Große modulare Kugelhaufenreaktoren mit passiven Sicherheitseigenschaften als ein Beitrag zur katastrophenfreien Kerntechnik : Flexibilität in Auslegung und Anwendung

Abstract

Worldwide investigations are carried out for different reactor concepts, in order to realize nuclear energy production in modular power plants. In that concept several small or middle sized reactors are joined together in a modular way to form one power plant. The size of MODUL-reactors is designed in such a way, that exelusively inherent safety properties perform the -control of accidents without active technical proceedings. In order to achieve this, the reactor should be relatively small. On the other hand, it should be relatively large for economic and competitive reasons. The range of possible development of the modular pebble-bed reactor for raising the power output are discussed in this study. Based an the MODUL 200 MW concept, the design of the "Great-Modul-Medul" reactor (GMM) with a power output of 500 MWth is introduced, in which the loading modus WLEMIL is applied with repeated circulation of the spheres through the core. A "Great-Modul-OTTO" GMO with a power output of 400 MWth is designd with only one pass of the pebbles (OTTO). comparison to the GMM, that has the advantage of being simpler in construction and in the method of operation. Furthermore, another simplifieation is studied consisting of the combination (PO) of "Peu a Peu" and "OTTO" loading rnodus. All designed cases show a favourable flexibility when changing the applieation of the reactor from steam cycle to gas turbine cycle or to seawater desalination. The study outlines, that the inherently determined limitation of the excess temperature in ease of a loss coolant accident and the ability for controling the water ingress reactivity are maintained for all variants being considered