Dissertation / PhD Thesis/Book

PreJuSER-36984

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Transport und Abscheidung von Tropfen im Primärkreis des Hochtemperaturreaktors bei Wassereinbruchstörfällen

Leber, A. (Corresponding author)FZJ*

2003
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/280

Report No.: Juel-4050

Abstract: In order to a catastrophic free nuclear reactor, the stability of the nuclear reactor must be guaranteed also in case of hypothetical accidents, that the consequences are limited to the power plant by self-acting mechanisms. In this paper, the inherent safety properties of the High-Temperature-Reactor (HTR) against water ingress accidents will be explained. The water ingress in the primary cycle of a HTR by a leakage of the steam generator is an accident, involving the stability of the reactor in two points. The additional moderation of neutrons by water molecules leads to reactivity effects. Further the fuel elements may be corroded leading to a formation of water gas. In case of a small leakage in the steam generator liquid water is injected in the primary circuit in form of small droplets, which can be transported by the gas flow into the core. The amount of water within the core is mainly dependant on the reactor protection system, the flow conditions in the primary circuit and the droplet size. Hypothetical accident scenarios will be defined in a first step considering the behaviour of the reactor protection system. In the second step, calculations to the formation of drops and the behaviour of the blower-unit under accident condition are done. Thereafter analytical and numerical calculation models for the transport and the separation of droplets will be developed. The calculation results will be validated with measurement results for the inertial separation of water droplets from an air flow. Furthermore analytical models to transfer the result to several conditions during the accident are described. Based on the transfer models the efficiency of the droplet separation in the primary circuit of a HTR is estimated in the experimental facility SEAT. The SEAT facility consists of a flow channel with integrated measurement for determining droplet sizes. It will be shown, that the installation of additional droplet separators in the primary circuit is useful with respect to the duration of the accident and drying the primary circuit alter the accident. In this context the separation efficiency is tested with différent types of separators in single or series arrangements. Finally a self-acting safety element is suggested, which consists of a droplet separator and a float arrangement for strongly reducing the duration ofthe accident.

Note: Record converted from VDB: 12.11.2012
Note: Aachen, Techn. Hochsch., Diss., 2003

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Contributing Institute(s):

1. Institut für Sicherheitsforschung und Reaktortechnik (ISR)

Research Program(s):

1. Nukleare Sicherheitsforschung (E04)

Appears in the scientific report 2003
Notes: Nachtrag

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