Discovery and design of nuclear fuels

ISSN:1369 7021 © Elsevier Ltd 2009NOVEMBER 2009 | VOLUME 12 | NUMBER 1120

Discovery and design of nuclear fuels

Nuclear fuels are complex, multi-component materials containing

actinides such as Th, U, Np, Pu, Am, Cm and their compounds in

specific fuel forms (oxides, nitrides, carbides, alloys, composites,

etc). Adding to the complexity and creating time-varying

composition, the presence of fission products such as Xe, Cs,

Sr, He, I, and Tc makes understanding the evolving properties of

nuclear fuels a major challenge. For example, sintering of ceramic

fuels requires a strict control of composition, thermal treatment,

pressure, and atmosphere1-3. The large number of control

parameters and the uncertainty associated with them often leads

to intractable problems. Similar issues impact the casting and

stability of metallic fuel rods4,5. Once in the reactor, the fuels

and structural materials (pressure vessels, pipes, ducts, etc.) are

subjected to radiation environments that continuously alter their

To facilitate the discovery and design of innovative nuclear fuels, multi-scale models and simulations are used to predict irradiation effects on properties such as thermal conductivity, oxygen diffusivity, and thermal expansion. The multi-scale approach is illustrated using results on ceramic fuels, with a focus on predictions of point defect concentration, stoichiometry, and phase stability. The high performance computer simulations include coupled heat transport, diffusion, and thermal expansion, and gas bubble formation and evolution in a fuel element consisting of UO2 fuel and metallic cladding. The second part of the paper is dedicated to a discussion of an international strategy for developing advanced, innovative nuclear fuels. Four initiatives are proposed to accelerate the discovery and design of new materials: (a) Create Institutes for Materials Discovery and Design, (b) Create an International Knowledgebase for experimental data, models (mathematical expressions), and simulations (codes), (c) Improve education and (d) Set up international collaborations.

Marius Stan

Los Alamos National Laboratory, Los Alamos, NM 87545, USA.

Email: [email protected]

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mailto:[email protected]

Discovery and design of nuclear fuels REVIEW

NOVEMBER 2009 | VOLUME 12 | NUMBER 11 21

thermo-mechanical properties6-10. It is well documented11 that

fuels exhibit radial and angular cracks and the severity of the

structural damage increases with burnup. Root causes of these

phenomena are fission-product migration and accumulation in gas

bubbles12-14 that create porosity and significantly slow down the

transport of heat.

To create improved nuclear fuels for the next generation of reactors,

scientists and engineers are partnering in research and development

work that follows the steps of the scientific method. Modern materials,

including nuclear fuels, are often developed using a combination of

discovery and design (see Box 1), with a certain emphasis on discovery.

To facilitate the discovery and design of innovative nuclear fuels and

structural materials, models and simulations are used to predict

irradiation effects on properties such as formation of point defects and

clusters19-27, chemical species and fission-product migration28-31, gas

bubbles formation32, thermal conductivity33-35, oxygen diffusivity36,37,

dislocations38-41, thermal expansion42, and phase stability/

transformations43,44. One of the most challenging aspects is modeling

the complex electronic structure of materials in general45, and the

actinides (especially Pu) in particular46,47 as well as the stability of their

phases48. Another challenge is modeling high temperature effects such

as entropic contributions to the free energy of liquids49.

Conventional nuclear fuelsRecent applications of a multi-scale methodology (see Box 2) to oxide

nuclear fuels resulted in predictions of irradiation effects on properties

such as thermal conductivity, oxygen diffusivity, and thermal expansion.

The methods cover a large spectrum of time and space scales, from

electronic structure to atomistic, to meso-scale, to continuum55.

For example, atomistic models of point defect have been used

to develop continuum thermo-chemical models of point defect

concentrations and oxygen diffusivity in uranium oxides19 and

plutonium oxides56. Several models include the dependence of the

properties on the oxygen content. Building on thermochemical

studies57-59, the models are further used to predict fuel thermodynamic

properties such as the free energy, and to simulate oxygen diffusion at

various temperatures and oxygen pressures.

Another example, this time at the meso-scale, is related to phase-

field simulations of gas bubbles formation and evolution in the fuel60.

Box 1. Scientific discovery and design of materialsThe definitions below are only intended to clarify the use of various

concepts in this paper. For this purpose, science is defined as a rigorous,

systematic use of observations and logic to support or falsify possible

explanations of natural phenomena. This is not that different from

the Britain’s Science Council definition, discussed in15. The scientific

method of investigating natural phenomena (recently under serious and

loving scrutiny16) consists of a series of steps that involve experimental,

theoretical, and computational methods.

An experiment is a procedure undertaken to make a discovery, test

a hypothesis, or demonstrate a known fact. This concept is strongly

anchored in immediate reality although recently the concepts of

“computer experiment” and “virtual experiment” have gained some

popularity. A theory is a formal statement of ideas which are proposed

to explain a class of facts or events. Computation is a procedure used

to determine the solution of a mathematical problem by means of a

computer.

Although the scientific method is observed, to various degrees, by

the entire materials science community, there are notable differences

in the scope and methodology, depending on the goal of the research,

the resources, and the scientific or engineering targets. Materials

discovery (see17 as an example) involves exploring and identifying

existing materials with desirable properties and functionality. The

emphasis is on conducting sound research in areas that are likely to lead

to materials with outstanding properties. As with any other discovery

enterprise, being capable and ready to identify the value of specific

results is the key.

Materials design (see18 as an example) aims at creating new materials

with predefined properties and functionality. After defining the properties

of interest, the focus is on optimizing specific parameters of existing

materials or creating completely new materials that exhibit the sought

after properties. The design methodology (Fig. 1) is quite cumbersome

and involves a series of steps and iterations that may or may not

converge toward a set of optimal parameters.

Fig. 1 The materials design methodology involves a series of steps, iterations, and periodic feedback between theory, experiment, and computation.

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REVIEW Discovery and design of nuclear fuels

NOVEMBER 2009 | VOLUME 12 | NUMBER 1122

Fig. 3 shows a comparison of experimental61 and simulation62 results.

The simulations capture well the nucleation, growth, and coalescence

of gas bubbles in the fuel grains and at the grain boundaries. The

simulations also predict the thermal conductivity dependence on the

porosity associated with the gas bubbles and the impact on the heat

release.

Similar results have been reported on PuO2 fuels56,63,64. Although

not as extensive, the work on other ceramic fuels such as nitrides65,66

or carbides (with application to coated particle fuels67,68), as well as

studies of surrogate materials based on cerium69 or dysprosium66 are

most encouraging.

Fuel performance (see Box 3) is another area that has benefited

from advanced models and simulations70. Understanding complex

phenomena in fuel elements provides important input to reactor

simulations, currently based on homogenization techniques77. Recent

studies have examined in more detail the thermochemistry of the

Box 2. Multi-scale models and simulationsThis section builds upon a recent discussion of modern epistemic

concepts42. A model is a logical description of how a system (material,

in our case) performs. Models can be empirical or theory-based.

Empirical models are collections of experimental observations fitted to

mathematical expressions, such as (but not only) polynomial functions.

When accurate, empirical models are highly valuable for technological

applications. Theory-based models are built upon fundamental principles

developed within or across scientific disciplines (physics, chemistry, etc).

The multi-science models avoid trial-and-error exercises and aim at

providing a deeper understanding of material’s (fuel’s) behavior. Theory-

based models are expected to have better predictive character.

A simulation is the process of conducting experiments or running

computer programs to reproduce, in a simplified way, the behavior of a

system (nuclear fuel, in our case). Simulations describe the evolution of

the system along a certain coordinate, most often the time (correlated

with the burnup level for the case of nuclear fuels).

Both the models and the simulations must be subject to verification

and validation50. Verification is the process by which the fidelity of a

numerical algorithm with respect to underlying mathematical

representation of a model or simulation is established and the errors

in its solution are quantified. Validation is the process through which

the scientific community comes to accept that a particular model

or simulation reliably describes real world behavior. Most validation

processes involve comparison with experimental data. A critical

component, uncertainty quantification is the process of characterizing

and reducing uncertainties of measurements, model predictions, and

simulation results.

To account for all the important materials properties and reactor

phenomena, the multi-scale models and simulations must address a wide

range of space and time scales, starting with the nucleus and the atomic

electronic structure (nm) all the way to the reactor components (meters),

and from defect formation (pico-seconds) to the operating characteristic

times (months, years). Fig. 2 illustrates some of the theoretical and

computational methods used in the multi-scale approach42,51-53. The

information is transferred between scales via characteristic parameters

such as density, energy, temperature, or grain size distribution54. Meso-

scale and continuum methods are often “atomistically informed”, in the

sense that some of the parameters in the methods are optimized against

the output of atomistic calculations.

Fig. 2 Multi-scale theoretical and computational methods used for materials model development and computer simulations.

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fuel-clad interactions78,79 and the influence of temperature and fuel

stoichiometry changes on the coupling of heat and species transport in

a UO2 fuel element with stainless steel clad80. The results show that

the counterbalancing of the Soret and Fickian fluxes is responsible for

the variation of oxygen concentration in the fuel pellet. Furthermore,

the simulations demonstrate that including the dependence of thermal

conductivity and density on non-stoichiometry can lead to changes

in the calculated centerline temperature that exceed 100 K (Fig. 4).

Additional simulations involved transient regimes and the examination of

the time lag in the response of the temperature and non-stoichiometry

distributions with respect to sudden changes in heat generation rate and

oxygen removal rate. Current work at Los Alamos includes studies of the

effects of porosity on thermal conductivity and thermal expansion81, and

simulations of clad deformation.

Advances in theoretical, experimental and computational capabilitiesAddressing the materials challenges requires a closely coupled

experimental, theoretical, and computational effort directed at

both the scientific and the engineering issues. In this partnership,

new experimental investigation methods such as synchrotron light

sources and proton radiography increase the potential of “in-situ”

characterization of radiation effects on nuclear fuels and provide new

validation opportunities. In addition, theory and high performance

computing expand the investigation space to identify and resolve new

scientific problems.

All top 500 fastest supercomputers in the world can now reach

over a teraflops (1012 operations per second) and the number of

petaflop (1015 operations per second) supercomputers is increasing

BOX 3. Fuel performance capabilitiesA fuel performance capability (FPC) consists of a computer code or

a set of codes that contain models of fuel properties and are able to

simulate phenomena in the nuclear fuel during operation71,72. In a

more general version of this concept, the fuel performance is evaluated

in the entire fuel element (fuel plus clad) and validated “in-pile”73. In

addition to experimental Post Irradiation Examination (PIE), the fuel

performance capabilities are increasingly complex tools in support of

fuel characterization and optimization.

A preliminary design of a new generation Advanced Fuel

Performance Capability (AFPC) was recently proposed42. To

address the nuclear fuels material properties and phenomena, the

capability includes specific computational modules and interacts

with an external database that is continuously updated with the

most advanced models of fuel and materials properties and the

necessary nuclear data. To achieve a consistent predictive character,

many such capabilities are moving away from empirical models and

include theory based models65,70. Other requirements are related to

numerical algorithm design, uncertainty quantification, and software

engineering, including

the use of nested (linear + non-linear) solvers74,75, multi-level

preconditioning, running parallel on large-scale supercomputers, and

easy adaptation to heterogeneous computational platforms.

Fig. 5 shows various paths for fuel performance code development,

using as starting point the USA empirical codes FRAPCON and LIFE.

The blue line represents the path of using “of the shelf” Advanced

Scientific Computing Initiative (ASCI) codes that have been developed

at national laboratories for national security applications, followed by

the addition of physics-based models specific to nuclear fuels. The red

line represents the path chosen by scientists who are interested in first

testing the science-based models in commercial codes such as Comsol

and Abaqus, and only later migrating the codes to high-performance

computers. The best solution might be a balanced approach to

designing a new fuel performance code (green line), based on the

experience accumulated by the European scientists in developing

Transuranus and Pleiades.

As the predictive capabilities continue to improve, fuel performance

codes are expected to become an integral component of nuclear fuels

design and licensing, and of nuclear waste certification processes76.

Fig. 3 Top: Fission gas bubbles in UO2 irradiated in a Pressurized Water Reactor at burnup level 25GWd/t. The sample was annealed at 1275 ºC for 5 hours. Bottom: Phase Field simulations of gas bubble evolution.

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at a fast pace82. Already, neutron diffusion calculations, as well as

some reactor hydrodynamics simulations83,84 are being performed on

such resources. As exaflop computers (1018 operations per second)

are being designed, there is a tremendous opportunity for involving

high-performance computing in nuclear fuels design. However,

high-performance computing requires far more than high-speed

computing. It requires science-based models, innovative numerical

methods, and the ability to generate new ideas85. Here are a few

predictions of exascale computing results and how they can spark

transformational science in support of nuclear fuels discovery and

design:

• Quantum Mechanical calculations of electronic structure properties

of systems consisting of trillions of atoms, compared to the current

hundreds of atoms. Such simulations will predict properties such as

free energy of formation of multi-component metallic and ceramic

fuels.

• Quantum Mechanical calculations at finite (room, high)

temperature, in contrast to the current (mostly) 0 K results. This

will enable predictions of properties such as phonon spectra, heat

capacity, bulk moduli, and stress-strain curves in temperature

regimes relevant to manufacturing, operation, and storage of

nuclear materials.

Fig. 5 Classification of some of the codes currently used for fuel performance and paths towards designing a new generation fuel performance capability.

Fig 4. Simulation of heat transport in a UO2+x fuel element with metallic clad. The temperature profile demonstrates that including the stoichiometry x in the thermal conductivity model changes the predicted centerline temperature by more than 100 K.

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• Atomistic (e.g. Molecular Dynamics) simulations of a much larger

number of atoms (1020), compared to the current state of the art

(108). Such capability will allow for simulations of radiation effects

and damage in heterogeneous regions of the fuel, such as grains and

interfaces.

• Atomistic simulations (e.g. coupled Molecular Dynamics and

Monte Carlo) of coupled neutron transport and radiation

cascades in systems consisting of trillions of atoms, for hours or

even days. This will open up an unprecedented investigative space

to include: simulations of fission-products diffusion in the grain and

at the grain boundary, gas bubbles nucleation, and swelling. It will

also enable access to critical phenomena such as stress corrosion

cracking86.

• Meso-scale diffuse-interface (phase-field) or sharp-interface (level-

set) simulations of microstructure evolution under irradiation. These

simulations will most likely be “atomistically informed” and will

include defect formation and recombination processes occurring in

radiation cascades. These simulations will assist the optimization of

advanced, innovative nuclear fuel forms and the design of radiation

resistant structural materials.

• Multi-scale, embedded simulations, covering large time and

space domains. Such simulations will improve on the “first

principles” character of the multi-scale methodology. However,

including all atoms in the simulation of a specific reactor

component is not only impossible but is also undesirable.

Developing comprehensive models and running simulations “at

scale” in sync with a smart transfer of information between scales

remains the best approach.

Innovative nuclear fuelsDiscovery and design will play a crucial role in developing innovative

nuclear fuels and structural materials for the new generations of

fission and fusion reactors87-91. Besides the optimization of the current

fabrication methods, high performance computing will open many

doors to investigating new phenomena in materials. Advances in

theory, experimental techniques, and computational science will lead

to completely new ways of doing science. What will be next? How

about building materials “atom by atom” to create structures capable

of accommodating the local radiation environment? How about “self-

healing” nuclear reactors that recover after accidents? The range of

innovative science is only limited by our imagination.

An integral component of the innovative fuel development is the

understanding of thermal, mechanical, and chemical properties of the

fissile materials, the source of energy in a nuclear reactor. The multi-

scale approach described in the previous section for U-Pu fuels can

be extended to multi-component systems containing Th (ThO2 based

fuels are already here92), Am (already in some mixed oxide fuels93),

Np, Cm and their mixtures, in fuel forms such as ceramics, alloys, and

composites. That requires several essential steps:

• Developing theory-based models of the free energy of the

subsystems, such as the binary and ternary phases.

• Developing theory-based models of the mobility of species

(actinides, fission products, oxygen, nitrogen, etc).

• Performing simulations of coupled thermal and neutron transport,

species diffusion, and deformation in the multi-component

materials that are major candidates for innovative fuels.

Such a study is extraordinarily complex, requires a tremendous

amount of work, and should start now. It takes years to develop a

good understanding of the properties and phenomena in new, multi-

component materials.

One of the goals that bring together the scientific and engineering

communities is to control the properties and phenomena in irradiated

nuclear fuels and materials. As shown in the previous sections,

to achieve this goal the international community must engage in

developing theory-based models that enhance the understanding

of irradiation effects on materials properties and developing the

computational science required to perform high-performance

simulations.

Another important goal is to discover or design new, innovative

fuels and materials for nuclear energy applications. That involves

creating an integrated theoretical, experimental, and computational

validation process and engaging the national and international

communities in solving problems of high complexity.Fig. 6 Schematic representation of the main components of an Institute for Materials Discovery and Design (IMDD).

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Achieving these goals requires a new paradigm that favors a much

stronger coupling of the various components of the multi-scale model

and simulation methodology as well as a new level of collaboration

and integration among experimentalist, theorists, and computational

scientists. The sub-sections below outline a few components of a

strategy intended to increase the chances of both controlling properties

and discovering and/or designing better nuclear fuels and structural

materials for the new generations of nuclear reactors.

Institutes for materials discovery and designCreating national and international institutes (centers, hubs, etc)

dedicated to accelerating the discovery and design of improved

materials is an immediate and potentially most rewarding initiative.

The mission of such centers is to provide the scientific environment

and resources (people, supercomputers, and funding) for the

development of theory-based models, simulations, and computational

tools able to assist the discovery and design of nuclear fuels and

structural materials.

The institutes will bring together scientists that are trained in

all three areas: experiment, theory, and simulation, and experts in

one. The model development work will cover a wide range of space

and time scales requiring a well balanced portfolio of expertise. The

participants will collaborate in developing and performing atomistic,

meso-scale, and continuum simulations of irradiation effects and

transport phenomena in reactor materials, to predict and control point

defect formation, microstructure evolution, and materials performance

in reactor environments.

The centers will include state of the art laboratories for small-

scale experiments, computational materials science hubs for model

development and remote simulations on high-performance computers,

meeting rooms equipped with advanced visualization capabilities, and

offices for staff, guest scientists and students (Fig. 6). It is critical for

IMDDs to bring together both mature and early career scientists, in a

work environment that allows for uninterrupted time for science.

Knowledgebase for data, models, and simulationsEvery day, a tremendous amount of data is created as a result of

performing experiments and running simulations. Besides numerical

data storage, analysis, and retrieval much progress was made on

the management of information regarding models (mathematical

expressions), simulations (codes), and the visual representations of their

results (pictures, animations).

As a consequence, creating, updating, and maintaining an

international “knowledgebase” that includes experimental data, models

(mathematical expressions), and simulation results (tables, graphs,

diagrams), all linked to publications and web sites, is now possible. The

knowledgebase will have a user-friendly interface and will use advance

query techniques capable of retrieving numbers, text, and images. The

knowledge-base will be updated with information from the IMDDs

and will serve as a resource for national laboratories, universities, and

companies.

No doubt that such an effort will face numerous challenges,

especially in the area of proprietary information, licensing of fuel

performance codes, and non-proliferation. There is however a

significant amount of fundamental scientific information, such

as thermal, mechanical and chemical properties of generic multi-

component fuels and structural materials, phase stability (phase

diagrams), and transport (diffusion) of elements, that can be shared

without infringing upon restricted data.

EducationThe most important resources for creating innovative nuclear fuels

are the nuclear engineers, materials scientists, physicists, chemists,

computers scientists, etc. Their contribution is essential in advancing

the integrated experimental, theoretical, and computational work

and they are the supreme validation authorities. In recent years, the

nuclear engineering community has taken steps toward engaging

prestigious scientists in nuclear fuels research via conferences and

workshops. Scientists are often tempted to direct their studies toward

the most interesting and challenging scientific areas rather than the

most technologically relevant ones; their attraction to nuclear energy

research is rooted in curiosity. To increase the scientific interest, well-

funded national programs must be created to support fundamental

science in the area of nuclear energy and increase the likelihood of

breakthrough discoveries and creative design.

Computational scientists and software engineers are major

participants in designing and writing fuel performance codes. However,

strong teaming among engineers, scientist, and software developers

is key to creating science-based, high-performance codes capable of

running on the present petaflop and the future exaflop computational

platforms. To expand and improve the quality of the models and

simulations, the international nuclear fuels community must develop a

large pool of experts to cover the necessary theoretical, experimental,

and computational tasks. That can be achieved by including “Models

and Simulation of Nuclear Fuels and Structural Materials” in the

materials science and nuclear engineering programs at universities

across the world.

The involvement of the national and international decision factors

(politicians and managers) in the scientific meetings is an encouraging

recent development. More and more decision factors are becoming

aware of the scientific and computational challenges faced by the

nuclear fuels community and can better provide guidance and financial

support for the future research and development programs.

International collaborationsIn addition to improved experiments, models, simulations, and

computational capabilities, a coherent nuclear energy program requires

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national and international collaborations. To cover the necessary

areas of expertise, organizing workshops and sessions on models and

simulations of nuclear materials at international conferences is a

natural strategy component. Only two of the many important scientific

meetings in this area are discussed below.

The Materials Models and Simulations for Nuclear Fuels (MMSNF)

workshop series aims at stimulating discussions and research to

advance theory-based model development, high-performance

computer simulations, and experimental validation for nuclear fuels

applications. The workshops series started in June 9-10, 2003 in

Santa Fe, NM, USA with support from the Advanced Fuel Cycle

Initiative program, funded by the USA Department of Energy,

and the Los Alamos National Laboratory. The workshops usually

bring together around fifty experts in experiments, theory, and

models and simulations from twelve countries or more. The most

recent edition of the workshop (Albuquerque, USA) resulted in an

evaluation of atomistic, meso-scale, and continuum simulation

methods and their impact on nuclear fuel design. The next edition

(MMSNF-9) will be part of the Nuclear Materials Conference, NuMat

2010, in Germany.

The Working Party on Multi-scale Modelling of Fuels and Structural

Materials for Nuclear Systems (WPMM) was created in January

2008, with guidance and support from the Nuclear Energy Agency

(NEA), to address scientific and engineering aspects of fuels and

structural materials. The main goal of WPMM is to establish multi-

scale models and simulations as validated predictive tools for the

design of nuclear systems, fuel fabrication, and fuel performance.

The main tasks include: identification of fundamental problems,

development of atomistically-informed models and simulations of

nuclear fuels and structural materials properties, promoting high

performance computer simulations, and maintaining synergy with

experimental work. Validation of simulation and model predictions is

also a priority as well as the development of new applied mathematics

and software tools.

More initiatives of this type are needed to increase the quality

and intensity of the debate over scientific and engineering problems

relevant to nuclear fuels (including spent fuels94) and nuclear energy

in general95. In many areas, such as the thermo-mechanical and

chemical properties of the fuels, the number of components of the

system subject to investigation is so large (thousands) that no country

alone can study all of them in a reasonable timeframe. Partition of

work and good international collaboration form the best strategy for

increasing the understanding and controlling the properties of such

materials.

Summary and outlookNew generation, innovative nuclear fuels will be complex, multi-

component systems that must perform well in the radioactive

and corrosive reactor environment. The development of such fuels

involves scientific methods focused on both discovery and design.

In this context, multi-scale models and simulations are capable of

investigating a wide range of space and time scales and interact with

fuel performance capabilities to create complex tools in support of

fuel characterization and optimization. In particular, high performance

computing can contribute to increasing the predictive character of

models and simulations and can inspire new ways of doing science.

This approach is expected to become an integral component of nuclear

fuels design, licensing, and waste certification processes.

A new strategy for nuclear fuel development, that involves

discovery and design as equal partners and drivers, is discussed in this

paper. The strategy promotes a much stronger coupling of the various

components of the multi-scale model and simulation methodology and

a much stronger collaboration and integration among experimentalist,

theoreticians, and computational scientists. To this end, it is important

to create research institutes for materials discovery and design and to

create and maintain an international knowledgebase for data, models,

and simulation results. The strategy advocates for direct interactions

among scientists, engineers, and decision factors (politicians and

managers) via international workshops and conferences.

Such initiatives, complemented by other ideas from the international

community, will provide the framework for a stronger integration of

theory, experiments and simulations, leading to an improved control of

the properties and phenomena in reactor materials, and the discovery

and design of new, innovative nuclear fuels and structural materials.

AknowledgementsThis work was occasionally supported by the U. S. A. Department of

Energy via the Advanced Fuel Cycle Initiative (AFCI), the Global Nuclear

Energy Partnership (GNEP), and the Nuclear Energy Advanced Models

and Simulations (NEAMS) Programs.

Further informationInteresting web pages:MMSNF-7: http://itu.jrc.ec.europa.eu/index.php?id=36&type=&iEntryU

ID=164&iEntryPID=68

NEA: www.nea.fr

Roadrunner supercomputer: www.lanl.gov/roadrunner/

High Performance Computing workshop: www.cels.anl.gov/events/

workshops/extremecomputing/nuclearenergy/agenda.php.

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Discovery and design of nuclear fuels

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