Consequences of size increases and thermodynamic constraints on steam-powerplant availability: comparison between nuclear and fossil-fueled units.


By comparing the two largest thermoelectric units recently brought into operation in Italy (i.e., a 660-MWsub(e) fossil-fueled supercritical unit and an 860-MWsub(e) nuclear direct cycle BWR), we obtain information on the effects of size limits on powerplant availability. We assume that torsional vibrations are among the most severe causes of damage, while short circuits at the generator terminals cause the most serious fault in a power-station. Computer-aided simulation of the dynamical behaviour of the two units shows the nuclear unit to be less severely stressed, thus producing longer life and better long-term reliability. Spena,-A. (Rome Univ. (Italy). Ist. di Fisica Tecnica); Chiricozzi,-E. (L'Aquila Univ. (Italy). Ist. di Elettrotecnica)