The Boric Distribution In Liquid Phase Of Evaporation Tower In Nuclear Power Plant's Boron Recycling System

Most of the nuclear power plant equipment in our country are imported from abroad.In order to break the foreign monopoly, we must research and design some equipments independently.This article's research projects are from CGNPC(China Guangdong Nuclear Power Company),whose program is called "The key technology research of the waste system's evaporator tower and degassing tower".This paper is a part of this project,mainly includes the following aspects:Boric acid is a kind of toxicant of reactivity control in nuclear reactor.It has irreplaceable advantage compare with control rod in the aspect of reactivity regulation and the control of nuclear reactor power.Boron recycling system is a subsystem of the nuclear waste disposal system, and its main effect is to recovery boron from the primary circuit coolant and supply the primary circuit for reusing.It can reduce the environmental pollution and save the economic costs.So this article simply introduce the status of nuclear power development at home and abroad,and compare the different trend of nuclear power development at home and abroad.This paper introduce the important role of boric acid in nuclear reactor control and the function of boron recycling system, system process, main equipment and characteristics in detail.Evaporation tower is one of the most important unit of boron recycling system.According to the different boiling point and volatile between the water and boron,we can separate them with water heating,so we can get some distilled liquid with a small number of boron and some concentrated solution with a great number of boron.This topic regard the evaporation tower which is designed independently by CGNPC as research target,and regard the evaporation process as basic fundamental,testify that the liquid entrainment is the biggest factor in evaporation.Through analyzing the characteristic of evaporator tower,the model of boric distribution in liquid phase ofevaporation tower is found,which is basic on the liquid entrainment.In the case of known dimensional parameters, the boron concentration in each layer are given, and according to the design specification,the plate number is 3 by calculated.Then doing experiment on the experimental bench.This paper will introduce the experimental bench and test plan, and record all the experimental data.Results show that in the case of the plate number by calculated,the separation between boric-acid and water can meet the requirements, namely the boron of distilled liquid is under 5PPM.In the end of the paper,the prospect of evaporator tower technical examination research and computational simulation is proposed.