地铁站火灾烟气三维动态场模拟

由于城市地铁的建设在我国迅速发展,地铁站的火灾防范和安全疏散成为一个重要的研究课题。为了探讨地铁站火灾烟气的发展流动规律,笔者根据我国大多数现有地铁站的建筑结构模式建立了双层地铁车站的物理模型,并采用CFD的方法完成了火灾烟流三维动态的场模拟。在模拟中采用Rosseland辐射模型,将火源设定为放热量随时间变化的热源。计算结果表明在没有机械通风的情况下,烟气6分钟就将充满整个地铁站,人员难以在规范要求的时间内安全疏散。该研究成果可以为地铁站火灾发生时人员的安全疏散及烟气的控制提供一定的理论基础。     

哈密地区新型建筑材料天然放射性核素含量及居民受照剂量估算

用放射化学分析方法对哈密地区主要新型建材中＾２２６Ｒａ、＾２３２Ｔｈ、＾４０Ｋ含量分析测定。结果表明，放射性核素比活度限制值内照射指数和外照射指数平均范围值分别为０．０２－０．２６，０．０３－０．６６。花岗岩石材和涂釉制品最高，装饰材料最低。建材所致居民内、外照射年有效剂量当量为０．０６－０．９６ｍＳｖ．ａ＾－１，明显低于哈密地区室内环境γ辐射及氡子体所致居民年有效剂量当量实际调查值１．４３ｍＳｖ     

高风险移动放射源风险管控模糊综合评价

根据高风险移动放射源辐射安全风险特点与辐射事故经验反馈,结合辐射安全监管部门和企业实际,在充分调研的基础上,构建高风险移动放射源辐射安全风险管控评价指标体系,体系分为目标层、准则层和方案层,准则层8项指标,方案层40项指标。采用层次分析法确定各指标权重,运用模糊综合评价方法对甘肃省7家高风险移动放射源企业进行评价,结果表明决策层指标权重较大,与实际情况相符。     

当代世界50起重大毒性灾害初析

本文对当代世界１９３０～１９９２年５０起重大毒性灾害进行了分析。其中药物中毒６起，食物中毒７起，环境污染８起，毒气泄漏５起，有毒化学品与有毒气体爆炸９起，核爆炸与核辐射６起，恐怖行为２起，其它毒性灾害７起。本文还对减轻毒性灾害的基本对策进行了探讨。     

Radiation heat transfer in transient dust cloud flame propagation

This study investigates the impact of radiation heat transfer and heat conduction on dust cloud combustion. Radiation plays a very important role in the stability of dust cloud flame, and increasing the amount of radiation drastically raises the possibility of instability and explosion in a dust cloud mixture. Flame speed, which is a function of mixture characteristics, can exhibit a fluctuating behavior. By using the discrete heat source method, it would be possible to study the transient propagation of dust flames. Thus, the propagation speed of flame can be obtained, and as time goes by, the transient speed of dust flame will reach its steady state value. By considering the radiation effect, better agreement is observed between the obtained results and experimental data.     

Effect of sunlight radiation,rainfall and droplet spectra of sprays on persistence of bacillus thuringiensis deposits after application of dipel® 76af formulation onto conifers

Abstract

The effect of sunlight radiation, rainfall and droplet spectra of sprays on per ‐sistence of a Bacillus thuringiensis subspp. kurstaki (Btk) formulation, DiPel^® 76AF, was examined after application onto spruce [Picea glauca (Moench) Voss] foliage. The investigation consisted of three studies: (i) Study I: a laboratory microcosm study to examine the photostability of DiPel 76AF deposits on foliage after different periods of exposure to two radiation intensities, (ii) Study II: a laboratory microcosm study to examine the rainfastness of foliar deposits after exposure to different amounts of rainfall consisting of two separate droplet spectra, and (iii) Study III: a field microcosm study to investigate the influence of two different droplet spectra of DiPel 76AF sprays on foliar persistence of Btk under natural weathering conditions. In all studies, persistence of Btk was investigated both by bioassay [using spruce budworm (Choristoneura fumiferana Clemens)] and total protein assay.

The findings of Study I indicated that bioactivity of foliar deposits decreased with increasing duration of exposure to radiation, and with increasing radiation intensity. The half‐life (DT₅₀, the exposure period required for 50% of the initial bioactivity to disappear) was 5.1 d for the low intensity, and 3.9 d for the higher intensity. In contrast with the bioassay results, the total protein levels [determined by the bicinchoninic acid (BCA) method] showed no decrease with increasing duration of exposure, or with increasing radiation intensity.

The findings of Study II indicated that bioactivity of foliar deposits decreased with increasing cumulative rainfall. A new term, RF₅₀ [the amount of rain (in mm) required to washoff 50% of the initial deposit], was introduced to understand the relationship between rainfall intensity and reduction in bioactivity. When the same amount of rain was applied in different droplet sizes, the RF₅₀ value was high (5.2 mm) for the small rain droplets, and was low (2.9 mm) for the large rain droplets. Similar to the bioassay results, the total protein concentrations (determined by the BCA method) decreased with increasing amount of rain and with increasing rainfall intensity. The RF₅₀ value (obtained using ng protein /cm²) was 5.4 mm for the small rain droplets, and was 3.4 mm for the large rain droplets.

The field microcosm study indicated that when DiPel 76AF was applied in small droplets (D_v.5 of 65 μm), the persistence of bioactivity was ca 8.0 d, whereas when it was applied in large droplets (D_v.5 of 130 nm) it was ca 11 d. Bioactivity decreased with time after spray, and the DT₅₀ was 1.98 d for the spray of small droplets, and 2.87 d for that of large droplets. Similar to the bioactivity, the total protein concentrations also decreased with time after spray, and the DT₅₀ values for the small and large droplet spectra were 3.45 and 6.07 d respectively.     

广东省部分饮用水源地水中总α和总β放射性水平

调查广东省不同地区饮用水源地水中总α、总β放射性水平,分丰水期和枯水期2次各采集20个不同水样,按照《生活饮用水标准检验方法放射性指标》(GB/T 5750.13—2006),利用BH1227型低本底α、β测量仪测定样品。结果表明,40个水样中总α、总β放射性水平分别为0.017 Bq/L~0.286 Bq/L和0.027 Bq/L~0.397 Bq/L,测量值均在正常本底波动范围之内,放射性指标符合国家《生活饮用水卫生标准》(GB 5749—2006)。     

新疆建筑材料用工业废渣及其建材产品的辐射水平

报道了分布在新疆１３个地州市８０多个厂家的建材用工业废渣及其建材产品的放射性检测结果。多数废渣及其产品的放射性水平低于国家规定的限制（控制）标准，可以用作建筑材料，少数地区的部分工业废渣明显高于限制标准，不能用作建筑材料．必须健全放射性检测和管理制度．     

Abundance and diversity of aquatic macroinvertebrate communities in lakes exposed to Chernobyl-derived ionising radiation

Littoral (lake shore) macroinvertebrate communities were studied in eight natural lakes affected by fallout from the Chernobyl accident. The lakes spanned a range in ¹³⁷Cs contamination from 100 to 15500 kBq m⁻² and estimated external dose rates ranged from 0.13 to 30.7 μGy h⁻¹. General linear models were used to assess whether abundance of individuals, taxon richness, Berger-Parker dominance and Shannon-Wiener diversity varied across the lakes. Step-wise multiple regressions were used to relate variation in total abundance, taxon richness, Berger-Parker dominance, Shannon-Wiener diversity, taxon richness within major groups of macroinvertebrates and abundance of the more common individual taxa to the measured environmental characteristics (conductivity, pH, total hardness and phosphate; lake area, lake maximum depth and total external dose) of the lakes. No evidence was found in this study that the ecological status of lake communities has been influenced by radioactive contamination from the Chernobyl accident. Indeed, the most contaminated lake, Glubokoye, contained the highest richness of aquatic invertebrates. Taxon richness in the eight study lakes varied from 22 (Svyatskoe #7) to 42 (Glubokoye) which spans a range typical for uncontaminated lakes in the region. Since ⁹⁰Sr is readily-absorbed by Mollusca, estimated dose rates to this group exceeded those for other invertebrate groups in two lakes (Perstok and Glubokoye). However this study found no association between mollusc diversity or abundance of individual snail species and variation between lakes in the external radiation dose. Indeed Glubokoye, the lake most contaminated by ⁹⁰Sr, had the highest richness of freshwater snails per sample (an average of 8.9 taxa per sample).     

Nationwide indoor 222Rn and 220Rn map for India: a review

Considering the role of radon in epidemiology, an attempt was made to make a nation-wide map of indoor ²²²Rn and ²²⁰Rn for India. More than 5000 measurements have been carried out in 1500 dwellings across the country comprising urban and nonurban locations. The solid state nuclear track detectors based twin cup ²²²Rn/²²⁰Rn discrimination dosimeters were deployed for the measurement of indoor ²²²Rn, ²²⁰Rn and their progeny levels. The geometric means of estimated annual inhalation dose rate due to indoor ²²²Rn, ²²⁰Rn and their progeny in the dwellings was 0.94 mSvy⁻¹ (geometric standard deviation 2.5). It was observed that the major contribution to the indoor inhalation dose was due to indoor ²²²Rn and its progeny. However, the contribution due to indoor ²²⁰Rn and its progeny was not trivial as it was found to be about 20% of the total indoor inhalation dose rates. The indoor ²²²Rn levels in dwellings was significantly different depending on the nature of walls and floorings.