Publications associées à Découverte de la fission nucléaire

Nuclear Excitation by Free Muon Capture

Fabrizio Carbone, Ivan Madan, Simone Gargiulo

Efficient excitation of nuclei via exchange of a real or virtual photon has a fundamental importance for nuclear science and technology development. Here, we present a mechanism of nuclear excitation based on the capture of a free muon into the atomic orbi ...

AMER PHYSICAL SOC2022

Interface Tracking Investigation of the Sliding Bubbles Effects on Heat Transfer in the Laminar Regime

Konstantin Mikityuk, Lubomír Bures

Helium gases are utilized to remove fission products from the molten salt fast reactor (MSFR) core during operation. Helium gases and other volatile fission products may be introduced into the intermediate heat exchanger channels. The effect of these gases ...

2022

Towards the Validation of Noise Experiments in the CROCUS Reactor Using the TRIPOLI-4 Monte Carlo Code in Analog Mode

Andreas Pautz, Vincent Pierre Lamirand, Oskari Ville Pakari

Intrinsic neutron noise experiments offer a non-invasive manner to measure the prompt decay constant or reactivity of fissile systems. Using the fluctuations in the density of fission chains, one can infer the kinetics parameters via correlation analysis s ...

2021

Artificial Neural Networks as Surrogate Models for Uncertainty Quantification and Data Assimilation in 2-D/3-D Fuel Performance Studies

Andreas Pautz, Mathieu Hursin, Carlo Fiorina, Alessandro Scolaro, Daniel Jerôme Siefman

This paper preliminarily investigates the use of data-driven surrogates for fuel performance codes. The objective is to develop fast-running models that can be used in the frame of uncertainty quantification and data assimilation studies. In particular, da ...

2020

Data assimilation of post irradiation examination experiments to adjust fission yields

Andreas Pautz, Daniel Jerôme Siefman, Mathieu Hursin

Nuclear data, especially fission yields, create uncertainties in the predicted concentrations of fission products in spent fuel. Herein, we present a new framework that extends data assimilation methods to burnup simulations by using data from post-irradia ...

E D P SCIENCES2020

Experimental and numerical study of stochastic branching noise in nuclear reactors

Oskari Ville Pakari

Noise analysis applied to nuclear reactor physics is a powerful tool to investigate a reactor's kinetic parameters, and more generally underlying physical processes determining core behavior. The kinetic parameters are the coefficients of simplified time-d ...

EPFL2020

In Situ Observation of Coulomb Fission of Individual Plasmonic Nanoparticles

Marcel Drabbels, Ulrich Lorenz, Pavel Olshin, Jonathan Mark Voss

Reshaping plasmonic nanoparticles with laser pulses has been extensively researched as a tool for tuning their properties. However, in the absence of direct observations of the processes involved, important mechanistic details have remained elusive. Here, ...

2019

Modelling of fuel fragmentation, relocation and dispersal during Loss-of-Coolant Accident in Light Water Reactor

Vladimir Vladimirov Brankov

Recent LOCA tests with high burnup fuel at the OECD Halden Reactor Project and at Studsvik demonstrated the susceptibility of the fuel to fragment to small pieces, to relocate and possibly cause a hot-spot effect and to be dispersed in the event of claddin ...

EPFL2017

Gamma-ray spectrometric measurements of fission rate ratios between fresh and burnt fuel following irradiation in a zero-power reactor

Rakesh Chawla

The gamma-ray activity from short-lived fission products has been measured in fresh and burnt UO2 fuel samples after irradiation in a zero-power reactor. For the first time, short-lived gamma-ray activity from fresh and burnt fuel has been compared and fre ...

Elsevier2013

Fission Rates Measured Using High-Energy Gamma-Rays from Short Half-Life Fission Products in Fresh and Spent Nuclear Fuel

Hanna Kröhnert

In recent years, higher discharge burn-ups and initial fuel enrichments have led to more and more heterogeneous core configurations in light water reactors (LWRs), especially at the beginning of cycle when fresh fuel assemblies are loaded next to highly bu ...

EPFL2011

Freshly induced short-lived gamma-ray activity as a measure of fission rates in lightly re-irradiated spent fuel

Rakesh Chawla, Hanna Kröhnert

A new measurement technique has been developed to determine fission rates in burnt fuel following re-irradiation in a zero-power research reactor The development has been made in the frame of the LIFE@PROTEUS program at the Paul Scherrer Institute which ai ...

2010

Impact of new gadolinium cross sections on reaction rate distributions in 10x10 BWR assemblies

Rakesh Chawla, Fabian Jatuff

Radial distributions of the total fission rate and the238U- capture-to-total-fission (C 8/F tot) ratio were measured in SVEA-96+ and SVEA-96 Optimal assemblies during the LWR-PROTEUS program. Fission rates predicted using MCNPX with JEFF-3.1 cross sections ...

American Nuclear Society2009

Modelling of fission gas behaviour in high burnup nuclear fuel

Paul Blair

The safe and economic operation of nuclear power plants (NPPs) requires that the behaviour and performance of the fuel can be calculated reliably over its expected lifetime. This requires highly developed codes that treat the nuclear fuel in a general mann ...

EPFL2008

Interpretation of high-burnup fuel annealing tests

Rakesh Chawla, Paul Blair

The growth of the porosity in high-burnup fuel is of particular interest when considering the effect of fission gas retention within the high-burnup structure (HBS). A mechanistic model of porosity growth under annealing conditions for light water reactor ...

Atomic Energy Society of Japan2008

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

Calculations on fission gas behaviour in the high burnup structure

Rakesh Chawla, Paul Blair

The behaviour of fission gas in high burnup fuel during steady-state and transient conditions is of special interest for safety reasons. Despite this, mechanistic models that reflect the fission gas transport processes and reliably predict the evolution of ...

Elsevier2006

Isobaric production cross sections from 0.6 GeV proton irradiation of neptunium and thorium using mass spectrometry

Rakesh Chawla

A high-fluence proton irradiation of neptunium was the last experiment in PSIs programme ATHENA related to accelerator-based transmutation. The principal aim of the programme has been to provide experimental data for the validation of theoretical models in ...

Elsevier2006

Importance of the MUSE experiments for emerging ADS concepts from the nuclear data viewpoint

Rakesh Chawla, Michaël Plaschy, Gérald Rimpault

The current investigation, conducted in the general framework of the MUSE program ("MUltiplication avec une Source Externe"), considers the representativity of a specific configuration of its fourth phase (M4SC2), which is driven by an external D(d,n)He3 o ...

Elsevier2005