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ICHMT DIGITAL LIBRARY ONLINE

ISSN 961-91393-0-5

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Year 1995

• 1Heat and Mass Transfer in Severe Nuclear Reactor Accidents
Proceedings of International Symposium - 22 -26 May, 1995, Kusadasi, Turkey

708 pages

Volume price - $176.00

ESCALATING AND PROPAGATING MELT/COOLANT INTERACTIONS IN THE KROTOS EXPERIMENTS: STATUS OF KNOWLEDGE

H. Hohmann
Commission of the European Communities, Ispra, Italy

D. Magallon
Commission of the European Communities, Ispra, Italy

A. Yerkess
Commission of the European Communities, Ispra, Italy

I. Huhtiniemi
Commission of the European Communities, Ispra, Italy

Michael L. Corradini
Engine Research Center and Engineering Physics, University of Wisconsin, Madison, Wisconsin, USA

M. Burger
Institut für Kernenergetik und Energiesysteme, University of Stuttgart, Germany

M. Buck
Institut für Kernenergetik und Energiesysteme, University of Stuttgart, Germany

E. V Berg
Institut für Kernenergetik und Energiesysteme, University of Stuttgart, Germany

ABSTRACT

The experimental programme KROTOS at JRC Ispra is aimed at providing benchmark data to examine the effect of fuel-coolant mixing conditions on explosive energetics for both simulant materials and prototypical core materials. With such data one can assess the mechanistic fuel coolant coarse mixing models and the explosion models which describe propagation and expansion of steam explosions. So far in the KROTOS experiments no energetic explosions with a water UO₂-ZrO₂/water mixture have been observed, even making use of an external trigger. In sharp contrast, the mixing of simulant material, such as Al₂O₃. with water can often produce a supercritical explosion, even without the aid of an external trigger. Important interfacial instability mechanisms that result in breakup of the melt jet when it is poured into the coolant have been incorporated into the coarse mixing model TEXAS and the jet breakup model IKEJET. The predictive capabilities and limitations of these models are discussed and some possible improvements suggested. Explosion models TEXAS and IDEMO are described and computational results are compared with experimental data for the KROTOS tests 28 (Al₂O₃ ) and 32 (UO₂-ZrO₂). Although the computational and experimental results are not in complete agreement they do reveal essential differences in the jet breakup behaviour during coarse mixing that can help explain why one mixture is potentially explosive and the other is not.