Assessment of the radiological impacts of a zircon sand processing plant

The paper presents the results of a study on radiological impacts resulting from a zircon sand processing plant located in the North-Eastern part of Italy. Activity concentrations of radionuclides found in materials associated with this industrial process are presented as well as the results of the assessment of the annual effective doses to the workers and the members of the public. Gamma-spectrometric analyses were performed on "raw" sands, end-products, and soils sampled near the plant. Thermoluminescent dosimeters, electric pumps and electret ion chambers were used to measure the external irradiation, the indoor dust concentrations and the radon concentrations, respectively. The ground-level air concentration of radioactive particulate near the plant and the deposition of particulate matter were estimated by a Gaussian model (ISCLT3). Finally, the annual effective doses, calculated as provided for by Directive 96/29/Euratom, were estimated to be 1.7 mSv y(-1) for workers and 4.4 microSv y(-1) for members of the public.     

Health and environmental impacts of a fertilizer plant--Part II: assessment of radiation exposure

In the previous paper the authors have studied the radioactive pollution caused by a complex fertilizers production plant. In this paper, the effective doses to the plant workers and to members of the population surrounding the industrial site are estimated. The authors have considered external irradiation, inhalation and ingestion of dust and inhalation of radon and radon daughters as the main occupational exposure routes. After estimating the single contributions, the total effective dose has been calculated as the sum of said contributions. Calculations have been differentiated according to the different tasks of the company employees. The estimated annual effective doses range from 0.6 to 1.4 mSv y(-1). Annual individual effective doses to local residents, resulting from internal and external irradiation caused by particulate matter emitted into the atmosphere by the plant have been estimated. The maximum individual dose rate is estimated to be about 4 microSv y(-1).     

Naturally occurring radioactive material (NORM) from a former phosphoric acid processing plant

In recent years there has been an increasing awareness of the radiological impact of non-nuclear industries that extract and/or process ores and minerals containing naturally occurring radioactive material (NORM). These industrial activities may result in significant radioactive contamination of (by-) products, wastes and plant installations. In this study, scale samples were collected from a decommissioned phosphoric acid processing plant. To determine the nature and concentration of NORM retained in pipe-work and associated process plant, four main areas of the site were investigated: (1) the 'Green Acid Plant', where crude acid was concentrated; (2) the green acid storage tanks; (3) the Purified White Acid (PWA) plant, where inorganic impurities were removed; and (4) the solid waste, disposed of on-site as landfill. The scale samples predominantly comprise the following: fluorides (e.g. ralstonite); calcium sulphate (e.g. gypsum); and an assemblage of mixed fluorides and phosphates (e.g. iron fluoride hydrate, calcium phosphate), respectively. The radioactive inventory is dominated by 238U and its decay chain products, and significant fractionation along the series occurs. Compared to the feedstock ore, elevated concentrations (< or =8.8 Bq/g) of 238U were found to be retained in installations where the process stream was rich in fluorides and phosphates. In addition, enriched levels (< or =11 Bq/g) of 226Ra were found in association with precipitates of calcium sulphate. Water extraction tests indicate that many of the scales and waste contain significantly soluble materials and readily release radioactivity into solution.     

Radioactive impact in sediments from an estuarine system affected by industrial wastes releases

A big fertilizer industrial complex and a vast extension of phosphogypsum piles (12 km2), sited in the estuary formed by the Odiel and Tinto river mouths (southwest of Spain), are producing an unambiguous radioactive impact in their surrounding aquatic environment through radionuclides from the U-series. The levels and distribution of radionuclides in sediments from this estuarine system have been determined. The analyses of radionuclide concentrations and activity ratios have provided us with an interesting information to evaluate the extension, degree and routes of the radioactive impact, as well as for the knowledge of the different pathways followed for the radioactive contamination to disturb this natural system. The obtained results indicate that the main pathway of radioactive contamination of the estuary is through the dissolution in its waters of the radionuclides released by the industrial activities and their later fixation on the particulate materials. Tidal activity also plays an important role in the transport and homogenization along the estuary of the radioactivity released from the fertilizer plants.     

Global Radioactive Contamination Background in Terrestrial Ecosystems 13 Years after the Chernobyl Accident

The contents of ¹³⁷Cs in the soil, plant, and animal samples collected in the ecosystems of protected areas from the White Sea to the Black Sea in 1999 slightly differ from those in the period between 1980 and 1984. As a result of global fallout after the Chernobyl accident, the content of radioactive cesium in the soil has increased only on the territory of the Biological Station of Moscow State University at the White Sea, whereas that in the litter and plants has increased in virtually all areas studied. The isotope content in animals is actually equal to that recorded between 1980 and 1984. The mobility of ¹³⁷Cs in the soil–plant link has increased, which may be due to fallout after the accident. The duration of a complete radionuclide cycle in ecosystems decreases from 10 half-life periods in northern regions to 2.5 half-life periods in the southern regions. The Chernobyl disaster has caused no significant changes in the global radioactive background in the European part of the Russian Federation.     

钢铁工业用水概况及节水浅析

根据对部分钢铁企业工业用水量及污水排放量调查结果表明，钢铁企业中水的重复利用率偏低，但另一方面也说明这些企业在节水方面具有很大潜力，因此，在钢铁企业中开展节水和污水治理的研究工作具有重大现实意义。     

Anomalous concentrations of atmospheric plutonium-238 over Paris

Analysis of monthly rain samples collected in Paris reveals that ²³⁸Pu/ ^239,240Pu activity ratios, usually about 0·04, the fallout value, rose suddenly to 25 in October 1982. Abnormal ratios continued to be observed during the following months. Excess ²³⁸Pu from atmospheric nuclear tests can be eliminated as a possible cause. No correlation was found either with identified satellite re-entries or with atmospheric radioactive anomalies already detected in Northern Europe prior to the Chernobyl accident. Different potential industrial sources are discussed here, but the authors remain unable to identify the origin of the abnormally high ratio. This study shows that a careful investigation of ²³⁸Pu fallout is needed if environmental processes are to be traced via plutonium activity ratios.     

Radiological characteristics and investigation of the radioactive equilibrium in the ashes produced in lignite-fired power plants

Coal- and lignite-fired power plants produce significant amounts of ashes, which are quite often being used as additives in cement and other building materials. In many cases, coal and lignite present high concentrations of naturally occurring radionuclides, such as 238U, 226Ra, 210Pb, 232Th and 40K. During the combustion process, the produced ashes are enriched in the above radionuclides. The different enrichment of the various radionuclides within a radioactive series, such as that of 238U, results in the disturbance of radioactive secular equilibrium. An extensive research project for the determination of the natural radioactivity of lignite and ashes from Greek lignite-fired power plants is in progress in the Nuclear Engineering Department of the National Technical University of Athens (NED-NTUA) since 1983. This paper presents detailed results for the natural radioactivity, the secular radioactive equilibrium disturbance and the radon exhalation rate of the fly-ash collected at the different stages along the emission control system of a lignite-fired power plant as well as of the bottom-ash. From the results obtained so far, it may be concluded that 226Ra radioactivity of fly-ash in some cases exceeds 1 kBq kg(-1), which is much higher than the mean 226Ra radioactivity of surface soils in Greece (25 Bq kg(-1)). Furthermore, the radioactivity of 210Pb in fly-ash may reach 4 kBq kg(-1). These results are interpreted in relation to the physical properties of the investigated nuclides, the temperature in the flue-gas pathway, as well as the fly-ash grain size distribution. It is concluded that towards the coldest parts of the emission control system of the power plant, the radioactivity of some natural nuclides is gradually enhanced, secular radioactive equilibrium is significantly disturbed and the radon exhalation rate tends to increase.     

Variation of nutrient and metal concentrations in aquatic macrophytes along the Rio Cachoeira in Bahia (Brazil)

The use of cuprous fungicides in cocoa production in the southern part of the state of Bahia (Brazil) for decades has caused an accumulation of copper in various components of the cocoa plantations, and a contamination of regional freshwater ecosystems is suspected. Urban and industrial sources are supposed to contribute to water pollution and eutrophication of the Rio Cachoeira, the main river in this region. In order to study the metal contamination and nutritional status of this freshwater ecosystem, samples of the aquatic macrophytes Eichhornia crassipes and Pistia stratiotes were collected at seven sites along the river course. The samples were analysed for their copper, aluminium, chromium, nitrogen and phosphorus concentrations. The levels of heavy metals increased in the downstream direction, particularly in the roots of water hyacinth. A dramatic increase of nitrogen and phosphorus concentrations in water as well as in plant tissues was found in samples collected downstream from the city of Itabuna. Metal input and eutrophication were attributed to agricultural, industrial and urban sources in the region. Biomonitoring of the water quality using aquatic macrophytes as accumulative indicator plants is recommended in addition to chemical water analyses.     

Social metrics in the process industry: background,theory and development work

Sustainable development as the leading global development paradigm and sustainability as a cornerstone of modern industrial development have guided this development work on social metrics in the process industry. This study addresses the development of social metrics in the process industry and for metal production, in particular, at the plant level. The developed social indicators are one part of the overall sustainability index that aims to present a balanced and holistic view of plant-level sustainability performance, encompassing information on all different dimensions. This development work was preceded by the benchmarking and review of existing global reporting frameworks, initiatives and the literature. Current indicators of industrial sustainability mainly satisfy the needs of corporate-level management and capital investors. Therefore, plant-level indicators are critically needed to support and fill potential gaps in corporate-level assessments and management with a special emphasis on plant-level sustainability. The purpose of our development work for social indicators was to operationalise the concept of sustainability and associated performance measurement at the plant level. The development of social indicators was carried out through workshops with industry partners. As a joint effort, eight core social indicators and their associated sub-indicators were developed. We also report the results of our benchmarking and review of existing frameworks, initiatives and the literature. The social part of the overall sustainability index provides the information on both in-plant sustainability performance and the direct and indirect impacts of plant-level operations on the surrounding society including various stakeholders, interest groups and citizens.     

Results of the European Commission Marina II study: part II--effects of discharges of naturally occurring radioactive material

Enhanced levels of naturally occurring radioactive materials (NORM) are produced through various industrial operations and may lead to discharges to the marine environment. A recent study, called MARINA II, carried out for the European Commission considered discharges of radionuclides from the NORM industries to north European marine waters and their consequences. There are two main sources that were considered in the study. The use of phosphogypsum during the production of phosphoric acid by the fertiliser industry and the pumping of oil and gas from the continental shelf in the North Sea which produces large quantities of water contaminated with enhanced levels of naturally occurring radionuclides. Discharges of alpha emitting radionuclides from these two industries have contributed significantly to the total input of alpha emitters to north European waters over the period 1981-2000 (data were not available prior to 1981). Discharges due to the use of phosphogypsum have declined since the early 1990s and are now very low. Discharges from the oil and gas industries stabilised in the second half of the 1990s and are now the major contributor to alpha discharges to the region. As most European countries do not report discharges of radioactivity with the water produced during extraction, there is considerable uncertainty in the discharges used in the study. The impact of the discharges has been estimated both in terms of the effect on non-human biota and the radiological impact for people. In the 1980s the radiation dose rates to marine biota in the region around a phosphate plant on the north-west coast of England were as high due to the discharges from the phosphate plant as those near to the Sellafield reprocessing plant due to its discharges. In recent years the additional dose to marine biota in this region due to the past NORM discharges is of the same order of magnitude as the natural background. The collective dose rate was estimated to determine the radiological impact on people. The peak collective dose rate from the NORM industries occurred in 1984 and was just over 600 manSv y(-1). The collective dose rate fell with time as discharges from the phosphate industry reduced and was estimated as under 200 manSv y(-1) in 2000.     

Mesoscale modelling of radioactive contamination formation in Ukraine caused by the Chernobyl accident

This work is devoted to the reconstruction of time-dependent radioactive contamination fields in the territory of Ukraine in the initial period of the Chernobyl accident using the model of atmospheric transport LEDI (Lagrangian-Eulerian DIffusion model). The modelling results were compared with available 137Cs air and ground contamination measurement data. The 137Cs atmospheric transport over the territory of Ukraine was simulated during the first 12 days after the accident (from 26 April to 7 May 1986) using real aerological information and rain measurement network data. The detailed scenario of the release from the accidental unit of the Chernobyl nuclear plant has been built (including time-dependent radioactivity release intensity and time-varied height of the release). The calculations have enabled to explain the main features of spatial and temporal variations of radioactive contamination fields over the territory of Ukraine on the regional scale, including the formation of the major large-scale spots of radioactive contamination caused by dry and wet deposition.     

Social sustainability performance indicators – experiences from process industry

Sustainable industrial development can be advanced through the development and application of sustainability metrics. This study addressed the application of social sustainability metrics to the measurement of sustainability performance within process industry and to metal production at the plant level in particular. The applied social sustainability indicators are one part of the overall sustainability index which aims at presenting a balanced and holistic view of plant-level sustainability performance. Application of plant-level indicators can support informed decision-making and fill in potential gaps in corporate-level assessments and reporting initiatives with respect to plant-level social sustainability performance. The social part of the overall index provides information on both in-plant sustainability performance and on the direct and in-direct impacts of plant operations on the surrounding society with special emphasis on the supply chain and emerging social due diligence aspects. The results of pilot implementation of social indicators in Ruukki Lappohja plant indicated a very high level of social sustainability performance with minor areas of improvement such as social risk management auditing covering the whole supply chain, suppliers communication on social responsibility requirements to workers and sub-suppliers, signing of the code of conduct by employees and reporting on policies on local community relations, safety in supply chain covering suppliers and contractors and factory health and safety performance in relation to average field of industry performance in this field.     

Sedimentary radioactive tracers and diffusive models

This paper examines the underlying assumptions and consequences of applying a steady-state equation to sediment profiles of radioactive tracers in order to deconvolute sedimentation from bioturbation processes modelled as a diffusive type process.Several factors follow immediately from this investigation:

(i)

if the observed radioactive concentration increases with depth over any finite depth range then the proposed steady-state, constant flux equation is not applicable. Any increase in radioactive concentration with depth implies a negative mixing coefficient which is a physical impossibility;

(ii)

when the radioactive concentration systematically decreases with increasing sedimentary depth then solutions to the steady-state conservation equation exist only when either the constant solid state flux to the sediment surface is small enough so that a positive mixing coefficient results or when the mixing coefficient is small enough so that a positive flux results.

If the radioactive concentration, porosity and/or density of the solid phase are such that the proposed equation is inappropriate (because no physically acceptable solution exists) then one must abandon the proposed steady-state equation.Further: if the flux of solid sediment to the sediment surface varies with time then, of course, a steady-state conservation equation is also inappropriate.Simple examples illustrate that the assumption of steady-state restricts the applicability of this modelling approach to a relatively small sub-set of expected situations in the real world.     

Cesium isotope ratios as indicators of nuclear power plant operations

There are multiple paths by which radioactive cesium can reach the effluent from reactor operations. The radioactive ¹³⁵Cs/¹³⁷Cs ratios are controlled by these paths. In an effort to better understand the origin of this radiation, these ¹³⁵Cs/¹³⁷Cs ratios in effluents from three power reactor sites have been measured in offsite samples. These ratios are different from global fallout by up to six fold and as such cannot have a significant component from this source. A cesium ratio for a sample collected outside of the plant boundary provides integration over the operating life of the reactor. A sample collected inside the plant at any given time can be much different from this lifetime ratio. The measured cesium ratios vary significantly for the three reactors and indicate that the multiple paths have widely varying levels of contributions. There are too many ways these isotopes can fractionate to be useful for quantitative evaluations of operating parameters in an offsite sample, although it may be possible to obtain limited qualitative information for an onsite sample.     

Mapping large areas of radioactively contaminated land with a self adapted, handheld, GPS coupled, scintillation detector

In Belgium, during several decennia, a phosphate plant discharged radium chloride containing waste water into two small rivers. One of those is part of a hydrographically very complex ecosystem with lots of small tributaries and hundreds of hectares of flooding zones. Hence, the river banks and large parts of these flooding zones have become contaminated with radium, heavy metals and chlorides. During a foot campaign, using a home made portable data logging system, consisting of a commercial 2.5 kg NaI detector, a computer mouse sized GPS, and a small pocket PC, the radioactive contamination of about 600 ha of sometimes very rough terrain was measured and mapped. The resulting very detailed radium contamination maps shed a whole new light on the water flow patterns of the ecosystem. The apparatus can also be used for efficiently guiding sampling campaigns for investigating other types of contamination. The ground maps are also compared to existing maps from helicopter measurements, evaluating strengths and weaknesses from both methods.     

Distribution and migration of 95Zr in a tea plant/soil system

(95)Zr is a primary radionuclide in the radioactive liquid efflux from a pressurized water reactor and one of the main radionuclides released after nuclear accidents. The fission yield of (95)Zr is as high as 6.2%, however, its environmental behavior has not been well documented. An experiment was conducted to evaluate the accumulation and distribution of (95)Zr in a tea plant/soil system. (95)Zr was accumulated primarily in the trunk of tea plants after being taken up from the soil. The radioactivity concentration of (95)Zr in the trunk increased slowly with time, then it reached a dynamic equilibrium 14 days after application. The radioactivity concentration of (95)Zr in the other parts of the tea plant was very low; only slighter greater than the detection limit. The results indicated that (95)Zr was not readily translocated in the tea plant. About 98.9% of applied (95)Zr was found to concentrate in the upper 5 cm layer after being sprayed onto the soil surface. The results indicated that (95)Zr could not readily move downwards with percolating water due to strong adsorption to surface soil.     

Nationwide survey on the natural radionuclides in industrial raw minerals in South Korea

A Nationwide survey on the natural radioactivity in industrial raw mineral commodities (17 kinds of domestic and 18 kinds of imported) that are representative minerals used in production and consumption in South Korea was conducted. The target industrial minerals can be categorized into two groups. The first group covers non-metallic and metallic raw minerals with low levels of radioactivity such as clay, silica sand, carbonates, bituminous and anthracite coal, iron ores, ilmenite, rutile, and phosphate ore. The other group comprises minerals with high levels of radioactivity including zircon and monazite. One hundred and sixty-four domestic and imported samples were analysed by gamma-ray spectroscopy using an HPGe detector. The (40)K content ranges from <0.00131 to 2.69Bq g(-1), and (226)Ra and (232)Th range over <0.0006 to 0.630 and <0.0008 to 0.474Bq g(-1), respectively. There was no anthropogenic radioactive signal in any of the samples.     

The pollution status and the toxicity of surface sediments in Izmit Bay (Marmara Sea), Turkey

Izmit Bay is one of the most polluted and populated enclosed sea in Turkey. It has been the centre of industrial activities for the last 30 years. Seven major sources enter the bay waters along the north coastline of the bay. This investigation forms part of continuing ecotoxicology studies in the Izmit Bay designed to constrain and minimise the pollution caused by flourishing industry and a growing population. Sediments sampled from the mouths of the major discharges of Izmit Bay were analysed for their organic carbon, total polycyclic aromatic hydrocarbon (t-PAH) and trace inorganic element (Cd, Al, As, Pb, Hg and Cu) contents and compared with those found in the sediments from the reference station in the outer bay (in the Marmara Sea). The toxicity of sediments was determined in the bulk and elutriate samples by using algal (Phaeodactylum tricornutum) batch bioassays. Chemical data showed that the sediments collected from the inner sites of the bay have been contaminated with Cd, Hg, As and PAHs. Organic carbon contents were also found higher. All the major industrial discharges into the bay are now biologically treated but bioassays performed with bulk sediments revealed that the recent sediments are toxic to the microalgae throughout the bay. The results are consistent with the previous toxicity studies performed with the industrial discharges.     

Radioactive contamination of wood and its products

This paper presents research on radioactive contamination of the three most common kinds of wood in Croatia--beech, oak and fir as well as acorn. Gamma-spectrometric measurements carried out on the samples of bark and wood of beech, oak, fir and acorn have shown radioactivity contents ranging from 1.6 +/- 0.1 to 37.3 +/- 0.5 Bq/kg from deposited 137Cs, whose concentrations in the soil of Croatia have increased after the Chernobyl accident. Measurements have also shown the radioactivity originating from 40K and 214Bi, which are part of the natural composition of the soil. The distribution of the radionuclides in wood has been discussed, as well as the impact of radioactive contamination of wood by the artificial radionuclide 137Cs upon the forest ecosystem. According to the corresponding model, it has been calculated that a 10 h daily stay in a typical family house increases the annual radiation dose of the population, due to the deposited 137Cs in the structure or furniture, by 343 microSv.