M. Herranz - Academia.edu (original) (raw)
Papers by M. Herranz
Journal of Radioanalytical and Nuclear Chemistry
This paper is the second chapter of a piece entitled “Low-level determination of Th-isotopes by a... more This paper is the second chapter of a piece entitled “Low-level determination of Th-isotopes by alpha spectrometry”. This Part 2 presents the results of the analysis of the first and last steps for Th-isotopes determination by alpha-particle spectrometry: the sample pre-treatment, total dissolution following different methods and lixiviation, and the test sample preparation methods, electrodeposition and microprecipitation, together with a brief analysis of the financial costs of the analyzed methods.
Journal of Radioanalytical and Nuclear Chemistry
A co-precipitation method followed by a liquid–liquid extraction and liquid scintillation countin... more A co-precipitation method followed by a liquid–liquid extraction and liquid scintillation counting is proposed to get low 226Ra detection limits when measuring complex samples. The sensitivity of the method is determined with an analysis of interfering agents on it. The ion-exchange followed by alpha spectrometry is also described and an analysis of the advantages and disadvantages of both methods is carried out. Then, a comparison between both methods, considering also time and cost analysis, is realised. Conclusions show that both methods provide similar values for uncertainties, critical values and chemical yields when similar sample size and measuring times are chosen.
AIP Conference Proceedings, 2008
In the accreditation process of a radioactivity measurements laboratory, according to ISO standar... more In the accreditation process of a radioactivity measurements laboratory, according to ISO standard 17025, proficiency tests play a fundamental role. These PTs constitute an irreplaceable tool for the validation of measuring methods. In the case of Spain, ENAC, which is the Spanish accreditation national body, requires that the laboratory has to take part in a PT for each one of
In the accreditation process of a radioactivity measurements laboratory, according to ISO standar... more In the accreditation process of a radioactivity measurements laboratory, according to ISO standard 17025, proficiency tests play a fundamental role. These PTs constitute an irreplaceable tool for the validation of measuring methods. In the case of Spain, ENAC, which is the Spanish accreditation national body, requires that the laboratory has to take part in a PT for each one of
Journal of Environmental Radioactivity, 2016
The radiological characterisation of outdoor air is always a complicated task due to the several ... more The radiological characterisation of outdoor air is always a complicated task due to the several radioactive emissions coming from the different radionuclides and also because of the very short half-lives of radionuclides in the natural radioactive series. In some places, this characterisation could result in unusual values because the natural presence of radionuclides with terrestrial origin can be modified by manmade activities. Nonetheless, this characterisation is useful not only for air quality control purposes but also because radon and its progeny in the outdoor air are the main contributors to human exposure from natural sources. In this study, we have carried out air particle sampling, followed by gamma-ray spectrometry, alpha spectrometry and beta counting determinations for this purpose. Subsequently, the outdoor air has been radiologically characterised through the obtained data and using a pre-existing analytical method to take into account the radioactive decays of short half-life radionuclides during sampling, sample preparation and measuring times. Bilbao was chosen to carry out this work. It is a medium-sized town located in northern Spain, close to the Atlantic Ocean and at sea level. This city has a recent industrial past as there were numerous steel mills and other heavy industries, including some quarries, and some open pit mines close to it, which concluded in a remediation program. So, it is a place where the air is potentially modified by manmade activities. The obtained results show that activity concentration values for long-lived radionuclides that precede radon and thoron are in the order of 10(-6) Bq m(-3) and long-lived ones after radon are around 10(-4) Bq m(-3). Thoron progeny are around 2 × 10(-2) Bq m(-3) and radon progeny are around 1.8 Bq m(-3). The mean radon equilibrium factor was 0.18. All of these values are close to the minimum UNSCEAR values, but show some variability, which highlights the importance of determining activity concentrations for each naturally occurring radionuclide and the equilibrium factor in the outdoor air.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2008
Journal of Radiological Protection, 2013
Shielded metal arc welding using covered electrodes is the most common welding process. Sometimes... more Shielded metal arc welding using covered electrodes is the most common welding process. Sometimes the covering contains naturally occurring radioactive materials (NORMs). In Spain the most used electrodes are those covered with rutile mixed with other materials. Rutile contains some detectable natural radionuclides, so it can be considered a NORM. This paper mainly focuses on the use of MCNP (Monte Carlo N-Particle Transport Code) as a predictive tool to obtain doses in a factory which produces this type of electrode and assess the radiological impact in a specific facility after estimating the internal dose.To do this, in the facility, areas of highest radiation and positions of workers were identified, radioactive content of rutile and rutile covered electrodes was measured, and, considering a worst possible scenario, external dose at working points has been calculated using MCNP. This procedure has been validated comparing the results obtained with those from a pressurised ionisation chamber and TLD dosimeters. The internal dose has been calculated using DCAL (dose and risk calculation). The doses range between 8.8 and 394 μSv yr(-1), always lower than the effective dose limit for the public, 1 mSv yr(-1). The highest dose corresponds to the mixing area.
Radiation Physics and Chemistry, 2011
ABSTRACT Among the different methods used to collect the tritiated water vapor (HTO) contained in... more ABSTRACT Among the different methods used to collect the tritiated water vapor (HTO) contained in the atmosphere, one of the most worldwide used is its collection using an air pump, which forces the air to pass through a dry silica gel trap. The silica gel is then distilled to remove the water collected, which is measured in a liquid scintillation counting system.In this paper, an analysis of the water collection efficiency of the silica gel has been done as a function of the temperatures involved, the dimensions of the pipe driving the air into the silica gel traps, the air volume passing through the trap and the flow rates used.Among the obtained conclusions, it can be pointed out that placing the traps inside a cooled container, the amount of silica gel needed to collect all the water contained in the air passing through these traps can be estimated using a weather forecast and a psychometric chart. To do this, and as thermal equilibrium between incoming and open air should be established, a suitable design of the sampling system is proposed.
Radiation Physics and Chemistry, 2004
Radiation Measurements, 2006
Environmental Pollution, 2000
Applied Radiation and Isotopes, 1995
Applied Radiation and Isotopes, 2012
The implementation of (63)Ni and (55)Fe determination methods in an environmental laboratory impl... more The implementation of (63)Ni and (55)Fe determination methods in an environmental laboratory implies their validation. In this process, the uncertainties related to these methods should be analysed. In this work, the expression of the uncertainty of the results obtained using separation methods followed by liquid scintillation counting is presented. This analysis includes the consideration of uncertainties coming from the different alternatives which these methods use as well as those which are specific to the individual laboratory and the competency of its operators in applying the standard ORISE (Oak Ridge Institute for Science and Education) methods.
Radiation Measurements, 2011
The determination process of the 90Sr and 89Sr contents in a sample, although it involves their r... more The determination process of the 90Sr and 89Sr contents in a sample, although it involves their radiochemical isolation, results always in a complex measurement process due to the interferences among their respective beta emissions and also among those of the daughter of 90Sr, 90Y, a beta emitter as well.In this paper, the process consisting in a double measurement method after the Sr radiochemical isolation is analyzed, developing the formulae to obtain activity concentrations, uncertainties and detection limits. A study of the trend of uncertainties and detection limits as function of the time in which the first measurement since the isolation is done, the delay between the two measurements and the activity concentration of each strontium isotope in the sample is carried out as well.Results show that with a very precise determination of the times involved in the whole process (isolation, measurement and duration of measurements) this method permits a reliable assessment of both strontium radioisotopes. The quicker the first measurement since the isolation is done and the longer the delay between measurements is chosen, the lower are the detection limits and the uncertainties of the activities obtained.
AIP Conference Proceedings, 2008
The vertical distribution of activity and inventories of atmospheric Pb-210 is being studied in S... more The vertical distribution of activity and inventories of atmospheric Pb-210 is being studied in Spanish soils, aiming to establish the reference levels in the zone, based on the type of soil and the annual rainfall. A homogeneous distribution grid (approx. 150×150 km each cell) has been established covering the peninsular land, trying to combine the varying soil types (remaining undisturbed
Journal of Radiological Protection, 2013
The shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes use covered ele... more The shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes use covered electrodes and flux cored wire as consumables. Among these consumables, ones containing rutile are the most widely used, and since they have a considerable natural radioactive content, they can be considered as NORM (naturally occurring radioactive material). To calculate the effective dose on workers during their use in a conservative situation, samples of slag and aerosols and particles emitted or deposited during welding were taken and measured by gamma, alpha and beta spectrometry. An analytical method was also developed for estimating the activity concentration of radionuclides in the inhaled air. (222)Rn activity concentration was also assessed. With all these data, internal and external doses were calculated. The results show that external doses are negligible in comparison with internal ones, which do not exceed 1 mSv yr(-1), either in this conservative situation or in any other more favourable one. Radionuclides after Rn in the radioactive natural series are emitted at the same activity concentration to the atmosphere, this being around 17 times higher than that corresponding to radionuclides before Rn. Taking into account these conclusions and the analytical method developed, it can be concluded that one way to assess the activity concentration of natural radionuclides in inhaled air and hence effective doses could be the early gamma-ray spectrometry of aerosols and particles sampled during the welding process.
Water, Air, and Soil Pollution, 2006
Toxicological & Environmental Chemistry, 1993
For a research project on the evaluation and distribution of radioactive pollutants in Biscay... more For a research project on the evaluation and distribution of radioactive pollutants in Biscay's plants and soils, it was necessary to establish an analytical procedure to detect and measure extremely low amounts of radioactive elements. For the project 15 cm cores of fourteen soils were taken and divided into three depth levels. Some of these soil samples (<2 mm) were i) air‐dried before radioactive measurements. Additionally, a few samples were measured again after being ii) selectively extracted with ammonium acetate at pH 7 (exchangeable), acetic acid (carbonate), hydroxylamine (associated to Fe‐Mn oxides) and hydrogen peroxide (related to sulphide and organic matter fraction) to estimate the distribution of constituents according to mineral soil species or iii) classified as clay+silt, fine and coarse sand, to study size partition.Radioactive measurements were made with a low‐level gamma spectrometer (Ge‐HP detector + analyser with 8000 channels) whose resolution was 1.64 keV with a relative efficiency of 24.8 per cent for the 1330 keV Co‐60 line. Calibration was made against a standard solution containing nine radio‐nuclides with gamma‐ray energies in the range from 88.03 to 1836 keV. The shielding was 15 cm thick of pre‐war iron. Original or derived soil samples were put into 0.25 liter Marinelli flasks and measured during 24 hours periods. Double distilled water background was discounted. Net peak areas were then analysed at 95% confidence by the Mariscotti method.K‐40 and several radionuclides from U‐Th series were identified as presumably natural constituents, but significant amounts of Cs‐137, a fission product, were also found in most of depth levels of the studied soils. The distribution of these radioactive constituents in some treated samples, according to soil species or fraction size is shown.
Toxicological & Environmental Chemistry, 1997
... the laboratory after preservation. Samples from the rivers Nervion (10), Ibaizabal (5), Cadag... more ... the laboratory after preservation. Samples from the rivers Nervion (10), Ibaizabal (5), Cadagua (8) and one sample from five small basins (Barbadún, Butrón, Oca,Lea and Artibay) were investigated. Radioactive data include ...
Radiation Measurements, 2007
Journal of Radioanalytical and Nuclear Chemistry
This paper is the second chapter of a piece entitled “Low-level determination of Th-isotopes by a... more This paper is the second chapter of a piece entitled “Low-level determination of Th-isotopes by alpha spectrometry”. This Part 2 presents the results of the analysis of the first and last steps for Th-isotopes determination by alpha-particle spectrometry: the sample pre-treatment, total dissolution following different methods and lixiviation, and the test sample preparation methods, electrodeposition and microprecipitation, together with a brief analysis of the financial costs of the analyzed methods.
Journal of Radioanalytical and Nuclear Chemistry
A co-precipitation method followed by a liquid–liquid extraction and liquid scintillation countin... more A co-precipitation method followed by a liquid–liquid extraction and liquid scintillation counting is proposed to get low 226Ra detection limits when measuring complex samples. The sensitivity of the method is determined with an analysis of interfering agents on it. The ion-exchange followed by alpha spectrometry is also described and an analysis of the advantages and disadvantages of both methods is carried out. Then, a comparison between both methods, considering also time and cost analysis, is realised. Conclusions show that both methods provide similar values for uncertainties, critical values and chemical yields when similar sample size and measuring times are chosen.
AIP Conference Proceedings, 2008
In the accreditation process of a radioactivity measurements laboratory, according to ISO standar... more In the accreditation process of a radioactivity measurements laboratory, according to ISO standard 17025, proficiency tests play a fundamental role. These PTs constitute an irreplaceable tool for the validation of measuring methods. In the case of Spain, ENAC, which is the Spanish accreditation national body, requires that the laboratory has to take part in a PT for each one of
In the accreditation process of a radioactivity measurements laboratory, according to ISO standar... more In the accreditation process of a radioactivity measurements laboratory, according to ISO standard 17025, proficiency tests play a fundamental role. These PTs constitute an irreplaceable tool for the validation of measuring methods. In the case of Spain, ENAC, which is the Spanish accreditation national body, requires that the laboratory has to take part in a PT for each one of
Journal of Environmental Radioactivity, 2016
The radiological characterisation of outdoor air is always a complicated task due to the several ... more The radiological characterisation of outdoor air is always a complicated task due to the several radioactive emissions coming from the different radionuclides and also because of the very short half-lives of radionuclides in the natural radioactive series. In some places, this characterisation could result in unusual values because the natural presence of radionuclides with terrestrial origin can be modified by manmade activities. Nonetheless, this characterisation is useful not only for air quality control purposes but also because radon and its progeny in the outdoor air are the main contributors to human exposure from natural sources. In this study, we have carried out air particle sampling, followed by gamma-ray spectrometry, alpha spectrometry and beta counting determinations for this purpose. Subsequently, the outdoor air has been radiologically characterised through the obtained data and using a pre-existing analytical method to take into account the radioactive decays of short half-life radionuclides during sampling, sample preparation and measuring times. Bilbao was chosen to carry out this work. It is a medium-sized town located in northern Spain, close to the Atlantic Ocean and at sea level. This city has a recent industrial past as there were numerous steel mills and other heavy industries, including some quarries, and some open pit mines close to it, which concluded in a remediation program. So, it is a place where the air is potentially modified by manmade activities. The obtained results show that activity concentration values for long-lived radionuclides that precede radon and thoron are in the order of 10(-6) Bq m(-3) and long-lived ones after radon are around 10(-4) Bq m(-3). Thoron progeny are around 2 × 10(-2) Bq m(-3) and radon progeny are around 1.8 Bq m(-3). The mean radon equilibrium factor was 0.18. All of these values are close to the minimum UNSCEAR values, but show some variability, which highlights the importance of determining activity concentrations for each naturally occurring radionuclide and the equilibrium factor in the outdoor air.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2008
Journal of Radiological Protection, 2013
Shielded metal arc welding using covered electrodes is the most common welding process. Sometimes... more Shielded metal arc welding using covered electrodes is the most common welding process. Sometimes the covering contains naturally occurring radioactive materials (NORMs). In Spain the most used electrodes are those covered with rutile mixed with other materials. Rutile contains some detectable natural radionuclides, so it can be considered a NORM. This paper mainly focuses on the use of MCNP (Monte Carlo N-Particle Transport Code) as a predictive tool to obtain doses in a factory which produces this type of electrode and assess the radiological impact in a specific facility after estimating the internal dose.To do this, in the facility, areas of highest radiation and positions of workers were identified, radioactive content of rutile and rutile covered electrodes was measured, and, considering a worst possible scenario, external dose at working points has been calculated using MCNP. This procedure has been validated comparing the results obtained with those from a pressurised ionisation chamber and TLD dosimeters. The internal dose has been calculated using DCAL (dose and risk calculation). The doses range between 8.8 and 394 μSv yr(-1), always lower than the effective dose limit for the public, 1 mSv yr(-1). The highest dose corresponds to the mixing area.
Radiation Physics and Chemistry, 2011
ABSTRACT Among the different methods used to collect the tritiated water vapor (HTO) contained in... more ABSTRACT Among the different methods used to collect the tritiated water vapor (HTO) contained in the atmosphere, one of the most worldwide used is its collection using an air pump, which forces the air to pass through a dry silica gel trap. The silica gel is then distilled to remove the water collected, which is measured in a liquid scintillation counting system.In this paper, an analysis of the water collection efficiency of the silica gel has been done as a function of the temperatures involved, the dimensions of the pipe driving the air into the silica gel traps, the air volume passing through the trap and the flow rates used.Among the obtained conclusions, it can be pointed out that placing the traps inside a cooled container, the amount of silica gel needed to collect all the water contained in the air passing through these traps can be estimated using a weather forecast and a psychometric chart. To do this, and as thermal equilibrium between incoming and open air should be established, a suitable design of the sampling system is proposed.
Radiation Physics and Chemistry, 2004
Radiation Measurements, 2006
Environmental Pollution, 2000
Applied Radiation and Isotopes, 1995
Applied Radiation and Isotopes, 2012
The implementation of (63)Ni and (55)Fe determination methods in an environmental laboratory impl... more The implementation of (63)Ni and (55)Fe determination methods in an environmental laboratory implies their validation. In this process, the uncertainties related to these methods should be analysed. In this work, the expression of the uncertainty of the results obtained using separation methods followed by liquid scintillation counting is presented. This analysis includes the consideration of uncertainties coming from the different alternatives which these methods use as well as those which are specific to the individual laboratory and the competency of its operators in applying the standard ORISE (Oak Ridge Institute for Science and Education) methods.
Radiation Measurements, 2011
The determination process of the 90Sr and 89Sr contents in a sample, although it involves their r... more The determination process of the 90Sr and 89Sr contents in a sample, although it involves their radiochemical isolation, results always in a complex measurement process due to the interferences among their respective beta emissions and also among those of the daughter of 90Sr, 90Y, a beta emitter as well.In this paper, the process consisting in a double measurement method after the Sr radiochemical isolation is analyzed, developing the formulae to obtain activity concentrations, uncertainties and detection limits. A study of the trend of uncertainties and detection limits as function of the time in which the first measurement since the isolation is done, the delay between the two measurements and the activity concentration of each strontium isotope in the sample is carried out as well.Results show that with a very precise determination of the times involved in the whole process (isolation, measurement and duration of measurements) this method permits a reliable assessment of both strontium radioisotopes. The quicker the first measurement since the isolation is done and the longer the delay between measurements is chosen, the lower are the detection limits and the uncertainties of the activities obtained.
AIP Conference Proceedings, 2008
The vertical distribution of activity and inventories of atmospheric Pb-210 is being studied in S... more The vertical distribution of activity and inventories of atmospheric Pb-210 is being studied in Spanish soils, aiming to establish the reference levels in the zone, based on the type of soil and the annual rainfall. A homogeneous distribution grid (approx. 150×150 km each cell) has been established covering the peninsular land, trying to combine the varying soil types (remaining undisturbed
Journal of Radiological Protection, 2013
The shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes use covered ele... more The shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes use covered electrodes and flux cored wire as consumables. Among these consumables, ones containing rutile are the most widely used, and since they have a considerable natural radioactive content, they can be considered as NORM (naturally occurring radioactive material). To calculate the effective dose on workers during their use in a conservative situation, samples of slag and aerosols and particles emitted or deposited during welding were taken and measured by gamma, alpha and beta spectrometry. An analytical method was also developed for estimating the activity concentration of radionuclides in the inhaled air. (222)Rn activity concentration was also assessed. With all these data, internal and external doses were calculated. The results show that external doses are negligible in comparison with internal ones, which do not exceed 1 mSv yr(-1), either in this conservative situation or in any other more favourable one. Radionuclides after Rn in the radioactive natural series are emitted at the same activity concentration to the atmosphere, this being around 17 times higher than that corresponding to radionuclides before Rn. Taking into account these conclusions and the analytical method developed, it can be concluded that one way to assess the activity concentration of natural radionuclides in inhaled air and hence effective doses could be the early gamma-ray spectrometry of aerosols and particles sampled during the welding process.
Water, Air, and Soil Pollution, 2006
Toxicological & Environmental Chemistry, 1993
For a research project on the evaluation and distribution of radioactive pollutants in Biscay... more For a research project on the evaluation and distribution of radioactive pollutants in Biscay's plants and soils, it was necessary to establish an analytical procedure to detect and measure extremely low amounts of radioactive elements. For the project 15 cm cores of fourteen soils were taken and divided into three depth levels. Some of these soil samples (<2 mm) were i) air‐dried before radioactive measurements. Additionally, a few samples were measured again after being ii) selectively extracted with ammonium acetate at pH 7 (exchangeable), acetic acid (carbonate), hydroxylamine (associated to Fe‐Mn oxides) and hydrogen peroxide (related to sulphide and organic matter fraction) to estimate the distribution of constituents according to mineral soil species or iii) classified as clay+silt, fine and coarse sand, to study size partition.Radioactive measurements were made with a low‐level gamma spectrometer (Ge‐HP detector + analyser with 8000 channels) whose resolution was 1.64 keV with a relative efficiency of 24.8 per cent for the 1330 keV Co‐60 line. Calibration was made against a standard solution containing nine radio‐nuclides with gamma‐ray energies in the range from 88.03 to 1836 keV. The shielding was 15 cm thick of pre‐war iron. Original or derived soil samples were put into 0.25 liter Marinelli flasks and measured during 24 hours periods. Double distilled water background was discounted. Net peak areas were then analysed at 95% confidence by the Mariscotti method.K‐40 and several radionuclides from U‐Th series were identified as presumably natural constituents, but significant amounts of Cs‐137, a fission product, were also found in most of depth levels of the studied soils. The distribution of these radioactive constituents in some treated samples, according to soil species or fraction size is shown.
Toxicological & Environmental Chemistry, 1997
... the laboratory after preservation. Samples from the rivers Nervion (10), Ibaizabal (5), Cadag... more ... the laboratory after preservation. Samples from the rivers Nervion (10), Ibaizabal (5), Cadagua (8) and one sample from five small basins (Barbadún, Butrón, Oca,Lea and Artibay) were investigated. Radioactive data include ...
Radiation Measurements, 2007