FUELING OF D2O REACTORS .2.

The transition of fresh natural uranium cores to burnup equilibrium is demonstrated in the case of fueling for the nuclear power plant Atucha (Argentina). The loading operations were determined by use of the heterogeneous 3-D code TRISIC. A stationary burnup distribution was already obtained after approx. 420fpd. During the last 18 months (April 1975-September 1976) the availability factor was 94%, the capacity factor of 92% was only a little below this value. The number of defective fuel pins which occurred up to the present is low, having a failure rate below 0. 05%.