Experimental results from an ECR source using an octupole

The large superconducting ECR source, ECREVIS (Louvain-la-Neuve) has shown better charge state distribution (CSD) than smaller sources like MINIMAFIOS or the Berkeley source. Computer simulation indicates that the reason could be a lower average electron energy in the smaller sources. It has been suggested by Jongen that the size of the magnetic gradients in the source could be the energy limiting factor, and that the average electron energy could be increased by replacing the usual sextupole by an octupole. After an extensive series of tests, the sextupole of the Berkeley source was replaced by an octupole. After modification, the CSD have been substantially improved in the direction of higher charge states, with a substantial reduction of low charge state intensity. The intensity of higher charge states like argon 14+ or krypton 18+ increased by one order of magnitude. The new CSD are now very similar to those of the large ECREVIS source, indicating a probable gain in average electron energy.     

Construction and Operation of an Electromagnetic Shower Detector

An electromagnetic shower detector consisting of lead glass blocks and scintillator hodoscopes was constructed. During calibration runs detector resolutions were measured for single incident electrons. Performance of the detector for ?° and multi-photon showers, including sizable backgrounds, was studied during actual data runs.     

Characterization of heat transfer and temperature distributions in an electrically heated model of an LMFBR blanket assembly

This paper describes results of an experimental program to reduce uncertainties associated with the thermal-hydraulic design and analysis of LMFBR blanket assemblies. These assemblies differ significantly from fuel assemblies in design detail and operating conditions. In blanket assemblies, heat transfer occurs over a wide range of complex operating conditions. The range and complexity of conditions are the result of flux and power gradients which are an inherent feature of the blanket region and the power generation level in an assembly which can vary from 20 kW to 2 MW. To provide effective cooling of all assemblies and economical operation, coolant is metered to groups of assemblies in proportion to their ultimate power level. As a result, the assembly flow can be in the laminar, transition or turbulent range. Because of the wide range of heat generation rates and the range of coolant flow velocities, heat transfer from rods to coolant may take place in the forced, natural or mixed convection mode. Under low flow conditions, buoyancy affects the flow pattern in the bundle, and thus, alters the temperature distribution. The complexities are further compounded since, in addition to temperature gradients within an assembly, there are also significant temperature differences between adjacent assemblies. This results in heat transfer by conduction between adjacent assemblies, which tends to further distort flow and temperature patterns.Since these effects cannot be accurately predicted analytically, full-size radial blanket assembly heat transfer tests are being conducted using electrically heated fuel rod simulators in flowing sodium. A 61-rod electrically heated radial blanket assembly mockup of prototypic dimensions was designed, constructed and installed in a 200 gpm (45 m³/hr) sodium test loop.Heat transfer tests are being conducted over a wide range of power and sodium flow rates with this full-scale, vertical, electrical-resistance-heated rod bundle. The rod bundle is extensively instrumented by thermocouples located at six distinct elevations in the wire wrap and inside the heater cladding. Tests were conducted covering the flow range from fully turbulent to fully laminar with approximately constant power-to-flow ratio. The power input patterns included across bundle gradients of 2.8 to 1 and 2.0 to 1 maximum to minimum, uniform power input to all rods and a dished distribution with low power in the central row and high power in the two rows of rods adjacent to the duct walls.The test program provided experimentally measured axial and transverse temperature profiles for the test model over a range of anticipated plant operating conditions. The data were used to (a) determine the effect of Reynolds Number, power gradients and power-to-flow ratio on transverse and axial temperature profiles and particularly on peak and peripheral channel temperatures; (b) determine the effect of inter-assembly heat transfer on peak temperatures and temperature distributions; and (c) determine the effect of buoyancy on temperature profiles.     

Fluence and dose measurements for an accelerator neutron beam

The 3 MV Van de Graaff accelerator at McMaster University accelerator laboratory is extended to a neutron irradiation facility for low-dose bystander effects research. A long counter and an Anderson-Braun type neutron monitor have been used as monitors for the determination of the total fluence. Activation foils were used to determine the thermal neutron fluence rate (around 10⁶ neutrons s⁻¹). Meanwhile, the interactions of neutrons with the monitors have been simulated using a Monte Carlo N Particle (MCNP) code. Bystander effects, i.e. damage occurring in cells that were not traversed by radiation but were in the same radiation environment, have been well observed following both alpha and gamma irradiation of many cell lines. Since neutron radiation involves mixed field (including gamma and neutron radiations), we need to differentiate the doses for the bystander effects from the two radiations. A tissue equivalent proportional counter (TEPC) filled with propane based tissue equivalent gas simulating a 2 μm diameter tissue sphere has been investigated to estimate the neutron and gamma absorbed doses. A photon dose contamination of the neutron beam is less than 3%. The axial dose distribution follows the inverse square law and lateral and vertical dose distributions are relatively uniform over the irradiation area required by the biological study.     

Mechanical Design and Analysis of an Indirect-drive Cryogenic Target

Cryogenic target based on indirect-drive concept is concerned widely in the inertial confinement fusion field. An indirect-drive cryogenic target is designed to field on the SGIII laser device of China. Capsule and hohlraum design refers to the NIF ignition target Rev5. The target fabrication encounters many engineering issues because of complicated structures and low temperature experimental environment. A tapered capillary is used to feed and support the capsule. And a jacket is designed to solve capillary fixing, gas filling, sealing and other structural issues. Forming a uniform fuel ice-layer on the capsule inner faces withstanding gravity or surface tension effect is a key feature of this cryogenic target. Thermal mechanical package is designed to have the best capacity of controlling temperature gradient across the capsule with a thermally noncontact method. Thermal analyses conclude the best interface conductance arguments and jacket material for the TMP design. Besides, structural reliability of the target after cooling is conservatively analyzed with an optimized model.     

Gamma-Rays and Fast Neutrons Streaming about an Annular Duct

Leakage radiation from an infinite plane source reaching the rear surface of a shield provided with an annular duct has been evaluated numerically. The plane of the infinite source is divided into eight zones, for the convenience of integration, and the contribution of each zone is calculated separately by ray analysis. The distribution of the radiation flux and dose rate around the duct have been systematically obtained for different shielding materials and source energies, and the effect of changing duct geometry is also analyzed.

Among the contributions from the different zones, it is found that the predominant portion is provided by zones outside the annular area, and that this predominance extends even to the region of shield surface directly above the duct. It is also demonstrated that Rockwell's expression based on Line-of-Sight method is included as a special case of the present formula, which is applicable not only to γ-rays, but also to fast neutrorts.     

Concept and safety studies of an integrated pyroprocess facility

The Korea Atomic Energy Research Institute (KAERI) has been developing pyroprocess facilities for the dry processing research of spent fuel for over 10 years since 1997. A hot cell facility, named the Advanced spent fuel Conditioning Process Facility (ACPF), for the demonstration of a head-end part of pyroprocess was developed in November 2005. An inactive demonstration facility for the integrated pyroprocess, named the PyRoprocess Integrated inactive Demonstration (PRIDE) facility, has been developing since 2007. This facility is equipped with several types of pyroprocess equipment, such as a decladding/voloxidation device, a powder mixing device, electro-reduction equipment, electro-refining equipment, electro-winning equipment, Cd distillation equipment, waste salt regeneration & solidification equipment, and a salt distillation equipment. Safety evaluation and safety related systems are also required to inhibit the release of radioactivity into the environment. Accident evaluations and argon flow characteristics are studied for ensuring the expected safety issues. These conceptual and safety studies will be also used to obtain the basic requirements for design of the Engineering Scale Pyroprocess Facility (ESPF) which is the demonstration facility for feasibility of pyroprocess commercialization.     

一种辐照加速器用电子枪的结构设计

本文针对于辐照加速器用电子枪的使用环境及自身的特点,在结构设计过程中,重点考虑了阴极热子组件的相关设计及电子枪对中性的保证方法,从而设计出了一种能够随时更换阴极热子组件的辐照加速器用电子枪,同时根据其结构特点设计了相关的模夹具,减少了在装架过程中产生的累计误差,保证了电子枪的对中性.通过试验验证,在高压为60-65 k...     

一种沙漏型电磁隔振器的设计与研究

为了使隔振器在小幅振动时能保持良好的隔振性能,本研究提出了一种具有较高机电耦合性能的沙漏型电磁隔振器设计方法,并结合次优Bang-bang控制算法完成了隔振器的理论建模与隔振性能仿真分析。结果表明:在正弦基础位移激励下,当最大主动力为1.0 N时,共振峰处位移响应幅值下降了62.64%,且随着最大主动力的增大,控制效果变好;在随机激励下,当最大主动力分别为0.5 N和1.0 N时,位移响应的均方根值(RMS)分别下降49.12%和69.29%。因此,本研究所设计的沙漏型电磁隔振器在主动闭环控制下可实现良好的隔振效果,且相比传统电磁隔振器,具有不需要附加弹簧、所需控制电流小等优点。     

Sheath Criterion for an Electronegative Plasma Sheath in an Oblique Magnetic Field

The sheath criterion for an electronegative plasma composed of hot electrons,hot negative ions and cold positive ions in an oblique magnetic field is investigated.We discuss the effects of negative ions and external magnetic field on the sheath criterion.We find that the ion Mach number is of relatively low value because of Coulomb attraction between positive and negative ions.Also the ion Mach number depends on the magnitude and the angle of the magnetic field as well as the initial velocity of ion flow.     

一体化工具去污装置的设计与应用

核电站的工具常因沾污后不能复用而报废,不仅需要采购大量新工具,还增加了放射性废物产生量,增加了核电站运营成本。设计了一种融去污、漂洗、干燥为一体的去污装置。经实践,达到了工具复用、减少废物产生量、降低运营成本的目的。介绍了装置的结构、原理及使用方法,并指出了该装置的不足之处。     

基于改进型Brovey算法的高光谱数据融合技术

借鉴IHS变换融合算法的改进方法和思路,提出了对Brovey融合算法的改进措施,减少了融合图像的光谱特征畸变。同时,克服了IHS变换等方法只能同时融合3个波段数据的缺点,实现了利用改进型Brovey算法融合高光谱图像和高空间分辨率影像。通过实验表明,改进的Brovey融合算法与原Brovey算法相比,不但完成了三波段以上数据的融合,而且减少了融合图像的光谱畸变,取得了较好的融合效果。     

一起放射源遭破坏的辐射事故及处理

介绍了某水泥厂发生的放射源遭破坏的辐射事故。描述了事故的发生、处理及处置过程。分析了事故发生的直接原因和根本原因。以期能对辐射源安全监管提供借鉴。     

Mikrosondenuntersuchungen an bestrahltem urancarbid

A shielded Cameca microbrobe, MS 46, was used to examine a UC sample canned in SAP and irradiated to a burnup of 0.7%. An annular zone at about 40% of the outer sample radius was seen to contain precipitates loaded with fission products: microbrobe analysis showed the precipitates to be U₂ (Tc, Ru, Rh)C₂. Small amounts of palladium can be stabilized in this phase. Zirconium and molybdenum were verified in homogeneous distribution in the fuel. The Vickers hardness of the irradiated UC is 1000–1200 kp/mm². No signs of incompatibility with the canning material were detected.