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21.
王载勇 《核电子学与探测技术》2006,26(2):144-145
介绍了如何提高3H、14C样品的探测效率,进行了计量技术的研究.使用4πβ(LS)活度国家基准刻度3H、14C溶液的放射性活度. 相似文献
22.
小冲杆试验方法以其所需测试样品尺寸小而带来的样品感生放射性小等优势,越来越多地应用于核材料力学性能评价领域。本文设计了一套利用光栅尺直接测量样品变形的小冲杆试验装置,较传统装置精度有明显提高。利用该套装置对注量为10×1019 cm-2(E≥1 MeV)快中子辐照的国产A508 3钢材料进行了小冲杆测试研究,探索了针对放射性样品从制备到测试的试验方法,并获得了国产A508 3钢材料的小冲杆屈服特征值、抗拉特征值和韧脆转变温度与标准试验之间的关系式。 相似文献
23.
质子加速器适用于为硼中子俘获治疗提供中子源,其中子源强及能谱较反应堆中子源更具可调性。中子靶物理计算分析是加速器中子源设计的基础,为其提供粒子能量、流强等参数需求分析,并为靶体结构尺寸设计、中子慢化和屏蔽分析等提供前端参数。本文利用MCNPX蒙特卡罗程序,通过对质子打靶的中子产额和能谱、靶体能量沉积、打靶后靶材放射性活度和中子出射空间角分布等进行研究,提出能量2.5 MeV质子轰击100~200 μm锂靶的设计,并用模拟计算数据论证其合理性。该设计中子源在1 mA流强质子轰击下,源强可达9.74×1011 s-1;拟设计15 mA、2.5 MeV质子束产生的中子源,在治疗过程中靶材放射性活度累积最大值约为1.44×1013 Bq。 相似文献
24.
25.
Álvaro E. Faria 《时间序列分析杂志》2011,32(6):607-617
Dynamic spatial Bayesian (DSB) models are proposed for the analytical modelling of radioactivity deposition after a nuclear accident. The proposed models are extensions of the multi‐variate time‐series dynamic linear models of West and Harrison (1997) to Markov random field processes. They combine the outputs from a long‐range atmospheric dispersal model with measured data (and prior information) to provide improved deposition prediction in space and time. Two versions of a Gaussian DSB model were applied to the radioactivity deposition in Bavaria over a 15 days period during the Chernobyl nuclear accident. One version had fixed functional forms for its spatial variances and covariances while the other allowed those to adapt and ‘learn’ from data in the conjugate Bayesian paradigm. There were two main sources of information for radioactivity deposition in our application: radioactivity measurements at a sparse set of 13 monitoring stations, and the numerical deposition evaluation of the atmospheric dispersal K‐model for the points of a 64 × 64 regular grid. We have analysed the temporal predictions (one‐step‐ahead forecasting) of those DSB models to show that the dispersal K‐model tended in general to underestimate the deposition levels at all times while the DSB models corrected for that although with different degrees of adjustment. 相似文献
26.
根据国标6763—86的要求,对山东省冶金、化工、电力、煤碳、矿山和黄河淤沙等六大系统的66样废渣的放射性物质进行了普遍调研和测评,并提出在建材系统的开发和使用意见。 相似文献
27.
28.
Thomas G. Hobbs 《Journal of research of the National Institute of Standards and Technology》2000,105(2):275-283
A variety of commonly available household and industrial ceramic items and some specialty glass materials were assayed by alpha pulse counting and ion chamber voltage measurements for radioactivity concentrations. Identification of radionuclides in some of the items was performed by gamma spectroscopy. The samples included tableware, construction tiles and decorative tiles, figurines, and other products with a clay based composition. The concentrations of radioactivity ranged from near background to about four orders of magnitude higher. Almost every nuclide identification test demonstrated some radioactivity content from one or more of the naturally occurring radionuclide series of thorium or uranium. The glazes seemed to contribute most of the activity, although a sample of unglazed pottery greenware showed some activity. Samples of glazing paints and samples of deliberately doped glass from the World War II era were included in the test, as was a section of foam filled poster board. A glass disc with known 232Th radioactivity concentration was cast for use as a calibration source. The results from the two assay methods are compared, and a projection of sensitivity from larger electret ion chamber devices is presented. 相似文献
29.
M. Pedretti O. Cremonesi L. Foggetta A. Giachero A. Giuliani P. Gorla C. Nones M. Pavan C. Salvioni S. Sangiorgio 《Journal of Low Temperature Physics》2008,151(3-4):841-847
The main problem for experiments using the bolometric technique to search for rare events is the contribution of surface contamination
to the background. In this paper a new technique for the identification of the origin of events will be described. The idea
is to shield the main bolometer with bolometric shields. Tests on small and large prototypes and the promising results will
be reported.
相似文献
30.
Wataru Sugiyama Tomoo Yamamura Ki Chul Park Hiroshi Tomiyasu Yoshinobu Shiokawa Hidetsugu Okada Yuji Sugita 《Progress in Nuclear Energy》2005,47(1-4):448-453
Disposition of low-level radioactive wastes has been performed in supercritical water with RuO2 as a catalyst without the addition of any oxidizing materials. These wastes arose from nuclear power plants etc., constituting of nonflammable organic materials, such as fire resistant sheeting and rubber gloves. We investigated the distribution behavior of iron and cobalt attached to nonflammable organic materials, in solid, liquid and gas phases during the decomposition of this method. The distributions of these elements under various conditions (initial amounts) were determined by using their radioisotopes as simulated low-level radioactive wastes in order to ease the detection of trace amounts of elements even in solid and gas phases. Iron and cobalt were found only in the solid phase when non-radioactive iron hydroxide was added as a precipitation reagent before the supercritical-water reaction. 相似文献