Stylianos Alexakis

Hellenic Centre for Marine Research

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C. Tsabaris

Hellenic Centre for Marine Research

D. L. Patiris

Hellenic Centre for Marine Research

FΚ

Filothei Κ. Pappa

University of the Aegean

G. Eleftheriou

Hellenic Centre for Marine Research

Effrossyni G. Androulakaki

Hellenic Centre for Marine Research

Spyridoula Konstantina Roumelioti

National Technical University of Athens

E.G. Androulakaki

Hellenic Centre for Marine Research

Aristides Prospathopoulos

Hellenic Centre for Marine Research

M. Kokkoris

National Technical University of Athens

R. Vlastou

National Technical University of Athens

Cooperative Institutions

Hellenic Centre for Marine Research

National Technical University of Athens

Institute of Oceanography

City University of New York

City College of New York

University of the Aegean

National Centre of Scientific Research "Demokritos"

European Organization for Nuclear Research

Institute of Nuclear and Particle Physics

National Taiwan University of Arts

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An Optimized Quantification Method for Marine Radioactivity Measurements: Application in the Southern Caspian Sea Using the KATERINA Underwater γ-Spectrometer

Journal of Marine Science and Engineering (2023)

C. Tsabaris Effrossyni G. Androulakaki Stylianos Alexakis

The underwater gamma-ray spectrometer KATERINA was calibrated in a special tank and then demonstrated in the Southern Caspian Sea to determine the radioactivity levels in seawater as well as in the sediment. The simulated marine efficiency of the in situ detection system was validated analyzing the high energetic (1764 keV of 214Bi and 2614 keV of 208Tl) gamma-ray peaks using their known activity concentration as determined from the low energy emissions. The analysis of the in situ gamma-ray spectra in a short acquisition time period provided quantitative data for 226Ra and 232Th progenies as well as for 40K. A satisfactory analysis was performed for quantifying the observed energy peaks in the seawater and sediment measurements acquired at the south coast of the Caspian Sea. The spectrum in the water tank was also analyzed using full spectrum analysis methods, and the reproduced spectrum was in a very good agreement with the experimental spectrum giving as an output the activity concentrations of the observed radionuclides.

Energy spectrum

Gamma ray spectrometer

10.3390/jmse11040725

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Citations (1)

Rainfall Investigation by Means of Marine In Situ Gamma-ray Spectrometry in Ligurian Sea, Mediterranean Sea, Italy

Journal of Marine Science and Engineering (2021)

D. L. Patiris Sara Pensieri C. Tsabaris Roberto Bozzano Effrossyni G. Androulakaki

Marine in situ gamma-ray spectrometry was utilized for a rainfall study at the W1M3A observing system in Ligurian Sea, Mediterranean Sea, Italy. From 7 June to 10 October 2016, underwater total gamma-ray counting rate (TCR) and the activity concentration of radon daughters 214Pb, 214Bi and potassium 40K were continuously monitored along with ambient noise and meteorological parameters. TCR was proven as a good rainfall indicator as radon daughters’ fallout resulted in increased levels of marine radioactivity during and 2–3 h after the rainfall events. Cloud origin significantly affects TCR and radon progenies variations, as aerial mass trajectories, which extend upon terrestrial areas, result in higher increments. TCR and radon progenies concentrations revealed an increasing non-linear trend with rainfall height and intensity. 40K was proven to be an additional radio-tracer as its dilution was associated with rainfall height. 40K variations combined with 214Bi measurements can be used to investigate the mixing of rain- and seawater. In comparison with measurements in the atmosphere, the application of marine in situ gamma-ray spectrometry for precipitation investigation provided important advantages: allows quantitative measurement of the radionuclides; 40K can be used, along with radon daughters, as a radio-tracer; the mixing of rain- and seawater can be associated with meteorological parameters.

TRACER

10.3390/jmse9080903

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Citations (5)

Integration of Underwater Radioactivity and Acoustic Sensors into an Open Sea Near Real-Time Multi-Parametric Observation System

Sensors (2018)

Sara Pensieri D. L. Patiris Stylianos Alexakis Marios N. Anagnostou Aristides Prospathopoulos

This work deals with the installation of two smart in-situ sensors (for underwater radioactivity and underwater sound monitoring) on the Western 1-Mediterranean Moored Multisensor Array (W1-M3A) ocean observing system that is equipped with all appropriate modules for continuous, long-term and real-time operation. All necessary tasks for their integration are described such as, the upgrade of the sensors for interoperable and power-efficient operation, the conversion of data in homogeneous and standard format, the automated pre-process of the raw data, the real-time integration of data and metadata (related to data processing and calibration procedure) into the controller of the observing system, the test and debugging of the developed algorithms in the laboratory, and the obtained quality-controlled data. The integration allowed the transmission of the acquired data in near-real time along with a complete set of typical ocean and atmospheric parameters. Preliminary analysis of the data is presented, providing qualitative information during rainfall periods, and combine gamma-ray detection rates with passive acoustic data. The analysis exhibits a satisfactory identification of rainfall events by both sensors according to the estimates obtained by the rain gauge operating on the observatory and the remote observations collected by meteorological radars.

Upgrade

Data logger

Data Processing

Real-time data

10.3390/s18082737

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Citations (14)

An Integrated Wave Monitoring Network for the Hellenic Seas

Takvor Soukissian Ioannis Morfis Stylianos Alexakis

In this paper, an integrated wave monitoring network for the Hellenic Seas is presented and its components are described. The network is comprised from wave buoys and nautical X-band radars covering most of the important areas of the Hellenic seas as regards complicated wave propagation patterns. The buoy wave monitoring network is part of the POSEIDON system for the monitoring, information and forecasting of the state of the Hellenic Seas. The X-band wave radar network is under development within the context of the OKEANOS project in co-operation with the Hellenic Navy Hydrographic Service. The measuring techniques and principles of both types of devices (buoys and X-band radars) are also described. The wave measurements from the network are mainly used for improving the operational wave forecasts provided by the Hellenic Centre for Marine Research (HCMR), for individual planning purposes and in the design and construction of coastal and offshore structures. Two experimental coastal sites have been selected for comparing the radar wave data with data from directional wave buoys and the WAM wave model.

Buoy

Sea state

Wave model

Wave radar

Wave height

10.1115/omae2008-58030

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An in-situ gamma-ray spectrometer for the deep ocean

Applied Radiation and Isotopes (2018)

C. Tsabaris E.G. Androulakaki Stylianos Alexakis D. L. Patiris

Subsea

Gamma ray spectrometer

Imaging spectrometer

10.1016/j.apradiso.2018.08.024

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Citations (23)

Atmospheric in situ gamma-ray spectrometry for precipitation investigation

Acta Geophysica (2023)

D. L. Patiris C. Tsabaris Katerina Livanou Spyridoula Konstantina Roumelioti Stylianos Alexakis

Abstract The underwater gamma-ray spectrometer GeoMAREA was utilized for in situ continuous monitoring of radon progenies in the atmosphere near the city of Anavyssos, Attica, Greece, during the period from 1 November 2017 until 1 April 2018. The acquired spectra before and during rainfalls were used to derive rainwater’s spectra revealing that the major contributors to the observed photo-peaks are the progenies of 222 Rn ( 214 Pb, 214 Bi). The total counting rate of the spectra and the counting rate of the net areas of 352 keV and 609 keV photo-peaks ( 214 Pb and 214 Bi, respectively) proved to be effective parameters for rainfall identification and investigation. Statistical analysis did not reveal a significant association between radon progenies and temperature, pressure, humidity and dew point during rainfalls or dry meteorological conditions. However, preferable wind directions for rainwater rich in radon progenies revealed the impact of the atmospheric masses trajectories before a precipitation event. According to HYSPLIT modelling of selected rainfall events, air masses that pass over terrestrial areas at low altitudes (< 1500 m above ground level) 48 h before the event result in rainwater enriched in radon progenies. On contrary, air masses that pass before an event over terrestrial areas at higher altitudes (> 3000 m above ground level) result in rainwater of low radon progenies concentration. Overall, the method was considered promising for continuous in situ measurements of radon progenies in the atmosphere and may extend the use of radon as a tracer for studies related to climate investigation.

Rainwater Harvesting

Dew point

HYSPLIT

Gamma ray spectrometry

10.1007/s11600-023-01090-9

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Citations (5)

In situ characterization using natural radio-tracers in a submarine freshwater spring, Kiveri, Greece

Journal of Environmental Radioactivity (2021)

C. Tsabaris Vassilis Zervakis H. Georga Filothei Κ. Pappa Stylianos Alexakis

10.1016/j.jenvrad.2021.106583

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GeoMAREA: A Gamma‐ray spectrometer for in‐situ marine environmental applications

HNPS Advances in Nuclear Physics (2020)

C. Tsabaris Effrosini G. Androulakaki D. L. Patiris Fotis Maragos G. Eleftheriou

A new medium resolution (based on a 2″x2″CeBr3 crystal) gamma-ray spectrometer named “GeoMAREA” was developed and applied for measuring radioactivity in aquatic environments. The system is capable for qualitative and quantitative measurement of radionuclides in aquatic environments with maximum depth of deployment up to 600 m. A special software is developed to fulfill different demands of the end-users in order to: a) provide real time data using the cable mode, b) perform communication tasks with a data center transferring (near) real time data, c) provide time series in sequential buffers for continuous monitoring in a stand-alone mode and d) provide profile data and subsequently maps using mobile vehicles (underway mode). The spectrometer was calibrated first using point sources for energy, energy resolution and efficiency. The system offers activity concentrations of all detected gamma-ray emitters in Bq/m3 using the marine efficiency calibration, which is reproduced via the MCNPX code [1]. Two experimental points were used for validation of the theoretical estimation obtained by two reference sources (137Cs and 40K) diluted in a water-filled tank. Currently, GeoMAREA is deployed in a closed aquatic system where groundwater discharges (Anavalos, Kiveri, Greece). A first estimation of the intrinsic background of the crystal at the emission energy area of 40K is estimated. Additionally, an inter-comparison exercise with the low resolution system KATERINA II [2], is also described.

Radiation monitoring

Mode (computer interface)

10.12681/hnps.3012

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Citations (0)

Design of an Interactive Cellular System for the Remote Operation of Ocean Sensors: A Pilot Study Integrating Radioactivity Sensors

Journal of Marine Science and Engineering (2021)

Stylianos Alexakis C. Tsabaris

Ocean in-situ sensors are crucial for measuring oceanic parameters directly from the sea in a spatial and temporal basis. Real-time operation is used in many applications related to decision support tools and early warning services in case of accidents, incidents and/or disasters. The design of the proposed system is described as a rapid-response detection system, which aims to measure natural and artificial radioactive contaminants or other crucial ocean parameters, to replace the traditional method of sampling. The development of an interactive cellular system is undertaken using a commercial router that is programmed according to sensor specifications. A radioactivity sensor is integrated in a communication box enabling self-powered operation with a solar panel. The proposed system operates in (near) real-time mode and provides gamma-ray spectra by integrating the sensor and the appropriate electronic modules in it. Additionally, an on-site experiment was conducted to test the operability of the system in a real environment close to the sea, for monitoring fallout due to rainfall and snowfall events. The main intense radionuclides that were observed by different energy lines, were radon progenies (214Bi, 214Pb). The continuous operation of the whole system was controlled by operating the system during the winter period.

Radiation monitoring

10.3390/jmse9080910

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Citations (6)

Surveillance of the seashore using the KATERINA II geo-referenced detection system

HNPS Advances in Nuclear Physics (2023)

C. Tsabaris D. L. Patiris Christos Maramathas Efrosyni Androulakaki G. Eleftheriou

In this work, the design and initial demonstration of the KATERINA II detection system for rapid mapping of radionuclides in areas near to seashore is presented. A new development has been realized by integrating a GPS module in KATERINA II detection system and synchronizing its data with the acquired spectra in real-time. The new system may be used in a backpack, for areas with low activity concentration, or can be installed in an unmanned vehicle, for observing and mapping the source(s) of radioactivity, e.g. at the seashore, in areas with high contamination. A quantitative solution is provided for natural and artificial radionuclides, taking into account the characteristics of the detector, the parameters of measurement geometry and a mean beach sand/sediment composition. This paper reports field results for site characterization issues through automated analysis of gamma-ray spectra including low-level and low-energy γ-emitters. Perspectives of the future application of the system in a worldwide basis are related to radionuclides mapping and the assessment of dose rates in seashore areas that may be contaminated due to the operation of nuclear power plants, desalination plants and NORM industries, and/or due to the decommissioning of nuclear installations.

Nuclear decommissioning

Radiation monitoring

10.12681/hnpsanp.2473

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Citations (2)