First escaping fast ion mesurements in ITER-like geometry using an activation probe

More research is needed to develop suitable diagnostics for measuring alpha particle confinement in ITER and techniques relevant for fusion reactor conditions need further development. Based on nuclear reactions, the activation probe is a novel concept first tested in JET. It may offer a more robust solution for performing alpha particle measurements in ITER. This paper describes the first escaping fast ion measurements performed at ASDEX Upgrade (AUG) tokamak using an activation probe. A detailed analysis, outside the scope of this contribution, will be published in a journal paper.JRC.D.4-Standards for Nuclear Safety, Security and Safeguard

Fission product activity ratios measured at trace level over France during the Fukushima accident

International audienceThe nuclear accident of Fukushima Dai-ichi (Japan) which occurred after the tsunami that impacted the northeast coasts of Japan on March 11th, 2011 led to significant releases of radionuclides into the atmosphere and resulted in the detection of those radionuclides at a global scale. In order to track airborne radionuclides from the damaged reactors and to survey their potential impact on the French territory, the French Institute of Radiation Protection and Nuclear Safety (Institut de Radioprotection et de Sureté Nucléaire IRSN) set up an enhanced surveillance system to give quick results as needed and later give quality trace level measurements. Radionuclides usually measured at trace levels such as 137Cs and in a very sporadic way 131I were reported. Radionuclides that we had never measured in air since the Chernobyl accident 134Cs, 136Cs, the mother/daughter pairs 129mTe-129Te and 132Te-132I, and 140La (from the mother-daughter pair 140Ba- 140La) were also reported. Except the 131I/137Cs ratio, activity concentration ratios were constant. These ratios could be used to help source term assessment, or as data for transfer studies realized after the passage of contaminated air masses, typically using the 134Cs/137Cs ratio. © 2013 Elsevier Ltd

Leda: A gamma-gamma coincidence spectrometer for the measurement of environment samples

This paper presents a new gamma-gamma coincidence spectrometer to measure the radioactivity in environmental samples. This system, called Leda, is made of 2 HPGe and 1 NaI(Tl). The different analysis channels (single, in coincidence or in anti-coincidence) possible thanks to the digital electronics are described. Results obtained with environmental samples are shown. Despite its low efficiency, this method improves the detection limits for all emitters due to its very low background, and thus decreases the counting time

Low level measurement of 60^{60}Co by gamma ray spectrometry using γ–γ coincidence

International audienceThis paper presents the latest development of the laboratory to measure the natural and artificial massic activities in environmental samples. The measurement method of coincident emitters by gamma–gamma coincidence using an anti-Compton device and its digital electronics is described. Results obtained with environmental samples are shown. Despite its low efficiency, this method decreases detection limits of 60Co for certain samples compared to conventional gamma-ray spectrometry due to its very low background

Characterisation of naturally occurring radionuclides in the lower Rhone River (France): Preliminary results from suspended solid monitoring

Long term time series acquired in the frame of radioecological monitoring programmes are useful tools for exploring the variability of naturally occurring radionuclide contents. The data set was established in order to investigate the role of discharge, flood type and flood chronicles on such variability within the suspended sediments. Preliminary results show that radionuclide geochemical properties as well as suspended sediment nature and particle residence time may in some particular cases significantly affect the U-Th series nuclide equilibrium. © 2013 WIT Press

Environmental consequences of uranium atmospheric releases from fuel cycle facility II. The atmospheric deposition of uranium and thorium on plants

International audienceUranium and thorium isotopes were measured in cypress leaves, wheat grains and lettuce taken in the surroundings of the uranium conversion facility of Malvési (South of France). The comparison of activity levels and activity ratios (namely 238U/232Th and 230Th/232Th) in plants with those in aerosols taken at this site and plants taken far from it shows that aerosols emitted by the nuclear site (uranium releases in the atmosphere by stacks and 230Th-rich particles emitted from artificial ponds collecting radioactive waste mud) accounts for the high activities recorded in the plant samples close to the site. The atmospheric deposition process onto the plants appears to be the dominant process in plant contamination. Dry deposition velocities of airborne uranium and thorium were measured as 4.6×10-3 and 5.0×10-3ms-1, respectively. © 2014 Elsevier Ltd

Spectral unmixing applied to fast identification of γ-emitting radionuclides using NaI(Tl) detectors

International audienceSpectral unmixing was investigated for fast spectroscopic identification in γ-emitter mixtures at low-statistics in the case of measurements performed to prevent illegal nuclear material trafficking or for in situ environmental analysis following a radiological or nuclear accident. For that purpose, a multiplicative update algorithm based on full-spectrum analysis was tested in the case of a 3″x3″ NaI(Tl) detector. Automatic decision-making was addressed using Monte Carlo calculations of decision thresholds and detection limits. The first results obtained with a portable instrument equipped with a 3″x3″ NaI(Tl) detector designed for the control of food samples by non-expert users following a radiological or nuclear accident, are also presented

Actinides and decay products in selected produce and bioindicators in the vicinity of a uranium plant

Cypress needles collected at the edge of the Malvési uranium facility (SW France) exhibit enhanced activities of actinides and some decay products (uranium, americium, plutonium, 230Th, 226Ra) compared to a remote site. These enhanced activities resulted from the release of U via smokestacks and passive release from former artificial ponds located inside the nuclear site. Enhanced activities are also observed in selected produce (wheat, lettuce, fruits) sampled from the edge of the site. However, excess actinides measured in wheat grains in 2007 are inconsistent with the activities and the uranium ratio measured in the soils. This result suggests that the studied annual crops were contaminated mainly through the short-term release of airborne actinides, and that other transfer pathways, such as, uptake through the roots or adhesion of soil particles, were negligible. © 2011 The Royal Society of Chemistry