A control approach investigation of the Xe-100 plant to perform load following within the operational range of 100 - 25 - 100%

This paper describes the Xe-100 plant load following analyses done in Flownex® thermal-fluid system simulation software for normal operation from 100 - 25 - 100% electrical power. The plant model encompasses all major components in the Xe-100 plant's primary helium side including the pebble bed reactor, helium circulator, and steam generator, which transfers heat to the secondary steam side feeding steam to a steam-turbine in the Rankine cycle. The requirement for load following was to have a ramp rate of 5% per minute when the turbine-generator power level ramps down from full power to 25% power level and back to full power. The control approach, which pairs selected manipulated variables namely the: reactor control rods; helium circulator speed; feed water pump speed; turbine throttle valve to selected controlled variables namely the: reactor outlet temperature; main steam temperature; main steam pressure; turbine-generator power, is discussed in this paper. The controller actions on the manipulated variables and their response during the load following signal are illustrated. The deviation of the controlled variables during load following are shown within their required limits. This paper shows that the Xe-100 plant can achieve a 100 - 25 - 100% electrical load ramp at a rate of 5% per minute.