DCS安装、调试中的抗干扰问题

认为在安装过程中 ,电导耦合、电感耦合、电磁感应及接地电位波动等均可成为DCS(集散控制系统 )的干扰源。分析了四种干扰源的成因。提出了几种主要的抗干扰措施 ,即接地、屏蔽、电缆选择及隔离。对各种抗干扰措施的施工与注意事项作了介绍     

金属填充聚合物屏蔽EMI包装材料

在介绍电磁蔽原理的基础上,分析了金属填充聚合物复合材料屏蔽效能主要影响因素,并了屏蔽ＥＭＩ包装材料的研究现状与发展。     

Design of the reflection magnet and its shielding effect analysis for the neutral beam injector of EAST

In this paper,a reflection magnet to be installed in the EAST neutral beam injection system is simulated and designed.The field intensity of reflection magnet of 42-cm maximum bending radius is about 1.539×10-1 T for 100 keV deuterium beam.The shielding cage is formed by rods.Using the ANSOFT software,the magnetic shielding effect was estimated at about 3% at the magnet pole region.     

Review on the addition of boron compounds to radiation shielding concrete

The effects of the addition of three commercially available boric compounds (boric acid, boric frit, and borax) on the shielding properties of two radiation shielding concrete, made of carbonate and hematite aggregates, have been investigated. The results show that boric acid (H₃BO₃) and its frit have deleterious effect on the setting of ordinary cement in ratios 0.5-1% of the total weight of the concrete.Adding Borax (Na₂B₄O₇) has no significant effect on strength of concrete in the range up to 1% by wt, but it has significant effects on shielding efficiency in thick concrete shields (100 cm) as it reduces the capture gamma rays up to 80% better than unborated concretes.     

耐高盐高强度膜屏蔽剂的研制与性能评价

基于膜屏蔽暂堵理论,用抗高温、抗盐阳离子成膜聚合物和具有超强封堵效果的微米级纤维素、超细碳酸钙等材料复配研制出膜屏蔽剂BXP-2,介绍了BXP-2的研制方法和作用机理.室内评价结果表明,BXP-2在高浓度、高价金属盐溶液中具有提高黏度和切力、降滤失的作用,当其浓度高于2%时,溶液切力即可满足悬浮钻屑的需要,非常适宜于各种盐水、饱和盐水钻井液的配制;BXP-2的成膜强度高,膜弹性模量在1 500 Pa以上,其泥饼的抗冲刷能力强,能封堵砂粒粒径小于0.9 mm的石英砂床;BXP-2的含量达到3.0%时,膜屏蔽钻井液的结构力升高,能减少共沉降中钻屑的含量,能防止钻井液静止时钻屑沉降、堆积卡钻.经现场应用100余口井表明,BXP-2钻井液抑制性强,能防止井壁坍塌,保护油气层,综合效果好.     

Shielding design and analyses of KIPT neutron source facility

Argonne National Laboratory (ANL) of USA and Kharkov Institute of Physics and Technology (KIPT) of Ukraine have been collaborating on the conceptual design development of a neutron source facility. An electron accelerator drives a sub-critical facility (ADS) is used for generating the neutron source. The facility will be utilized for performing basic and applied nuclear researches, producing medical isotopes, and training young nuclear specialists. Monte Carlo code MCNPX has been utilized as the major design tool for the design, due to its capability to transport electrons, photons, and neutrons at high energies. However the ADS shielding calculations with MCNPX need enormous computational resources and the small neutron yield per electron makes sampling difficulty for the Monte Carlo calculations. The high energy electrons (E > 100 MeV) generate very high energy neutrons and these neutrons dominant the total radiation dose outside the shield. The radiation dose caused by high energy neutrons is ∼3-4 orders of magnitude higher than that of the photons. However, the high energy neutron fraction within the total generated neutrons is very small, which increases the sampling difficulty and the required computational time. To solve these difficulties, the user subroutines of MCNPX are utilized to generate a neutron source file, which record the generated neutrons from the photonuclear reactions caused by electrons. This neutron source file is utilized many times in the following MCNPX calculations for weight windows (importance function) generation and radiation dose calculations. In addition, the neutron source file can be sampled multiple times to improve the statistics of the calculated results. In this way the expensive electron transport calculations can be performed once with good statistics for the different ADS shielding problems. This paper presents the method of generating and utilizing the neutron source file by MCNPX for the ADS shielding calculation and similar accelerator facilities, and the accurate radiation dose analyses outside the shield using modest computational resources.     

蒙特卡罗程序EGS4在γ照射量积累因子计算中的应用

使用蒙特卡罗程序EGS4计算了入射光子能量范围从0.015 MeV到15 MeV、屏蔽厚度达到40个平均自由程的普通混凝土的γ照射量积累因子,程序计算中使用的是PHOTX光子截面库、各向同性点源和无限均匀介质模型,针对深穿透问题采用了粒子分裂技巧,并考虑了轫致辐射、荧光效应和相干(瑞利)散射对积累因子的影响。并将本文的计算结果与相关文献进行了比较分析,表明本文使用EGS4计算的积累因子数据是可靠的,可以更广泛的使用蒙特卡罗方法来计算γ照射量积累因子。     

Target set-up for measurements with the use of a Si-ball detector

The thin n-p⁺ layer of Si n⁺-n-p⁺ wafers composing the light charged particles detectors can be easily damaged by scattered beam projectiles or heavy products of the nuclear reaction in target material. Such damages of the sensitive part of the wafer may in consequence shorten the detector life-time. This could be avoided by protecting the sensitive part of the detector with shielding that stops the heavy projectiles.Due to the compact configuration of the detectors in a small Si-ball counters placing the shielding in front of each wafer could be difficult and therefore a target-shielding assembly is proposed.     

碳化硅表面镀钴的电磁屏蔽效能研究

本文将碳化硅经过预处理（除油-粗化-敏化-活化-还原）后分别在不同的pH值（9、10、11）的镀液中进行化学镀钴,镀液温度为80℃,施镀时间为60 min。研究镀液的不同pH值对试样电磁屏蔽效能的影响。结果表明：镀液的pH值为10时获得的镀钴碳化硅,在11GHz屏蔽效能达到最大,其值为8.4dB。     

10—in单球rem计测量中能重离子反应中子剂量当量的理论修正

中能重离子反应出射的中子具有较复杂的能谱,在穿过混凝土屏蔽层后,其能谱发生显著的变化。考虑到中子rem计的能量响应,在中能重离子反应出射中子理论计算能谱和角分布的基础上,估算了屏蔽层外中子能谱的变化和用10-in单球rem计在屏蔽层外测量中能重离子反应中子剂量当量时的理论修正系数。