Publications associées à Uranium 234

The isotopic signature of U(V) during bacterial reduction

Marinella Mazzanti, Rizlan Bernier-Latmani, Margaux Camille Andréa Molinas, Radmila Faizova, Ashley Richards Brown

The two-step electron transfer during bacterial reduction of UVI to UIV is typically accompanied by mass-independent fractionation of the 238U and 235U isotopes, whereby the heavy isotope accumulates in the reduced product. However, the role of the UV inte ...

2024

Analysis of the preliminary campaign for the PETALE program

Andreas Pautz, Vincent Pierre Lamirand, Thomas Jean-François Ligonnet, Axel Guy Marie Laureau

The PETALE program aims to provide new experimental data to constrain the stainless steel nuclear data. In this frame, a preliminary measurement campaign has been performed to characterize the neutron flux in key positions of the CROCUS reactor and to deve ...

EDP SCIENCES S A2023

Implementing Multi-Electron Transfer Strategies in Uranium Chemistry

Dieuwertje Katelijn Modder

In the last decades, the activation of small molecules has attracted increasing attention for their use as cheap and abundant feedstock. Low-oxidation state uranium complexes have displayed high reactivity towards small molecules thanks to their unique pro ...

EPFL2023

Data-Driven Predictive Models: Calculational Bias in Characterization of Spent Nuclear Fuel

Characteristics of the spent nuclear fuel (SNF) are typically calculated, requiring validation a priori. The validation process relies on the difference between calculations and measurements, namely the bias. Usually, predicting the bias based on benchmark ...

EPFL2022

Multi-electron Transfer by U(II) and Masked U(II) Complexes

Marinella Mazzanti

Complexes of uranium in low oxidation state have shown the ability to activate non-reactive small molecules such as N-2. However, the multi-electron transfer required for such activation remains limited in uranium chemistry. Here, we review our recent rese ...

SWISS CHEMICAL SOC2022

Dynamical Control of Nuclear Isomer Depletion via Electron Vortex Beams

Fabrizio Carbone, Simone Gargiulo

Some nuclear isomers are known to store a large amount of energy over long periods of time, with a very high energy-to-mass ratio. Here, we describe a protocol to achieve the external control of the isomeric nuclear decay by using electron vortex beams who ...

AMER PHYSICAL SOC2022

Nanoscale mechanism of UO2 formation through uranium reduction by magnetite

Rizlan Bernier-Latmani, Barbora Bártová, Thomas La Grange, Zezhen Pan

Uranium (U) is a ubiquitous element in the Earth's crust at similar to 2 ppm. In anoxic environments, soluble hexavalent uranium (U(VI)) is reduced and immobilized. The underlying reduction mechanism is unknown but likely of critical importance to explain ...

Nature Research2020

Non-crystalline tetravalent uranium species in the subsurface: formation and stability

Luca Loreggian

Uranium (U) contamination of ground and surface waters poses an acute hazard on the ecosystem and human health. Since the discovery of microbial U(VI) reduction, U bioremediation has been explored as a promising and cost-effective method compared to tradit ...

EPFL2019

Ferrocene-Based Tetradentate Schiff Bases as Supporting Ligands in Uranium Chemistry

Marinella Mazzanti, Lucile Sylvie Danielle Chatelain

Uranyl(VI), uranyl(V), and uranium(IV) complexes supported by ferrocene-based tetradentate Schiff-base ligands were synthesized, and their solid-state and solution structures were determined. The redox properties of all complexes were investigated by cycli ...

American Chemical Society2015

Neutronics Experiments and Analysis Related to Strong Moderation Heterogeneity in LWRs

Dominik Rätz

The Supercritical-Water-Cooled Reactor (SCWR) is the Generation IV reactor concept most closely related to current light water reactors (LWRs). The SCWR builds on the vast experience with today's LWRs and supercritical coal-fired power plants. Water at sup ...

EPFL2012

Analysis of Advanced Sodium-cooled Fast Reactor Core Designs with Improved Safety Characteristics

Kaichao Sun

In order to meet the steadily increasing worldwide energy demand, nuclear power is expected to continue playing a key role in electricity production. Currently, the large majority of nuclear power plants are operated with thermal-neutron spectra and need r ...

EPFL2012

Experimental validation of reaction rate distributions for a SVEA-96+ BWR assembly with hafnium control blades

Rakesh Chawla, Fabian Jatuff, Michaël Plaschy, Flavio Dante Giust

The accurate estimation of reactor physics parameters related to the presence of cruciform absorber blades in boiling water reactors (BWRs) is important for safety assessment and for achieving flexible operation during the cycle. Characteristics that are a ...

Atomic Energy Society of Japan2009

Comparison of 3D reaction rate distributions measured in an optima2 BWR assembly with MCNPX predictions

Rakesh Chawla, Fabian Jatuff, Michaël Plaschy

As part of a joint research programme between the Paul Scherrer Institute (PSI) and swissnuclear, with the co-operation of the Leibstadt nuclear power plant in Switzerland and fuel suppliers Westinghouse Sweden, measurements and calculations have been made ...

Elsevier Science Ltd.2008

Characterisation of radial reaction rate distributions across the 92-pin section of a SVEA-96 Optima2 assembly

Rakesh Chawla, Fabian Jatuff, Michaël Plaschy

Characterisation of the SVEA-96 Optima2 boiling water reactor assembly, in terms of the radial distributions of normalised total fission and 238U capture rates, is reported at its central elevation, i.e. at the 92-pin section, where the one-third part-leng ...

Elsevier Science Ltd.2008

Management of actinide waste inventories in nuclear phase-out scenarios

Rakesh Chawla, Marco Cometto

The improvement of the "radiological cleanliness" of nuclear energy is a primary goal in the development of advanced reactors and fuel cycles. The multiple recycling of actinides in advanced nuclear systems with fast neutron spectra represents a key option ...

Elsevier Ltd2008

Modeling U(VI) biomineralization in single- and dual- porosity porous media

David Andrew Barry

Uranium extraction, processing and storage have resulted in a legacy of uranium-contaminated groundwater aquifers worldwide. An emerging remediation technology for such sites is the in situ immobilization of uranium via biostimulation of dissimilatory meta ...

American Geophysical Union2008

Radial and azimuthal 235U fission and 238U capture distributions in BWR UO2 pins: CASMO-4 and MCNP4C versus activation foil measurements

Rakesh Chawla, Fabian Jatuff, Michaël Plaschy

In the context of the LWR-PROTEUS program, radial and azimuthal 235U fission (F5) and 238U capture (C8) rate distributions have been calculated for zero-burnup pins of a Westinghouse SVEA-96 Optima2 boiling water reactor fuel assembly using the stochastic ...

ANS2007

Characterisation of high-burnup LWR fuel rods through gamma tomography

Stefano Caruso

Current fuel management strategies for light water reactors (LWRs), in countries with high back-end costs, progressively extend the discharge burnup at the expense of increasing the 235U enrichment of the fresh UO2 fuel loaded. In this perspective, standar ...

EPFL2007

Comparisons of deterministic neutronic calculations with Monte Carlo results for an advanced BWR fuel assembly with hafnium control blades

Rakesh Chawla, Filippo Tani, Fabian Jatuff, Michaël Plaschy, Flavio Dante Giust

From the neutronic viewpoint, the optimization of BWR core designs is strongly related to the accurate determination of flux variations inside and around fuel assemblies. These fluctuations, which are mainly due to the high heterogeneity of the fuel and mo ...

Atomic Energy Society of Japan2006

Optimised non-invasive method to determine 238U-captures-to-total-fissions in reactor fuel

Rakesh Chawla, Fabian Jatuff

High-resolution gamma spectroscopy was performed on individual fuel rods of a fresh, highly heterogeneous Boiling Water Reactor (BWR) fuel assembly, after irradiation at low power in the PROTEUS reactor at PSI, to determine the ratio of neutron captures in ...

Elsevier2006