Dynamics Analysis of a Nuclear Boiler
A dynamics analysis of a nuclear boiler based on a steam-generating, pressure-tube, heavy-water-moderated design is presented. In effect the plant is very similar to a La Mont recirculating cycle. A detailed mathematical model to represent plant dynamics (linearized, full power) is discussed with special reference to the boiling channel, steam drum, and recirculating loop. A simplified model is derived for analogue computer studies. Dynamic performance is discussed in terms of: (1) boiler only (no reactivity feedbacks): influence of pressure feedbacks, steam drum design, subcooling, recirculating delay; (2) complete plant (including reactor): as above but including influence of void coefficient. The two most important results are: (1) the strong dependence of plant behaviour/stability on the degrees of float allowed to pressure; (2) the possibility of designing an inherently stable and self-regulating plant with a small positive void coefficient. Finally, conclusions are drawn on the complete dynamic analysis under the heads: (1) optimal plant design; (2) control system design; (3) development of analytical/computing methods; (4) research into two-phase physics.