在反应堆退役、核废物处理、去污以及环境监测中,都需要对α放射性核素进行准确地测量,因此。放射性活度计量是电离辐射计量很重要的一个方面。小立体角法测量α核素活度的方法是很早发展起来的比较简单的方法,具有很高的测量准确度,要求的测量设备简单。介绍了所研制的装置的技术性能以及与屏栅电离室双边比对的结果。在1996年全国比对中,装置对~(241)Am的测量结果与比对结果平均值偏差在0.2％以内。 Alpha reactor radionuclides need to be accurately measured in reactor decommissioning, nuclear waste disposal, decontamination and environmental monitoring. Radioactive metrology is a very important aspect of ionizing radiation measurements. The method of measuring the activity of a-nuclide by the small solid angle method is a relatively simple method that has been developed very early. It has a high measurement accuracy and requires a simple measuring device. The technical performance of the device developed and the results of bilateral comparison with the screen ionization chamber are introduced. In the national comparisons in 1996, the average deviation of ~ (241) Am between the measurement results and the comparison results was less than 0.2%.