Examinando por Autor "Pardo, Rafael"

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210Po and major ions in drainage water from soil treated with various types of fertilizers
(Taylor & Francis Online, 2007-10-29) Jiménez, Fernando; López, Raúl; Debán, Luís; Pardo, Rafael; García-Talavera, Marta
The levels of 210Po, nutrients (NH4+, NO3−, PO43−) and major ions (Na+, K+, Mg2+, Ca2+, F−, NO2−, Br−, Cl−,SO42−) were determined, by means of lysimeter experiences, in drainage waters for agricultural soils untreated and treated with different types of fertilizers (animal manure, sewage sludge and NPK synthetic fertilizer) applied at several rates. Analytical determinations were performed by using α-spectrometry in the case of 210Po, or Ion Exchange liquid chromatography for the other ionic species. Statistical uni andmultivariate analysis of the results shown significant differences among lixiviates according to the different fertilizer treatments. Sewage sludge and manure applications resulted in similar compositions of lixiviates with low 210Po levels, whereas synthetic fertilizers produced higher 210Po concentrations and different concentration patterns of ionic species when applied at or above the recommended rates. All 210Po levels were well below the limits proposed by the 2001/928/ Euratom Recommendation. The concentrations of the rest of the ionic species, exception made from NH4+ and NO3−, were also below the limits proposed by Spanish regulations
Analysis of the Background Levels of Tritium in Precipitation in Valladolid (Spain)
(Elsevier, 2005-11-21) Pequeño, Miriam; García-Talavera, Marta; López, Raúl; Debán, Luís; García, Eulogio; Pardo, Rafael; Peña, Victor
An accurate knowledge of background tritium levels in precipitation is important for a number of applications using tritium as a radiotracer. In this paper, we present a study of the levels of tritium precipitation in Valladolid (Spain) based on measurements of samples collected during a period of three years. Seasonal variations in the 3H activity have been detected. The anomalous values with respect to the general trend are discused in terms of the synoptic conditions associated to the precipitation event.
Levels of 131I and Six Natural Radionuclides in Sludge from the Sewage Treatment Plant of Valladolid, Spain
(Springer Nature Switzerland AG, 2010-09-02) Jiménez, Fernando; Debán, Luis; Pardo, Rafael; López, Raúl; García-Talavera, Marta
The levels of 131I and six natural radionuclides (238U, 226Ra, 210Pb, 228Ra, 224Ra, and 40K) were determined in sewage sludge samples obtained from an urban wastewater treatment plant that services a medium-sized town in Spain. Secondary treatment of wastewater consisting of anaerobic, anoxic, and oxic stages is collectively called A2O processing. Radio analytical determinations were performed by gamma spectrometry using a highpurity germanium detector. This technique has proven useful in identifying local radioactive pollution. This type of pollution was consistently detected throughout the year, with several increases associated with authorized discharges from hospitals. Finally, we examined the radiation dose that workers are exposed to due to the presence of 131I in the sludge. We found inhalation risk to be negligible, with external radiation as the main source of exposure to 131I.
Natural radiation doses to the population in a granitic region in Spain
(Oxford University Press, 2004-08-01) López, Raúl; García-Talavera, Marta; Pardo, Rafael; Debán, Luís; Nalda, José Constantino
The global average effective dose from natural radiation sources is estimated to be 2.4 mSv y−1. Nevertheless, local variations in the radiation exposure may differ by orders of magnitude. In this paper, we study a rural area in western Salamanca (Spain) where doses are potentially well above the stated average value. Its geology consists mostly of granite and schist, presenting various uranium mineralisations, some of which were exploited in former years. Water samples, both surface and groundwater, were collected in selected villages and measured by liquid-scintillation spectrometry. 222Rn in dwellings was determined in dwellings by means of short-term measurements, using Picorad vials and long-term measurements with CR-39 detectors. The committed effective doses to the inhabitants due to indoor 222Rn and 222Rn and 226Ra in drinking water were assessed using the dose conversion factors proposed in the UNSCEAR 2000 report.
Nitrocellulose Propellants Standard Stability Tests Enhancement Employing Semiconductor Sensors
(Wiley Online Library, 2022-10-17) Duro, Victor; López, Raúl; del Águila, Yeud; Pardo, Rafael; Debán, Luis
Nowadays, solid propulsion is the workhorse of a wide range of applications, from gun ammunition to missiles; and Nitrocellulose, NC, is still widely used in propellant compositions. However, its long-time storage represents a serious risk due to NC natural autocatalytic degradation process, that may lead to severe accidents. Some National Surveillance Programs continue using the so-called Stability Tests to monitor Nitrocellulose condition and storage risks; nevertheless, most users consider these tests technologically outdated and difficult to achieve a precise interpretation. This manuscript deals with this NC stability challenge, developing an innovative technology but maintaining Stability Tests phenomenological behaviour, in order to quantify naturally emitted nitrogen oxides, NOx, from Nitrocellulose vapours, as the main indicator for propellants degradation degree. However, accurate NOx quantification is usually strongly interfered by other naturally emitted vapours from gunpowder components, both in Stability Tests and in the technological proposal. Consequently, this document not only describes the technology and main development milestone, but individual components are also studied to reach a proper essay validation, employing Metal Oxide sensors, MOx. Additionally, signal deconvolution is presented to sharpen the NOx determination from interferences with two real samples (NC gunpowder), which are natural and artificially aged, determining performance of sensors and comparing conclusions with those from classical tests. Finally, presented results have shown insignificant interference of other chemicals present in the gunpowder over NOx quantification. According to these conclusions, this technology can be considered a technological improvement on NC Stability Tests.
The determination and monitoring of 131I activity in sewage treatment plants based on A2/O processes
(Elsevier, 2010-08-13) Jiménez, Fernando; López, Raúl; Pardo, Rafael; Debán, Luis; García-Talavera, Marta
131I, a radionuclide used in nuclear medicine facilities, is habitually dumped into domestic sewer systems, which causes its control in municipal sewage treatment plants (STP) to become necessary. In this paper, we describe a procedure for the determination of the 131I activity based on its precipitation as silver (I) iodide, its dissolution with cyanide in ammonia medium and its measurement by the liquid scintillation counting technique (LSC). After optimization, this LSC procedure allows the determination of 131I activities with a limit of detection (CCb) of 11 mBq kg 1. The procedure was successfully validated by comparison with the ISO 10703:2007 normative and requires both less sample volume and measurement time than the standard procedure. The method has been applied to the monitoring of 131I in the STP of Valladolid (Spain), which found activities below the maximum allowed by legislation and showed a near constant background 131I activity in the influents with punctual increases corresponding to authorized spills. The mean 131I removing efficiency of the STP was 52%.