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Rosabianca Trevisi – One of the best experts on this subject based on the ideXlab platform.

  • A study on natural radioActivity and radon exhalation rate in building materials containing norm residues: preliminary results
    Construction and Building Materials, 2018
    Co-Authors: Federica Leonardi, Cristina Nuccetelli, Michał Bonczyk, Małgorzata Wysocka, B. Michalik, M. Ampollini, S. Tonnarini, Jan Antoni Rubin, K. Niedbalska, Rosabianca Trevisi

    Abstract:

    Abstract This paper contains preliminary results of a study on the physical and radiological characterization of concrete samples containing NORM. The natural radionuclides content in term of 226Ra, 228Ra, 232Th, 40K and the radon exhalation rate of the samples were determined. Two series of samples of concrete were prepared: samples belonging to both series were made of the same basic components (Portland cement CEM I 42,5R as binder, aggregate and plasticizer) but different amount of NORM residues and mineral additives were used. The concrete samples were characterize in term of absolute density, permeability, total and open porosity. The radiological content was evaluated by using gamma spectrometry and the radon exhalation rate measurements were performed using the dynamic method. Moreover, the Activity Concentration Index (I), introduced by the 2013/59/Euratom Directive, has been used in order to evaluate if concrete samples could exceed the reference level for effective dose due to gamma radiation in building materials.

  • Gamma exposure from building materials – A dose model with expanded gamma lines from naturally occurring radionuclides applicable in non-standard rooms
    Construction and Building Materials, 2018
    Co-Authors: Tom Croymans, Cristina Nuccetelli, Rosabianca Trevisi, Sonja Schreurs, Federica Leonardi, Wouter Schroeyers

    Abstract:

    Abstract Building materials are a significant source of gamma rays exposure due to the presence of naturally occurring radionuclides. In order to protect the public from harmful radiation, the European Basic Safety Standards (Council directive 2013/59/Euratom) (European Council, 2014) introduced a one-size-fits-all building(s) (materials) Activity Concentration Index (ACI) based on a limited set of gamma lines. The ACI is considered “as a conservative screening tool for identifying materials that may cause the reference level (i.e. 1 mSv/y) laid down in article 75(1) to be exceeded”. Regarding calculation of dose, many factors such as density and thickness of the building material, as well as factors relating to the type of building, and the gamma emission data need to be taking into account to ensure accurate radiation protection. In this study the implementation of an expanded set of 1845 gamma lines, related to the decay series of 238U, 235U and 232Th as well as to 40K, into the calculation method of Markkanen (1995), is discussed. The expanded calculation method is called the Expanded Gamma Dose Assessment (EGDA) model. The total gamma emission intensity increased from 2.12 to 2.41 and from 2.41 to 3.04 for respectively the 238U and 232Th decay series. In case of 40K a decrease from 0.107 to 0.106 is observed. The 235U decay series is added, having a gamma emission intensity of 3.1. In a standard concrete room, the absorbed dose rates in air (DA) per unit of Activity Concentration of 0.849, 0.256, 1.08, 0.0767 nGy/h per Bq/kg are observed. The use of weighted average gamma lines increased the DA with 6.5% and 1% for respectively the 238U and 232Th decay series. A decrease of 4.5% is observed in the DA of 235U decay series when using the weighted average gamma lines in comparison to its non-averaged variant. The sensitivity of the EGDA model for density, wall thickness, presence of windows and doors and room size is investigated. Finally, a comparison of the Index and dose calculations relevant for the dose assessment within the European legislative framework applicable towards building materials is performed. In cases where the ACI and density and thickness corrected dose calculation of Nuccetelli et al. (2015) cannot provide guidance, the EGDA allows performing more accurate dose assessment calculations leading to effective doses which can be several 100 µSv/y lower.

  • Alkali-activated concrete with Serbian fly ash and its radiological impact.
    Journal of environmental radioactivity, 2016
    Co-Authors: Cristina Nuccetelli, Rosabianca Trevisi, Ivan Ignjatović, Jelena Dragaš

    Abstract:

    Abstract The present paper reports the results of a study on different types of fly ash from Serbian coal burning power plants and their potential use as a binder in alkali-activated concrete (AAC) depending on their radiological and mechanical properties. Five AAC mixtures with different types of coal burning fly ash and one type of blast furnace slag were designed. Measurements of the Activity Concentrations of 40 K, 226 Ra and 232 Th were done both on concrete constituents (fly ash, blast furnace slag and aggregate) and on the five solid AAC samples. Experimental results were compared by using the Activity Concentration assessment tool for building materials – the Activity Concentration Index I, as introduced by the EU Basic Safety Standards (CE, 2014). All five designed alkali-activated concretes comply with EU BSS screening requirements for indoor building materials. Finally, Index I values were compared with the results of the application of a more accurate Index – I(ρd), which accounts for thickness and density of building materials (Nuccetelli et al., 2015a). Considering the actual density and thickness of each concrete sample Index – I(ρd) values are lower than Index I values. As an appendix, a synthesis of main results concerning mechanical and chemical properties is provided.

Cristina Nuccetelli – One of the best experts on this subject based on the ideXlab platform.

  • A study on natural radioActivity and radon exhalation rate in building materials containing norm residues: preliminary results
    Construction and Building Materials, 2018
    Co-Authors: Federica Leonardi, Cristina Nuccetelli, Michał Bonczyk, Małgorzata Wysocka, B. Michalik, M. Ampollini, S. Tonnarini, Jan Antoni Rubin, K. Niedbalska, Rosabianca Trevisi

    Abstract:

    Abstract This paper contains preliminary results of a study on the physical and radiological characterization of concrete samples containing NORM. The natural radionuclides content in term of 226Ra, 228Ra, 232Th, 40K and the radon exhalation rate of the samples were determined. Two series of samples of concrete were prepared: samples belonging to both series were made of the same basic components (Portland cement CEM I 42,5R as binder, aggregate and plasticizer) but different amount of NORM residues and mineral additives were used. The concrete samples were characterize in term of absolute density, permeability, total and open porosity. The radiological content was evaluated by using gamma spectrometry and the radon exhalation rate measurements were performed using the dynamic method. Moreover, the Activity Concentration Index (I), introduced by the 2013/59/Euratom Directive, has been used in order to evaluate if concrete samples could exceed the reference level for effective dose due to gamma radiation in building materials.

  • Radiological aspects for use of woodchip ashes in building industry
    Construction and Building Materials, 2018
    Co-Authors: Massimo Garavaglia, Cristina Nuccetelli, Silvia Bucci, Elena Caldognetto, Giuseppe Candolini, Massimo Faure Ragani, Concettina Giovani, M. Magnoni, Ilaria Peroni, R. Rusconi

    Abstract:

    Abstract The use of woodchips of local origin for heating purposes is a diffused practice in some areas, like northern Italian alpine and sub-alpine zones, where large woods and forests extensions occur. In recent years, many thermal plants producing energy using woodchips as fuel have been constructed, supplying single edifices and delivering heated water to small communities through district heating. Unfortunately, due to the Chernobyl fall-out, particularly relevant in many mountain areas of northern Italy, woodchips of local origin are often contaminated with relevant 137 Cs traces: therefore, the woodchips burning aimed at water heating produces ashes in which the 137 Cs Activity Concentration is highly enriched with respect to that of the raw material. Typical Activity Concentrations of 137 Cs in such ashes span a range from a few hundreds to several thousands Bq/kg. These combustion ashes are subject to different fates, according to reuse opportunities and law restrictions (not referred to the radiological aspects). Landfill disposal is the most common general option, together with the use in compost production plants and concrete factories. In this paper, we focused in particular to the use of concrete containing highly contaminated ashes, being considered as the most relevant from the radioprotection point of view. Therefore, some evaluations of the public exposure to radiations coming from concrete utilized as building material and containing woodchip ashes with high radioActivity levels (specifically 137 Cs and 40 K) have been done. The dose estimates for a person living in a house built with “contaminated” concrete were made using both standardized gamma radiation exposure indices and simulation models. The results are presented and discussed. Finally, a new formulation of the Activity Concentration Index I is proposed for a safe and radioprotection sound use of building material containing woodchip ashes.

  • Gamma exposure from building materials – A dose model with expanded gamma lines from naturally occurring radionuclides applicable in non-standard rooms
    Construction and Building Materials, 2018
    Co-Authors: Tom Croymans, Cristina Nuccetelli, Rosabianca Trevisi, Sonja Schreurs, Federica Leonardi, Wouter Schroeyers

    Abstract:

    Abstract Building materials are a significant source of gamma rays exposure due to the presence of naturally occurring radionuclides. In order to protect the public from harmful radiation, the European Basic Safety Standards (Council directive 2013/59/Euratom) (European Council, 2014) introduced a one-size-fits-all building(s) (materials) Activity Concentration Index (ACI) based on a limited set of gamma lines. The ACI is considered “as a conservative screening tool for identifying materials that may cause the reference level (i.e. 1 mSv/y) laid down in article 75(1) to be exceeded”. Regarding calculation of dose, many factors such as density and thickness of the building material, as well as factors relating to the type of building, and the gamma emission data need to be taking into account to ensure accurate radiation protection. In this study the implementation of an expanded set of 1845 gamma lines, related to the decay series of 238U, 235U and 232Th as well as to 40K, into the calculation method of Markkanen (1995), is discussed. The expanded calculation method is called the Expanded Gamma Dose Assessment (EGDA) model. The total gamma emission intensity increased from 2.12 to 2.41 and from 2.41 to 3.04 for respectively the 238U and 232Th decay series. In case of 40K a decrease from 0.107 to 0.106 is observed. The 235U decay series is added, having a gamma emission intensity of 3.1. In a standard concrete room, the absorbed dose rates in air (DA) per unit of Activity Concentration of 0.849, 0.256, 1.08, 0.0767 nGy/h per Bq/kg are observed. The use of weighted average gamma lines increased the DA with 6.5% and 1% for respectively the 238U and 232Th decay series. A decrease of 4.5% is observed in the DA of 235U decay series when using the weighted average gamma lines in comparison to its non-averaged variant. The sensitivity of the EGDA model for density, wall thickness, presence of windows and doors and room size is investigated. Finally, a comparison of the Index and dose calculations relevant for the dose assessment within the European legislative framework applicable towards building materials is performed. In cases where the ACI and density and thickness corrected dose calculation of Nuccetelli et al. (2015) cannot provide guidance, the EGDA allows performing more accurate dose assessment calculations leading to effective doses which can be several 100 µSv/y lower.

Wouter Schroeyers – One of the best experts on this subject based on the ideXlab platform.

  • Radiological evaluation of industrial residues for construction purposes correlated with their chemical properties
    The Science of the total environment, 2018
    Co-Authors: Zoltan Sas, Niels Vandevenne, Rory Doherty, Raffaele Vinai, Jacek Kwasny, Mark Russell, Wei Sha, Marios Soutsos, Wouter Schroeyers

    Abstract:

    Abstract This study characterises the naturally occurring radionuclide (NOR) contents of a suite of secondary raw materials or industrial residues that are normally disposed of in landfills or lagoons but now are increasingly used in green concretes. This includes ashes from a variety of industrial processes and red mud from aluminium production, as well as air pollution control residue and cement kiln dust. The chemical composition of the samples was determined with X-ray fluorescence spectroscopy (XRF). The Ra-226, Th-232 and K-40 Activity Concentrations were obtained by gamma spectrometry, and the results were compared with recently published NOR databases. The correlation between the NOR contents and the main chemical composition was investigated. The radioactive equilibrium in the U-238 chain was studied based on the determination of progeny isotopes. The most commonly used calculation methods (Activity Concentration Index and radium equivalent Concentration) were applied to classify the samples. The radon exhalation rate of the samples was measured, and the radon emanation coefficient was calculated. Significant correlation was found between the NORs and certain chemical components. The massic exhalation demonstrated a broad range, and it was found that the emanation coefficients were significantly lower in the case of the residues generated as a result of high-temperature combustion processes. The results showed a weak correlation between the Ra-226 Concentration and the radon exhalation. This emphasises that managing the Ra-226 content of recycled material by itself is not sufficient to control the radon exhalation of recycled materials used in building products. The investigated parameters and their correlation behaviour could be used to source apportion materials found during the process of landfill mining and recovery of material for recycling.

  • Gamma exposure from building materials – A dose model with expanded gamma lines from naturally occurring radionuclides applicable in non-standard rooms
    Construction and Building Materials, 2018
    Co-Authors: Tom Croymans, Cristina Nuccetelli, Rosabianca Trevisi, Sonja Schreurs, Federica Leonardi, Wouter Schroeyers

    Abstract:

    Abstract Building materials are a significant source of gamma rays exposure due to the presence of naturally occurring radionuclides. In order to protect the public from harmful radiation, the European Basic Safety Standards (Council directive 2013/59/Euratom) (European Council, 2014) introduced a one-size-fits-all building(s) (materials) Activity Concentration Index (ACI) based on a limited set of gamma lines. The ACI is considered “as a conservative screening tool for identifying materials that may cause the reference level (i.e. 1 mSv/y) laid down in article 75(1) to be exceeded”. Regarding calculation of dose, many factors such as density and thickness of the building material, as well as factors relating to the type of building, and the gamma emission data need to be taking into account to ensure accurate radiation protection. In this study the implementation of an expanded set of 1845 gamma lines, related to the decay series of 238U, 235U and 232Th as well as to 40K, into the calculation method of Markkanen (1995), is discussed. The expanded calculation method is called the Expanded Gamma Dose Assessment (EGDA) model. The total gamma emission intensity increased from 2.12 to 2.41 and from 2.41 to 3.04 for respectively the 238U and 232Th decay series. In case of 40K a decrease from 0.107 to 0.106 is observed. The 235U decay series is added, having a gamma emission intensity of 3.1. In a standard concrete room, the absorbed dose rates in air (DA) per unit of Activity Concentration of 0.849, 0.256, 1.08, 0.0767 nGy/h per Bq/kg are observed. The use of weighted average gamma lines increased the DA with 6.5% and 1% for respectively the 238U and 232Th decay series. A decrease of 4.5% is observed in the DA of 235U decay series when using the weighted average gamma lines in comparison to its non-averaged variant. The sensitivity of the EGDA model for density, wall thickness, presence of windows and doors and room size is investigated. Finally, a comparison of the Index and dose calculations relevant for the dose assessment within the European legislative framework applicable towards building materials is performed. In cases where the ACI and density and thickness corrected dose calculation of Nuccetelli et al. (2015) cannot provide guidance, the EGDA allows performing more accurate dose assessment calculations leading to effective doses which can be several 100 µSv/y lower.

  • Measurement of radioActivity in building materials – Problems encountered caused by possible disequilibrium in natural decay series
    Construction and Building Materials, 2018
    Co-Authors: Boguslaw Michalik, Wouter Schroeyers

    Abstract:

    Abstract The determination of the Activity Concentration of naturally occurring radionuclides in construction materials is based on the principles of gamma-spectrometry. Gamma spectrometry is a comparative method and therefore includes many parameters that are specific to the test sample and measurement circumstances. Consequently, several of the testing conditions must be verified prior to testing and/or require correction to obtain accurate results. Besides problems encountered during the measurement, the interpretation of the results and calculation of the Activity indices, needed for material classification, may lead to significant mistakes. Current regulation in the European Union requires to calculate an Activity Concentration Index (Index I) using the Activity Concentration of 226Ra, 232Th and 40K. Not all of these radionuclides are directly measurable by gamma spectrometry and, to determine the Index, additional assumptions have to be made about secular equilibrium in uranium and thorium decay series. These assumptions are often not valid in case of NORM (Naturally Occurring Radioactive Materials) where long term lack of secular equilibrium in the uranium and/or thorium decay series is often observed. As a consequence, this may result in an underestimation or overestimation of the Index. The article discusses specific disequilibrium situations in building materials. Sources for potential inaccurate determinations and misinterpretation are identified and practical mitigation options are proposed.