A reliability analysis for the decay heat removal system of a 1000-MW(e) gas-cooled fast breeder reactor (GCFBR) has been carried out. It relates only to the GCFBR specific systems required after

  1. the maximum depressurization accident
  2. normal shutdown.
Non-GCFBR specific systems such as the electrical supply system and the containment back-pressure system were not included in the analysis. For these analyses, the method of fault trees was used to describe the different failure combinations of the system. The calculations were performed with the system analysis program SAP-1, which combines analytical and simulation methods to find the failure probability and the unavailability of the system. The results of the analysis show that the unavailability governs the reliability of the system; a computed value of 3 × 10−4 was obtained for the unavailability of the system after a maximum depressurization accident, and a value of 4 × 10−8 was obtained for the unavailability of the system after normal shutdown.