Publications by authors named "Karfopoulos K"

Naturally Occurring Radioactive Material (NORM) may pose radiological risks across various industrial processes. Characterizing NORM is challenging due to radionuclide diversity, complex material matrices, and the multiple analytical techniques required. This study documents an Intercomparison Exercise (ICE) on the radioanalytical characterization of NORM, organized by International Atomic Energy Agency and EEAE to evaluate participants' abilities to implement appropriate radioanalytical techniques and promote harmonization, thus contributing to ongoing optimization efforts into radiation protection of workers and the public.

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The goal of this study is to provide a benchmark for the use of Monte Carlo simulation when applied to coincidence summing corrections. The examples are based on simple geometries: two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions. The coincidence corrective factors are computed for four radionuclides.

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The goal of this work was to develop a methodology for risk assessment in case of an accident originating from a nuclear power plant, and consequently, to improve the relevant radiation monitoring network. In specific, the study involved risk estimation in Greece from a transboundary nuclear power plant accident. The tool employed was JRODOS (Java-based Real-time Decision Support), which is a system for off-site emergency management of radioactive material in the environment.

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This work aims at providing a Monte-Carlo based methodology for calculating true coincidence correction (TCC) factors for volume sources of varying density. All simulations were carried out using the most recent version of Monte Carlo code PENELOPE. The main program PENMAIN was used for the calculation of full energy peak efficiencies.

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Article Synopsis
  • An internal consistency test was conducted to evaluate the calculation of coincidence-summing correction factors F for volume sources, using exact equations from three ideal measurement configurations.
  • The test was performed on 33 sets of F values submitted by 21 different teams, with most sets passing the evaluation.
  • However, the results from the quasi-point source approximation did not pass, revealing a qualitative indication of bias in the calculated values of F.
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Monte Carlo (MC) simulation is widely used in gamma-ray spectrometry, however, its implementation is not always easy and can provide erroneous results. The present action provides a benchmark for several MC software for selected cases. The examples are based on simple geometries, two types of germanium detectors and four kinds of sources, to mimic eight typical measurement conditions.

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This paper presents the Compton Suppression System, recently installed at the Nuclear Engineering Department of NTUA. The system consists of an XtRa Ge detector coupled with a NaI(Tl) guard detector. The electronic set-up allows for the simultaneous collection of both the suppressed and the unsuppressed spectra.

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The radionuclides released during the accident at the Fukushima Daichii nuclear power plant following the Tōhoku earthquake and tsunami on 11 March 2011 were dispersed in the whole north hemisphere. Traces of (131)I, (134)Cs and (137)Cs reached Greece and were detected in air, grass, sheep milk, ground deposition, rainwater and drainage water. Members of Six Greek laboratories of the national network for environmental radioactivity monitoring have collaborated with the Greek Atomic Energy Commission (GAEC) and carried out measurements during the time period between 11 March 2011 and 10 May 2011 and reported their results to GAEC.

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Article Synopsis
  • The study focuses on comparing different methods for correcting coincidence summing effects in radioactive measurements.
  • It specifically looks at three volume sources containing liquid radioactive solutions, utilizing the same experimental conditions across all participants.
  • The results include corrective factors for different energies of the isotopes (152)Eu and (134)Cs, considering various distances between the source and detector, which are thoroughly discussed.
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In the case of a nuclear or radiological accident a rapid estimation of the qualitative and quantitative characteristics of the potential radioactive pollution is needed. For aerial releases the radioactive pollutants are finally deposited on the ground forming a surface source. In this case, in-situ γ-ray spectrometry is a powerful tool for the determination of ground pollution.

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The concentration of trace elements and radionuclides in fly ash particles of different size can exhibit significant variation, due to the various processes taking place during combustion inside a coal-fired power plant. An investigation of this effect has been performed by analyzing samples of fly ash originating in two different coal-fired power plants, after separation into size fractions by sieving. The samples were analyzed by gamma-ray spectrometry, including low-energy techniques, radon exhalation measurement and instrumental neutron activation analysis for the determination of Al, As, Ga, K, La, Na, Mn, Mg, Sr, Sc, and V.

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A comparison of the coincidence summing correction methods is presented. Since there are several ways for computing these corrections, each method has advantages and drawbacks that could be compared. This part of the comparison was restricted to point sources.

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Article Synopsis
  • The primary focus is to analyze how different simulation parameters influence the full energy peak efficiency of HPGe detectors.
  • The study utilizes the Monte Carlo simulation code called PENELOPE for carrying out these calculations.
  • Understanding these effects can enhance the accuracy of detector efficiency assessments in various applications.
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