膨润土/石灰粉改良土壤的降氡效果  

Reduction of radon exhalation rate through soil modified with bentonite/lime powder

作　　者：邓慧娟[1] 肖德涛[1] 丘寿康[1] 何正忠[1] 居治豪 肖峰[1] Deng Huijuan Xiao Detao Qiu Shoukang He Zhengzhong Ju Zhihao Xiao Feng(School of Nuclear Science and Technology, University of South China, Hunan Hengyang 421001)

机构地区：[1]南华大学核科学技术学院,湖南衡阳421001

出　　处：《辐射防护》2017年第4期280-286,共7页Radiation Protection

基　　金：国家自然科学基金资助项目(11475082;11275096);环保部核与辐射安全监督管理技术项目(2016HBB05-2)

摘　　要：在土壤中添加不同比例的膨润土或石灰粉,比较添加前后土壤覆盖层厚度相同时的降氡效果。本研究利用具有稳定氡析出率的标准模块(35 cm×35 cm×12 cm)作为源项,并自制截面为正方形(30 cm×30 cm)高度可调的实验箱,实验时尽量保持含水率和压实度一致。实验结果表明:随土壤中膨润土或石灰粉添加比例的增大降氡效果越好,且添加膨润土比石灰粉降氡效果更好;对结果进行曲线拟合分析,得出了添加不同比例膨润土或石灰粉的土壤覆盖厚度与降氡效果的对数关系式,并计算出了相应的氡扩散系数;推导出了在满足退役管理限值0.74 Bq·m^(-2)·s^(-1)时,覆盖前氡析出率与所需覆盖土壤厚度的关系式,可用于待治理氡析出率表面的保守覆盖厚度的计算。通过经济比较分析,得出了在添加比例较低时,所需费用比原始土壤高,添加比例较高时,所需费用比原始土壤低,且所需费用随着添加比例的增加而减小。To compare the effectiveness of radon suppression with the addition of different proportions of bentonite or lime powder in soil,a standard module（ 35 cm × 35 cm × 12 cm） with a stable radon exhalation rate as the source term and a height adjustable experiment box with cross section of 30 cm × 30 cm were used.The soil moisture content and degree of compaction were kept consistent during the experiment. The results showed the better suppression effect of radon with increasing proportions of bentonite or lime powder,while bentonite more effective in radon suppression than lime powder. The fitting lines showed the logarithmic relationship between radon suppression effect and covering thickness with different proportions of bentonite or lime powder. The logarithmic equation was obtained and the corresponding diffusion coefficient of radon was calculated. The relationship between the radon exhalation rate before covering and the thickness of covered soil has been deduced to meet the required management limit of 0. 74 Bq · m-2· s-1,which could provide a conservative calculation for the covering thickness for the required surface radon exhalation rate. The economic comparison analysis showed that the cost for adding lower proportions of materials would be higher than the original soil,and vice versa. The cost would decrease with the increasing proportions of materials.

关 键 词：膨润土 石灰粉 氡析出率 

分 类 号：S156[农业科学—土壤学]