Research Of The Improvement Of Adjuster Control Of Heavy Water Reactor Power Plant

The purpose of this thesis is to research the problem exists in the control of adjusters in CANDU6 reactor, and to raise the improvement control scheme to avoid the cycling movement of adjusters when they are driven.As a reactivity mechanics, there are 21 adjusters that are separated into 7 groups. Under abnormal conditions, adjusters need to be withdrawn or inserted to control the reactor power. But as Bank#7 adjusters being withdrawn and Bank#4 adjusters being inserted, the adjusters encounter the problem of cycling movement and can't finish the supposed function. The cycling of adjusters disturbs the reactor power very much and can't ends until the human intervention.In the research, the deterministic method and software simulation are adopted, and the root cause found out is: The reactivity worth of adjusters and Liquid Zone Control system deviates from the designed value, which makes the speeds of inducing reactivity are not matched, and caused a big reactor power error when the adjusters move. On the other hand, the control logic of adjusters has problem, under the situation of the big reactor power error induced by adjusters movement, the speed of adjusters driven is mistakenly accelerated, which causes the reactor power error increase to the limit of turn around the adjusters and result the cycling movement of adjusters.To the root cause of the problem, several possible improvement control schemes are composed, after comparison and verification, 2 sets of completed scheme is provided at the end.The improved control scheme can solve the existing problem of adjusters, increase the reliability of the reactor power control systems and reduce the work of human intervention.