Gamma-Ray Imaging for Generating 3D Dose Rate Maps
Gamma-Ray Imaging for Generating 3D Dose Rate Maps
复制标题
用于生成 3D 剂量率图的伽马射线成像
DOI：
10.1115/icem2011-59123
复制
发表时间：
2011
影响因子：
2.8
通讯作者：
Edmund Cracknell
中科院分区：
文献类型：
--
作者：
K. Hughes;Edmund Cracknell
在核工业，特别是在退役和清理领域，已经确立了伽马射线成像的使用，以确定伽马剂量率升高的原因。自1990年代中期首次使用以来，Babcock RadScan等伽马射线成像设备一直被用来制作彩色叠加图，以二维显示放射性污染物的位置和分布。这些信息对于帮助项目经理规划清理和屏蔽活动，确保所开展的所有工作都具有成本效益和ALARP是非常有价值的。Babcock最近开展的工作展示了根据伽马射线成像工作的输出生成剂量率场的3D地图的能力。结合伽马射线成像测量和合成剂量图是计划退役的一个非常有力的工具。传统的伽马射线图像提供了对存在的剂量率来源的明确识别，而3D剂量图允许确定人员的剂量摄取。此外，有可能量化清理或屏蔽对剂量率的影响，为项目团队提供确定最佳选择的衡量标准。遵循一个简单的步骤，从伽马射线成像数据生成3D剂量图。首先，建立了厂区模型。该模型可以从现有的工厂图纸、激光扫描测量或对工厂进行的简单物理测量中生成。该模型包括关于植物结构的屏蔽特性的信息，并且可以很容易地修改以演示添加更多屏蔽或减少任何源项的效果。对来自诸如RadScan的伽马射线成像仪的数据进行分析，以产生放射性核素特定活动的分布。这些活动被输入到模型中并形成源项。使用伽马射线成像仪生成源项的优点是，在模型中准确地表示了源的位置和分布，从而确保生成准确的剂量图。一旦模型完成，就使用ATTILA等辐射传输建模代码进行分析，以生成3D剂量图(尽管也有其他代码可以执行相同的功能)。本文描述了如何使用该技术为客户生成3D剂量图的示例，并以早期与RadScan的工作为基础，RadScan提供定量的细胞内分析。
The use of gamma-ray imaging has become established in the nuclear industry, especially in the fields of decommissioning and clean-up, for identifying the origins of elevated gamma dose rates. Since their first use in the mid 1990s, gamma-ray imaging devices, such as the Babcock RadScan, have been used to produce colour overlay plots that indicate, in two dimensions, the locations and distribution of radioactive contaminants. This information is invaluable in helping project managers to plan clean-up and shielding activities, ensuring that all work carried out is cost effective and ALARP. Recent work undertaken by Babcock demonstrates the capability to generate 3D maps of dose rate fields from the output of gamma-ray imaging work. The combination of gamma-ray imaging survey and resultant dose map is a very powerful tool for planning decommissioning. The conventional gamma-ray image provides an unambiguous identification of the origins of the dose rates present whilst the 3D dose map allows the dose uptake to personnel to be determined. Furthermore, the ability to quantify the effect of clean-up or shielding on the dose rates is possible, providing project teams with a metric for determining the best option available. A simple procedure is followed to generate 3D dose maps from gamma-ray imaging data. Firstly a model of the plant area is constructed. This model can be generated from existing plant drawings, from laser scan surveys, or from simple physical measurements taken on plant. The model includes information about the shielding properties of the plant structures, and can be easily modified to demonstrate the effect of adding more shielding, or of reducing any of the source terms. The data from a gamma-ray imager, such as RadScan, are analysed to generate distributions of radionuclide specific activities. These activities are entered into the model and form the source term. The advantage of using a gamma ray imager to generate the source term is that the location and distribution of the source is accurately represented in the model, thus ensuring that accurate dose maps are generated. Once the model has been completed it is analysed using a radiation transport modelling code such as Attila to produce the 3D dose maps (although other codes are available which could perform the same function). This paper describes an example of how this technique has been used to generate 3D dose maps for a customer and builds on earlier work with RadScan which provides quantitative in-cell assay.© 2011 ASME