Interpretation of reactivity insertion accident transient on research reactors on example of Spert-IV-D 12/25 Benchmark

E. Ivanov, L. Maas, F. Ecrabet

TopSafe 2012, Helsinki, Finland, April 22-26, 2012

Abstract

As the technical support of the French Nuclear Safety Authority (ASN), IRSN is in charge of the safety assessment of Research Reactors. Due to their particularities (high reactivity insertion potential, use of aluminium fuel plate – low melting point), an energetic water melt fuel interaction can occur in these reactors in case of accidental transients such as reactivity initiated accidents (RIAs).
One of the objectives of IRSN is to evaluate the consequences (and the associated uncertainties) of this accident, taken into account in safety demonstration. In this context, IRSN deals with the SPERT-IV-D 12/25 benchmark in the framework of a Coordinated Research Project on “Innovative methods in Research Reactor Analysis: Benchmark against Experimental data on Neutronics and Thermal-hydraulics Computational Methods and Tools for Operation and Safety Analysis of Research Reactors”. The SPERT-IV experiments have been performed in the USA in the sixties to demonstrate the core response to limited reactivity step insertions. The SPERT-IV-D 12/25 benchmark allows studying the complex dynamic effects for reactors with highly enriched metal fuel plates in a water moderator. The purpose of this paper is to present the methodology developed at IRSN to reproduce the reactivity evolution for models intended to simulate reactivity insertion accidents.

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