The shrink-swell phenomenon is caused by variations in the vapor-liquid ratio in the evaporating section of a boiler or steam generator (SG). The shrink-swell phenomenon in the liquid level of boilers and steam generators can dramatically limit control system's ability to regulate level. This is particularly true at low power rates, below the range of steam and feedwater flowmeters, where single-element controls must function.
Process Control Consultant Greg Shinskey has more than 3 decades of experience as a systems engineer, and his article "Taming the Shrink-Swell Dragon" he wrote about how after a thorough analysis at Maanshan II, a nuclear power plant in southern Taiwan, a control system upgrade provided the means to tame the shrink-swell dragon taking up residence in the steam generators of the 950-MW pressurized-water reactor nuclear power plant.
