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Détails du magazine
Format
Magazine
eISSN
1508-5791
Première publication
25 Mar 2014
Période de publication
4 fois par an
Langues
Anglais

Chercher

Volume 61 (2016): Edition 4 (December 2016)

Détails du magazine
Format
Magazine
eISSN
1508-5791
Première publication
25 Mar 2014
Période de publication
4 fois par an
Langues
Anglais

Chercher

13 Articles

Proceedings of the Summer School of Plasma Diagnostics Phdiafusion 2015: “Soft X-Ray Diagnostics for Fusion Plasma” Bezmiechowa, Poland, 16-20 June 2015

Accès libre

Diagnostics of laser-produced plasmas

Publié en ligne: 26 Oct 2016
Pages: 393 - 401

Résumé

Abstract

We present the general challenges of plasma diagnostics for laser-produced plasmas and give a few more detailed examples: spherically bent crystals for X-ray imaging, velocity interferometers (VISAR) for shock studies, and proton radiography.

Mots clés

  • laser-produced plasmas
  • inertial-confinement fusion (ICF)
  • X-ray imaging
  • VISAR
Accès libre

Optimization of soft X-ray tomography on the COMPASS tokamak

Publié en ligne: 26 Oct 2016
Pages: 403 - 408

Résumé

Abstract

The COMPASS tokamak is equipped with the soft X-ray (SXR) diagnostic system based on silicon photodiode arrays shielded by a thin beryllium foil. The diagnostic is composed of two pinhole cameras having 35 channels each and one vertical pinhole camera with 20 channels, which was installed recently to improve tomographic inversions. Lines of sight of the SXR detectors cover almost complete poloidal cross section of the COMPASS vessel with a spatial resolution of 1-2 cm and temporal resolution of about 3 μs. Local emissivity is reconstructed via Tikhonov regularization constrained by minimum Fisher information that provides reliable and robust solution despite limited number of projections and ill-conditionality of this task. Improved border conditions and numerical differentiation matrices suppressing artifacts in reconstructed radiation were implemented in the code. Furthermore, a fast algorithm eliminating iterative processes was developed, and it is foreseen to be tested in real-time plasma control.

Mots clés

  • soft X-ray
  • tomography
  • Tikhonov regularization
  • tokamak
Accès libre

Comparison of silicon drift detectors made by Amptek and PNDetectors in application to the PHA system for W7-X

Publié en ligne: 26 Oct 2016
Pages: 409 - 412

Résumé

Abstract

The paper presents comparison of two silicon drift detectors (SDD), one made by Amptek, USA, and the second one by PNDetector, Germany, which are considered for a soft X-ray diagnostic system for W7-X. The sensitive area of the first one is 7 mm2 × 450 μm and the second one is 10 mm2 × 450 μm. The first detector is cooled by a double-stage Peltier element, while the second detector is cooled by single-stage Peltier element. Each one is equipped with a field-effect transistor (FET). In the detector from Amptek, the FET is mounted separately, while in the detector from PNDetector, the FET is integrated on the chip. The nominal energy resolution given by the producers of the first and the second one is 136 eV@5.9 keV (at -50°C) and 132 eV@5.9 keV (at -20°C), respectively. Owing to many advantages, the investigated detectors are good candidates for soft X-ray measurements in magnetic confinement devices. They are suitable for soft X-ray diagnostics, like the pulse height analysis (PHA) system for the stellarator Wendelstein 7-X, which has been developed and manufactured at the Institute of Plasma Physics and Laser Microfusion (IPPLM), Warsaw, in collaboration with the Max Planck Institute for Plasma Physics (IPP), Greifswald. The diagnostic is important for the measurements of plasma electron temperature, impurities content, and possible suprathermal tails in the spectra. In order to choose the best type of detector, analysis of technical parameters and laboratory tests were done. Detailed studies show that the most suitable detector for the PHA diagnostics is the PNDetector.

Mots clés

  • plasma diagnostic
  • pulse height analysis
  • solid-state detectors
Accès libre

Diagnostic systems for the nuclear fusion and plasma research in the PF-24 plasma focus laboratory at the IFJ PAN

Publié en ligne: 26 Oct 2016
Pages: 413 - 418

Résumé

Abstract

This paper presents a set of diagnostics dedicated to PF-24 - new medium size - plasma focus (PF) device built and operated at the Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN). The PF-24 can operate at energy level up to 93 kJ and charging voltage up to 40 kV. Each condenser is connected with a specially designed spark gap with a very small jitter, which ensures a high effi ciency and a low current rise time. The working parameters of PF-24 generator make it a suitable tool for testing new detection systems to be used in fusion research. Four types of such detection systems are presented in this article: three diagnostic systems used to measure electric quantities (Rogowski coil, magnetic probe, capacitance probe), neutron counter based on beryllium activation, fast neutron pinhole camera based on small-area BCF-12 plastic scintillation detectors and high-speed four-frame soft X-ray camera with microchannel plate.

Mots clés

  • diagnostics for DD fusion products
  • fast neutron sources
  • plasma diagnostics
  • plasma focus
  • plasma imaging
Accès libre

Energy composition of high-energy neutral beams on the COMPASS tokamak

Publié en ligne: 26 Oct 2016
Pages: 419 - 423

Résumé

Abstract

The COMPASS tokamak is equipped with two identical neutral beam injectors (NBI) for additional plasma heating. They provide a beam of deuterium atoms with a power of up to ~(2 × 300) kW. We show that the neutral beam is not monoenergetic but contains several energy components. An accurate knowledge of the neutral beam power in each individual energy component is essential for a detailed description of the beam- -plasma interaction and better understanding of the NBI heating processes in the COMPASS tokamak. This paper describes the determination of individual energy components in the neutral beam from intensities of the Doppler-shifted Dα lines, which are measured by a high-resolution spectrometer viewing the neutral beam-line at the exit of NBI. Furthermore, the divergence of beamlets escaping single aperture of the last accelerating grid is deduced from the width of the Doppler-shifted lines. Recently, one of the NBI systems was modified by the removal of the Faraday copper shield from the ion source. The comparison of the beam composition and the beamlet divergence before and after this modification is also presented.

Mots clés

  • tokamak
  • neutral beam injection (NBI)
  • Doppler effect
  • beam composition
  • beamlet divergence
Accès libre

Nuclear fusion and its large potential for the future world energy supply

Publié en ligne: 26 Oct 2016
Pages: 425 - 432

Résumé

Abstract

An overview of the energy problem in the world is presented. The colossal task of ‘decarbonizing’ the current energy system, with ~85% of the primary energy produced from fossil sources is discussed. There are at the moment only two options that can contribute to a solution: renewable energy (sun, wind, hydro, etc.) or nuclear fission. Their contributions, ~2% for sun and wind, ~6% for hydro and ~5% for fission, will need to be enormously increased in a relatively short time, to meet the targets set by policy makers. The possible role and large potential for fusion to contribute to a solution in the future as a safe, nearly inexhaustible and environmentally compatible energy source is discussed. The principles of magnetic and inertial confinement are outlined, and the two main options for magnetic confinement, tokamak and stellarator, are explained. The status of magnetic fusion is summarized and the next steps in fusion research, ITER and DEMO, briefly presented.

Mots clés

  • energy
  • nuclear fusion
  • tokamak
  • stellarator
Accès libre

Modelling of the soft X-ray tungsten spectra expected to be registered by GEM detection system for WEST

Publié en ligne: 26 Oct 2016
Pages: 433 - 436

Résumé

Abstract

In the future International Thermonuclear Experimental Reactor (ITER), the interaction between the plasma and the tungsten chosen as the plasma-facing wall material imposes that the hot central plasma loses energy by X-ray emission from tungsten ions. On the other hand, the registered X-ray spectra provide alternative diagnostics of the plasma itself. Highly ionized tungsten emits extremely complex X-ray spectra that can be understood only after exhaustive theoretical studies. The detailed analyses will be useful for proper interpretation of soft X-ray plasma radiation expected to be registered on ITER-like machines, that is, Tungsten (W) Environment in Steady-state Tokamak (WEST). The simulations of the soft X-ray spectra structures for tungsten ions have been performed using the flexible atomic code (FAC) package within the framework of collisional-radiative (CR) model approach for electron temperatures and densities relevant to WEST tokamak.

Mots clés

  • X-ray spectra
  • tokamak
  • tungsten L
  • M
  • N
  • X-ray lines
  • GEM detection system
Accès libre

Diagnostics of the plasma parameters based on the K X-ray line positions for various 4d and 4f metals

Publié en ligne: 26 Oct 2016
Pages: 437 - 441

Résumé

Abstract

This paper shows the theoretical predictions of the outer-shell ionization effect on the positions of Kα1,2,1,3, and K β2 X-ray lines for some 4d-transition metals (molybdenum and palladium) and 4f rare-earth elements (dysprosium and ytterbium). The ionization energy shifts have been evaluated using the multiconfiguration Dirac-Fock method, containing Breit interaction and quantum electrodynamic (QED) corrections. The presented results are important for obtaining the information about some parameters of plasma generated by different sources, especially by pulsed power machine and short-pulse lasers.

Mots clés

  • plasma diagnostic
  • outer-shell ionization
  • K X-ray lines
Accès libre

Calculation of edge ion temperature and poloidal rotation velocity from carbon III triplet measurements on the COMPASS tokamak

Publié en ligne: 26 Oct 2016
Pages: 443 - 451

Résumé

Abstract

A high-resolution spectroscopic system for the measurements of the CIII triplet at 465 nm was installed at the COMPASS tokamak. The Doppler broadening and shift of the measured spectral lines are used to calculate the edge ion temperature and poloidal plasma rotation. At first, the spectroscopic system based on two-grating spectrometer and the calibration procedure is described. The signal processing including detection and removal of spiky features in the signal caused by hard X-rays based on the difference in the behaviour of Savitzky-Golay and median filters is explained. The detection and position estimation of individual spectral lines based on the continuous wavelet transform is shown. The method of fitting of Gaussians using the orthogonal distance regression and estimation of the error of estimation of the rotation velocity and ion temperature is described. At the end, conclusions about the performance of the spectroscopic system and its shortcomings based on summary of results calculated from 2033 processed spectral lines measured in 61 shots are drawn and the possible enhancements are suggested.

Mots clés

  • high-resolution spectroscopy
  • spectra processing
  • peak detection
  • line detection
  • line fitting
  • poloidal plasma rotation
  • ion temperature

Regular Paper

Accès libre

Modelling of thermal hydraulics in a KAROLINA calorimeter for its calibration methodology validation

Publié en ligne: 26 Oct 2016
Pages: 453 - 460

Résumé

Abstract

Results of numerical calculations of heat exchange in a nuclear heating detector for nuclear reactors are presented in this paper. The gamma radiation is generated in nuclear reactor during fission and radiative capture reactions as well as radioactive decay of its products. A single-cell calorimeter has been designed for application in the MARIA research reactor in the National Centre for Nuclear Research (NCBJ) in Świerk near Warsaw, Poland, and can also be used in the Jules Horowitz Reactor (JHR), which is under construction in the research centre in Cadarache, France. It consists of a cylindrical sample, which is surrounded by a gas layer, contained in a cylindrical housing. Additional calculations had to be performed before its insertion into the reactor. Within this analysis, modern computational fluid dynamics (CFD) methods have been used for assessing important parameters, for example, mean surface temperature, mean volume temperature, and maximum sample (calorimeter core) temperature. Results of an experiment performed at a dedicated out-of-pile calibration bench and results of numerical modelling validation are also included in this paper.

Mots clés

  • computional fluid dynamics (CFD)
  • differential calorimeter
  • gamma heating
  • gamma rays
  • Jules Horowitz Reactor (JHR)
  • modelling of thermal hydraulics
  • nuclear heating
  • nuclear reactor
  • research reactor MARIA
Accès libre

Study on radiation-induced radicals giving rise to stable EPR signal suitable for the detection of irradiation in L-sorbose-containing fruits

Publié en ligne: 26 Oct 2016
Pages: 461 - 465

Résumé

Abstract

The stable and complex EPR signals produced by the action of ionizing radiation on crystalline L-sorbose (C6H12O6) separated from rowan berries (Sorbus aucuparia) were studied. Isothermal heating of the samples at the temperature close to the melting point of L-sorbose (140°C) results in the modification and simplification of the EPR signal involved. In the EPR signal of heated L-sorbose, the isotropic quartet was distinguished. In the differential spectrum obtained by subtraction of normalized spectra of unheated and heated L-sorbose, the isotropic doublet was identified in addition. The DFT fitting offers the probable assignment of the EPR signals to specific radical structures.

Mots clés

  • sorbose
  • crystallite
  • electron paramagnetic resonance (EPR)
  • irradiation
Accès libre

Influence of natural radium contamination of barium chloride on the determination of radium isotopes in the water samples using α/β liquid scintillation spectrometry

Publié en ligne: 26 Oct 2016
Pages: 467 - 471

Résumé

Abstract

The determination of radium isotopes in drinking water by liquid scintillation technique requires some reagents that are used for separating radium from water samples. One of the main reagents is BaCl2·H2O. This paper presents the study of this compound and shows that barium chloride reagent is naturally contaminated with226Ra. The 226Ra activity concentration in BaCl2·H2O reagent produced by chemical companies from Poland and other countries is equal to a few dozen Bq/kg. Furthermore, 14 mL of 0.10 M BaCl2·H2O solution is the optimum amount which should be used for the chemical procedure. At the optimum amount of barium chloride and 2-hour measurement, the detection limit of 226Ra and 228Ra of the liquid scintillation counting method is equal to 5 and 30 mBq per sample, respectively.

Mots clés

  • α/β liquid scintillation spectrometry
  • barium chloride
  • radium isotopes
  • detection limit
Accès libre

Radiocatalytic degradation of dissolved organic compounds in wastewater

Publié en ligne: 26 Oct 2016
Pages: 473 - 476

Résumé

Abstract

Wastewater containing a high concentration of organic substances was exposed to gamma radiolysis in the presence and absence of a catalyst (TiO2); radiolysis and radiocatalysis were performed by means of continuous and discontinuous irradiation. Dissolved organic carbon (DOC) was the parameter used to estimate the concentration of organic compounds without interference by the high mineral content. The data was well fitted to the pseudo-first-order kinetic model of Langmuir-Hinshelwood. From a [DOC]0 = 140 ± 7 mg/L, the higher DOC degradation (74%) and apparent rate constant (Kapp = 0.083 h-1) were found using discontinuous radiocatalysis. This process could be an alternative method of treatment of industrial or municipal wastewater

Mots clés

  • wastewater
  • dissolved organic carbon
  • radiocatalysis
13 Articles

Proceedings of the Summer School of Plasma Diagnostics Phdiafusion 2015: “Soft X-Ray Diagnostics for Fusion Plasma” Bezmiechowa, Poland, 16-20 June 2015

Accès libre

Diagnostics of laser-produced plasmas

Publié en ligne: 26 Oct 2016
Pages: 393 - 401

Résumé

Abstract

We present the general challenges of plasma diagnostics for laser-produced plasmas and give a few more detailed examples: spherically bent crystals for X-ray imaging, velocity interferometers (VISAR) for shock studies, and proton radiography.

Mots clés

  • laser-produced plasmas
  • inertial-confinement fusion (ICF)
  • X-ray imaging
  • VISAR
Accès libre

Optimization of soft X-ray tomography on the COMPASS tokamak

Publié en ligne: 26 Oct 2016
Pages: 403 - 408

Résumé

Abstract

The COMPASS tokamak is equipped with the soft X-ray (SXR) diagnostic system based on silicon photodiode arrays shielded by a thin beryllium foil. The diagnostic is composed of two pinhole cameras having 35 channels each and one vertical pinhole camera with 20 channels, which was installed recently to improve tomographic inversions. Lines of sight of the SXR detectors cover almost complete poloidal cross section of the COMPASS vessel with a spatial resolution of 1-2 cm and temporal resolution of about 3 μs. Local emissivity is reconstructed via Tikhonov regularization constrained by minimum Fisher information that provides reliable and robust solution despite limited number of projections and ill-conditionality of this task. Improved border conditions and numerical differentiation matrices suppressing artifacts in reconstructed radiation were implemented in the code. Furthermore, a fast algorithm eliminating iterative processes was developed, and it is foreseen to be tested in real-time plasma control.

Mots clés

  • soft X-ray
  • tomography
  • Tikhonov regularization
  • tokamak
Accès libre

Comparison of silicon drift detectors made by Amptek and PNDetectors in application to the PHA system for W7-X

Publié en ligne: 26 Oct 2016
Pages: 409 - 412

Résumé

Abstract

The paper presents comparison of two silicon drift detectors (SDD), one made by Amptek, USA, and the second one by PNDetector, Germany, which are considered for a soft X-ray diagnostic system for W7-X. The sensitive area of the first one is 7 mm2 × 450 μm and the second one is 10 mm2 × 450 μm. The first detector is cooled by a double-stage Peltier element, while the second detector is cooled by single-stage Peltier element. Each one is equipped with a field-effect transistor (FET). In the detector from Amptek, the FET is mounted separately, while in the detector from PNDetector, the FET is integrated on the chip. The nominal energy resolution given by the producers of the first and the second one is 136 eV@5.9 keV (at -50°C) and 132 eV@5.9 keV (at -20°C), respectively. Owing to many advantages, the investigated detectors are good candidates for soft X-ray measurements in magnetic confinement devices. They are suitable for soft X-ray diagnostics, like the pulse height analysis (PHA) system for the stellarator Wendelstein 7-X, which has been developed and manufactured at the Institute of Plasma Physics and Laser Microfusion (IPPLM), Warsaw, in collaboration with the Max Planck Institute for Plasma Physics (IPP), Greifswald. The diagnostic is important for the measurements of plasma electron temperature, impurities content, and possible suprathermal tails in the spectra. In order to choose the best type of detector, analysis of technical parameters and laboratory tests were done. Detailed studies show that the most suitable detector for the PHA diagnostics is the PNDetector.

Mots clés

  • plasma diagnostic
  • pulse height analysis
  • solid-state detectors
Accès libre

Diagnostic systems for the nuclear fusion and plasma research in the PF-24 plasma focus laboratory at the IFJ PAN

Publié en ligne: 26 Oct 2016
Pages: 413 - 418

Résumé

Abstract

This paper presents a set of diagnostics dedicated to PF-24 - new medium size - plasma focus (PF) device built and operated at the Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN). The PF-24 can operate at energy level up to 93 kJ and charging voltage up to 40 kV. Each condenser is connected with a specially designed spark gap with a very small jitter, which ensures a high effi ciency and a low current rise time. The working parameters of PF-24 generator make it a suitable tool for testing new detection systems to be used in fusion research. Four types of such detection systems are presented in this article: three diagnostic systems used to measure electric quantities (Rogowski coil, magnetic probe, capacitance probe), neutron counter based on beryllium activation, fast neutron pinhole camera based on small-area BCF-12 plastic scintillation detectors and high-speed four-frame soft X-ray camera with microchannel plate.

Mots clés

  • diagnostics for DD fusion products
  • fast neutron sources
  • plasma diagnostics
  • plasma focus
  • plasma imaging
Accès libre

Energy composition of high-energy neutral beams on the COMPASS tokamak

Publié en ligne: 26 Oct 2016
Pages: 419 - 423

Résumé

Abstract

The COMPASS tokamak is equipped with two identical neutral beam injectors (NBI) for additional plasma heating. They provide a beam of deuterium atoms with a power of up to ~(2 × 300) kW. We show that the neutral beam is not monoenergetic but contains several energy components. An accurate knowledge of the neutral beam power in each individual energy component is essential for a detailed description of the beam- -plasma interaction and better understanding of the NBI heating processes in the COMPASS tokamak. This paper describes the determination of individual energy components in the neutral beam from intensities of the Doppler-shifted Dα lines, which are measured by a high-resolution spectrometer viewing the neutral beam-line at the exit of NBI. Furthermore, the divergence of beamlets escaping single aperture of the last accelerating grid is deduced from the width of the Doppler-shifted lines. Recently, one of the NBI systems was modified by the removal of the Faraday copper shield from the ion source. The comparison of the beam composition and the beamlet divergence before and after this modification is also presented.

Mots clés

  • tokamak
  • neutral beam injection (NBI)
  • Doppler effect
  • beam composition
  • beamlet divergence
Accès libre

Nuclear fusion and its large potential for the future world energy supply

Publié en ligne: 26 Oct 2016
Pages: 425 - 432

Résumé

Abstract

An overview of the energy problem in the world is presented. The colossal task of ‘decarbonizing’ the current energy system, with ~85% of the primary energy produced from fossil sources is discussed. There are at the moment only two options that can contribute to a solution: renewable energy (sun, wind, hydro, etc.) or nuclear fission. Their contributions, ~2% for sun and wind, ~6% for hydro and ~5% for fission, will need to be enormously increased in a relatively short time, to meet the targets set by policy makers. The possible role and large potential for fusion to contribute to a solution in the future as a safe, nearly inexhaustible and environmentally compatible energy source is discussed. The principles of magnetic and inertial confinement are outlined, and the two main options for magnetic confinement, tokamak and stellarator, are explained. The status of magnetic fusion is summarized and the next steps in fusion research, ITER and DEMO, briefly presented.

Mots clés

  • energy
  • nuclear fusion
  • tokamak
  • stellarator
Accès libre

Modelling of the soft X-ray tungsten spectra expected to be registered by GEM detection system for WEST

Publié en ligne: 26 Oct 2016
Pages: 433 - 436

Résumé

Abstract

In the future International Thermonuclear Experimental Reactor (ITER), the interaction between the plasma and the tungsten chosen as the plasma-facing wall material imposes that the hot central plasma loses energy by X-ray emission from tungsten ions. On the other hand, the registered X-ray spectra provide alternative diagnostics of the plasma itself. Highly ionized tungsten emits extremely complex X-ray spectra that can be understood only after exhaustive theoretical studies. The detailed analyses will be useful for proper interpretation of soft X-ray plasma radiation expected to be registered on ITER-like machines, that is, Tungsten (W) Environment in Steady-state Tokamak (WEST). The simulations of the soft X-ray spectra structures for tungsten ions have been performed using the flexible atomic code (FAC) package within the framework of collisional-radiative (CR) model approach for electron temperatures and densities relevant to WEST tokamak.

Mots clés

  • X-ray spectra
  • tokamak
  • tungsten L
  • M
  • N
  • X-ray lines
  • GEM detection system
Accès libre

Diagnostics of the plasma parameters based on the K X-ray line positions for various 4d and 4f metals

Publié en ligne: 26 Oct 2016
Pages: 437 - 441

Résumé

Abstract

This paper shows the theoretical predictions of the outer-shell ionization effect on the positions of Kα1,2,1,3, and K β2 X-ray lines for some 4d-transition metals (molybdenum and palladium) and 4f rare-earth elements (dysprosium and ytterbium). The ionization energy shifts have been evaluated using the multiconfiguration Dirac-Fock method, containing Breit interaction and quantum electrodynamic (QED) corrections. The presented results are important for obtaining the information about some parameters of plasma generated by different sources, especially by pulsed power machine and short-pulse lasers.

Mots clés

  • plasma diagnostic
  • outer-shell ionization
  • K X-ray lines
Accès libre

Calculation of edge ion temperature and poloidal rotation velocity from carbon III triplet measurements on the COMPASS tokamak

Publié en ligne: 26 Oct 2016
Pages: 443 - 451

Résumé

Abstract

A high-resolution spectroscopic system for the measurements of the CIII triplet at 465 nm was installed at the COMPASS tokamak. The Doppler broadening and shift of the measured spectral lines are used to calculate the edge ion temperature and poloidal plasma rotation. At first, the spectroscopic system based on two-grating spectrometer and the calibration procedure is described. The signal processing including detection and removal of spiky features in the signal caused by hard X-rays based on the difference in the behaviour of Savitzky-Golay and median filters is explained. The detection and position estimation of individual spectral lines based on the continuous wavelet transform is shown. The method of fitting of Gaussians using the orthogonal distance regression and estimation of the error of estimation of the rotation velocity and ion temperature is described. At the end, conclusions about the performance of the spectroscopic system and its shortcomings based on summary of results calculated from 2033 processed spectral lines measured in 61 shots are drawn and the possible enhancements are suggested.

Mots clés

  • high-resolution spectroscopy
  • spectra processing
  • peak detection
  • line detection
  • line fitting
  • poloidal plasma rotation
  • ion temperature

Regular Paper

Accès libre

Modelling of thermal hydraulics in a KAROLINA calorimeter for its calibration methodology validation

Publié en ligne: 26 Oct 2016
Pages: 453 - 460

Résumé

Abstract

Results of numerical calculations of heat exchange in a nuclear heating detector for nuclear reactors are presented in this paper. The gamma radiation is generated in nuclear reactor during fission and radiative capture reactions as well as radioactive decay of its products. A single-cell calorimeter has been designed for application in the MARIA research reactor in the National Centre for Nuclear Research (NCBJ) in Świerk near Warsaw, Poland, and can also be used in the Jules Horowitz Reactor (JHR), which is under construction in the research centre in Cadarache, France. It consists of a cylindrical sample, which is surrounded by a gas layer, contained in a cylindrical housing. Additional calculations had to be performed before its insertion into the reactor. Within this analysis, modern computational fluid dynamics (CFD) methods have been used for assessing important parameters, for example, mean surface temperature, mean volume temperature, and maximum sample (calorimeter core) temperature. Results of an experiment performed at a dedicated out-of-pile calibration bench and results of numerical modelling validation are also included in this paper.

Mots clés

  • computional fluid dynamics (CFD)
  • differential calorimeter
  • gamma heating
  • gamma rays
  • Jules Horowitz Reactor (JHR)
  • modelling of thermal hydraulics
  • nuclear heating
  • nuclear reactor
  • research reactor MARIA
Accès libre

Study on radiation-induced radicals giving rise to stable EPR signal suitable for the detection of irradiation in L-sorbose-containing fruits

Publié en ligne: 26 Oct 2016
Pages: 461 - 465

Résumé

Abstract

The stable and complex EPR signals produced by the action of ionizing radiation on crystalline L-sorbose (C6H12O6) separated from rowan berries (Sorbus aucuparia) were studied. Isothermal heating of the samples at the temperature close to the melting point of L-sorbose (140°C) results in the modification and simplification of the EPR signal involved. In the EPR signal of heated L-sorbose, the isotropic quartet was distinguished. In the differential spectrum obtained by subtraction of normalized spectra of unheated and heated L-sorbose, the isotropic doublet was identified in addition. The DFT fitting offers the probable assignment of the EPR signals to specific radical structures.

Mots clés

  • sorbose
  • crystallite
  • electron paramagnetic resonance (EPR)
  • irradiation
Accès libre

Influence of natural radium contamination of barium chloride on the determination of radium isotopes in the water samples using α/β liquid scintillation spectrometry

Publié en ligne: 26 Oct 2016
Pages: 467 - 471

Résumé

Abstract

The determination of radium isotopes in drinking water by liquid scintillation technique requires some reagents that are used for separating radium from water samples. One of the main reagents is BaCl2·H2O. This paper presents the study of this compound and shows that barium chloride reagent is naturally contaminated with226Ra. The 226Ra activity concentration in BaCl2·H2O reagent produced by chemical companies from Poland and other countries is equal to a few dozen Bq/kg. Furthermore, 14 mL of 0.10 M BaCl2·H2O solution is the optimum amount which should be used for the chemical procedure. At the optimum amount of barium chloride and 2-hour measurement, the detection limit of 226Ra and 228Ra of the liquid scintillation counting method is equal to 5 and 30 mBq per sample, respectively.

Mots clés

  • α/β liquid scintillation spectrometry
  • barium chloride
  • radium isotopes
  • detection limit
Accès libre

Radiocatalytic degradation of dissolved organic compounds in wastewater

Publié en ligne: 26 Oct 2016
Pages: 473 - 476

Résumé

Abstract

Wastewater containing a high concentration of organic substances was exposed to gamma radiolysis in the presence and absence of a catalyst (TiO2); radiolysis and radiocatalysis were performed by means of continuous and discontinuous irradiation. Dissolved organic carbon (DOC) was the parameter used to estimate the concentration of organic compounds without interference by the high mineral content. The data was well fitted to the pseudo-first-order kinetic model of Langmuir-Hinshelwood. From a [DOC]0 = 140 ± 7 mg/L, the higher DOC degradation (74%) and apparent rate constant (Kapp = 0.083 h-1) were found using discontinuous radiocatalysis. This process could be an alternative method of treatment of industrial or municipal wastewater

Mots clés

  • wastewater
  • dissolved organic carbon
  • radiocatalysis

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