Dynamic Simulation of a Forced Circulation Radioactive Waste Evaporating System

Abstract

A dynamic simulation program is developed to simulate a forced circulation evaporating system of Kori Nuclear Power Plant in Korea. Energy and mass balances about vapor and liquid phases are used to describe interaction among system components such as vapor body, heater jacket and condenser. In order to simulate entrainment carryover in sieve tray column and wire mesh pad, Kister's and Carpenter-Othmer's correlations are adopted, respectively. A new correlation formula is also suggested here to simulate geometric effect of vapor body. Fuzzy heuristic controller and conventional controllers such as P, PI and PID controls are incorporated to observe their responses to given disturbance. Simulations show good agreement with the real operation data. It is also identified that vapor velocity or flow rate in sieve tray column determines the system decontamination factor (DF), and that the longer the vapor body is, the less entrainment carryover occurs out of vapor body. In addition, wire mesh pad is identified to maintain very high deentrainment efficiency even though vapor velocity may show large fluctuation. With respect to system control, fuzzy heuristic controller approaches to new steady state faster than conventional controllers do. Also fuzzy controller maintains higher DF during the transient and is stronger against time delay of control components.