Nuclear Fuel Cycle and Materials Section

Nuclear Power Reactor Fuel Engineering


Technical Meeting on Accident Tolerant Fuel Concepts for Light Water Reactors

13 October - 17 October 2014
Oak Ridge National Laboratory, Oak Ridge, TN, USA






Please be informed that the new Scientific Secretary is Mr John Killeen (see the updated Information Sheet). Please address all correspondence to him.

Background

Reliability of nuclear fuel plays a key role in ensuring safety, competitiveness and public acceptance of nuclear power. The Fukushima accident has especially demonstrated the necessity for detailed analysis of all aspects of fuel design and performance related to both normal and accident conditions, including severe beyond-design-basis accidents with durable loss of active fuel cooling. The behaviour of in-core materials, especially of fuel cladding, in extreme high temperature and corrosive environments is among the primary factors that define accident evolution. Currently used Zirconium alloy claddings are particularly susceptible to high temperature exothermic reaction with steam that leads to massive oxidation of the cladding and generation of large amount of hydrogen. This runaway reaction significantly exacerbates the course of accident progression at high temperatures (>1200ÂșC) and complicates mitigation of accident consequences.

The basis for consideration of alternative fuel materials and design concepts in a number of countries is enhanced safety margins under severe accidents. These efforts were particularly intensified after the events at Fukushima with the goal of developing a so-called Accident Tolerant Fuel (ATF). Unlike the conventional Light Water Reactor UO2-Zircaloy fuel, ATF should withstand beyond-design-basis LOCAs for much longer periods, and similarly tolerate a loss of in-pool cooling during long-term storage of irradiated fuel. At the same time, it is necessary that ATF concepts should either reasonably compare with or improve upon standard UO2-Zr alloy clad fuel in terms of normal operation characteristics, economics, reliability, and spent fuel management.

A variety of possible approaches for ATF development are now being examined in international research efforts including: modifications and advancement of Zr-based claddings such as use of coatings, replacement of Zr alloys by alternative high-performance materials (e.g. Advanced Fe-based alloys, refractory materials, or SiC-based materials), and replacement of UO2 by other fuel concepts and compositions with enhanced thermal, chemical, fission product retention, and other advantageous operational properties. Given the complexity and cost of these long-term R&D activities, many corresponding projects have been initiated at both national and international (e.g. IAEA, NEA/OECD, WNA) levels. Accordingly, an adequate level of coordination among these efforts is required to avoid duplications, enhance productivity, and to assure complementarity wherever possible.

Practical information for participants

The Technical Meeting will be held in the ORNL with a Technical Visit to some experimental facilities. General guidance for ORNL visitors is located at http://www.ornl.gov/visit-ornl. More detailed practical information for TM participants will be provided later on.

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