Untersuchungen zur Übertragung der Sicherheitseigenschaften des Modulreaktors auf einen grossen Leistungsreaktor

The German industries and research institutions have developed the HTR module reactor, which is strongly characterized by inherent safety features. The power output is limited to about 200 MWth because of its core configuration. lt has been investigated in this work, whether the safety features of the module reactor can be transferred to larger power reactors. For this purpose the conceptual design of a ring core pebble bed reactor has been made wich a thermal power output of 3000 MW. By means of computer calculations, the principal physical, thermohydraulical und safety features of the ring reactor have been studied. lt has been shown that the 3000-MWth ring reactor basically possesses the same safety characteristics as the small module reactor. At reactivity disturbances, the reactor is shut down passively by the strongly negative temperature coefficient. The decay heat removal is also realized based on the passive principle. In the case of a total loss of coolant, the maximum fuel element temperature remains below 1600°C ; and consequently the retention of fission products in the fuel elements is fully attained. The control of xenon oscillations takes place inherently due to the mutual coupling between the local power production and the fuel temperature