关键词：
bremsstrahlung;plasma accelerators;plasma applications;plasma light propagation;radioactive waste processing;relativistic electron beams;tin
摘要：
Photo-transmutation of long-lived nuclear waste induced by a high-charge relativistic electron beam (e-beam) from a laser plasma accelerator is demonstrated. A collimated relativistic e-beam with a high charge of approximately 100 nC is produced from high-intensity laser interaction with near-critical-density (NCD) plasma. Such e-beam impinges on a high-Z convertor and then radiates energetic bremsstrahlung photons with flux approaching 1011 per laser shot. Taking a long-lived radionuclide 126Sn as an example, the resulting transmutation reaction yield is the order of 109 per laser shot, which is two orders of magnitude higher than obtained from previous studies. It is found that at lower densities, a tightly focused laser irradiating relatively longer NCD plasmas can effectively enhance the transmutation efficiency. Furthermore, the photo-transmutation is generalized by considering mixed-nuclide waste samples, which suggests that the laser-accelerated high-charge e-beam could be an efficient tool to transmute long-lived nuclear waste.
摘要：
A novel method has been improved for analyzing atmospheric pollutant metals (Be, Mn, Fe, Co, Ni, Cu, Zn, Se, Sr, Cd, and Pb) by laser ablation inductively coupled plasma mass spectrometry. In this method, solid standards are prepared by depositing droplets of aqueous standard solutions on the surface of a membrane filter, which is the same type as used for collecting atmospheric pollutant metals. Laser parameters were optimized, and ablation behaviors of the filter discs were studied. The mode of radial line scans across the filter disc was a representative ablation strategy and can avoid error from the inhomogeneous filter standards and marginal effect of the filter disc. Pt, as the internal standard, greatly improved the-correlation coefficient of the calibration curve. The developed method provides low detection limits, from 0.01 ng m(-3) for Be and Co to 1.92 ng m(-3) for Fe. It was successfully applied for the determination of atmospheric pollutant metals collected in Lhasa, China. The analytical results showed good agreement with those obtained by conventional liquid analysis. In contrast to the conventional acid digestion procedure, the novel method not only greatly reduces sample preparation and shortens the analysis time but also provides a possible means for studying the spatial distribution of atmospheric filter samples. (C) 2017 Elsevier B.V. All rights reserved.
作者机构：
[Xu, Zhenghua; Min, Z.] School of Math and Physics, University of South China, Hengyang, 421001, China;[Wen, Shiwei] School of Computer Science and Technology Software School, University of South China, Hengyang, 421001, China;[Song, Yingming] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China
通讯机构：
[Xu, Z.] S;School of Math and Physics, University of South China, Hengyang, China
关键词：
Dose Distribution of Radioactive Source;Mathematical Structural Method;Sparse Grid Data
摘要：
In the case of loss of the source of the radioactive source, the distribution of radiation field needs to be mastered, which is an important basis for radioactive sources search strategy and the evacuation of the radiation area. In this paper, the inversion of the particle field is put forward by a function constructed for solid radioactive sources. we made use of mathematical construction techniques to construct dose function tactfully. An inversion model is established which is based on the dose of nodes in the grid. The dose of the grid lines is restored by the cubic spline interpolation. According to an idea of dose dominance of adjacent point, the function of interior point of grid is structured, which is consistent with the characteristics of the radiation field. During the simulation experiment, the dose of node is obtained by MCNP code based on the Monte Carlo method. It is verified that the dose function is close to the real dose field.
作者机构：
[Zhang, Feng-Shou; Fu, Yan-long; Li, Chang-kai] Beijing Normal Univ, Coll Nucl Sci & Technol, Minist Educ, Key Lab Beam Technol & Mat Modificat, Beijing 100875, Peoples R China.;[Zhang, Feng-Shou; Fu, Yan-long; Li, Chang-kai] Beijing Radiat Ctr, Beijing 100875, Peoples R China.;[Mao, Fei] Univ South China, Sch Nucl Sci & Technol, Hengyang 421001, Peoples R China.;[Wang, Feng] Beijing Inst Technol, Sch Phys, Beijing 100081, Peoples R China.;[Zhang, Feng-Shou] Natl Lab Heavy IonAccelerator Lanzhou, Ctr Theoret Nucl Phys, Lanzhou 730000, Peoples R China.
通讯机构：
[Zhang, Feng-Shou] B;[Zhang, Feng-Shou] N;Beijing Normal Univ, Coll Nucl Sci & Technol, Minist Educ, Key Lab Beam Technol & Mat Modificat, Beijing 100875, Peoples R China.;Beijing Radiat Ctr, Beijing 100875, Peoples R China.;Natl Lab Heavy IonAccelerator Lanzhou, Ctr Theoret Nucl Phys, Lanzhou 730000, Peoples R China.
摘要：
Nonadiabatic dynamics simulations are performed to investigate the electronic stopping power of a helium ion moving through ZnTe crystalline thin films under channeling conditions. Using ab initio time-dependent density-functional theory, we found by direct simulation that electronic stopping power versus projectile velocity deviates from velocity proportionality and displays a transition between two velocity regimes for helium ions channeling along middle crystalline axes in 〈100〉 and 〈111〉 channels and also in a 〈110〉 channel with low-impact parameters. This transition causes a change in the slope of the energy loss versus ion velocity curve at a characteristic velocity related to the impact parameter and the lattice plane spacing. It may be an indication of extra energy loss channel beyond the electron-hole excitation. To analyze it, we checked the charge transfer between the moving projectiles and host atoms. It is found that the soft transition between two velocity regimes can be attributed to the resonant coherent excitation stimulated by the time-periodic potential experienced by the channeling ion and also the charge exchange in close encounters between Helium ion and host atoms.
摘要：
Fast wave in the ion-cyclotron resonance frequency (ICRF) range is a promising candidate for non-inductive current drive (CD), which is essential for long pulse and high performance operation of tokamaks. A numerical study on the ICRF fast wave current drive (FWCD) and mode-conversion current drive (MCCD) in the Experimental Advanced Superconducting Tokamak (EAST) is carried out by means of the coupled full wave and Ehst-Karney parameterization methods. The results show that FWCD efficiency is notable in two frequency regimes, i.e., f ≥ 85 MHz and f = 50–65 MHz, where ion cyclotron absorption is effectively avoided, and the maximum on-axis driven current per unit power can reach 120 kA/MW. The sensitivity of the CD efficiency to the minority ion concentration is confirmed, owing to fast wave mode conversion, and the peak MCCD efficiency is reached for 22% minority-ion concentration. The effects of the wave-launch position and the toroidal wavenumber on the efficiency of current drive are also investigated.
作者机构：
[王珂; 宋英明; 谭至宇; 高庆瑜; 徐宇超] Institute of Nuclear Science and Technology, University of South China, Hengyang, 421001, China;[张璐; 杨永伟] Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, 730000, China
作者机构：
[谢金森; 谢芹; 于涛; Zeng, Wen-Jie; 刘紫静; 陈珍平; 何丽华] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China;[谢金森; 谢芹; 于涛; Zeng, Wen-Jie; 刘紫静; 陈珍平; 何丽华] Virtual Simulation Experimental Teaching Center on Nuclear Energy and Technology, University of South China, Hengyang, 421001, China
通讯机构：
School of Nuclear Science and Technology, University of South China, Hengyang, China
作者机构：
[李新霞; 路兴强; 陈诗佳; 龚学余] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China;[何志雄] Southwestern Institute of Physics, Chengdu, 610041, China
通讯机构：
School of Nuclear Science and Technology, University of South China, Hengyang, China
作者机构：
[郑平卫; 何丽华; 黄千红; 邓盛; 龚学余] School of Nuclear Science and Technology, University of South China, Hengyang, 421001, China;[郑平卫] School of Environmental Protection and Safety Engineering, University of South China, Hengyang, 421001, China
通讯机构：
School of Nuclear Science and Technology, University of South China, Hengyang, China
摘要：
A typical 1000MW pressurized-water reactor (PWR) unit model of China’s living nuclear power plant (NPP) units is built based on MAAP4[1] in this paper. Different severe accidents cases caused by different LOCA area on hot leg of primary loop are studied. And different mitigation measures are focused to evaluated their effectiveness. The study indicates that during the accident, the larger broken area LOCA case caused the more severe rector core damaged. However, it is important to inject water into the reactor core in good time. And that can mitigate the severe accident progress effectively.
