[en] This work aims to give an overview of the index of total beta activity and the activity index beta rest in surface waters of the main Spanish rivers. These indices are a parameter over water quality that CEDEX comes determined by order of the Ministry of Agriculture, Food and Environment, in water policy. (Author)

[en] The standard ISO/IEC 17025:2005 of general requirements for the technical competence of testing and calibration laboratories, provides that a laboratory shall have quality control procedures for monitoring the validity of tests and calibrations ago. In this paper, the experience of Isotopic Applications Laboratory (CEDEX) in controlling the accuracy rate of total beta activity in samples of drinking water, inland waters and marine waters is presented. (Author)

[en] The determination of radiological water quality is useful for a wide range of environmental studies. In these cases, the gross alpha activity is one of the parameters to determine. This parameter permits to decide if further radiological analyses are necessary in order to identify and quantify the presence of alpha emitters in water. The usual method for monitoring the gross alpha activity includes sample evaporation to dryness on a disk and counting using ZnS(Ag) scintillation detector. Detector electronics is provided with two components which are adjustable by the user the high-voltage applied to the photomultiplier tubes and the low level discriminator that is used to eliminate the electronic noise. The high-voltage and low level discriminator optimization are convenient in order to reach the best counting conditions. This paper is a preliminary study of the procedure followed for the setting up and optimization of the detector electronics in the laboratories of CEDEX for the measurement of gross alpha activity. (Author)

[en] Tritium is an essential tool for hydrological investigations such as the identification of modern recharge in aquifers, the estimation of hydraulic parameters related to pollutant transfer and the determination of the turnover time of groundwater. natural tritium is produced in the upper atmosphere from the interaction of cosmic radiation with atmospheric gases. The nuclear tests carried out in the 1959s and 1960s into the atmosphere increased the natural levels of tritium. Since the maximum of bomb 3H reached in the early 1960s, the tritium content of precipitation has decreased, and during the last few years, has approached to natural levels. Therefore, the demand for analysis of tritium in a large number of water samples and of decreasing tritium concentration has stimulated the development of electrolysis as the most practical and economical tritium enrichment method. Nevertheless, in some ground water systems and in the oceans, the tritium concentration is near the detection limit. There is therefore an urgent need to achieve a higher level of sensitivity for measurements. (Author) 6 refs

[en] Radon-222, 222Rn, is a naturally radioactive noble gas with a half-life of 3.82 days. It is a product of the 238U disintegration chain with 226Ra as parent isotope. Radon gas has traditionally been linked to magmatic and seismic activity. In order to improve volcanic surveillance networks, 222Rn monitoring in volcanic areas is carried out by measuring its concentration in air and soils. Also, since radon-222 is soluble in water, the gas may also be dissolved into groundwater flows. The quantity of dissolved 222Rn depends on different factors such as the characteristics of the aquifer, water-rock interaction, water residence time and material content of radium. In Tenerife there are a vast number of excavated galleries, subhorizontal water mining tunnels, that drain the main aquifer in the island. Thirteen of them have been selected in order to monitor the dissolved radon-222 concentration since October 2019 every three months. This set of galleries surrounds the main volcanic complex in the island, Teide-Pico Viejo, located in Las Cañadas caldera in central Tenerife. Before sampling, 10 ml of Opti-Fluor O scintillation cocktail for selective extraction of radon-222, two-phase counting method, was transferred into a 20 ml vial. During the sampling, 10 ml of water were injected into the bottom of the vial. The vial was then tightly capped, vigorously shaken and transported to the laboratory for analysis. Water samples were measured using the liquid scintillation system Quantulus 1220 from PerkinElmer. In this work, we show the main and preliminary results, which includes both spatial and temporal distribution of the dissolved radon concentration measured in the selected sampling points for the studied period. There are galleries showing a high stability, with radon-222 activity concentrations around 20 Bq/L, whereas others show a clear seasonal influence. The maximum dissolved 222Rn value detected was 29.2 ± 2.1 Bq/L. The detection limit is 0.5 Bq/l using a 30 minutes counting time. Besides, this dataset has been compared to data previously reported by other authors, in order to find changes in dissolved radon-222 emission across time. Finally, in the aim of finding interesting relationships, dissolved 222Rn values have been studied together with in situ groundwater parameters measured in the field (temperature, pH and electric conductivity) and, in some of the sampling points, also with dissolved CO2 concentration and isotopic ratio 3He/4He corrected for air contamination, (R/Ra)c, which are parameters directly related to volcanic activity.

[en] A straightforward evaluation of the shielding constant in the H₂ molecule is presented. (Auth.)

[en] The radiological quality of drinking water in Spain is regulated by Nuclear Security Guideline No, 7.7 (Rev.1) of the Nuclear Security Council (NSC). this guideline establishes the protocol to follow when the radiological level exceeds 0,1 Bq.l''1. When this level is passed, the responsible alpha emitter must be identified; ''210 Po, ''226Ra, ''230Th, ''239Pu, ''224Ra, ''234 U and ''138 U. Activity due to these isotopes is usually determined using alpha spectrometry with semiconductor detectors. This method allows the activity of the alpha emitters to be determined with a good sensitivity. however, it requires long radiochemical isolations and long counting times, so the method is not suitable for rough estimate radiological analysis. In this preliminary work, we present the conditioning of the sample-precipitate that is essential for further radiochemical isolations. (Author) 9 refs

[en] In order to assure that the radiation portal monitors (RPM), which are installed in companies adheres to the Protocol for the monitoring of radioactive content of the metallic materials (hereafter Protocol), work correctly and that they have the appropriate detection characteristics, the procedures recommended are the following: 1) elaboration of a report of the initial installation of the equipment, 2) periodic verifications that assure the correct equipment operation and, 3) static and dynamic annual calibrations using a cesium-137 source. The criteria for selecting these procedures are based on standard related to the portals in the frontiers of ANSI-N 42-35, IC-62244 and the guide for IAEA, TS-1-1240. These procedures are similar to those established in a quality management system. They have simple and clear definitions, in addition to rapid and economic execution. the tests defined in these procedures allow to obtain the quantitative physical parameters of the standard ISO-11929 using static and dynamic measurements. (Author)17 refs.

[en] An environmental radiological monitoring network in the Spanish sea waters was set up by CEDEX in 1993. Water radioactivity is determined quarterly in eleven sampling points along the Spanish coast. The gross alpha activity is one of the parameters to be determined. The usual method for monitoring the gross alpha activity includes sample evaporation to dryness on a disk and counting using ZnS(Ag) scintillation detector. Nevertheless, the gross alpha activity determination in saline waters, such as sea waters, is troublesome, because mass attenuation is high and a very small of water is needed (0.2 ml). The coprecipitation method allows to analyze 500 ml water samples, so the detection limit is reduced and sensitivity is improved. In this work, the coprecipitation method was used to determine the gross alpha activity in the radiological network of the Spanish coast sea waters during 1996 and 1997. Gross alpha activity was very homogenous. It averaged 0.0844±0.0086 Bq.1''1 and ranged from 0.062 to 0.102 Bq.1''1. In collaboration with CIEMAT a set of samples was analyzed, they averaged 0.0689±0.0074 Bq.1''1 and ranged from 0.056 to 0.082 Bq.1''1. (Author) 5 refs

[en] The objective is to design prototypes of neutron detection, operating performing dynamic measurements when the sample or the detector is moving. BI-detectors ZnS (Ag) were used, along with other gamma detectors NaI (Tl) and PVT, with different configurations, it can detect neutrons and analyzing the number of detections and the energy spectrum of the gamma emissions.