International Workshop on Nuclear Fuel Modelling to Support Safety and Performance Enhancement for Water-Cooled Reactors

Background

Advanced techniques for fuel modelling have progressed considerably in the last decade in part aided due to progress in high-performance computational capability. At the engineering scale, this has resulted in improved mechanistic description within fuel performance codes with a trend to progressively replace empirical models and correlations with physical models that allow, in principle, extension of the predictive capability of the codes beyond the domain for which experimental results are available. As an example, mesoscale codes (at the fuel-grain scale, typically microns) provide predictions of microstructure evolution and determine their impact on fuel properties, describing phenomena such as grain-boundary sweeping, grain growth, bubble nucleation, growth and coalescence, precipitation of solid fission products, their speciation and phase separation. Inclusion of these models within engineering-oriented fuel performance codes offers improved predictions of thermal conductivity, elastic constants, swelling, and fission-gas release under conditions beyond their usual range of validity and creates an exploratory capability. At the OECD Nuclear Energy Agency, the importance of fuel modelling and its improvement through development of phenomenological representations has been recognized, and multiple technical groups related to materials modelling and the support of advanced fuels and safety codes are considering these issues. A prime example is the Working Party on Multiscale Modelling of Fuels and Structural Materials for Nuclear Energy Systems, and in particular the Expert Group on Multiscale Modelling of Fuels, which published in October 2015 a State-of-the-Art Report on Multi-scale Modelling of Nuclear Fuels. To improve the coordination of these activities and to identify future needs within the NEA and in the broader technical world, a workshop on Nuclear fuel modelling in support of safety and performance enhancement for water-cooled reactors was proposed.

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Objectives and scope

The main objectives of the workshop were:

to identify areas where advanced rod-scale, mesoscale or microscale plus multiscale integration modelling of nuclear fuels was contributing or would contribute to significant progress on or insights into fuel safety and/or fuel performance for water-cooled reactors; the focus was on the design and operation of nuclear fuel, with consideration of nominal and off-nominal operating conditions including design-basis accidents
to identify impacts the advanced modelling approaches might have on the current nuclear fuel design safety limits (evolution or new types of safety limits)
to identify gaps in models/information and possible experimental needs
to identify areas for enhanced international collaboration and contribution by the NEA.

The workshop included keynote presentations, technical talks and panel discussions involving experts from a broad spectrum of stakeholders, including R&D organisations, academia, industry and regulatory bodies within NEA member countries, as well as representatives of others international bodies. The workshop topics included major insights related to performance and safety improvements during normal operation and under off-normal conditions for water-cooled reactors nuclear fuel, including:

release of fission gases
formation of high burn-up structures (rim and MOX clusters)
fuel swelling (diametral and axial) and PCI
the impact of dopants such as gadolinia
analytical investigation of the margins associated with fuel-safety criteria including uncertainties
other issues such as clad oxidation, CRUD deposition, fretting, fuel assembly bowing
factors affecting burn-up and cycle length, power uprates, and more flexible modes of operation
reduction of uncertainties in the fuel design process and consequences on the licensing margins
fuel fragmentation under LOCA conditions.

Schedule and registration

Schedule

15 December 2016: registration opened
24 February 2017: deadline for registration
7 March 2017: workshop opened at 9 am, OECD Conference Centre, Paris

Registration

There was no fee for participation in this workshop.

General co-chairs

Kemal Pasamehmetoglu, INL (USA), Chair of NEA Expert Group on Accident Tolerant Fuels for LWRs
Marc Petit, IRSN (France), Chair of NEA Working Group on Fuel Safety
Ted Besmann, University of South Carolina (USA), Chair of NEA Working Party on Multiscale Modelling of Fuels and Structural Materials

Scientific advisory committee

T. Besmann (USC)	G. Rossiter (NNL)
M. Freyss (CEA)	D. Tsurikov (Kurchatov Institute)
V. Garat (AREVA)	P. van Uffelen (EC-JRC)
C.B. Lee (KAERI)	C. Valot (CEA)
S. Middleburgh (Westinghouse)	M. Veshchunov (IAEA)
M. Moatti (EDF)	N. Waeckel (EDF)
F. Nagase (JAEA)	W. Wiesenack (IFE-HRP)
K. Pasamehmetoglu (INL)	B. Wirth (UT-ORNL)
M. Petit (IRSN)	K. Yueh (EPRI)

Working documents

Working area for members of the organising committee (password protected | reminder)

Workshop material for registered participants only (password protected | reminder)

When?

7 - 9 March 2017

OECD Conference Centre, 2 rue André Pascal, Paris, France

Contact

davide.costa@oecd-nea.org