From postmaster-at-dl.ac.uk Tue Feb 10 05:39:57 2009 Received: from mserv9.dl.ac.uk (mail.dl.ac.uk [148.79.80.67]) by physmail.rutgers.edu (8.13.8+Sun/8.13.8) with ESMTP id n1AAdpea013010 for ; Tue, 10 Feb 2009 05:39:57 -0500 (EST) X-DL-MFrom: X-DL-Connect: Received: from cselnx9 (cselnx9.dl.ac.uk [193.62.112.177]) by mserv9.dl.ac.uk (8.13.1/8.13.1) with ESMTP id n1AAOFcb020687; Tue, 10 Feb 2009 10:24:15 GMT Message-ID: <22479407.1234261304138.JavaMail.xyg-at-cselnx9> Date: Tue, 10 Feb 2009 10:21:44 +0000 (GMT) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [ PSI-K ] Post-doc position in CEA Saclay From: "PSI-K" To: "PSI-K" Content-Type: text/html X-Greylist: Sender IP whitelisted, not delayed by milter-greylist (mserv9.dl.ac.uk [148.79.80.67]); Tue, 10 Feb 2009 10:24:25 +0000 (GMT) X-CCLRC-SPAM-report: 0.19 : AWL,BAYES_00,HTML_00_10,HTML_MESSAGE,HTML_MIME_NO_HTML_TAG,MIME_HTML_ONLY X-Spam-Checked: Spamassassin version 3.1.8, by Rutgers Physics X-Spam-Score: -1.0, tests=AWL,BAYES_00,HTML_MESSAGE,HTML_MIME_NO_HTML_TAG,MIME_HTML_ONLY X-Scanned-By: MIMEDefang 2.64 on 128.6.228.213 Status: R X-Status: X-Keywords: An announcement has been added in the "PSI-K" site at PSI-K (http://cselnx9.dl.ac.uk:8080/portal)


Subject: Post-doc position in CEA Saclay

Category: Job

From: Jean-Paul Crocombette

Date: 10-Feb-2009 10:21

Message:


ab initio phase diagram of the (U-Pu-C) and (U-Pu-O) systems


Team
The position is opened for summer or fall 2009 in the Physical Metallurgy Laboratory of French Atomic Energy Commission, CEA/SRMP, in Saclay, 25 km south of Paris, France. 
The Post-doc will be part of a group of 15 theoretical researchers working on material science at the atomic scale with a focus on diffusion properties and behaviour under irradiation

Presentation of the subject

This post-doc funded by the European Seventh Research Framework Programme F-BRIDGE (Basic Research for Innovative Fuel Design for GEN IV systems) is part of a large experimental and numerical effort, using basic research, to provide a better understanding and description of the thermodynamic properties of advanced fuels for Generation IV nuclear reactors

Uranium carbides as well as uranium oxides are contemplated for these future nuclear fuels. Under operation uranium atoms will partly transform into plutonium atoms. In this context, the goal of this post-doc is to develop a thermodynamic description of the (U-Pu-C) and (U-Pu-O) systems based on a cluster expansion at the atomic scale obtained from ab initio electronic structure calculations.

Cluster expansion on a rigid lattice based on ab initio calculations have proven very powerful to describe the phase diagrams of alloys (i.e. relative stability of phases, solubility limits and order disorder transitions). They are also the basic ingredient of successful modelling of the kinetic evolution of the composition of these alloys through atomic diffusion and/or under ballistic mixing due to irradiation processes.
The carbide system (U-Pu-C) will be considered first. A cluster expansion describing in an approximate manner the energetics of any particular occupancies of the equilibrium atomic sites shall be obtained. To do so a database will be build from devoted ab initio electronic structure calculations that will give the energetics of real or fictitious atomic structures. From this database the cluster expansion will be obtained by a fitting procedure (using e.g. the ATAT code, http://www.its.caltech.edu/~avdw/atat/). This cluster expansion will then be used in equilibrium Monte-Carlo simulations or in Cluster Variation Method simulations to study the temperature-composition phase diagram. One thus will end up with an atomistic description of the phase diagram of the (U-Pu-C) systems. The oxygen system (U-Pu-O) will then be tackled applying the same methodology.

In a second step the cluster interaction models will be enriched to allow the description of the energies of atomic migrations as a function of the surroundings of the moving atom. Once again we shall begin with the U-Pu-C alloy. With this improved model one will be able to tackle the kinetic evolution of the local composition of the alloy under thermal and/or irradiation solicitations. This will be done by Atomic Kinetic Monte-Carlo simulations or in mean field simulations. We will be able therefore to obtain the evolution and steady states of the (U-Pu-C) system under thermal ageing or irradiation. Considering the U-Pu-O alloy will be more challenging and will involve methodological developments. Indeed, this system being insulating, charge effects which have no equivalent in the metallic systems may play a role in the kinetics.
Methodological work will be therefore needed to establish a satisfactory way to accommodate smoothly these effects.  The methodological development will be directly tested and applied on the U-Pu-O system.

Conditions
The initial contract, starting anytime in summer or fall 2009, will be for one year with an easy extension for one more year. The salary is approximately 2200 euros per months.
The administrative conditions are :
-PhD thesis prepared outside of a CEA laboratory ;
-Thesis defence less than two years old (if French nationality) ;
-Maximum one previous post-doc (outside CEA) or less than 6 months unemployment since thesis defense (if French nationality) ;
-Aged under thirty (if French nationality).

Applications
Please send CV, motivation letter and letters of recommendation or contact information for references to :

Jean-Paul Crocombette
CEA Saclay, Service de Recherches de Métallurgie Physique (SRMP)
91191 Gif/Yvette Cedex
jean-paul.crocombette-at-cea.fr
http://crocombette.free.fr/




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