比于comeSn,计算效率具有显著优势,对于三维pin-by-pin稳态KAIST-3A算例,加速比为10倍以上;对于栅元均匀化的二维七群瞬态C5G7-TD2系列基准算例,加速比约为30倍。
