High-Temperature Reactor Fuel element Characterization with the Küfa Device

Modern fuel elements for high-temperature reactors (HTRs) contain a large number of spherical fuel particles embedded in three layers of coating materials. These are designed to ensure mechanical stability and retention of fission products under normal and transient conditions, regardless of the radiation damage sustained in-pile. In hypothetical depressurization and loss-of-forced-circulation (D-LOFC) accidents, fuel elements of modular HTRs are exposed to temperatures several hundred degrees higher than during normal operation, causing increased thermomechanical stress on the coating layers. At ITU, a vigorous experimental program is being pursued with the aim of characterizing the performance of irradiated HTR fuel under such accident conditions. A cold finger device (Küfa), operational in ITU¿s hot cells since 2006, has been used to perform heating experiments on eight irradiated HTR fuel pebbles from the AVR experimental reactor and from dedicated irradiation campaigns at the High-Flux Reactor in Petten, The Netherlands. Gaseous fission products are collected in a cryogenic charcoal trap, while volatiles are plated out on a water-cooled condensate plate. A quantitative measurement of the release is obtained by gamma spectroscopy. In this paper, we present an overview of experimental results from the Küfa testing as well as the ongoing development of new experimental facilities.

KELLERBAUER Alban;  BOTTOMLEY Paul;  FREIS Daniel;  RONDINELLA Vincenzo;  VAN UFFELEN Paul; 

2010-07-21

International Youth Nuclear Congress

JRC59743

http://www.iync.org/media-center.html?func=fileinfo&id=162,    https://publications.jrc.ec.europa.eu/repository/handle/JRC59743,