Interlaboratory comparison on 137Cs activity concentration in fume dust

Proceeding of the 9th International Topical Meeting on Industrial Radiation and Radioisotope Measurement Applications, 6-7 July 2014, Valencia, Spain.; International audience; A comparison was conducted, between 11 European National Metrology Institutes and EC-JRC, on measurement of Cs-137 activity concentration in fume dust. As test material an activity standard produced from real contaminated fume dust was used. The standard material consisted of 13 cylindrical samples of compressed fume dust. The material contained Cs-137 and Co-60 of reference activity concentrations of (9.72 +/- 0.10) Bq/g and (0.450 +/- 0.018) Bq/g, respectively, for the reference date of 1 June 2013, determined using the comparison results. The organization and results of the intercomparison, as well as the process of obtaining reliable reference values are presented

60Co in Cast Steel Matrix: a European Interlaboratory Comparison for the Characterisation of New Activity Standards for Calibration of Gamma-ray Spectrometers in Metallurgy

International audience; Two series of activity standards of Co-60 in cast steel matrix, developed for the calibration of gamma-ray spectrometry systems in the metallurgical sector, were characterised using a European interlaboratory comparison among twelve National Metrology Institutes and one international organisation. The first standard, consisting of 14 disc shaped samples, was cast from steel contaminated during production ("originally"), and the second, consisting of 15 similar discs, from artificially-contaminated ("spiked") steel. The reference activity concentrations of Co-60 in the cast steel standards were (1.077 +/- 0.019) Bq g(-1) on 1 January 2013 12h00 UT and (1.483 +/- 0.022) Bq g(-1) on 1 June 2013 12h00 UT, respectively

Improvement of a low-level mesurement system used at LNHB

Proceedings of the 20th International Conference on Radionuclide Metrology and its Applications (ICRM), 8-11 June 2015, Vienna, Austria. Organizer TU Wien. Editors Franz-Josef Maringer, Dirk Arnold, Uwe Wätjen.International audienceIn this new approach, the active shielding of a low level spectrometer is monitored by an extendable dead time used as an "extendable GATE" signal. This concept is directly inspired from the live-timed anti coincidence system implemented at LNE-LNHB (MTR2 modules). This allows a significant reduction in the cost and complexity of the system since several electronic modules are replaced by only one module dedicated specifically to this type of experiment. Settings of this new approach are detailed and results are discussed

Mise au point d’un dispositif de comptage compact équipé de SiPM pour l’analyse par scintillation liquide

National audienceDans le cadre de l’analyse en situation de crise, le Laboratoire de Mesure Nucléaire (LMN) de l’IRSN a étudie un compteur à scintillation liquide compact, basé sur une détection des photons par SiPM (photomultiplicateurs au silicium), permettant la mesure d’échantillons marqués en émetteurs alpha ou beta et préparés par scintillation liquide (frottis, eau, solides). Ce nouveau compteur innovant et développé par les ateliers Laumonier est équipé de 4 détecteurs SiPM répartis de part et d’autre d’une chambre de comptage compacte et étanche à la lumière. Chaque SiPM est constitué de 16 diodes SPAD (Single-photon avalanche diode), le dispositif est maillé par 128 diodes permettant de détecter individuellement les photons. Dans notre dispositif, ces détecteurs SiPM viennent remplacer les traditionnels photomultiplicateurs, habituellement rencontrés en scintillation liquide. L’interface du nouveau compteur, en cours de développement au LMN et codé en python, permet de compter les coïncidences doubles et ainsi discriminer le signal issu d’une désintégration alpha ou beta du bruit de fond, réduisant ainsi le rapport signal/bruit. La compacité du dispositif de comptage (hauteur et diamètre de 20cm) et sa mise en œuvre simplifiée (faible consommation électrique et connexion USB) font de cet équipement une solution qui devra être simple à mettre en œuvre en cas de crise, pour tous les utilisateurs. Enfin, l’utilisation des SPAD permet de cartographier l’échantillon et ainsi détecter une zone de contamination dans l’échantillon analysé

On scattering effects for volume sources in low-energy photon spectrometry

International audienceIn this study, different aspects of the Compton scattering inside volume sources are illustrated using experimental approach and Monte Carlo simulation. For the low-energy range (below 100 keV) scattered events represents around 30% of the whole spectrum. Influence of the source-detector geometry is discussed. The scattering effects induce strong differences in spectrum shape for different geometrical conditions. This should influence efficiency transfer factors. A new approach is proposed, including the scattered events, to avoid complex peak area determination

Validation of efficiency transfer for Marinelli geometries

International audienceIn the framework of environmental measurements by gamma-ray spectrometry, some laboratories need to characterize samples in geometries for which a calibration is not directly available. A possibility is to use an efficiency transfer code, e.g., ETNA. However, validation for large volume sources, such as Marinelli geometries, is needed. With this aim in mind, ETNA is compared, initially to a Monte Carlo simulation (PENELOPE) and subsequently to experimental data obtained with a high-purity germanium detector (HPGe)

Preparation of spiked grass for use as an environmental radioactivity reference material

Proceedings of the 19th International Conference on Radionuclide Metrology and its Applications 17–21 June 2013, Antwerp, BelgiumInternational audienceMeasurement of radionuclides from environmental samples includes a wide variety of matrix compositions and densities. To improve the traceability of environmental monitoring, LNE-LNHB intends to produce mixed γ-ray reference materials with a known mass activity and a composition as representative as possible of real environmental samples. This paper describes the preparation and characterization of a low density treated grass matrix spiked with mixed γ-emitters. This material was used in a proficiency test exercise whose results are presented

Characterization of a cosmic suppression spectrometer

International audienceIn this work, PENELOPE2008 and MCNP5 software packages were used to investigate the effect of simulation parameters such as cut-off energy of photons and electrons on the detector response function and peak escape intensity to assess their influence on the efficiency determination. The results showed a general agreement between the two codes, however both the intensity of escape peaks and total efficiency computed with PENELOPE2008 are higher than those obtained with MCNP5. Moreover, the calculated efficiencies are typically 8% higher than what is experimentally found in the low energy range. Further investigation was required to obtain better agreement and lead to better estimate of the real germanium crystal dimensions and dead layer

Primary standardization of SIR-Spheres based on the dissolution of the 90 Y-labeled resin microspheres

International audienceThe project "Metrology for molecular radiotherapy" is a collaborative European project initiated to bring together expertize in ionizing radiation metrology and nuclear medicine research. This project deals with the development of personalized dosimetry to individual patients who are undergoing molecular radiotherapy (also known as targeted radionuclide therapy). The general aim is to provide a metrological traceability to primary standards for individual dosimetry in the case of molecular radiotherapy. In particular, one objective is the standardization of Y-90-labeled resin microspheres SIR-Spheres (Sirtex, Sydney, Australia) used for the treatment of liver cancer by radioembolization. The present paper describes the primary measurements carried out using the Triple to Double Coincidence Ratio (TDCR) method applied after the complete dissolution of the SIR-Spheres in the Sirtex vial. A method for the dissolution was developed to optimize the homogeneity of the solution to enable the primary measurements based on Cherenkov and liquid scintillation counting. A comprehensive description of the protocol implemented for the microsphere dissolution is reported. First calibration factors obtained with the reference ionization chambers at LNE-LNHB are also given

Determination of environmental gaseous 129I trapped in charcoal cartridges by ICP-MS/MS

International audienceFor environmental monitoring and radioecological studies, organic and inorganic 129I is often trapped in active charcoal. The analysis of this radionuclide can be difficult because of the low-level activities involved and its physico-chemical properties (e.g., volatility and multiple oxidation degrees). This study proposes a new method for 129I analysis by ICP-MS/MS, which consists in the extraction of iodine from charcoal by acid digestion followed by purification using a commercial specific resin. This new method allows reaching environmental levels of gaseous 129I near the fuel reprocessing plant of La Hague (France) with a limit of detection of only 2 mBq sample-1