Performance improvement of a radioactive forced circulation evaporator system

Abstract EN

Evaporation is a proven method for treatment of liquid radioactive wastes providing both good decontamination and high concentration.

In a radioactive waste treatment plant a forced circulation evaporator is used to reduce the volume of radioactive liquid wastes arising from different applications of nuclear industries.

The safe operation, limiting the composition of the liquid radioactive waste at a prescribed value, with high performance efficiency, requires good control for the evaporator operating pressure and the level of liquid waste inside the separator part of the evaporator.

The aim of this work was to improve the safety and performance of a forced-circulation evaporator used in a liquid radioactive wastes treatment plant.

In this respect, a level controller system for this type of evaporator was designed, where proportional (P), proportional Integral (PI) and deadbeat response controllers for the separator level system were suggested.

Moreover, an ideal 2×2(2 inputs and 2 outputs) decoupler controller for controlling the operating pressure and the product composition was developed.

Computer results demonstrated that the deadbeat response has been successfully obtained from the developed separator control system.

The maximum overshoot in the unit-step response curve was reduced to 25% and the settling time also was reduced to more than the half; about 26 minutes using Ziegler-Nichols tuning technique.

The designed decoupling controller has been found effective in achieving a good trade-off between stability and performance