基于DSP的计算机泄漏发射同步信息的提取

针对计算机行同步信号产生的泄露发射信息问题,提出一种提取该信息的相关检测算法,介绍利用Matlab仿真软件模拟提取行同步的策略,给出该算法在数字信号处理上的具体实现过程。在ICETEK-C6713-A EVM实验平台上进行同步信息截取实验,结果证明该方法具有较好的鲁棒性。     

794矿尾矿渣场镭比活度计算法参数试验结果分析

介绍了利用镭比活度计算法确定核工业794矿铀尾渣场氡析出率所用参数——氡射气系数和氡扩散系数的测量结果及其分析对比,野外采样室内化学分析镭比活度与γ能谱测量镭比活度对比,探讨了在北方气候条件下,铀尾渣场氡射气系数和扩散系数的变化规律和特点,以及这些参数测量的最佳气候和季节,并对镭比活度计算法的特点和测量结果进行了分析。     

地下空间氡的产生机理及通风控制

本文建立了土壤和建材的氡析出模型,在充分考虑各个影响因素的前提下,推导出了土壤和建材的表面析氡率公式,并依据此公式,进而推导出了室内氡浓度与通风换气效率的关系式。应用以上公式,对一典型的地下空间模型进行了计算,结果表明:地下空间氡的主要来源是土壤氡气的逸出,约占总析氡量的70豫～90豫;在较高的氡浓度状态下,室内氡浓度对通风十分敏感,增大地下空间的通风换气率,会使空气氡浓度大幅度的降低。因此,若按照地下空间的标准新风量进行设计,控制室内氡水平在400Bq/m3以内是很容易的,但是若要控制室内氡水平在200Bq/m3以内,则至少需要25.2m3/h的人均新风量,考虑新风不能得到完全利用,所需引入的室外新风量至少为31.5m3/h(以地下商场为例)。     

键盘按键信息的近场截获研究

计算机键盘在正常工作时会伴随产生电磁骚扰噪声,未授权人员若窃取这些电磁噪声经分析处理便可还原键盘的按键信息.经测试发现键盘的电磁辐射主要来自键盘内的印制电路板(Printed Circuit Board,PCB)及接口电缆互连结构,在连接处产生共模电压源并激励PCB板和接口电缆构成的共模回路向外发射电磁波.通过建立理论模型,分析了键盘产生伴随电磁辐射的机理,并基于该模型对PCB板-电缆互连结构进行了定量计算及电磁全波仿真.用实验的方法在近场截获了键盘的按键信息.实验结果表明:计算机键盘伴随产生的电磁骚扰噪声中含有按键信息并可在近场被截获.     

射气测量探寻断裂构造的应用效果

氡气异常表明,珊瑚矿区的石灰山断层与笔架山断层之间存在一条交椅岭断层;黄花村一带第四系覆盖下有2条隐伏断裂带,并可能为控矿构造。     

Radon emanation from radium specific adsorbents

Pilot studies were undertaken to quantify the total activity of radon that is eluted following no-flow periods from several Ra-226 adsorbents loaded to near exhaustion. The adsorbents studied included two types of barium sulphate impregnated alumina (ABA-8000 and F-1) and Dowex MSC-1 resin treated by either barium hydroxide or barium chloride. In parallel, radium loaded plain activated aluminas and Dowex MSC-1 resin were similarly investigated. The results revealed that radon was quantitatively eluted during the first few bed volumes of column operation after no-flow periods. Although similar radon elution profiles were obtained, the position of the radon peak was found to vary and depended on the adsorbent type. Radon levels up to 24 and 14 kBq dm⁻³ were measured after a rest period of 72 h from radium exhausted Dowex MSC-1 treated with barium chloride and F-1 impregnated alumina with barium sulphate, respectively. The eluted radon values measured experimentally were compared to those calculated theoretically from accumulated radium quantities for the different media. For plain adsorbents, an agreement better than 10% was obtained. For treated resin-types a consistency within 30% but for impregnated alumina-types high discrepancy between respective values were obtained.     

铀尾矿库滩面含水量分布与氡析出率预测

描述了中国核工业集团公司衡阳铀厂尾矿库滩面的含水量分布,以及含水量与氡析出率的关系。给出含水量与深度呈指数关系分布,与距离呈线性关系分布。并通过对排干水后尾矿库含水量测算,给出了该铀厂尾矿库表面氡析出率预测结果。     

铀矿样氡射气系数γ能谱法的应用及可靠性分析

采用γ能谱法对我国北方某铀矿样氡射气系数进行测量,并对该方法的可靠性进行分析。基于同类矿石平行样测量结果的分析,发现γ能谱法对同类样品的测量结果一致性较好。同一个样品不同氡累积时间所测结果的重复性较好,表明在所采用的样品密封时间内,矿样中的自由氡和束缚氡已达到平衡状态。基于单一特征核素特征峰净计数以及各核素总净计数2种方式均可准确计算得到氡射气系数,并将基于2种方式求得的氡射气系数标准不确定度进行比较,发现采用特征核素总γ净计数的测量结果稳定性更好。通过对γ能谱法进行应用和可靠性分析,为γ能谱法测量氡射气系数的推广及基于此方法的后续研究提供参考。     

Calibration of Electret-Based Integral Radon Monitors Using NIST Polyethylene-Encapsulated 226Ra/222Rn Emanation (PERE) Standards

The recently developed ²²²Rn emanation standards that are based on polyethylene-encapsulated ²²⁶Ra solutions were employed for a first field-measurement application test to demonstrate their efficacy in calibrating passive integral radon monitors. The performance of the capsules was evaluated with respect to the calibration needs of electret ionization chambers (E-PERM^®, Rad Elec Inc.). The encapsulated standards emanate well-characterized and known quantities of ²²²Rn, and were used in two different-sized, relatively-small, accumulation vessels (about 3.6 L and 10 L) which also contained the deployed electret monitors under test. Calculated integral ²²²Rn activities from the capsules over various accumulation times were compared to the averaged electret responses. Evaluations were made with four encapsulated standards ranging in ²²⁶Ra activity from approximately 15 Bq to 540 Bq (with ²²²Rn emanation fractions of 0.888); over accumulation times from 1 d to 33 d; and with four different types of E-PERM detectors that were independently calibrated. The ratio of the electret chamber response E_Rn to the integral ²²²Rn activity I_Rn was constant (within statistical variations) over the variables of the specific capsule used, the accumulation volume, accumulation time, and detector type. The results clearly demonstrated the practicality and suitability of the encapsulated standards for providing a simple and readily-available calibration for those measurement applications. However, the mean ratio E_Rn/I_Rn was approximately 0.91, suggesting a possible systematic bias in the extant E-PERM calibrations. This 9 % systematic difference was verified by an independent test of the E-PERM calibration based on measurements with the NIST radon-in-water standard generator.     

Demonstration of a Method to Suppress Radon Emanation from Uranium-bearing Wastes

The authors have previously done a theoretical study of radon emanation and quantitatively demonstrated that a small pore of even nanometer size with moisture in its microscopic grain structure can give as high a radon emanation coefficient as around 0.18. Therefore, it was concluded necessary to remove pores of any size in the grain in order to suppress radon emanation. Melting of uranium-bearing wastes is one of the best technologies for this purpose. In order to verify this theoretical finding, a series of experiments was carried out using three test samples; unprocessed, cemented and vitrified calcium superphosphate. Calcium superphosphate was chosen because it resembles a uranium-bearing waste like sludge in terms of both radioactive nuclide adhesion on the grain surface of the waste matrix (surface contamination) and the grain geometric shape. As expected from the theory, radon emanation from the vitrified sample was extremely low compared to the unprocessed sample. On the other hand, radon emanation from the cemented sample remained very high. The present study opens doors to suppression of radiation exposure from radon and to safe disposal which does not depend on integrity of the final waste form and the site cover soil.