Radon exposure in uranium mining industry vs. exposure in tourist caves.

There is a fairly general consensus among health physicists and radiation professionals that exposure to radon progeny is the largest and most variable contribution to the population's exposure to natural sources of radiation. However, this exposure is the subject of continuing debate concerning the validity of risk assessment and recommendations on how to act in radon-prone areas. The purpose of this contribution is to situate the radon issue in Spain in two very different settings. The first is a uranium mining industry located in Saelices el Chico (Salamanca), which is under strict control of the Spanish Nuclear Safety Council (CSN). We have measured radon concentrations in different workplaces in this mine over a five-year period. The second setting comprises four tourist caves, three of which are located in the province of Cantabria and the fourth on the Canary Island of Lanzarote. These caves are not subject to any administrative control of radiation exposure. Measured air 222Rn concentrations were used to estimate annual effective doses due to radon inhalation in the two settings, and dose values were found to be from 2 to 10 times lower in the uranium mine than in the tourist caves. These results were analysed in the context of the new European Basic Safety Standards Directive (EU-BSS, 1996).

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.

Conversion factors for external gamma dose derived from natural radionuclides in soils.

Field in situ gamma radiation exposure rates and laboratory measured radioactivity contents of 1500 Spanish soils were compared. The main objective was to determine if published theoretically derived conversion factors would yield accurate quantitative activity concentration (Bq kg(-1)) for the data carried out in different surveys developed by our laboratory during the last ten years. The in situ external gamma dose rate results were compared to laboratory gamma analysis of soils samples gathered from each site, considering the concentrations of seven radionuclides: 40K, 214Pb, 214Bi, 212Bi, 212Pb, 208Tl and 228Ac. The coefficient of correlation found between these variables indicate a good relationship. A discussion of the factors contributing to the uncertainties as well as measurement procedure are also given in this paper.

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.

Radioactivity in Spanish spas.

There are large number of spas in Spain and there is a lack of data concerning their radioactivity. The levels of radioactivity in a wide sample of Spanish spas were measured with special attention being paid to the radon and radium concentrations in the water, and to radon concentration in the indoor air of the spas. This study is primarily concerned with the radioactivity of the spas of one region in Spain--Cantabria--and particularly one spa where we measured radon levels in water as high as 824 Bq/l and over 5000 Bq/m3 in the air of the rooms. We then considered a wider sample including virtually all of the radioactive spas in the country. The results indicate that a fairly large number of spas have radon levels in water that are moderately high and they are used for the treatment of diseases without radiation protection measures for patients or staff at the spas.

[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.