Reliability comparison of two designs of low pressure regeneration of the 1000 MW unit at the Temelin nuclear power plant

Simplified block diagrams are presented of the two designs. Design I is of a three-branch type and consists of a total of 12 small heaters. Design II is of a single-branch type and contains 6 heaters. During operation various combinations of heater failures may arise. Reliability analysis of the designs of low-pressure regeneration was carried out using the failure tree method. For failures of both designs the time of duration of these failures was calculated from the steady state coefficient of unavailability; from these times was derived the undelivered amount of power. The comparison only considered bare designs without any accessories. Of the two, design II may be considered better with regard to reliable operation. (J.B.). 3 figs., 1 tab., 6 refs