摘要
本文简要介绍一种对放射性微粒污染的地表砂土中放射性核素活度的就地测量方法。在实验测量中,所关注的测量区域是半径为r的圆形地面,污染层厚度为l,探测器置于圆心上方h高度处。测量中使用了"取样扣除"技术,即先在现场用就地HPGeγ谱仪直接测量,然后刮去污染层,回填与刮出土壤同质量的不含人工核素的"空白砂土",再测量一次。将两次测得的净计数率相减后计算出污染层土壤中被测核素的比活度;同时取污染砂土样品送实验室分析测量。当r取0.80m,l为0.02m,h为0.50m时,对污染核素137Cs,在9个实验点上的就地测量结果与样品实验室分析结果相比,最大偏差为37%。
A kind of in-situ measurement method is introduced in this paper, by which the radioactivity in the clayey sand of ground surface contaminated by radioactive particulates can be investigated. In the experiments, the circular plane regions whose radius is r are concerned, and the thickness of contaminated layer is l ; the detector is mounted above the centre of circular plane region, and it＇ s height is h. The technique called ＂ sampling deduction＂ was used in the measurements. At one spot, the first in-situ measurement was performed directly, then the second measurement was carried out after the contaminated layer were wiped out and filled with ＂clean clayey sand＂ （ in which there were no ^137 Cs）. The radioactivity of contaminated layer was calculated through the net count rate of the second measurement which was subtracted from the first measurement. The contaminated layer samples which were wiped out are collected overall for laboratofial measurement and analysis. When r, h and l were 0.80 m, 0.50 m and about 0.02 m respectively, the results showed that the maximum deviation of ^137 Cs was 37 percent when making the comparison of measuring results betwean laboratorial analysis and the in-situ measuremert method.
出处
《辐射防护》
CAS
CSCD
北大核心
2007年第5期277-281,共5页
Radiation Protection
