Discussion: Papers 3,4 & 5

M. H. BUTTERFIELD The work described in Paper 3 is based on records taken while the SGHWR was operating in *decoupled' control, that is, while drum pressure was regulated by adjusting the turbine control valve. This form of control was put into the original design since the SGHWR was originally specified for base load operation. With its own isolated load the simulator demonstrates unstable load following. By going to 'coupled1 control in which steam pressure is regulated by modifying the core power, that is, heat input into the coolant circuit, the system is rendered stable supplying an isolated load with a 4% governor droop and grid inertia giving 4«5 Hz/s per full load mismatch.