部分建筑材料氡析出率测试分析

混凝土空心砌块、加气混凝土等新型建筑材料是目前房屋建筑通用的墙体建筑材料。本文通过实验测量了混凝土空心砌块、水泥砂浆、加气混凝土等建筑材料在相同的环境条件下氡析出的规律,测试了水泥砂浆覆面对建筑材料氡析出的影响,比较了部分建筑材料氡析出率的不同,为民用建筑防氡降氡设计和建筑材料的选用提供数据资料。     

乌鲁木齐地区居室内氡浓度影响因素再研究及防治对策探讨

在前期研究的基础上,对乌鲁木齐地区室内氡浓度的空间分布规律、以及室内氡在不同建筑构成、墙体建筑材料、室内装修程度及开窗习惯间的分布差异等进行了再研究,综合乌鲁木齐地区住宅内氡浓度的影响因素,有针对性的提出了乌鲁木齐地区的已建住宅的降氡措施和新建住宅的防氡措施。     

871防氡涂料的研制

本文介绍了用于降低室内墙体氡析出率的871防氡涂料的研制,及其在实验室和现场实验的效果。对~(226)Ra含量在752—1341Bqkg~(-1)范围内的碳化砖样品,分别于涂刷871涂料前、后在容积6.65L的容器中密封24h,测得氢气浓度为c_0和c_1,所得防氡(析出)效率η(η=(C_0-C_1)/C_0)达90％左右;连续观察1年半,η可稳定在80％左右。在8间平衡当量氡浓度为158—1295Bqm~(-3)的碳化砖建房中,涂刷871防氡涂料四遍,防氡效率大多高于80％。295防氡涂料还具有色泽好、成膜性强、耐磨、施工方便、价格便宜、原材料广泛等优点,是一种较理想的用于住房的防氡涂料。     

建材制品中测定氡的影响因素及其在防氡建材分析中的应用

粒度对建材制品的氡释放水平影响较大,当粉碎的粒径为5 mm时氡的释放量最大,粒径变大或减小时氡的释放水平都逐渐减小.温度对建材制品中氡的释放也有显著的影响,从20℃开始几乎每升高5℃,氡浓度就会增加一倍,尤其是在25℃以后,氡的浓度上升更快.测得温度对粉煤灰试块氡释放影响的活化能Ea=77194.19 Jmol-1,指前因子为A=4.54×1015 s-1.氡的浓度随时间延长而逐渐增大,36 h后,氡的释放和衰减达到平衡,这时氡浓度波动值的相对标准偏差为2.1%.本方法应用于防氡涂料的防氡率测定时相对标准偏差为3.8%,用于功能基元材料防氡砂浆和防氡腻子的影响研究,结果是可靠的.     

一种适于湿热环境的防氡涂层

利用自制的防氡涂料,在释氡模块氡提供的辐射环境下,对防氡涂层的防氡性能和防氡稳定性进行了研究。结果表明：在1^#释氡模块氡辐射环境下,涂覆0.8 mm厚的防氡涂层,消泡剂的较佳添加量为0.3%（质量分数,下同）。在消泡剂添加量为0.3%时,随着涂覆厚度的增加,防氡效率提高,当涂覆厚度大于2.0 mm后,防氡效率趋于稳定。在分别添加灰钙、白水泥、石膏和沉淀硫酸钡4种快干助剂的防氡涂层中,仅添加沉淀硫酸钡的防氡涂层的防氡效率明显下降,而添加其他3种快干助剂对防氡涂层的防氡效率基本无影响。在防氡稳定性中,白水泥和石膏的加入在一定程度上降低了防氡涂层的防氡稳定性,而添加灰钙对防氡涂层的防氡稳定性几乎无影响。在湿热和2^#释氡模块氡辐射环境下,防氡涂层仍具有良好的耐湿热老化和防氡性能。     

地下工程氡防护方法及能力研究北大核心CSCD

为科学确定地下工程氡防护措施,本文根据地下工程氡防护经验,梳理了典型氡防护方法,并通过实际测量和性能实验,评价各种氡防护方法。结果表明,通风降氡是地下工程降氡普遍方法,对12000 m^(3)空间按照2 m^(3)/s风速通风1小时能够降低空气中氡浓度三分之一左右;吸附降氡能够对人员活动集中区域进行局部降氡,采用自研的移动降氡装置工作2小时能够使80 m^(3)含氡空气的氡浓度降低55%左右;屏蔽降氡能够对高氡析出率区域进行重点降氡,采用聚酰亚胺树脂防氡材料能够使阻氡效率大于99.5%。不同降氡方法都有其适用范围和优缺点,应根据地下工程实际情况进行优化设计。     

一种建筑材料氡面射气系数测量方案研究

本文从氡在非破碎建筑材料中稳态运移方程出发,推导出建筑材料所析出的氡与建材氡面射气系数关系式,从而很方便地根据积累腔室中的氡浓度积累曲线计算出建筑材料氡面射气系数.该方法充分考虑了氧在建筑材料中的衰减,并通过测量预先充入测量装置中的氡在各时间点的浓度值推导出测量装置的泄漏率,提高了测量结果的精度.由于长时间积累测量存在...     

建筑材料氡析出率变化

收集了4类共19个来自不同生产企业的建筑材料样品,对样品的放射性活度浓度和氡析出率进行测量.测量结果表明:若建筑材料的原材料相近,加工工艺相近的企业生产的建筑材料的氡析出率变化不大;若原材料差别较大,加工工艺不同,即使是生产同类建筑材料,成品建筑材料的放射性核素镭活度浓度相近,但氡析出率的差别很大.     

一种简易表面氡析出率测量装置的设计

氡及其子体是天然本底辐射剂量的主要贡献者,是当前的一个研究热点。设计了一种简易的表面氡析出率测量装置,可以用来测量某些样品表面的氡析出率。为了了解所设计装置的性能,对不同氡析出率大小的样品进行了测量,同时对这种防氡涂料的防氡效果进行了测评。测量结果表明,该测量装置可较为准确地给出所测样品的表面氡析出率,且性能稳定、操作简便,可改进余地较大,缺点是测量耗时较长。     

关于在建材放射性含量标准中增加氡析出率控制指标的建议

采用高纯锗γ谱仪和活性碳盒法对选取的26个来自不同产地的建筑材料样品中的放射性核素比活度和氡析出率进行了测量。结果表明,建筑材料中镭含量与氡析出率之间并不完全相关。我国现行国家标准"建筑材料放射性核素限量"(GB 6566-2001)中仅以内外照射指数作为控制指标,没有对氡析出率进行控制,而建筑材料中氡析出率与室内氡浓度密切相关。因此建议国家建筑材料放射性核素限量标准中增加氡析出率控制指标。     

煤渣砖居室内放射性水平初步调查

介绍了我国5个不同省、市共28间居室的放射性水平调查结果。采用就地γ谱仪Falcon 5000、连续测氡仪器RAD7和瞬时γ剂量率仪FHZ672E-10分别测量了居室墙体中²²⁶Ra、²³²Th、⁴⁰K的活度浓度、室内²²²Rn浓度和γ剂量率。结果表明,24间煤渣砖居室墙体内²²⁶Ra、²³²Th、⁴⁰K的活度浓度均值分别为(86±30)Bq/kg、(83±20)Bq/kg、(759±207)Bq/kg,4间红砖居室墙体测量数据均值分别为(51±6)Bq/kg、(54±5)Bq/kg、(632±59)Bq/kg;两类墙材室内²²²Rn浓度均值分别为(96±42)Bq/m³和(40±4)Bq/m³,γ剂量率均值分别为(133±25)nGy/h和(120±8)nGy/h。通过分析室内²²²Rn浓度及γ剂量率与墙体中²²⁶Ra、²³²Th、⁴⁰K活度浓度的关系,可知煤灰渣的综合利用,导致了室内的辐射水平升高;初步估算了所测实心煤灰渣和加气块或空心砌块墙材所建居室所致居民年有效剂量,范围分别为1.6~4.9 mSv/a和1.8~5.4 mSv/a。     

Investigation of environmental activity levels of bone-coal mining area in five provinces

During 1991-1993, the activity levels of the bone-coal mines were investigated in Zhejiang, Hubei. Hunan,Jiangxi and Anhui Province, respectively, where the reserve of bone-coal is about 90% of our country‘s total reserve.The average ofγ radiation doserate level measured for bone-coal, bone-coal cinder (BCC) and bone-coal cinder brick (BCCB) in these provinces is about 500 nGy/h, 400 nGy/h and 700 nGy/h respectively, while that for fields, roads and houses made of BCCB in corresponding regions of these provinces is about 200 nGy/h, 260 nGy/h and 300 nGy/h respectively. It is shown that the environmental activity level of bone-coal mining area is about 3 times higher than the reference spots.     

Investigation on natural radionucildes levels in multiple media in bone-coal mine areas of five provinces

This paper reports methods and results of the investigation of natural radionuclides levels in multiple media in the bone-coal mine areas in Hubei, Hunan, Jiangxi, Zhejiang, and Anhui Provinces. In the studied bone-coal mine areas, the specific activities of ^238U and ^226Ra in the soil samples were 0.37 and 0.24 Bq/g, respectively; the specific activities of ^226Ra in the samples of bone-coal, bone-coal cinder and bone-coal cinder brick （BCCB） were 1.3, 1.4 and 0.9 Bq/g, respectively. In the water samples collected fiom the bone-coal mine areas, the average concentrations of natural uranium and ^226Ra were 33μg/L and 58 mBq/L, respectively, while in the water samples collected from outside the bone-coal mine areas, they were 3.4μg/L and 45 mBq/L, respectively. In addition, the specific activities of ^238U and ^226Ra in air aerosol samples from the bone-coal mine areas were 0.6 and 0.5 mBq/m^3, respectively.     

Relationship between nuclear graphite moderator brick bore profile measurement and irradiation-induced dimensional change

A stress analysis for a hypothetical nuclear graphite moderator brick is presented, considering dimensional and other property changes due to fast neutron irradiation, to illustrate the relationship between the change in moderator brick bore profile and dimensional change of the material. The results give the stresses and deformations of the brick during operation and at shutdown, with the effect of irradiation creep on the deformation of the brick also considered. The analyses provide information useful to reactor designers and operators for planning graphite monitoring campaigns.     

新闻村两种类型住房中氡气土水平初步调查

采用氡Tu暴露量的平等测量方法对湖南省衡阳县樟木乡新闻村17户采用不同墙体材料建造的住房中的氡Tu水平进行了累积测量。测量结果表明，土砖或土坯建造的房屋中的Tu水平约为用红砖建造的房屋中的10倍，而两种类型住房中的氡水平在通风状况相似时，差别不大；住在土坯（或土砖）房中的居民受Tu及其子体照射而得到的剂量与受到的氡及其子体所致剂量相当。     

西宁市建筑主体材料放射性水平及氡析出率的研究

采用低本底多道NaI(Tl)γ能谱仪和ERS-2-S氡钍射气析出仪对西宁市建筑主体材料中天然放射性核素比活度及氡的析出率进行测定,并按照相关标准进行评价。结果表明,除红砖、碎石和砂子外,其他建筑材料中~(40) K的比活度均低于西宁市区土壤~(40) K的平均值,红砖、灰渣砖、加气块和水泥中~(226) Ra和~(232) Th的平均比活度均高于该区域土壤中相应核素的平均值。所调查建筑材料内、外照指数均小于1,其放射性水平满足国标限量要求;部分样品的居民接受有效剂量当量率略高于最大允许限值1mSv/a,生产加工过程中须控制工业废渣的使用。     

The development of a stress analysis code for nuclear graphite components in gas-cooled reactors

Most of the UK nuclear power reactors are gas-cooled and graphite moderated. As well as acting as a moderator the graphite also acts as a structural component providing channels for the coolant gas and control rods. For this reason the structural integrity assessments of nuclear graphite components is an essential element of reactor design. In order to perform graphite component stress analysis, the definition of the constitutive equation relating stress and strain for irradiated graphite is required. Apart from the usual elastic and thermal strains, irradiated graphite components are subject to additional strains due to fast neutron irradiation and radiolytic oxidation. In this paper a material model for nuclear graphite is presented along with an example of a stress analysis of a nuclear graphite moderator brick subject to both fast neutron irradiation and radiolytic oxidation.     

Cementation of hydroxide precipitates containing certain radioactive elements

it is shown that the following radioactive materials can be incorporated into cement brick so as to form an integral part of the composition: precipitates consisting of ferric hydroxide, aluminum hydroxide, manganese hydroxide, a sulfate-silica mass, ash obtained by combustion of rags, paper, and wood. Systems (and the requisite qonditions) for cementation on the basis of these waste products have been developed. The cement consumption is 20–50% depending on the composition of the waste products. Some isotopes are incorporated more firmIy in cement brick than others (Nb and Ru are better incorporated than Cs and St).Translated from Atomnaya Énergiya, Vol. 17, No. 2, pp. 124–129, August, 1964     

凉水河畔热释光断代结果比较

对样品进行光晒退处理后测定热释光(TL)强度,得到TL断代结果。实验表明记年累积起点消楚,回零完全的标本是TL断代理想的测试对象。光晒退校正可获得可靠的TL断代结果,但河流沙土等地质标本在记年累积不太明确时将导致测年结果不准确。     

室内氡浓度及其控制措施

在不同时期,对不同建筑类型的建筑物,北京砖混房居室及办公室的室内氡浓度进行了监测,年平均氡平衡当量浓度分别为10．9,10．0,15．9Bq/m^3。估算了氡所致有效剂量为0.67mSv,略低于世界平均水平。对于室内氡含量较高的情况,提出控制措施。