The Research And Development Of The Digital Auto-startup & Power Regulating System Of China Advanced Research Reactor

China Advanced Research Reactor (CARR), a light water cooled, heavy water moderated, inverse neutron trap reactor, is being constructed in China Institute of Atomic Energy in 21st Century. High flux neutron can be educed from the core, so CARR can meet the need of preceding basic research, e.g. neutron scattering experiment, and the need of the nuclear industry, national defense, and Country economy. The main technical indexes of CARR can attain the advanced level in the world.The auto-startup and power regulating system is one of the important control system of CARR, which control the neutron flux manually or automatically by control the movement of 6 control rods (2 safety rods, 4 shim rods) manually or automatically. The power regulating function of system can overcome the disturbance and maintain the stability of the reactor after reactor power reaches the fixed value of power.The auto-startup and power regulating system of CARR adopts digital technology, and the computer takes on the entire manual and automatic function; the system is provided by the function of power regulation, as well as the function of reactor auto-startup and automatic transition between different power levels; the system must adopts certain moving logic to keep the 4 shim rods at the almost same position at any time; the electromagnetic mechanism driven by stepping motor, which has some kind of non-linear characteristic, is applied as the driver mechanism of shim rod for the first time in CARR. In addition to the physical characteristic of CARR, e.g. great rod worth of shim rod and obvious non-linearity, all these peculiarity bring forwards new requests on the auto-startup and power regulating system. By comprehensive theoretic analysis and simulation computation, we get the appropriate control methods and moving logic of 4 shim rods, learn the influence of parts' characteristic on system, and acquire the theoretic guidance and basis for the system design.The following research works are carried out in this paper:1. On the basis of abroad literature study, combined with the operating demands of CARR, the classic PID control is determined as the control scheme for the auto-startup and power regulating system;2. Discrete control theory is applied to analyze the closed loop system in order to prove the stability of it, and the main control parameters are attained by analysis, e.g. the sampling period and the proportional coefficient;3. Based on the simulation flat in Matlab-Simulink, simulation models of parts of closed loop system are founded, and actual characteristic of these parts is described in these models.4. Two kinds of control methods, the proportion methods and the period corrected proportion method, are put forward in this paper, and 2 controllers models for these 2 methods are founded. Two kinds of moving logic for 4 shim rods to keep them at almost same position are proposed in this paper, and by using Stateflow of Simulink, corresponding simulation models for 2 logic are founded.5. Comprehensive simulation computation about the power regulating process is carried out in this paper. The response of the closed loop system to step and slope reactivity disturbance is computed under different control methods, different moving logic of shim rods and different parts' characteristic. By simulation, the best control method and moving logic of shim rods for power regulation are gotten, the influence of parts' characteristic on the whole closed loop system is showed, and the capability of each part is requested.6. By detailed simulation computation about the process of reactor startup, power rising and descending, the control method and moving logic of shim rods for automatic reactor operations are acquired, and the function of automatic startup and power transition between different power levels of the system is realized.On the basis of theoretic analysis and simulation computation, a redundancy system is designed and developed. The system has 2 redundant channels, in which same modules are configured. The 2 channels are running simultaneity, but output from just one channel iseffective. Output from 2 channels can be switched from one channel to another undisturbedly by switcher, so redundant and hot standby CPU, power supply, communication and I/O are realized. The human Machine Interface is developed, and the control program is developing presently.The research and development of the digital auto-startup & power regulating system found a solid basis for the future stable operation of CARR, and the implementation of the system promotes the application of digital control technology for reactors in China.