Occupational exposures in two industrial plants devoted to the production of ammonium phosphate fertilisers.

In order to fill a gap in the open literature, occupational exposures and activity concentrations have been assessed in two NORM industrial plants, located in the south-west of Spain, devoted to the production of mono-ammonium phosphate (MAP) and di-ammonium phosphate (DAP) fertilisers. The annual effective doses received by the workers from these plants are clearly below 1 mSv yr(-1) and the contribution due to external radiation is similar to that due to inhalation. The contribution to the maximum effective doses due to inhalation of particulate matter has been estimated to be about 0.12 mSv yr(-1), while the (222)Rn concentrations inside the plants are of no concern. Consequently, no additional actions or radiological protection measures need to be taken to decrease the natural radiation received by the workers in these facilities.

Fate of anthropogenic radionuclides (90Sr, 137Cs, 238Pu, 239Pu, 240Pu, 241Am) in seawater in the northern Benguela upwelling system off Namibia.

A baseline study on anthropogenic radioactivity in the Namibian marine ecosystem, which is part of the northern Benguela upwelling system, known as one of the most productive ocean areas in the world, has been performed. A scientific cruise carried out in 2014 covering inshore and offshore areas, exhibiting different oceanographic features, has provided a basis for better understanding the distributions, ratios and inventories of six anthropogenic radionuclides (90Sr, 137Cs, 238Pu, 239Pu, 240Pu and 241Am) in seawater. Although 3H was also measured, due to extremely low levels, its behaviour was not studied. The main source of 90Sr, 137Cs, 239Pu, 240Pu and 241Am in the samples analysed was proven to be global fallout, a finding further confirmed by 240Pu/239Pu and 90Sr/137Cs ratios. Furthermore, the 238Pu SNAP-9A satellite accident signal was confirmed once again through the determination of the 238Pu/239+240Pu activity ratio. Inshore and offshore samples showed different patterns due to the unique oceanographic features of this upwelling system. The levels of anthropogenic radionuclides, comprehensively assessed for the first time in this region, are comparable with the few existing data and filled a critical gap for the Southern Atlantic Ocean.

Radiological and chemical risks by waste scales generated in the titanium dioxide industry.

Along the industrial process devoted to the production of titanium dioxide pigments by using ilmenite as main raw material, small residues amounts are generated, remaining clearly enriched in natural radionuclides and chemical pollutants. Between them, we can remark the scales enriched in both radium isotopes and lead, which are formed in the internal walls of pipes and some equipment. These scales are radiological anomalies that demand its mineralogical, elemental and radiometric characterization as a basis for a detailed radiological and toxicological assessment from the occupational and public point of view. In this work, several scales collected in a TiO2 pigment production plant in South of Spain have been mineralogically characterized by XRD, while information about their elemental composition and morphology have been obtained by applying the XRF and SEM techniques. In addition, radiometric determinations have been performed by gamma-ray and alpha-particle spectrometry. The performed study indicates that the radiological doses received due to the scales by the workers performing its conventional activities are clearly lower than 1 mSv/y. Special dosimetric and chemical controls could be needed for the workers in charge of the maintenance labours (which include the removal of the scales) if these workers belong to an external company devoted to perform maintenance operations in several NORM industries.

Optimisation of a batch thermal combustion method using a tube furnace oxidation system (pyrolyser) and LSC for carbon-14 determination in environmental matrices.

Accelerator mass spectrometry and benzene synthesis coupled with liquid scintillation spectrometry are often used for accurate measurements of 14C activity in the environmental matrices. Thermal oxidation is one of the methods employed for 14C determination in environmental matrices. In this method, the sample is oxidised at high temperature (600-900 °C) to convert carbon species to CO2 and trapped in an amine-based absorber for determining the activity in a liquid scintillation counting (LSC) system. In this study, the performance of a commercially available tube furnace system (pyrolyser), for batch combustion of samples, was evaluated for the determination of 14C specific activity in terrestrial biota samples. Significant improvements over the manufacturer specified method, which is primarily designed for analysis of samples with activity well above the environmental background level, was implemented to achieve accurate determination of 14C specific activity at ambient background level. In the improved method, the CO2 produced from the combustion of the sample was isolated from the combustion products through cryogenic trapping and then absorbed in the absorber (Carbo-Sorb E) through a simple off-line transfer process. This allowed (i) optimisation of CO2 absorption by the absorber (2.2477 g of CO2/10 mL), (ii) achieving good accuracy and precision in the measurements, and a minimum detectable activity value of 13 Bq kg-1C for a counting time of 300 min (7 Bq kg-1C for 1000 min), (iii) avoiding uncertainty associated with the determination of recovery of 14C in the combustion and trapping process, and (iv) elimination of the need for an independent determination of carbon content (%) for expressing the results in terms of 14C specific activity. The method is capable of yielding accurate results with a deviation of <2.4% from the target value for IAEA C3 quality assurance reference material (with a relative standard deviation of 1.40%, and relative error of 0.34%). The combined uncertainty (1σ) associated with the measurements was computed to be 3.4%. Upon optimisation, the suitability of the method for the determination of 14C specific activity in typical terrestrial biota samples of clean air region (region not affected by local anthropogenic sources) and for the quantification of a small increase in the 14C activity above ambient levels in the vicinity of a nuclear power plant is demonstrated.

210Po levels and distribution in different environmental compartments from a coastal lagoon. The case of Briozzo lagoon, Uruguay.

This paper presents the levels and distribution of 210Po in different compartments of a coastal lagoon on the east coast of Uruguay (South America). Activity concentrations of 210Po have been obtained in different matrices, such as water, superficial sediments, clams (Diplodon sp.), freshwaters snails (Pomacea sp.), zooplankton, and fishes (Jenynsia sp.), collected at different points of the lagoon and during several sampling campaigns. In addition, the organic matter content of the sediment was determined to study the variation of 210Po along the lagoon. The activity concentrations of 210Po in the water samples are in the range between 1.1 ± 0.2-3.5 ± 0.4 mBq/L while in the sediment samples vary between 17.1 ± 1.4 and 540 ± 12 Bq/kg, DW. In the case of biota, the ranges obtained were 182 ± 5-265 ± 6 Bq/kg, DW in clams and 134 ± 4-1245 ± 16 Bq/kg, DW in snail samples. A good correlation of 210Po with the organic fractions of the sediment was observed (r = 0.8798, p-value < 0.001), being obtained high values for the distribution coefficient Kd (104 -105). In the biota samples, a clear difference was observed in the 210Po concentration values in both species, mainly due to the different feeding habits of both aquatic organisms, as it is reflected in the associated concentration ratios (CR). In this paper, a good set of results of 210Po, Kd, and CR have been obtained in different matrices, enhancing the limited archives available for modelers concerning these parameters for 210Po and freshwater systems.

Pit lakes from Southern Sweden: natural radioactivity and elementary characterization.

Natural radioactivity in the environment is a field gaining more attention in last decades. This work is focused on the study of natural radioactivity complemented with elementary characterization at former non-uraniferous mining areas in Sweden. This aim is addressed through the study of mining lakes, called pit lakes, which are water bodies generated after opencast mining. Environmental matrices (water, sediments and rocks) from 32 Swedish pit lakes, commonly used for recreational purposes were radiometrically characterized via alpha (238U, 234U, 232Th, 230Th, 210Po isotopes) and gamma spectrometry (238U and 232Th series radionuclides). Additionally, ambient dose rate equivalent in the immediate surrounding of each pit lake was quantified. Physico-chemical parameters (pH, specific conductivity, dissolved oxygen, oxidation-reduction potential) and elemental composition (major and trace elements by ICP-MS) were analysed in water samples and elementary composition of sediments/rocks was measured by XRF and SEM-EDX in some specific cases. A non-negligible number of pit lakes (26%) with enhanced U levels in water was found. At some sites, rocks contained up to 4% of U in areas with high degree of interaction with local population. Concerning the elementary perspective, another popular site (due to its turquoise water) was found to have elevated dissolved heavy metal levels. Results obtained in this work prove that measurement of natural radioactivity is another component that should be included in routine analysis of characterization in mining areas, especially if restauration of post-mining sites is intended for human recreational.

Insights into the Pu isotopic composition (239Pu, 240Pu, and 241Pu) and 236U in marshland samples from Madagascar.

This work provides new insights into the presence of 239Pu, 240Pu, 241Pu, and 236U in the Southern Hemisphere through the study of peat bog cores from marshlands in Madagascar (19°S). 210Pb, 238Pu and 239+240Pu activities were characterized by alpha spectrometry in previous studies. Here, Pu from alpha-spectrometry discs corresponding to 10 peat-bog cores (85 samples) was reassessed for the aim of completing its isotopic composition (239Pu, 240Pu, and 241Pu) by Accelerator Mass Spectrometry. In addition, 236U was studied in a single core exhibiting unusually low 240Pu/239Pu ratios. Integrated 240Pu/239Pu atom ratios in the single cores ranged above and below the (0-30°S) fallout average ratio, 0.173 ± 0.027, from 0.126 ± 0.003 to 0.206 ± 0.002, without a regional pattern, thereby demonstrating the heterogeneous distribution of the 239Pu and 240Pu signal. However, such a variability was not observed for 241Pu/239Pu, ranging from (6 ± 1) · 10-4 to (11 ± 1) · 10-4 and consistently below the (0-30°S) fallout ratio of (9.7 ± 0.3) · 10-4 (2012). The integrated 236U/239Pu atom ratio in the studied core, 0.147 ± 0.005, was also significantly lower than the values reported for the global fallout in the Northern Hemisphere, in the 0.20-0.23 range. Our results point out to stratospheric fallout as the main source of both 236U and 241Pu at the studied site, whereas 239Pu and 240Pu signals show the influence of tropospheric fallout from the low-yield tests conducted in Australia (1952-1958) by United Kingdom and in French Polynesia (1966-1975) by France despite the long relative distances (i.e. about 15,000 and 8500 km). It was also demonstrated that a representative number of samples is necessary in order to assess Pu contamination and its various origins in a specific region in the Southern Hemisphere due to the heterogeneous distribution, and results based on single sample analysis should be interpreted with caution.

226Ra, 210Po and lead isotopes in a pit lake water profile in Sweden.

A pit lake arises as a consequence of anthropogenic activities in opencast mining areas. These water bodies may be enriched in hazardous stable contaminants and/or in naturally occurring radionuclides depending on the local geological conditions. Mining legacy in Sweden produced hundreds of these pit lakes and most of them are used for recreational purposes in the southern part of the country. In this paper, one pit lake was selected for having enhanced levels of natural radionuclides. Physico-chemical parameters (temperature, pH, oxidation-reduction potential, dissolved oxygen and depth), elemental composition (via Inductive Coupled Plasma Mass Spectrometry) and radiometric characterization (via alpha spectrometry of 226Ra, 210Po and 210Pb) were carried along the depth of a 60 m depth pit lake, with the main aim to describe how natural radionuclides and elements behaves with depth in a non-uraniferous pit lake. Based on observed changes in physico-chemical parameters, a thermocline and a chemocline region were identified at around 10 and 30 m depth respectively. Concerning radionuclides, 226Ra ranged from 75 ± 3 up to 360 ± 12 mBq/kg while 210Po ranged from 11 ± 1 up to 71 ± 3 mBq/kg. 210Pb distribution with depth was also determined via secular equilibrium with 210Po after 2 years and also stable Pb was measured. Disequilibrium 226Ra-210Pb was found and the residence time of 210Pb in the water column was assessed. Additionally, different vertical distributions between 210Pb and Pb were found which points out different sources for different lead isotopes in the water body.

From radiometry to chronology of a marine sediment core: A 210Pb dating interlaboratory comparison exercise organised by the IAEA.

Laboratories from 14 countries (with different levels of expertise in radionuclide measurements and 210Pb dating) participated in an interlaboratory comparison exercise (ILC) related to the application of 210Pb sediment dating technique within the framework of the IAEA Coordinated Research Project. The laboratories were provided with samples from a composite sediment core and were required to provide massic activities of several radionuclides and an age versus depth model from the obtained results, using the most suitable 210Pb dating model. Massic concentrations of Zn and Cu were also determined to be used for chronology validation. The ILC results indicated good analytical performances while the dating results didn't demonstrate the same degree of competence in part due to the different experience in dating of the participant laboratories. The ILC exercise enabled evaluation of the difficulties faced by laboratories implementing 210Pb dating methods and identified some limitations in providing reliable chronologies.

Occupational dosimetric assessment (inhalation pathway) from the application of phosphogypsum in agriculture in South West Spain.

Phosphogypsum (PG) has been traditionally applied as Ca-amendment in saline marsh soils in SW Spain, where available PG has 710+/-40Bqkg(-1) of 226Ra. This work assesses the potential radiological risk for farmers through 222Rn exhalation from PG-amended soils and by inhalation of PG-dust during its application. A three-year field experiment was conducted in a commercial farm involving two treatments: control and 25tPGha(-1) with three replicates (each 0.5ha plots). The 222Rn exhalation rate was positively correlated with potential evapotranspiration, which explained 67% of the variability. Statistically significant differences between the control and PG treatments were not found for 222Rn exhalation rates, and mean values were within the lowest quartile of the typical range for 222Rn exhalation from soils. Airborne dust samples were collected during the application of PG and sugar-beet sludge amendments. The highest PG-attributable 226Ra concentration in the dust samples was 3.3x10(2)microBqm(-3), implying negligible dose increment for exposed workers.

Radiological evaluation of the transuranic remaining contamination in Palomares (Spain): A historical review.

This paper shows the studies carried out in Palomares (Almería, Spain) following the ground dispersion of nuclear material as a result of the air crash accident that took place in 1966, in which four nuclear bombs were involved. As a consequence of the Palomares accident, plutonium (Pu) and uranium (U) were dispersed over an area of approximately 2.3 km2 due to the chemical explosion of two of them. The most relevant activities carried out by CIEMAT, along with other national and international institutions in the Palomares scenario are detailed. These activities, performed for over 50 years, focus mainly in the characterization of the contamination source, in the continuous environmental and personal radiological monitoring programs, in the construction of a detailed superficial and 3-D mapping distribution of the remaining contamination and in the evaluation of the bioavailability of the transuranics still remaining in the area.

Some naturally occurring radionuclides (NORM) in a river affected by acid mining drainages.

The mining activities performed in the Iberian Pyrite Belt (south of Spain) have generated since long-time acid mining drainage (AMD) inputs to the Odiel River and its tributaries. These inputs are continuing nowadays, with origin mostly in the abandoned mines that cover the area, provoking a steady-state situation where the river waters present very low pH and very high concentrations of different heavy metals. In this work, the behavior of several natural radionuclides (210Po, Th- and U-isotopes) in water and sediment samples collected in the Odiel River and its tributaries have been analyzed and their levels determined looking for assessing the radiological environmental impact of the AMD.

Meteoric 10Be in aerosol filters in the city of Seville.

Cosmogenic radionuclides in the one-million-year half-life range, like 10Be, find application fields in several Sciences. They are powerful tools in Geology and Geochronology, as they are very important tracers on the Earth, being utilized as chronometer. Meteoric 10Be (T1/2 = 1.39 × 106 y) associated to aerosols can be used as a tracer of atmospheric processes and specifically as indicators of the cosmogenic interactions in lower Stratosphere, upper Troposphere, the air exchange between both and deposition processes on the Earth surface. The applications of 10Be are even more relevant when combined with other radionuclides such as 26Al. In order to provide new data about concentration 10Be in this type of samples, the first atmospheric air filters in Spain have been analysed. Values around 104 at/m3 (atoms per cubic meter of air) for 10Be have been obtained. Due to the location and the features of the sampling site (urban area, at sea level and mid latitude), a new radiochemical procedure was designed and developed in our laboratory for the Accelerator Mass Spectrometry (AMS) measurement of 10Be in this kind of samples. The samples were measured in SARA, the 1 MV AMS system at Centro Nacional de Aceleradores (CNA).

Levels, distribution and bioavailability of transuranic elements released in the Palomares accident (Spain).

The current levels and distribution of the remaining transuranic contamination present in the terrestrial area affected by the nuclear Palomares accident have been evaluated through the determination of the Pu-isotopes and (241)Am concentrations in soils collected 35 years after the accident. In addition, after confirming that most of the contamination is present in particulate form, some bioavailability laboratory-based experiments, based on the use of single extractants, were performed as an essential step in order to study the behaviour of the Pu contamination in the soils from the affected areas.

Numerical analysis of alpha spectra using two different codes.

This work presents an intercomparison between commercial software for alpha-particle spectrometry, Genie 2000, and the new free available software, Winalpha, developed by International Atomic Energy Agency (IAEA). In order to compare both codes, different environmental spectra containing plutonium, uranium, thorium and polonium have been analyzed, together with IAEA test alpha spectra. A statistical study was performed in order to evaluate the precision and accuracy in the analyses, and to enhance the confidence in using the software on alpha spectrometric studies.

Grey monazite (rare earths) mining in centre of Spain: Characterization and pre-operational radiological evaluation.

A radiological evaluation associated to the future mining of grey monazite nodules enriched in light rare-earths, from a modest superficial deposit located in the centre of Spain, has been performed at pre-operational level, and the main results are shown in this paper. Although the monazite nodules in the deposit are clearly enriched in radionuclides from the uranium and thorium series with activity concentrations higher than 1 Bq/g, the size of these nodules (in the 0.5 mm-2 mm grain size interval), its refractory behaviour that prevents the leaching or dissemination of natural radionuclides to waters or other ecosystem compartments and consequently the impact in the food chain, and its presence quite diluted in the deposit at concentrations of 2.5-3 kg/m3, conducted to conclude that pre-operationally the area to be mined for the extraction of the monazite is generating a negligible radiological impact in the public and the nearby environment. Additionally, the extraction of the raw material and the restoration of the area after mining (i.e. the mining activities which will be done in-situ, in the mining area) will be exempted of any radiological regulation attending to the European Union legislation being expected that will not generate a radiological impact.

Characterization of U/Pu particles originating from the nuclear weapon accidents at Palomares, Spain, 1966 and Thule, Greenland, 1968.

Following the USAF B-52 bomber accidents at Palomares, Spain in 1966 and at Thule, Greenland in 1968, radioactive particles containing uranium (U) and plutonium (Pu) were dispersed into the environment. To improve long-term environmental impact assessments for the contaminated ecosystems, particles from the two sites have been isolated and characterized with respect to properties influencing particle weathering rates. Low (239)Pu/(235)U (0.62-0.78) and (240)Pu/(239)Pu (0.055-0.061) atom ratios in individual particles from both sites obtained by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) show that the particles contain highly enriched U and weapon-grade Pu. Furthermore, results from electron microscopy with Energy Dispersive X-ray analysis (EDX) and synchrotron radiation (SR) based micrometer-scale X-ray fluorescence (micro-XRF) 2D mapping demonstrated that U and Pu coexist throughout the 1-50 microm sized particles, while surface heterogeneities were observed in EDX line scans. SR-based micrometer-scale X-ray Absorption Near Edge Structure Spectroscopy (micro-XANES) showed that the particles consisted of an oxide mixture of U (predominately UO(2) with the presence of U(3)O(8)) and Pu ((III)/(IV), (IV)/(V) or (III), (IV) and (V)). Neither metallic U or Pu nor uranyl or Pu(VI) could be observed. Characteristics such as elemental distributions, morphology and oxidation states are remarkably similar for the Palomares and Thule particles, reflecting that they originate from similar source and release scenarios. Thus, these particle characteristics are more dependent on the original material from which the particles are derived (source) and the formation of particles (release scenario) than the environmental conditions to which the particles have been exposed since the late 1960s.

On the presence of enriched amounts of 235U in hot particles from the terrestrial area affected by the Palomares accident (Spain).

The characterisation by ICP-MS of an isolated Pu-U hot particle originating from the nuclear weapons accident in Palomares (Spain) shows, for the first time, that its uranium content is highly enriched in (235)U. The enrichment has been confirmed by independent analyses of two surface soil samples collected in a heavily contaminated area close to the impact point of one of the bombs. This finding clarifies better the composition of the weapons involved in the accident and is of importance when the inventory of U and Pu in the contaminated area are to be calculated.

On the presence of plutonium in Madagascar following the SNAP-9A satellite failure.

This study examined the 238Pu and 239+240Pu activity concentration and the 240Pu/239Pu atomic ratio in peat bogs sampled in 2012 from marshlands in central Madagascar. The purpose was to investigate the presence of plutonium isotopes, 238, 239, 240Pu, from the 1964 satellite failure carrying a SNAP-9A radiothermal generator. With an average 238Pu/239+240Pu activity ratio of 0.165 ± 0.02 (decay corrected to 1964), the peat bogs in Madagascar exhibit similar values as the ones found in the southeastern African continent, except they are one order of magnitude higher than expected (0.025) from global fallout in the Southern Hemisphere. The 240Pu/239Pu atomic ratio showed a distinct decrease for layers dating back to the mid-1960s (down to 0.069 compared with an anticipated ratio of 0.17 for global fallout), indicating that the SNAP-9A failure also resulted in an elevated deposition of 239Pu. The obtained results demonstrate that further Pu analysis in Madagascar and in southeastern continental Africa is necessary to fully account for the regional Pu deposition from the SNAP-9A event.

Estimating the impact from Fukushima in Southern Spain by 131I and Accelerator Mass Spectrometry detection of 129I.

After the Fukushima accident, large amounts of radionuclides were discharged to the atmosphere. Some of them travelled long distances and were detected in places as far from Japan as Spain a few days after the accident. One of these radionuclides was 131I. Its isotope 129I (T1/2 = 15.7 × 106 years) was also expected to follow the same pathway. In this work, we present the results for the 129I concentration in the same atmospheric samples from Seville (Spain) where 131I activity was measured in 2011 by Baeza et al. (2012). 129I concentrations in aerosol and gaseous samples showed concentrations in the order of 104 and 105 atoms/m3, typically higher in the gaseous form with respect to the aerosol form. Also 129I in rainwater was measured, showing concentrations in the order of 108 atoms/L. The results show a very good agreement with the 131I profile, showing that, if background from other sources is not relevant, it is possible to estimate the impact of similar events years after them thanks to the sensitivity of techniques like Accelerator Mass Spectrometry.