With several databases available, including two sets of in situ measurements of the ambient gamma dose rate and an airborne survey of K, Th, U in soil, Belgium is a favourable case for exploring the mapping methodology for terrestrial radiation. The first step is the harmonization of the different data sets, taking in situ measurements with an ion chamber as the reference. Corrections are necessary, based on the data themselves (a) to the measurements of permanent monitoring stations, (b) to the data calculated from airborne measurements of the soil activity, due in particular to the attenuation by the forest cover, and (c) to the other data calculated from the soil activity, due to the lower activity of the upper layer. After subtracting the cosmic contribution, a harmonized database of the terrestrial gamma dose rate (TGDR) based on 379 in situ measurements was built, together with a harmonized data set of 30134 TGDR values calculated from the concentrations of K, Th, U in soil deduced from the airborne survey. The two data sets are in good agreement with each other for all statistical characteristics that were examined like basic statistics, qq-plots, analysis of variance (ANOVA) or variograms, which validates the airborne-based data set by the link with in situ ion chamber measurements. ANOVA reveals the strong relation between TGDR and the soil class, which justifies the use of a soil map as the framework for developing the TGDR map. The variograms show the absence of residual spatial correlations within soil classes. The two harmonized TGDR data sets were mapped at the nodes of a kilometric grid by the moving average method within soil groups. There is a rather good agreement between the maps, confirming the equivalence between the two data sets and the validation of the airborne based one, which can obviously give more detail. After reducing the maps to a 10 km x 10 km grid, the two data sets were used to check the accuracy of the Belgian part of the European TGDR contained in the European Atlas of Natural Radiation.

Aim: More than half the cobalt (needed for electric vehicles) originates form the southern part of DR Congo, and a substantial part of the cobalt is extracted by artisanal miners. We investigated working conditions and health parameters among cobalt artisanal miners around Kolwezi. Methods: In a cross-sectional study of 85 artisanal miners from two underground mines and 42 from open pits, we obtained socio-demographic and occupational data by questionnaire and measured oxygen saturation (SaO2) by pulse oximetry at four different time points: prior to descent into the shaft or quarry (T1), at 50 minutes in the shaft (T2); upon leaving the shaft (T3) and 10 minutes after having left the shaft (T4). In one underground mine, air radon concentrations (Radonova detectors) were monitored for 75-76 days at 10 different locations. Results: Miners working underground (at depths of 36 to 112 m) were somewhat older (34.8±6.8y) than those working in open pits (32.0±7.6y), and they worked more hours daily (12.6±1.2h) than controls (9.1±0.8h). All participants had SaO2 above 95% at T1 and T4, but SaO2 was below 90% in 25 (29%) underground miners at T2 (lowest value 74 %) and in 5 underground miners at T3. Values of SaO2 decreased linearly with depth of work at T2 (R2=0.14; p<0.0001), and also at T3 (R2=0.08; p=0.0021). Mean radon concentrations correlated with shaft depth (Spearman r = 0.70, p = 0.03). Conclusion: Substantial oxygen desaturation occurred during underground work in a high proportion of artisanal mineworkers. This is indicative of poor ventilation of the mine shafts. In addition to hypoxia, insufficient ventilation also leads to the accumulation of radon and risk of lung cancer.

To investigate the potential impact on ground- or surface water of natural radionuclides present in waste disposed onto landfills, activity concentrations in leachates, waste water treatment plant discharge and groundwater of several landfills in Belgium have been analysed. 16 currently in operation landfills for hazardous and non-hazardous waste and 10 legacy landfills have been investigated. Results indicate the presence of a slightly enhanced concentration of uranium and other radionuclides in some leachates of landfills in operation. For legacy landfills, enhanced uranium concentration is also observed in some groundwater wells. The presence of uranium in groundwater around landfills is always accompanied by a contamination with other heavy metals and chlorides. No clear linear correlation between concentration of uranium and other metals could be found however. Isotopic ratio between U-238 and U-234 has been calculated in the different water matrices and is close to one in contaminated groundwater, probably indicating an anthropogenic contamination. In all cases, the concentrations of natural radionuclides do not reach values of concern from radiation protection point of view.

The European Atlas of Natural Radiation developed by the Joint Research Centre (JRC) of the European Commission includes maps of potassium K and thorium Th. With several different databases available, including data (albeit not calibrated) from an airborne survey, Belgium is a favourable case for exploring the methodology of mapping for these natural radionuclides. Harmonized databases of potassium and thorium in soil were built by radiological (not airborne) and geochemical data. Using this harmonized database it was possible to calibrate the data from the airborne survey. Several methods were used to perform spatial interpolation and to smooth the data: moving average (MA) without constraint, or constrained by soil class and by geological unit. Overall, there was a reasonable agreement between the maps on a 1 × 1 km2 grid obtained with the two datasets (airborne data and harmonized soil data) with all the methods. The agreement was better when the maps are reduced to a 10 km × 10 km grid used for the European Atlas of Natural Radiation. The best agreement was observed with the MA constrained by geological unit.

Radon risk maps are usually based either on indoor radon data, or on measurements of soil gas radon and soil permeability. If these data are not available or not sufficient, it was suggested that other data could be used as an approximate substitute (a proxy) to the missing information, like the concentration of 238U or 226Ra in soils or the terrestrial gamma dose rate (TGDR). We examine here the correlation between airborne measurements of soil U and indoor radon, and between airborne U and TGDR, and their link with affected/unaffected areas. No clear correlation is found between airborne U and affected areas, as strongly affected areas are not characterised by a higher U level. Only the moderately affected area of Condroz can be connected to a higher U level, related to a few U anomalies. TGDR shows a rather good correlation with airborne U, but its relation with radon risk is less clear. Soil uranium and TGDR may help to screen out areas with very low U and very low TGDR, which have a low indoor radon risk, but they cannot be considered as good proxies for predicting radon-affected areas in Belgium.

An extensive network of dose rate monitoring stations continuously measures ambient dose rate across Europe, as part of the EURDEP system. Its purpose is early warning in radiological emergencies and documenting its temporal and spatial evolution. In normal conditions, when there is no contribution to the dose rate signal coming from fresh anthropogenic contamination, the data represent the radiation "background", i.e. the combined natural radiation and existing anthropogenic contamination (by global and Chernobyl fallout). These data are being stored, but have so far not been evaluated in depth, or used for any purpose. In the framework of the EU project 'European Atlas of Natural Radiation' the idea has emerged to exploit these data for generating a map of natural terrestrial gamma radiation. This component contributes to the total radiation exposure and knowing its geographical distribution can help establishing local 'radiation budgets'. A further use could be found in terrestrial dose rate as a proxy of the geogenic radon potential, as both quantities are related by partly the same source, namely uranium content of the ground. In this paper, we describe in detail the composition of the ambient dose equivalent rate as measured by the EURDEP monitors with respect to its physical nature and to its sources in the environment. We propose and compare methods to recover the terrestrial component from the gross signal. This requires detailed knowledge of detector response. We consider the probes used in the Austrian, Belgian and German dose rate networks, which are the respective national networks supplying data to EURDEP. It will be shown that although considerable progress has been made in understanding the dose rate signals, there is still space for improvement in terms of modelling and model parameters. An indispensable condition for success of the endeavour to establish a Europe-wide map of terrestrial dose rate background is progress in harmonising the European dose rate monitoring network.

A map of uranium concentration in soil has been planned for the European Atlas of Natural Radiation. This Atlas is being developed by the Radioactivity Environmental Monitoring (REM) group of the Joint Research Centre (JRC) of the European Commission. The great interest in uranium compared to other terrestrial radionuclides stems from the fact that radon (Rn-222) is in the decay chain of uranium (U-238) and that public exposure to natural ionizing radiation is largely due to indoor radon.With several different databases available, including data (albeit not calibrated) from an airborne survey, Belgium is a favourable case for exploring the methodology of uranium mapping. A harmonized database of uranium in soil was built by merging radiological (not airborne) and geochemical data. Using this harmonized database it was possible to calibrate the data from the airborne survey.Several methods were used to perform spatial interpolation and to smooth the data: moving average without constraint, by soil class and by geological unit. When using the harmonized database, it is first necessary to evaluate the uranium concentration in areas without data or with an insufficient number of data points.Overall, there is a reasonable agreement between the maps on a 1 km x 1 km grid obtained with the two datasets (airborne U and harmonized soil U) with all the methods. The agreement is better when the maps are reduced to a 10 km x 10 km grid; the latter could be used for the European map of uranium concentration in soil. (C) 2016 The Authors. Published by Elsevier Ltd.

Indoor radon data from Southern Belgium are organised in 35 geological units (GUs), most of which are homogeneous with respect to the radon risk. The percentage of cases above the reference level (400 Bq m(-3); 300 Bq m(-3) in the future) is calculated for these GUs from the observations and from the log-normal distribution fitted to the data. Affected areas are defined as areas with more than 1 % of houses above the reference level. In the north of the region, the old Palaeozoic basement is generally covered by Silesian, Cretaceous and Tertiary rocks, which are unaffected. The affected areas here are hot spots associated with specific Palaeozoic outcrops. In the south, there is generally no cover above Palaeozoic formations, which are often radon affected. The affected areas of Ardenne and Condroz dominate this part, but unaffected areas occur like Famenne and Gaume. About 48 % of the Walloon region is expected to be radon affected.

In the process of mapping indoor radon risk, an important step is to define geological units well-correlated with indoor radon. The present paper examines this question for the Walloon region of Belgium, using a database of more than 18,000 indoor radon measurements. With a few exceptions like the Carboniferous (to be divided into Tournaisian, Visean and Namurian-Westphalian) and the Tertiary (in which all Series may be treated together), the Series/Epoch stratigraphic level is found to be the most appropriate geological unit to classify the radon risk. A further division according to the geological massif or region is necessary to define units with a reasonable uniformity of the radon risk. In particular, Paleozoic series from Cambrian to Devonian show strong differences between different massifs. Local hot-spots are also observed in the Brabant massif. Finally, 35 geological units are defined according to their radon risk, 6 of which still present a clear weak homogeneity. In the case of 4 of these units (Jurassic, Middle Devonian of Condroz and of Fagne-Famenne, Ordovician of the Stavelot massif) homogeneity is moderate, but the data are strongly inhomogeneous for Visean in Condroz and in the Brabant massif. The 35 geological units are used in an ANOVA analysis, to evaluate the part of indoor radon variability which can be attributed to geology. The result (15.4–17.7%) agrees with the values observed in the UK.

The Belgian radiation protection authority (Federal Agency for Nuclear Control – FANC) has published in March 2013 a decree regulating the acceptance of NORM residues by non-radioactive waste treatment facilities. This regulation is based on the concept of “work activities involving natural radiation sources” in the sense of article 40 of the 96/29/EURATOM directive. The disposal or processing facilities which accept NORM residues with an activity concentration above a generic exemption level will be considered as “work activities” and submitted to declaration according to the Belgian radiation protection regulations. On basis of this declaration, specific acceptance criteria for the different types of processing/disposal of the residues (disposal on landfill, recycling into building materials, etc.) are imposed. FANC has drafted guidelines for these acceptance criteria. A methodological guide for the operators of the concerned facilities was also published. Moreover, sites where significant quantities of NORM residues are or have been disposed, are subjected to an environmental monitoring in the framework of the national program of radiological surveillance of FANC. FANC also introduced in its regulations the concept of anthropogenic radon-prone areas: e.g. former phosphogypsum stacks have been defined as anthropogenic radon-prone areas, which allows some form of regulatory control of these sites.

Due to economical factors and partly also to the concern about climate change, the concept of the passive house construction (”passivhaus”) is becoming more and more common in Belgium and other European countries. A pilot study in some 20 passive houses focussing on radon, airtightness and CO2 has been organised in the southern part of Belgium, where significantly increased indoor radon levels occur regularly. Although the airtight ness obs erved was always much higher than by traditional constructions, the radon level in one of the houses was over 700 Bq/m3. As the installation of a geothermal heating system is quite common for passive houses, it is currently investigated if a technical problem in its installation is at the origin of the observed high radon level. The measured CO2 levels were slightly higher than expected and in no house the air quality could be classified as being good or excellent according to existing ventilation standards. The observations indicate that the quality of the indoor environment in this new type of constructions has to be investigated in detail before it is becoming common practice.

s Accepted For Presentations and/or Poster Sessions 2012 International Radon Symposium July 24, 2012 Update: The following abstracts have been accepted for presentation and poster session presentation by the peer review committee of the 2012 International Radon Symposium, to held in Las Vegas, Nevada from October 14-17, 2012. An initial program will be published in early July, 2012 and this draft program will delineate times and whether the presentation is to be a poster session or an oral presentation. Some of these abstract presentations may occur during the joint meeting day and all presentations and publication of subsequent papers are contingent upon the researcher‘s acceptance and completion of the full requirements of the Symposium Proceedings Editorial committee. Please check the International Radon Symposium web site for ongoing program updates. www.internationalradonsymposium.org Abstracts Accepted For Presentations and/or Poster Sessions 2012 International Radon Symposium – Las Vegas, Nevada U.S.A.s Accepted For Presentations and/or Poster Sessions 2012 International Radon Symposium – Las Vegas, Nevada U.S.A. 2 RADON CONTROL IN NEW HOMES: A META-ANALYSIS OF 25 YEARS OF RESEARCH Angell, William Midwest Universities Radon Consortium (MURC), College of Design, University of Minnesota

Like in many countries, polluted industrial sites also exist in Belgium. Although the contamination is purely chemical in most cases, they may also contain a radioactive component. For chemically contaminated sites, extensive regulations and methodologies were already developed and applied by the different regional authorities. However and essentially because radioactivity is a federal competence, there was also a necessity for developing a legal federal framework (including an ER-methodology [1]) for remediation of radioactive contaminated sites. Most of the so-called radioactive contaminated sites are exhibiting a mixed contamination (chemical and radiological), and hence the development of such methodology had to be in line with the existing (regional) ones concerning chemical contamination. Each authority having their own responsibilities with regard to the type of contamination, this makes it more complicated and time-consuming finding the best solution satisfying all involved parties. To overcome these difficulties the legal framework and methodology — including the necessary involvement of the stakeholders and delineation of each party’s responsibilities — has to be transparent, clear and unambiguous. Once the methodology is developed as such and approved, the application of it is expected to be more or less easy, logic and straightforward. But is this really true? The aim of this document is to investigate as well the impact of factors such as the type of radioactive contamination — levels of contamination, related to NORM activity or not, homogeneous or heterogeneous, the differences in licensing procedures,… — on the application of the developed methodology and what could be the consequences in the long run on the remediation process. Two existing case studies in Belgium will be presented ([2]). The first case deals with a historical radium contaminated site, the second one with a phosphate processing facility still in operation, both with (very) low levels of radioactivity but containing very large volumes of contaminated materials. These case studies will demonstrate that, although the applied methodology will be the same in both cases, the impact of e.g. sampling strategy, scenario definitions, modelisations, final destination of the land, presence of chemotoxic components, dose or risk assessments, uncertainties, derivation of clean-up radionuclide guidelines, stakeholder involvement and waste treatment could be important on licensing, cost-estimate, planning and final outcome of the environmental remediation activities to be executed.

The Belgian metallurgical company, Union Minie`re, has been a key-player in the sector of radium production between 1922 and 1969. The factory based in Olen has extracted radium from minerals and produced radium sources during that period. The radium production facilities have been dismantled in the 70s but legacies of the former production have still to be remediated. An overview of these legacies and of their radiological characteristics will be given. Next to the sites related to radium production, other radium legacies are related to NORM industries, essentially from the phosphate sector (phosphogypsum and CaF2 stacks).

The red mud accident of October 4, 2010, in Ajka (Hungary) contaminated a vast area with caustic, saline red mud (pH 12) that contains several toxic trace metals above soil limits. Red mud was characterized and its toxicity for plants was measured to evaluate the soil contamination risks. Red mud radioactivity (e.g., (238)U) is about 10-fold above soil background and previous assessments revealed that radiation risk is limited to indoor radon. The plant toxicity and trace metal availability was tested with mixtures of this red mud and a local noncontaminated soil up to a 16% dry weight fraction. Increasing red mud applications increased soil pH to maximally 8.3 and soil solution EC to 12 dS m(-1). Shoot yield of barley seedlings was affected by 25% at 5% red mud in soil and above. Red mud increased shoot Cu, Cr, Fe, and Ni concentrations; however, none of these exceed toxic limits reported elsewhere. Moreover, NaOH amended reference treatments showed similar yield reductions and similar changes in shoot composition. Foliar diagnostics suggest that Na (>1% in affected plants) is the prime cause of growth effects in red mud and in corresponding NaOH amended soils. Shoot Cd and Pb concentrations decreased by increasing applications or were unaffected. Leaching amended soils (3 pore volumes) did not completely remove the Na injury, likely because soil structure was deteriorated. The foliar composition and the NaOH reference experiment allow concluding that the Na salinity, not the trace metal contamination, is the main concern for this red mud in soil.

A radon risk map for the Walloon region of Belgium, based on the two databases available, has been calculated and is presented in this work. The data are organized into geological units. For each unit, an average logarithmic standard deviation is calculated, after correcting the higher variability of short term data. The region is divided with an 1-km grid. For each node, the local geological unit is determined, as well as the corresponding logarithmic standard deviation. The logarithmic mean is evaluated by smoothing the data belonging to the same geological unit as the node. Assuming a log-normal distribution, a map that shows for each node the predicted percentage of buildings with an indoor radon concentration above the Action level (400 Bq/m(3)) is constructed. This is the first radon risk map for this region that fully takes into account the geological information.