Safety Considerations in the Design of a Unique Nuclear Steam Generator Feedwater Control System

Ontario Hydro's Bruce B Nuclear Generating Station has just been commissioned. It consists of four 800 MW CANDU-PHWR units. Each unit has eight integral-drum steam generators and four preheaters. These vessels have safety related design constraints. This paper will consider the importance of, and strategy used, in controlling the water level in the steam generators and preheater outlet feedwater pressure to satisfy these constraints. The results of computer simulations used in designing/verifying the control schemes and a comparison with actual plant performance will also be given.