Spanish experience on the design of radon surveys based on the use of geogenic information.

One of the requirements of the recently approved EU-BSS (European Basic Safety Standards Directive, EURATOM, 2013) is the design and implementation of national radon action plans in the member states (Annex XVIII). Such plans require radon surveys. The analysis of indoor radon data is supported by the existing knowledge about geogenic radiation. With this aim, we used the terrestrial gamma dose rate data from the MARNA project. In addition, we considered other criterion regarding the surface of Spain, population, permeability of rocks, uranium and radium contain in soils because currently no data are available related to soil radon gas concentration and permeability in Spain. Given that, a Spanish radon map was produced which will be part of the European Indoor Radon Map and a component of the European Atlas of Natural Radiation. The map indicates geographical areas with high probability of finding high indoor radon concentrations. This information will support legislation regarding prevention of radon entry both in dwellings and workplaces. In addition, the map will serve as a tool for the development of strategies at all levels: individual dwellings, local, regional and national administration.

The Spanish indoor radon mapping strategy.

Indoor radon mapping still represents a valuable tool for drawing the picture of the exposure of general public due to radon and radon progeny inhalation in a residential context. The information provided by means of a map is useful not only as awareness and strategic element for authorities and policy-makers, but also as a scientific start-up point in the design of epidemiological and other specific studies on exposure to natural radiation. The requirements for a good mapping are related to harmonisation criteria coming from European recommendations, as well as to national/local characteristics and necessities. Around 12,000 indoor radon measurements have been made since the Spanish national radon programme began at the end of the 1980s. A significant proportion of them resulted from the last campaign performed from 2009 to 12. This campaign completed the first version of a map based on a grid 10 × 10 km(2). In this paper, the authors present the main results of a new map together with the criteria adopted to improve the number of measurements and the statistical significance of them.

Intercomparison exercise on external gamma dose rate under field conditions at the laboratory of natural radiation (Saelices el Chico, Spain).

The last nuclear accident in Fukushima nuclear power plant has increased the necessity for measuring radiation in the environment. Therefore, radiation monitors providing results traceable throughout the country become essential and it is very important to test them under the same environmental conditions. The first intercomparison of natural radioactivity under field conditions was held in Saelices el Chico (Salamanca, Spain) in May 2011, including an exercise on environmental dose rate. This article presents the results achieved by 19 instruments belonging to 12 institutions from 7 different countries. The tested detectors are proportional counters, ionisation chambers, Geiger-Müller and scintillators measuring dose rate in three stations with reference values from 110 to 1800 nGy h(-1). All the results were given in terms of air kerma (nGy h(-1)) and the measurements show agreement within 25 % in all the sites. Evaluation criteria based on accuracy and statistical uncertainty were also carried out and 25 % of participants passed the test in all sites.

Population dose in the vicinity of old Spanish uranium mines.

Regional surveys were conducted to determine exposure to natural sources of radiation for people in the vicinity of old Spanish uranium mines. The surveys evaluated indoor radon concentrations and outdoor and indoor external gamma dose rates. Indoor radon concentrations were measured in 222 dwellings by means of nuclear track-etched detectors. The terrestrial gamma ray dose rate was measured outdoors and indoors at a total of 256 points and 115 points, respectively. Estimates mean annual effective doses for the six areas studied ranged from 3.2 to 5.1 mSv per year, which is between 1.2 and 2 times higher than the average national value.

Natural gamma radiation map (MARNA) and indoor radon levels in Spain.

During the last decade, the Department of Applied and Medical Physics has been involved in the development of a radiation protection programme. In the framework of this programme, measurements of indoor radon, principally, have been carried out nationwide. Geometric mean radon concentrations of 45 Bq m(-3) in the whole country and 130 Bq m(-3) in the high natural radiation area have been estimated. On the other hand, the so-called MARNA Project is developed into the framework of an agreement subscribed between the Spanish Nuclear Safety Council (CSN) and the National Uranium (ENUSA), the first phase of which has been the elaboration of the Natural Gamma Radiation Map of Spain on the scale of 1:1,000,000 using radiometric data generated in the 30 years of the lifetime of the ancient National Uranium Exploration and Investigation Plan mainly through airborne, carborne, and by foot surveys, within the MARNA Project itself. The lowest averaged dose rate from external gamma radiation (19.3 nGyh(-1)) was found in carbonate bedrock and the highest (87.7 nGyh(-1)) was found in granite and clay bedrock. This paper summarizes the main results obtained from the measurements performed in both projects, with special interest in those concerning the correlation between the data reported in order to conclude about the potential benefit of the MARNA maps in the definition of affected areas in the country.

Natural radiation exposure in the vicinity of Spanish nuclear power stations.

Nationwide and regional surveys have been conducted to evaluate natural radiation exposure of people in the vicinity of the Spanish nuclear power stations. In these surveys, indoor radon, external gamma dose rates outdoors and indoors and radioactivity in soils were measured. Measurements of indoor radon concentrations were performed in 214 dwellings by using nuclear track-etched detectors. External exposure from terrestrial gamma rays outdoors and indoors were measured in a total of 596 points. Radioactivity in soil samples collected at 293 sampling sites are also reported in this paper. By taking into account all sources of natural radiation exposure, mean annual effective doses to the population in the surroundings of the six Spanish nuclear power stations have been estimated and compared with those coming from their normal operation.

[The potability of the water in a region with a high level of natural radiation]. / Potabilidad del agua en una región de alto nivel de radiación natural.

BACKGROUND: The recent Spanish legislation on drinkable waters for public use includes a paragraph establishing the requirements to be fulfilled by waters in relation with their radioactivity and the methods to be used to measure it. As water radioactivity depends on the radioactive content of the grounds and rocks where it flows, it is possible to expect high levels in those zones whose characteristic is their high level of natural radiation. METHODS: For this reason, we have organized two measurement campaigns with the objective of characterizing the drinkable waters in an Spanish area, where the radioactive elements concentration in the ground is high. The methodology used is as described in legislation, using a low-bottomed proportional counter. RESULTS: The results we have obtained indicate that the zone, where measurements have been made, shows lower radioactivity levels than the legally established limits, nevertheless, at same time, there appear several points, where the radioactivity levels are high, showing values exceeding in great measure the legal limit for drinkable waters. CONCLUSIONS: With the results, we have obtained, its seems necessary that a greater attention is paid to drinkable waters in those points, where the radioactivity levels are high including corrective measures.