Search results for "Pluton"
showing 10 items of 80 documents
Resonant laser–SNMS for spatially resolved and element selective ultra-trace analysis of radionuclides
2018
The newly developed resonant laser–SNMS system at the IRS Hannover combines the high spatial and decent mass resolution of a TOF-SIMS instrument with the element-selective process of resonant laser ionization. This setup was characterized by use of synthetic uranium, plutonium and technetium samples to prepare and demonstrate the performance for measurements on environmental samples. The laser–SNMS system will be applied for the detection, visualization and ultra-trace analysis of radionuclide containing nanoparticles in environmental samples with strongly reduced or even completely omitted chemical preparation. The necessary suppression of isobaric contamination was demonstrated as well as…
Determination of the porosity, permeability and diffusivity of rock in the excavation-disturbed zone around full-scale deposition holes using the -PM…
1998
Abstract Three experimental holes the size of deposition holes in a KBS-3 type repository (depth 7.5 m and diameter 1.5 m) were bored in hard granitic rock in the Research Tunnel at Olkiluoto to study, among other things, the properties of the rock in the excavation-disturbed zone. In the analysis described in this report, the porosities, effective diffusivities and permeabilities of disturbed and intact rock were determined by using two novel methods: the 14 C -polymethylmethacrylate method and the He-gas method. In addition, the structure of the rock in the excavation-disturbed zone was assessed using both scanning electron and optical microscopy.
Contribution of recently measured nuclear data to reactor antineutrino energy spectra predictions
2013
This paper attempts to summarize the actual problematic of reactor antineutrino energy spectra in the frame of fundamental and applied neutrino physics. Nuclear physics is an important ingredient of reactor antineutrino experiments. These experiments are motivated by neutrino oscillations, i.e. the measure of the θ 13 mixing angle. In 2011, after a new computation of the reactor antineutrino energy spectra, based on the conversion of integral data of the beta spectra from 235 U, and 239;241 Pu, a deficit of reactor antineutrinos measured by short baseline experiments was pointed out. This is called the “reactor anomaly”, a new puzzle in the neutrino physics area. Since then, numerous new ex…
Efficiency of dihydroxamic and trihydroxamic siderochelates to extract uranium and plutonium from contaminated soils
2021
International audience; Actinide-based mineral phases occurring in contaminated soils can be solubilized by organic chelators excreted by plants, such as citrate. Herein, the efficiency of citrate towards U and Pu extraction is compared to that of siderophores, whose primary function is the acquisition of iron(III) as an essential nutrient and growth factor for many soil microorganisms. To that end, we selected desferrioxamine B (DFB) as an emblematic bacterial trishydroxamic siderophore and a synthetic analog, abbreviated (LCy,Pr)H2, of the tetradentate rhodotorulic acid (RA) produced by yeasts. Firstly, the uranyl speciation with both ligands was assessed in the pH range 2–11 by potentiom…
Resonance ionization mass spectroscopy for trace determination of plutonium in environmental samples
1997
Resonance ionization mass spectroscopy (RIMS) is a sensitive and isotope selective method and well suited for trace analysis of plutonium in the environment. After the chemical isolation of plutonium from soil, air filters or urine, e.g., it is electrolytically deposited as hydroxide on a tantalum backing and covered with a thin titanium layer. By heating such a sandwich filament in the RIMS-apparatus under vacuum an atomic beam of plutonium is produced. The atoms are ionized by a three-step resonant excitation using pulsed dye lasers, and the ions are mass-selectively detected with a time-of-flight (TOF) spectrometer and a multi channel plate detector. RIMS yields a low detection limit of …
Reworking of the Tarim Craton by underplating of mantle plume-derived magmas: Evidence from Neoproterozoic granitoids in the Kuluketage area, NW China
2011
Abstract Most Neoproterozoic granitoids in the Kuluketage area, northern Tarim Craton are characterized by strongly depleted HREE abundances and high Sr/Y and (La/Yb) N ratios, showing typical geochemical features of adakitic rocks. Zircon U–Pb dating of three adakitic plutons yielded Neoproterozoic ages (754 ± 4, 790 ± 3 and 798 ± 3 Ma). The adakitic granitoids exhibit low MgO and TiO 2 contents. Their low Cr, Co and Ni abundances, low ɛ Hf ( t ) values (−21 to −11) and high FeO T /MgO ratios (mostly 2.2–2.9) preclude the possibility of being derived from partial melts of delaminated lower crust. The relatively low ɛ Hf ( t ) values and old Hf two-stage model ages ( T DM 2 = 2 . 42 – 3 .0 …
Zvaigžņotā Debess: 2014/15, Ziema (226)
2014
Contents: “ZVAIGŽŅOTĀ DEBESS” FORTY YEARS AGO: J.Stradiņš. Vestige of Otto Schmidt in Latvia (abridged) ; Leonora Roze. All-Union Conference in Latvian State University (abridged) ; DEVELOPMENTS in SCIENCE: K.Schwartz. Gravitational Waves and Cosmic Inflation ; DISCOVERIES: A.Alksnis. Light Echoes from Supernova 2014J in Galaxy M82 ; A.Alksnis. Discovery of the Benešov Meteorites 20 Years after the Bolide Event ; I.Pundure. Giant Filament on the Sun Watched by NASA's SDO ; I.Pundure. MAVEN’s Mars Exploration Mission Started ; SPACE RESEARCH and EXPLORATION: R.Misa. Plasma Engines and Ad Astra Rocket Company ; LATVIAN SCIENTISTS: J.Freimanis. Reviewing My 60 Years of Life (concluded) ; KĀRLI…
TIVOLI, HADRIAN'S VILLA: THE PLUTONIUM PROJECT (COMUNE DI TIVOLI, PROVINCIA DI ROMA, REGIONE LAZIO)
2021
The Universities of Pavia and Oxford continued their investigations in Villa Adriana, in the area called Plutonium, traditionally interpreted as a reproduction of the Underworld, and located on one of the highest rises of the complex, in the east part of the Villa. The excavations took place from 1 to 21 July 2019. A team of 12 graduate students and postdoctoral researchers took part in the project, both from Oxford and Pavia Universities (S. Andronio, I. Bossolino, E. Casarotti, A. Dalgkitsi, E. Di Virgilio, V. Jukic Buca, A. Poldi Allai, G. Restaino, T. Runeckles, A. Verde). Dr Gilberto Montali, from the University of Palermo, supervised the architectural survey and documentation of the a…
Il progetto Plutonium di Villa Adriana: prime considerazioni a margine del nuovo rilievo e prospettive di ricerca
2020
Nel corso del 2016 e 2017 la missione congiunta delle università di Oxford e Pavia ha condotto una serie di campagne di ricognizione, rilevamento (georadar e geomagnetico) e rilievo architettonico nell'area nota dalla letteratura archeologica come pertinente al Plutonium e Inferi di Villa Adriana. Il complesso, situato nella sona nord-orientale della Villa, in corrispondenza di un rilievo naturale e ai margini della proprietà demaniale è costituito da tre elementi principali: 1) una grotta artificiale/ninfeo, collocata all'estremità di una valletta artificiale, interamente scavata nel tufo (gli Inferi); 2) un grosso edificio costruito su alte sostruzioni concamerate (il Plutonium); 3) una r…
Study of the oxidation mechanisms of Plutonium
2022
Oxidation is a key point when applied to a material such as plutonium. It is essential to understand the oxidation mechanisms in order to predict and prevent catastrophic oxidation, thus managing the reprocessing cost.The originality of this work lies in the coupling of different experimental techniques : in-situ X-ray diffraction, Photo-electron spectroscopy (XPS), FIB-SEM, Raman spectrometry and X-ray absorption (EXAFS) with numerical techniques : CALPHAD and Reverse Monte Carlo, in order to determine the oxidation mechanisms of the studied alloy : -phase stabilised PuGa 1 at%.Study of oxidation of this alloy at different temperatures and oxygen partial pressures showed the oxidation kin…