CC BY
20
DOI: 10.12845/bitp.44.4.2016.12
mgr Barbara Piotrowska1 mgr inz. Marian Fujak1 mgr inz. Krzysztof Isajenko1 mgr Sylwia Krawczynska2
Przyjçty/Accepted/Принята: 04.10.2016; Zrecenzowany/Reviewed/Рецензирована: 10.12.2016; Opublikowany/Published/Опубликована: 30.12.2016;
Building Materials Radioactivity in Poland3
Radioaktywnosc materialow budowlanych w Polsce
Радиоактивность строительных материалов в Польше
ABSTRACT
Introduction: The systematic research of the natural radioactivity of raw and building materials has been conducted in Poland since 1980. Basing on the results of these studies, carried out by both the Central Laboratory for Radiological Protection (CLOR) and over 30 other research laboratories in our country, the national database of natural radioactivity measurements has been set up. The database is supervised by the CLOR and contains the results of the measurements for more than 42 000 samples analysed since 1980 up till now. Due to the economic development of the country, since 1990 there has been an increase in the number of the natural radioactivity measurements of raw and building materials. Objective: The aim of this article is the presentation and evaluation selected of raw and building materials in terms of radiology. Method: In Poland the possibility of using different raw and ready building materials is classified due to the value of activity coefficients f and f2. Activity coefficient f specifies the content of natural isotopes in a test material and is the coefficient of the gamma radiation exposure to the whole body. Activity coefficient f2 specifies the content of radium 226Ra (mother of isotope 222Rn) in the test material and is the coefficient of the exposure of the lungs epithelium to the alpha radiation emitted by the decay products of radon, breathed into with air by the human respiratory system. Activity coefficients are described by the natural radioactivity of potassium 40K, radium 226Ra and thorium 228Th. Activity concentration of these radionuclides is determined by the MAZAR analyser with a scintillation detector. It is a three-window analyser, which measures samples in the range from 1.26 MeV to 2.85 MeV.
Results: This paper shows the values of activity coefficients f and f for a few selected raw and building materials like ash, concrete, cement and ceramics. Additionally, activity coefficients f and f2 for carbon are discussed. Carbon, as a precursor to a few building raws, (ash, slag, mixture of ash and slag) has been measured in significant amounts since 1996. Average value of its activity coefficient f was between 0.15 and 0.43 while an average index f was from 14.7 Bq/kg to 44.2 Bq/kg for results collected in 1980-2012. Average values of activity coefficients f and f2 for carbon are the lowest of all measured and compared materials described in this paper. Average value of activity coefficient f of ash as a by-product of coal combustion is a few times higher than for carbon and is higher than the limit value equals 1.0 for results from almost all years. Conclusions: In the paper, average value and range of dose rate for these several raw and building materials have been shown. An average dose rate is between 31.8 nGy/h for carbon up to 140.8 nGy/h for ash.
Keywords: building materials, natural radioactivity, 40K, 226Ra, 228Th Type of article: original scientific article
ABSTRAKT
Wprowadzenie: Od 1980 roku w Polsce prowadzone s^ systematyczne badania naturalnej promieniotworczosci surowcow i materialow budowlanych. W oparciu o wyniki badan m.in. Centralnego Laboratorium Ochrony Radiologicznej (CLOR) oraz ponad 30 innych laboratoriow badawczych w naszym kraju powstala ogolnopolska baza pomiarow promieniotworczosci naturalnej. Baza ta jest nadzorowana przez CLOR i zawiera wyniki pomiarow dla ponad 42 000 zbadanych probek od 1980 roku do chwili obecnej. W zwiqzku z rozwojem gospodarczym kraju, od 1990 roku nast^pil wzrost liczby pomiarow naturalnej radioaktywnosci surowcow i materialow budowlanych. Cel: Celem artykulu jest przedstawienie i ocena wybranych surowcow i materialow budowlanych pod wzglfdem radiologicznym. Metoda: W Polsce mozliwosc wykorzystania roznych surowcow i gotowych materialow budowlanych uzalezniona jest od wartosci wskaznikow aktywnosci f i f2. Wskaznik aktywnosci f okresla zawartosc naturalnych izotopow w badanym materiale i jest wspolczynnikiem narazenia calego ciala na promieniowanie gamma. Wskaznik aktywnosci f2 okresla zawartosc radu 226Ra w badanym materiale i jest wskaznikiem narazenia nablonka pluc na promieniowanie alfa emitowane przez produkty rozpadu radonu, pobrane wraz z powietrzem przez uklad oddechowy czlowieka. Wskazniki aktywnosci opisane s^ przez promieniotworczosc naturaln^ potasu 40K, radu 226Ra i toru 228Th. Stfzenie aktywnosci tych
1 Central Laboratory for Radiological Protection, Department of Dosimetry, Poland; [email protected];
2 Scientific and Research Centre for Fire Protection - National Research Institute (CNBOP-PIB), Poland;
3 Percentage contribution: B. Piotrowska - 35%, K. Isajenko - 25%, M. Fujak - 20%, S. Krawczynska - 20%;
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radionuklidow jest okreslana za pomoc^ analizatora MAZAR z detektorem scyntylacyjnym. Analizator jest trzyzakresowy. Mierzy probki w zakresach 1,26 do 1,65 MeV, od 1,65 do 2,30 MeV i od 2,30 do 2,85 MeV.
Wyniki: W artykule przedstawiono wartosci wskaznikow aktywnosci f i f2 dla kilku wybranych surowcow i materialow budowlanych, takich jak popiol, beton, cement i ceramika. Dodatkowo omowiono wskazniki aktywnosci f i f2 dla wfgla. Wfgiel jako prekursor kilku surowcow budowlanych (popiol, zuzel, mieszanina popiolowo-zuzlowa) mierzono w znacz^cych ilosciach od 1996 roku. Srednia wartosc jego wskaznika aktywnosci f wynosila od 0,15 do 0,43, podczas gdy sredni wskaznik f2 od 14,7 Bq/kg do 44,2 Bq/kg dla wynikow zebranych w latach 1980-2012. Srednie wartosci wskaznikow aktywnosci f i f2 wfgla s^ najnizsze sposrod wszystkich zmierzonych i porownanych materialow opisanych w niniejszym artykule. Srednia wartosc wskaznika aktywnosci f popiolu, jako produktu ubocznego spalania wfgla, jest kilka razy wyzsza niz w przypadku wfgla i jest wyzsza od wartosci granicznej rownej 1,0 w wynikach z prawie wszystkich lat.
Wnioski: W artykule przedstawiono wartosc sredni^ i zakres mocy dawki dla tych kilku wybranych surowcow i materialow budowlanych. Srednia moc dawki wynosi od 31,8 nGy/h w przypadku wfgla do 140,8 nGy/h w przypadku popiolu.
Slowa kluczowe: materialy budowlane, promieniotworczosc naturalna, 40K, 226Ra, 228Th Typ artykulu: oryginalny artykul naukowy
АННОТАЦИЯ
Введение: С 1980 года в Польше проводятся систематические исследования естественной радиоактивности сырья и строительных материалов. На основании результатов этих исследований, проводимых как Центральной лабораторией радиологической защиты (CLOR), так и более 30 другими научно-исследовательскими лабораториями в нашей стране была создана общенациональная база данных измерений естественной радиоактивности. Эта база данных находится под контролем CLOR и содержит результаты измерений более 42 000 образцов, проанализированных с 1980 по настоящее время.
В связи с экономическим развитием страны с 1990 года наблюдается увеличение числа измерений естественной радиоактивности сырья и строительных материалов.
Цель: Цель данной статьи состоит в представлении и оценке выбранного сырья и строительных материалов с точки зрения их радиологических свойств.
Метод: В Польше использование различных сырьевых материалов и готовых строительных материалов классифицируется относительно значений показателей активности f и f2. Показатель активности f определяет содержание природных изотопов в исследуемом материале и является фактором опасного воздействия гамма-излучения на целое тело). Показатель активности f определяет содержание радия 226Ra в исследуемом материале и является показателем опасного воздействия на альвеолы легких, вызванного альфа-излучением, эмитированного продуктами распада радия, которые поступают вместе с воздухом в дыхательную систему человека. Показатели активности описываются естественной радиоактивностью калия 40K, радия 226Ra и тория 228Th. Концентрация активности этих радионуклидов определяется при помощи анализатора MAZAR со сцинтилляционным детектором. Анализатор работает в трех диапазонах и измеряет образцы для значений от 1,26 до 1,65 MeV, от 1,65 до 2,30 MeV и от 2,30 до 2,85 MeV.
Результаты: В статье представлены показатели активности f и f2 для выбранного сырья и строительных материалов, таких как зола, бетон, цемент и керамика. Кроме того, в статье обсуждались показатели активности f и f2 угля. Уголь, который являлся предшественником некоторых строительных материалов (золы, шлака, смеси золы и шлака), измеряли достаточно часто начиная с 1996 года. Среднее значение показателя активности f колебалось от 0,15 до 0,43, в то время, как средний показатель f2 составял 14,7 Бк/кг до 44,2 Бк/кг для результатов, полученных в 1980-2012 годах. Средние значения показателей активности f и f2 угля являются самыми низкими из всех измеренных и сравниваемых материалов, описанных в этой статье. Среднее значение активности f1 золы в качестве побочного продукта от сжигания угля в несколько раз выше, чем угля, и выше, чем предельное значение 1,0 для результатов, собранных за все годы исследований.
Выводы: В статье представлено среднее значение и диапазон мощности дозы для нескольких типов сырья и строительных материалов. Средняя мощность дозы колеблется от 31,8 нГр/ч в случае угля, и до 140,8 нГр/ч для золы.
Ключевые слова: строительные материалы, естественная радиоактивность, 40K, 226Ra, 228Th Вид статьи: оригинальная научная статья
1. Introduction
At present, the evaluation of raw and building materials in terms of the presence of radioactivity concentration shall apply to the criteria published in the Ordinance of the Council of Ministers of 2 January 2007, (Journal of Laws No 4 pos. 29) "on the requirements regarding the content of natural isotopes of 40K, 226Ra and 228Th in the raw materials and the materials used in buildings intended for the dwelling of people and livestock, and also in the industrial waste used in buildings and control of the content of these isotopes". It is the primary and the only act specifying the requirements for raw and building materials used in various types of construction activities.
The regulation classifies the possibility of applying different raw and building materials in various types of housing by specifying two parameters [1]: • the qualification coefficient f - specifies the content of natural isotopes in the test material and is the coefficient of the gamma radiation exposure to the whole body,
• the qualification coefficient f2 (concentration of 226Ra) - specifies the content of the test material and is the coefficient of the exposure of the lungs epithelium to the radiation emitted by the decay products of radon, i.e. alpha particles breathed into with air by the human respiratory system.
The values of the activity coefficients f and f2 are described by the formulae (1) and (2):
f1 = SK/3000 [Bq/kg] + SJ300 [Bq/kg] + STh/200 [Bq/kg] (1)
f = Sa Bq/kg] (2)
where: SK, SRa and STh are the values of the activity concentration of the relevant radionuclides in Bq/kg.
Depending on the qualification coefficients, the raw and building materials are licensed to be utilized in various constructions.
The limit values of the activity coefficients f1 and f2 for the construction of dwellings are:
f = 1 and f2 = 200 Bq/kg
ИССЛЕДОВАНИЯ И РАЗВИТИЕ
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The measured values of f and f2 are being considered during the evaluation, but none can exceed the limit value by more than 20%, i.e.: f < 1.2 and f2 < 240 Bq/kg. The total uncertainty value of the measurements has also been limited to 20% of the value of the coefficients f and f2, not less than 0.8 of their limit values.
Very important, from the point of view of radiation protection, is an increase in exposure due to natural radiation sources that causes an increase in the annual effective absorbed dose of about 1mSv. The limit values of activity coefficients f and f2 meet the criterion of not exceeding the annual effective dose which equals 1mSv. Similar limits for housing apply in Norway, while in Lithuania and Finland limits for raw and construction materials relate only to activity index fj.
The limit values for the remaining applications in the construction industry are:
1. f1 = 2 and f2 = 400 [Bq/kg] regarding the industrial waste used in surface objects constructed in the built-up areas, or designed for built-up areas in the local urbanization plans, or for leveling of such areas;
2. f1 = 3,5 and f2 = 1000 [Bq/kg] regarding the industrial waste used in surface parts of the objects not mentioned in point 1 and for leveling of the areas not mentioned in the above point;
3. f1 = 7 and f2 = 2000 [Bq/kg] regarding the industrial waste used in the underground parts of the objects mentioned in point 2, and the underground constructions, including railway and road tunnels, excluding the industrial waste used in underground mining pits.
The gamma dose rate at the height of 1 m over the unlimited flat surface of the terrain of the average density of r = 1,6g/ cm3 is determined semi-empirically by the formula (3) [2]:
D = 0,043 SK + 0,43SRa + 0,66 STh [nGy/h] (3)
where Sf, SSTh - activity concentration in [Bq/kg] of respectively 40K, 226Ra (in radioactive equilibrium with daughter nuclides) and 228Th (in radioactive equilibrium with daughter nuclides).
In addition, the absorbed dose rate at 1 m above ground level, road or facility should not exceed 0.3 |iGy/h for the application of industrial waste to the levelling and the construction of roads, sports and recreational facilities.
2. Equipment and method
Most laboratories use the MAZAR analysers of the new generation or the AZAR ones of the older generation with the Nal (Tl) detector to determine the qualification coefficients f and f2
in Poland. These are three-windows analysers which determine the concentration of radioactive 40K, 226Ra and 228Th. The windows of analyser are 40K, 226Ra and 228Th in the ranges of 1.26 MeV to 1.65 MeV, 1.65 MeV to 2.30 MeV and 2.30 MeV to 2.85 MeV respectively. The efficiency calibration of the detector was performed with the use of volume standards 40K, 226Ra and 228Th and a standards matrix (for background). The standard source are Marinelli beakers of 1.5 dm3 volume and they are made for most laboratories by the Central Laboratory for Radiological Protection in Poland. The density of standard sources is equal 1.6 g/cm3, while the density of samples of raw and building materials are within the range 0.6 to 2.0 g/cm3. In order to minimize the outside gamma background, the detector is placed in a shielding house made of 50 mm lead. Shredded and screened through a 2 -millimetres-mesh sieve samples are packed into Marinelli beakers of 1.5 dm3 volume and sealed. The samples are measured after the time elapse to establish the radioactive equilibrium between 226Ra - 214Bi and 228Th - 208Tl after about 2 weeks. All measurements were made in the same geometry and once.
3. The results and discussion
The qualification coefficient f is representative for specifying the content of natural isotopes in the test material, because it contains natural radioactive isotopes, which are mostly in the earth crust such as 40K, 226Ra (represent 238U series) and 228Th (represent 232Th series). Other natural ra-dionuclides have minor significance.
Since 1990, there has been an increase in the number of qualification measurements of the natural radioactivity of raw and building materials, because of the economic development of the country. However, during the recent years the number of the natural radioactivity tests has been reduced, due to the wider usage of the construction materials of foreign origin, which are not subject to the mandatory testing in Poland.
The values of f and f2 for different raw and building materials (carbon, ash, cement, concrete and ceramics) are shown on Fig. 1 to Fig. 10 as a function of time.
Average values of the activity coefficients f and f2 for carbon are in the range of 0.15 to 0.43 (Fig. 1) and 14.7 Bq/kg to 44.2 Bq/kg (Fig. 2) respectively. In the whole period of time the values of f and f2 have not been exceeded. The difference between the minimum and maximum of f1 and f2 increases with the number of samples, which may be caused by measurements of materials of various geological origin (place of coal mining).
The value of f for carbon
0,8
0,4
The number of measured samples The average value of f1 The minimum value of f1 The maximum vallue of f1
i .i .. Vf
40 £ IE s s
u
20 H 0
1984 1987 1990 1993 1996 1999 2002 2005 2008 2011
Fig. 1. The value of f1 for carbon at different times S o urce: Own elaboration.
120
80
1981
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The value of f, for carbon
100 90 80 70 60 50 40 30 20 10 0
the maximum value of f2 The average value of f2 ^^^The minimum value of f2
[y
979 1982 1985 1988 1991 1994 1997 2000 2003 2006 2009 2012
Fig. 2. The value of f2 fo r carbon at different times Source: Own elaboration.
Fig. 3. The value of fi for ash at different times Source: Own elaboration.
Fig. 4. The value of f2 for ash at different times Source: Own elaboration.
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Fig. 5. The value of f for cement at different times Source: Own elaboration.
The value f2 for ceramics
Fig. 6. His; valueof f2 forcem ent at different times Source: Own elaboration.
3,5 3 2,5 Ï 2 s ТЙ > ë 15 1 0,5 The value of f for concrete 1 r The number of the measured samples ■ The average value of f1 The minimum value of f1 The maximum value of f1 mm The numner of the measured samples
1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 2007 2009 2011
Fig. 7. The value of f for concrete at different times Source: Own elaboration.
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Fig. 8. The value of f2 for concrete at different times Source: Own elaboration.
Fig. 9. The value of f1 for ceramics at different times Source: Own elaboration.
Fig. 10. The value of f2 for ceramics at different times Source: Own elaboration.
ИССЛЕДОВАНИЯ И РАЗВИТИЕ
Average value of the activity coefficients f for ash is above limit value f1lim = 1.0, but below permissible value (f2 < 1.2) if we want to use them for the construction of dwellings (except 2011). Average value of the activity coefficients f1 and f2 for ash ranges from 0.99 to 1.26 (Fig. 3) and 102.4Bq/kg to 135.1Bq/kg (Fig. 4) respectively [3]. Maximum value of f2 was above the limit value for the construction of dwellings almost every year (Fig. 4). Although after 1991 the number of measurements of samples significantly increased, the average value of the activity coefficients f and f2 for ash remains at a relatively constant level, which can be caused by constant concentration of natural radionuclides in the ash.
Average values of the activity coefficients f and f2 for cement are well below limit values in the period of 1979-2012.
4. Conclusion
The qualification coefficients f and f2 are almost constant only for ash taking into account the entire period of the monitoring of the raw and building materials. It means is important to control all of them. The highest level of the qualification coefficients f and f2 are for ash and the lowest is for carbon - it is due to the process of the concentration of the radionuclides caused by the combustion process.
The concentration coefficient for the combustion is 4.5 on average. Higher values of qualification coefficients f and f2 characterize the materials containing considerable amounts of industrial raw materials such as ash or slag.
The level of qualification coefficients f and f2 for the ceramics is approximately twice as low as for the ash. The average values of f during the study period since 1979 have not exceeded (except for ash in 2011) the limit for the applications in the construction of dwellings (f1 < 1.2).
Although the average value of qualification coefficient f2 for ceramics and cement is at similar level, the average value of f1 for ceramics is almost 2 times higher, because concentration of 40K dominates in natural activity.
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The range of average value of the activity coefficients f and f2 for cement is from 0.26 to 0.60 for f (Fig. 5) and from 34.3 Bq/kg to 82.6 Bq/kg for f2 (Fig. 6).
Average values of the activity coefficients f and f2 for concrete are in the range from 0.52 to 0.81 for f (Fig. 7) and from 50.3 Bq/kg to 84.8 Bq/kg for f2 (Fig. 8) and ratio f2to f1 remains almost equal 100.
Average value of the activity coefficients f1 and f2 for ceramics are in the range from 0.26 to 0.80 for f1 (Fig. 9) and from 33.0 Bq/kg to 76.7 Bq/kg for f2 (Fig. 10).
The table 1 shows the average value of the qualification coefficients f1 and f2 and a dose rate for the selected materials. The level of the qualification coefficients f1 is exceeded only for the ash, but the dose rate is still below 0.3 ^Sv/h.
The analysis of the number of values higher than the limits for the activity coefficients f1 and f2 for dwellings and public constructions in 1979-2012 shows that the trend of the average values of the activity coefficients f1 and f2 has remained constant for the last years.
The article was written within the project "An IT tool for assessing a risk of accidents in industrial companies posing a threat outside their areas" financed by the National Centre for Research and Development.
Literature
[1] Rozporz^dzenie Rady Ministrow z dn. 2 stycznia 2007 roku (Dz. U. Nr 4, poz. 29) (The Ordinance of the Council of Ministers of 2 January 2007, (Journal of Laws No 4 pos. 29).
[2] Beck H.L., The natural radiation environment, [in:] US Energy Research and Development Administration Report, Adams J.A. S., Lowder W.M. (eds.), The University of Chicago Press, Chicago 1972.
[3] Zak A., Isajenko K., Piotrowska B., Kuczbajska M., Z^bek A., Szczygielski T., Natural radioactivity of waste, „Nukleonika" 2008, 55(3), 387-391.
Table 1. Average dose rate with min and max value for selected materials in the period 1979-2012
Material Average f1 / Range of average f Average f2 / Range of average f2 [Bq/kg] Average dose rate / Range of average dose rate [nGy/h]
Carbon 0.24 26.2 31.8
(0.15 4 0.43) (14.7 44.2) (19.5 4 56.2)
Ash 1.08 119.2 140.8
(0.99 4 1.26) (102.4 + 135.1) (128.0 152.7)
Cement 0.38 48.9 50.5
(0.26 4 0.60) (34.3 + 82.6) (36.9 + 78.5)
Concrete 0.66 70.3 86.5
(0.52 4 0.81) (50.3 + 84.8) (67.1 + 105.5)
Ceramics 0.62 (0.26 4 0.80) 52.6 (33.0 + 76.7) 81.0 (34.2 + 104.8)
Source: Own elaboration.
Barbara Piotrowska, M.A. - since July 1, 2009 an employee of the Central Laboratory for Radiological Protection in the Department of Dosimetry as Deputy Head. Previously, she worked at the Military Institute of Chemistry and Radiometry. Engaged in gamma spectrometry since 1996. Currently, she works on natural radioactivity in raw and building materials, and conducts training in this field of research. She is the manager of the Technical accredited Laboratory of Natural Radioactivity Measurements in CLOR.
Marian Fujak, M.Sc.Eng. - nuclear physicist by profession (he graduated from the Faculty of Nuclear Physics of the Academy of Mining and Metallurgy in Krakow), in 2016 an employee of IAEA (International Atomic Energy Agency) in Monaco in the
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Department of Radiometry, Senior Research and low-level counting Assistant. In 2014-2015 he worked in the nuclear industry in Germany (decontamination EON nuclear power plant Stade, storage of nuclear materials Remlingen Asse II) as an engineering sciences specialist in nuclear measuring techniques. In 2012-2013 CLOR's employee in the Department of Dosimetry as a specialist. In 2008-2011 an employee of EAWAG -Aquatic Science and Technology Dübendorf (Switzerland) as a specialist in the field of nuclear measuring methods. Participant in the monitoring of radioactivity in the aquatic environment in Switzerland for the Ministry of Health. He collaborated in numerous national and international projects in the field of nuclear spectrometry.
Krzysztof Isajenko, M.Sc.Eng. - Deputy Director of the Central Laboratory for Radiological Protection (CLOR) in Warsaw, Head of Department of Dosimetry in CLOR, Head of the accredited Laboratory of Natural Radioactivity Measurements; graduated from the Faculty of Technical Physics and Applied Mathematics of the Warsaw University of Technology, a longtime member of the Exploration of the Sea of the Polish Academy of Sciences, lecturer at the Faculty of Physics at the Warsaw University of Technology, participant in many training courses on radiation protection and nuclear safety (both domestic and foreign), the author or co-author of numerous publications dealing with these topics.
Sylwia Krawczynska, M.A. - Deputy Director for Research and Development in the Scientific and Research Centre for Fire Protection - National Research Institute (CNBOP-PIB), an academic teacher at The Main School of Fire Service (SGSP), a graduate of the Faculty of Mathematics, Informatics and Mechanics of the University of Warsaw, doctoral studies at the Collegium of Economic Analysis of the Warsaw School of Economics, post-graduate studies Management in the United Threats at SGSP and Modern Methods of Strategic Management at the School of Management and Law and The School of Business Trainers. Since 2002, she has been related to the environment of firefighting and fire protection. The author of 13 publications in the field of mathematical modeling and economic analysis in the field of safety engineering, safety education and human resources management in the uniformed services. She has experience in the field of research projects at national and international level (FP5, FP6, FP7, Erasmus +).
