Measurement of natural radionuclides in U.K. diet

The levels of radium-226, lead-210 and polonium-210 in the U.K. diet have been determined. The important food groups contributing to the intake of these radionuclides have been identified. Seventy-five percent of the daily intake of radium-226 is derived from beverages, cereals, other vegetables, bread, sugars and preserves. Seventy-five percent of the intake of lead-210 and polonium-210 is derived from bread, milk, cereals, beverages, other vegetables, sugars and preserves, and meat products. The average daily intakes of these radionuclides are tentatively calculated to be 30 mBq for radium-226 and 82 mBq for both lead-210 and polonium-210. These levels are compared with data from other countries. The annual effective dose equivalents resulting from the intakes are approximately 3 muSv for radium-226 and 54 muSv from lead-210 and polonium-210 together. The differences between these doses and other current estimates are discussed.     

Spatial distribution of radionuclides in soil around a coal-fired power plant: 210Pb, 210Po, 226Ra, 232Th, 40K emitted with the fly ash and 137Cs from the worldwide weapon testing fallout

To determine the effect of airborne emissions of radionuclides from coal-fired power plants on the environment, the concentrations of the most important radionuclides were measured in soil samples from the local environments (0.4–5.2 km) as well as in fly ash. The spatial distribution of the radionuclides in the soil did not indicate any significantly increased concentrations in the area downwind of the plant compared to other areas; the ratios ²¹⁰Pb/²²⁶Ra and ²¹⁰Po/²²⁶Ra were within the range observed for unaffected soils. The emissions from the plant, though present, are obviously too small to significantly change the natural local distribution pattern of the radionuclides in the soil. A highly significant correlation between ⁴⁰K and ²³²Th was observed which was independent of the different types of soils found in this area. The concentration of ¹³⁷Cs in topsoil, which is the result of worldwide fallout from nuclear weapons testing, varied at some places even within a small distance (～ 2 km) by up to one order of magnitude. Furthermore, it was observed that the concentration of ¹³⁷Cs in soils from cropland was on average a factor of 2 less than in those from grassland. This variability has to be considered in planning monitoring programs around nuclear power plants, which may also release this radionuclide.     

Radioactivity release to the environment by thermal power stations using coal as a fuel

Coal contains naturally occurring radionuclides arising from the uranium and thorium series and ⁴⁰K. Coal burning is thus one of the sources of technologically enhanced exposures to natural radionuclides. Emissions from thermal power stations in gaseous and particulate form contain the radioisotopes, which are discharged to the environment causing radiation exposure to the population. This paper gives the results for coal and fly-ash samples from four thermal power stations in India. The radiation exposures due to the naturally occurring radionuclides discharged from these thermal power stations and those resulting from operation of nuclear power stations of Boiling Water Reactors (BWR) and Heavy Water Reactors (HWR) type are compared. From this study it is observed that exposure to the general population from ionising radiation originating from radionuclides from thermal power stations burning coal is as hazardous, if not more so, than exposure to radionuclides emitted from nuclear power stations of the type operating in India.     

Mercury in coal ash and its fate in the Indian subcontinent: A synoptic review

In the Indian subcontinent power generation is mainly dependent upon the thermal power units and coal is burnt as a fuel for the production of heat and electricity. In India, bituminous and sub-bituminous coals are used which contain over 40% of ash. At present, 80-90 million tons of fly ashes are generated from 85 existing coal based thermal power plants. Coal contains trace metals of which mercury is most toxic for humans and aquatic fauna. The problem of mercury in the society is not new, but in recent years the Indian subcontinent has gained the reputation of being "a dumping ground for mercury". This study focuses on mercury in fly ash and its releases to the atmosphere and soils cross the country. The utilisation of coal ash in India is also addressed although it is still in its nascent stage. About 10% of produced fly ashes are used in India whereas in Western countries its use is typically over 70%. Regulations from India's Ministry of Environment and Forestry should increase coal fly ash utilisation, although this would require that cost-effective new technology is put to use. As to the release of Hg from ashes disposed of in the environment, the scarce literature suggests that this is negligible or zero, and less problematic than wet or dry deposition of Hg from flue gases.     

青岛市粉煤灰综合利用途径探讨

本文较详细地论述了综合利用工业废渣的重要性,分析了本市电厂粉煤灰的性质和特征,探讨了有效地综合利用粉煤灰的途径,为从根本上解决本市电厂因粉煤灰积压,而造成的环境污染问题提供了切实可行的办法.     

石灰-粉煤灰固化巷道泥岩泥化物试验研究

通过无侧限抗压强度试验和微观结构分析,研究了石灰-粉煤灰固化某巷道底板泥岩泥化物的无侧限抗压强度随龄期发展的特性以及将其作为巷道路面基层材料的可行性.试验结果表明,采用一定配比石灰-粉煤灰处理后的泥化物,其28 d的无侧限抗压强度可达到1.78 MPa.分析认为,该固化泥化物可作为巷道路面的基层材料.     

浅谈粉煤灰及其应用现状与发展

分析了燃煤电厂粉煤灰的产生、成分、特性,论述了粉煤灰综合利用现状及我国粉煤灰应用的发展,进而得出粉煤灰的应用对促进国民经济建设和改善生态环境具有重要意义。     

Adsorption of mercury(II) by coal fly ash

Coal fly ash, an industrial solid waste, was found to have a good adsorption capacity for mercury(II). Adsorption of mercury(II) on coal fly ash conforms to Freundlich's adsorption model. Several parameters such as time of equilibration, effect of pH, effect of initial concentration of solute, effect of fly ash dose etc. were studied. The maximum adsorption was observed after shaking for 3 h. Solution pH was the most important parameter affecting the adsorption. The optimum pH range was 3.5–4.5. There was total adsorption of mercury below 10 mg l⁻¹. The performance of coal fly ash as an adsorbent was found to be significant when compared with activated powdered charcoal.     

Effect of fly ash and polypropylene fibres content on the soft soils

Fly ash is a waste produced from the burning of coal in thermal power stations. The staggering increase in the production of fly ash and its disposal in an environmentally friendly manner is increasingly becoming a matter of global concern. Efforts are underway to improve the use of fly ash in several ways, with the geotechnical utilization also forming an important aspect of these efforts. An experimental program was undertaken to investigate the effects of multifilament and fibrillated polypropylene fibre on the compaction and strength behavior of CH class soil with fly ash in different proportions. The soil samples were prepared at two different percentages of fibre content (i.e. 0.5 and 1% by weight of soil) and two different percentages of fly ash (i.e. 10 and 15% by weight of soil). A series of tests were prepared including optimum moisture content and laboratory unconfined compression strength tests, compaction tests and Atterberg limits test. The fibre inclusions increased the strength of the fly ash specimens and changed their brittle behavior into ductile behavior.     

不同工业废渣-石灰稳定土力学性质对比分析

研究了不同工业废渣-石灰稳定土的力学特性.分析了细粒径钢渣、煤矸石、粉煤灰及电厂炉渣的化学成分,根据它们各自的特点,通过不同配比方案、含水量条件下的击实试验,得出各种稳定土在不同配比方案下的最优含水量,在此基础上进行了无侧限抗压强度试验和抗压回弹模量试验,综合得出各种工业废渣-石灰稳定土的最优配比方案,并比较了它们的力学特性.对比结果表明:钢渣-石灰稳定土的早期强度和刚度相对较大,是较好的基层填料;废渣-石灰稳定土的早期强度随废渣含量的提高而增加;石灰与工业废渣质量比接近1:2时,活性氧化物的火山灰反应最为充分,废渣-石灰稳定土的早期强度达到最大.     

As(V) removal from aqueous solutions by fly ash

The present work examines the possible use of fly ash, a by-product of coal power stations, as a means of removing arsenic (V) from water, or equivalently, of restricting its movement in the solid wastes or the soil. Kinetic and equilibrium experiments were performed in order to evaluate the removal efficiency of lignite-based fly ash. Both adsorption and desorption experiments were done at three pH levels, namely 4, 7 and 10. The results indicated that arsenic can be removed from water by fly ash, yet the degree of removal depended markedly on the pH. Removal at pH 4, as demonstrated by the adsorption isotherms, was significantly higher than that at the other two pH values. For 80% removal of arsenic, the solid phase concentration at pH 4 was up to 4 times greater than that at the other two pH levels. During the desorption studies only a small amount of the pre-adsorbed arsenic was released into the water. This amount was practically independent of the initial fly ash loading. This indicates that adsorption of arsenic on fly ash is almost irreversible and, therefore, there are good prospects for arsenic fixation on fly ash in practical applications.     

Investigations on fly-ash and soil samples in the environment of a coal-fired power plant

In the main wind direction of a coal-fired power plant dust and soil samples have been collected to analyse the content of fly-ash coming from the power plant. The fly-ash particles are spherical and contain the natural radionuclides mainly Ra-226, Pb-210, Po-210 and K-40 in a higher concentration when compared with the original coal. The investigation of soil samples results in increased Pb-210 and Po-210 concentrations when compared with the natural environment. By presence of spherical particles in dust and soil samples the power plant can be identified as the emitter.     

Daily intakes of 238U, 234U, 232Th, 230Th, 228Th and 226Ra in the adult population of central Poland.

Activity concentration of the uranium and thorium series radionuclides was determined in foodstuffs and drinking water in central Poland. Annual and daily intake for the adult population was estimated from the concentrations determined and average annual consumption of food and water. The daily intakes (in mBq) were 22.1 (238U), 26.5 (234U), 2.38 (232Th), 4.06 (230Th), 11.2 (228Th) and 42.2 (226Ra). The intake of uranium isotopes occurred mainly with water; the main intake of thorium isotopes was with animal products, vegetables, cereals and potatoes, whereas 226Ra entered mainly with animal products, cereals and vegetables. From the intake and dose coefficients, the annual effective doses for the ingested radionuclides were calculated. The annual effective dose was 5.95 microSv, of which 72.4% originated from 226Ra.     

Physical and mechanical properties of municipal solid waste incineration residues with cement and coal fly ash using X-ray Computed Tomography scanners

A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e., incineration residues) are commonly disposed as landfill. Meanwhile, reclamation of landfill sites to create a new land space after their closure becomes an important goal in the current fewer and fewer land availability scenario in many narrow countries. The objective of this study is to reclaim incineration residue materials in the landfill site by using cement and coal fly ash as stabilizers aiming at performing quality check as new developed materials before future construction. Indeed, physical and mechanical properties of these new materials should be initially examined at the micro scale, which is the primary fundamental for construction at larger scale. This research examines quantitative influences of using the combination of cement and coal fly ash at different ratio on the internal structure and ability of strength enhancement of incineration residues when suffering from loading. Couple of industrial and micro-focus X-ray computed tomography (CT) scanners combined with an image analysis technique were utilized to characterize and visualize the behavior and internal structure of the incineration residues-cement-coal fly ash mixture under the series of unconfined compression test and curing period effect. Nine types of cement solidified incineration residues in term of different curing period (i.e., 7, 14, 28 days) and coal fly ash addition content (i.e., 0%, 9%, 18%) were scanned before and after unconfined compression tests. It was shown that incineration residues solidified by cement and coal fly ash showed an increase in compression strength and deformation modulus with curing time and coal fly ash content. Three-dimension computed tomography images observation and analysis confirmed that solidified incineration residues including incineration bottom and fly ash as well as cement and coal fly ash have the deliquescent materials. Then, it was studied that stabilized parts play a more important role than spatial void distribution in increment or reduction of compression strength.     

Sequential cropping of fly ash-amended soils: Effects on soil chemical properties and yield and elemental composition of plants

Fly ash from a western U.S. coal source was added to a calcareous soil and an acid soil at rates ranging up to and including 8% by weight. The treated soils were cropped to a native desert plant species followed by barley under greenhouse conditions, with the objective to monitor long-term effects of fly ash on soil and plant composition and plant productivity. Application of fly ash increased pH, EC, Ca, Mg, Na, B, and SO₄ in soil. The increase in soil pH of the calcareous soil was completely buffered following the first crop. Boron and SO₄ showed relatively low initial release but increased substantially upon cropping. Dry weight of shoots of the desert species and yield of barley grain were significantly improved upon addition of fly ash to soil. Data on analysis of plants showed positive response to S and Mo from fly ash, whereas the increase in Ca, B, and Na varied among soils and plants. The availability of P, Zn, Fe, and Mn to plants appeared to be diminished by fly ash. Low Cu:Mo ratios were found in the plants, suggesting potential problems of fly ash-treated crops intended for animal use. Although data on soil and plant analysis indicate substantial removal of fly ash-derived elements by plants, a long-term effect of the by-product on their chemical composition was evident.     

粉煤灰资源化利用的研究现状

粉煤灰是燃煤产生的一种工业固体废物,其资源化利用一直被世界各国政府和专家学者所关注.结合国内外文献,针对粉煤灰的性质特点,介绍了其在建筑建材、环保、农业、有用物质提取等方面的研究与应用现状,并提出了粉煤灰综合利用的几点建议.     

Radium migration through clay liners at waste disposal sites

The migration of 226Ra through the bottom compacted clay liner of the wastewater disposal reservoirs of an industrial plant that processes uranium ore was evaluated. An instrumental method for 226Ra analysis in soils, consisting of detector calibration, the determination of detector counting efficiency, cumulative counting of both background and soil samples in regular counting intervals, and photo-peak smoothing was developed. The 226Ra was analyzed by means of its granddaughter 214Bi, at a photo-peak of 609 keV. The results showed that most of the 226Ra which diffused from the solution into the soil was retained in the upper layer of the sample, and that just a small percentage migrated to the subjacent layers. This methodology is adequate for the assessment of the migration of radionuclides through soil layers and for environmental impact studies related to contamination of soils by radionuclides.     

高钙粉煤灰与矿渣的复合及大掺量用于高性能混凝土的研究

根据对上海三家电厂排放的高钙灰的活性和安定性的试验结果，提出了对含有较高游离氧化钙含量的高钙灰的改性工艺及其可行性，并将改性后的高钙灰大掺量用于高性能混凝土。结果显示：经改性处理后的高钙灰不仅能提高混凝土的耐久性，而且能获得显著的经济和社会效益。     

火力发电产生的高钙粉煤灰的改性研究

本文以电厂发电采用的循环流化床燃烧煤产生的高钙粉煤灰作为研究的对象,主要是为了找到高钙灰降钙的方法,在此基础上改善高钙灰的性能,然后把这种高钙灰利用到水泥生产或混凝土中,变废为宝,变害为利,合理综合利用。     

Investigation of mine and industry dumps in the FRG in relation to a possible release of natural radioactive elements

More than 350 dumps of mines and industries in two federal states of the FRG were recorded, measured radiometrically, evaluated, and some of them sampled. Most of the mine dumps belonged to old and smaller residues from lead/zinc and iron ore mining, while the largest depositions contain tailings of modern ore beneficiation of flyash disposal. All mine dumps from uranium exploration in Baden-Württemberg and Bavaria were investigated.The highest doses, up to 100 mSv/a, were found on the piles of the uranium exploration. These depositions, which are supervised and licensed, are followed, in terms of surface dose, by the old uncontroll mne dupms of silver/cobalt mining with doses up to 20 mSv/a. The numerous porphyry and granite quarries show doses between 1 and 2 mSv/a, as do flyash and slag dumps. The lowest doses were found on the dumps of the hydrothermal Pb/Zn and iron ore deposits, while the slag piles of iron ore processing showed higher thorium values.Assays for Ra-226 and Pb-210 of the materials deposited confirmed the radiometric results. Analyses of seepage waters and gallery waters showed only very few values exceeding the derived drinking water concentrations.