共查询到18条相似文献,搜索用时 109 毫秒
1.
2.
针对一种新型适合地下工程高湿度、不透气特殊环境的防氡涂层的性能进行了研究。局部静态法和RAD-7型α能谱氡气检测仪对防氡效率的测试结果表明,随涂覆厚度的增加防氡效率上升,当涂覆厚度为0.8mm时,新型防氡涂层的防氡效率为92.92%,涂覆厚度为2.0和2.4mm时,防氡效率分别为98.91%和99.02%。实干时间测试发现,温度为23.7℃、相对湿度RH为95%时,涂覆厚度为2.0mm的新型防氡涂层经12.1h完全干燥;耐老化性能研究显示,新型防氡涂层具有优异的耐高浓度氡辐射、耐湿热以及耐霉菌老化的性能。因此,这种新型防氡涂层可以很好地满足地下工程苛刻的应用要求。 相似文献
3.
本文介绍了常用的氡测量方法和测氡仪器,对氡测量技术进行了较详细分析,为选择适宜的方法进行氡浓度监测提供了参考。标准氡室的研制为各种测氡仪器的刻度和量值溯源性提供了技术支撑,保证了测量结果的准确可靠,文章简要介绍了国内外标准氡室的发展状况。 相似文献
4.
标准氡室在氡浓度量值溯源和传递中起着重要作用。为了保证测氡仪量值统一、准确可靠,建立了测氡仪检定装置。针对在建立标准过程中出现的流气式氡源泄漏、氡室实验累积氡浓度值与理论值不一致和液体镭源结晶等问题,重点研究多重密封、改造洗气管路、优化洗气模式及多重过滤等技术方法,并建立氡室累积氡浓度经验曲线和质量管理措施等。按照新建立的实验方法和实验流程,氡室实验调节氡浓度和理论累积氡浓度相对偏差在±3.8%以内,液体镭源长期稳定性在0.7%以内,符合氡室建标的计量性能要求。 相似文献
5.
6.
7.
8.
9.
在重庆,存在大量的地下工程,如人防工程,地下商场等,但至今没有发现对其中氡浓度进行检测的报道.本文介绍了地下工程中氡的来源,综述了当前使用的氡的检测方法,认为现在广泛使用于普通室内氡检测的方法需进一步改进才能应用于地下工程中氡的检测. 相似文献
10.
建筑石膏外加剂研究进展 总被引:13,自引:0,他引:13
石膏是国际上推崇使用的绿色建材.我国是石膏资源大国,具备发展石膏建材的资源和政策优势.使用外加剂是提升石膏基材料技术经济水平,推动石膏行业科技进步的最有效途径,也是高性能石膏基材料的核心技术.本文综述了国内外建筑石膏减水剂、缓凝剂、保水剂研究的现状,并对国内石膏外加剂研究与应用中存在的问题进行了分析. 相似文献
11.
G. Sciocchetti F. Scacco S. Tosti P. G. Baldassini E. Soldano 《Journal of research of the National Institute of Standards and Technology》1990,95(2):139-142
This paper gives the technical characteristics of the Italian Committee for Research and Development of Nuclear Energy and Alternative Energy (ENEA) radon chamber and the operational procedures developed for testing radon and daughters measuring equipment. Runs were carried out under different experimental conditions defined in terms of radon and daughter concentrations, equilibrium ratio (F-factor), and aerosol concentration and size distribution. Stable radon reference atmospheres with known equilibrium factors were obtained using standard aerosols. 相似文献
12.
Christer Samuelsson 《Journal of research of the National Institute of Standards and Technology》1990,95(2):167-169
Results from closed-can radon exhalation experiments must be interpreted bearing the time-dependent radon diffusion theory in mind. A rapid change from the free to final steady-state exhalation rate will take place for all samples that are thin compared with the radon diffusion length. The radon gas accumulating in a closed can corresponds to a free exhalation rate only if the outer volume of air is much larger than the pore volume of the enclosed sample, or the thickness of the sample is much larger than the radon diffusion length. 相似文献
13.
14.
R. F. Holub W. P. Stroud 《Journal of research of the National Institute of Standards and Technology》1990,95(2):121-126
One important requirement for accurate monitoring of radon in working environments, dwellings, and outdoors is to ensure that the measurement instrumentation is properly calibrated against a recognized standard. To achieve this goal, the U.S. Department of Interior Bureau of Mines (BoM) Radiation Laboratory has participated since 1983 in a program to establish international radon measurement standards. Originally sponsored by the Organization for Economic Cooperation and Development (OECD), the program is also sponsored by the International Atomic Energy Agency. While the National Institute of Standards and Technology (NIST) radium solution ampules are acceptable to all participating laboratories as a primary standard, a method of transferring radon from the NIST source into each laboratory’s primary counting apparatus is a critical problem. The Bureau’s method transfers radon from the primary solution by bubbling 3 L of air through it into a steel cylinder. After homogenizing the radon concentrations in the cylinder, eight alpha-scintillation cells are filled consecutively and measured in a standard counting system. The resulting efficiency is 81.7±1.2%. 相似文献
15.
Isabel M. Fisenne Andreas C. George Helen W. Keller 《Journal of research of the National Institute of Standards and Technology》1990,95(2):127-134
The ideal facility for assessing the quality of radon measurements at environmental levels consists of: (1) an instrument whose response to radon and its progeny is determined from measurements of a certified or standard 226Ra source, and (2) a calibration room with a known radon concentration.The linkage between these two elements and additional quality control requirements are discussed here for some Environmental Measurements Laboratory radon measurements programs. 相似文献
16.
K. D. Cliff 《Journal of research of the National Institute of Standards and Technology》1990,95(2):135-138
A procedure for the calibration of instruments for the detection of 222Rn in air is described. The method is based on the alpha-spectrometric determination of the concentration in air of 218Po in the calibration chamber. The calibration chamber is described, together with the method of maintaining a high aerosol concentration. The 218Po concentration at steady state in the chamber is found to be 98% of the 222Rn concentration typically. An assessment of the sources of uncertainty in the method presented indicate that the 222Rn concentration in the chamber can be determined with an overall uncertainty of about 7% at the 95% confidence level. 相似文献
17.
18.
E. L. Sensintaffar S. T. Windham 《Journal of research of the National Institute of Standards and Technology》1990,95(2):143-145
Zinc sulfide coated scintillation cells are the primary method for measuring radon-222 at the U.S. Environmental Protection Agency (EPA), Office of Radiation Programs (ORP), Eastern Environmental Radiation Facility (EERF). These cells are used to measure concentrations of radon in exposure chambers that are used to calibrate or test other devices or instruments. Individual cells are calibrated by analyzing samples of air with known concentrations of radon produced by emanation of radon from standard radium-226 solutions obtained from the National Institute of Standards and Technology. The calibration procedure includes ingrowth of radon-222 into equilibrium with the radium in the standard solution, transfer from the solution into an evacuated container, and dilution with a measured volume of air. Samples of the radon in air mixture are transferred to evacuated scintillation cells and sealed for 4 h prior to counting, which allows secular equilibrium to be established between the radon and its decay products.Calibration factors for each individual cell are computed by decay correcting the radon to the time of collection and calculating the ratio of count rate (cpm), corrected for background, to radon activity (Bq) for the specific volume of the cell. Four or more calibration factors are determined for each cell and aver-aged to provide the calibration factor used for measurements. Calibrations are repeated at 6-mo intervals, and the results of each calibration are compared to the previous averages. When calibration factors fall outside the 95% confidence interval, they are rejected and the cell is checked for defects prior to recalibration. 相似文献