An Experimental Comparison of Reactor Power Controllers Based on the Standard and Alternate Formulations of the Dynamic Period Equation

An experimental comparison was made of reactor power controllers based on the standard and alternate formulations of the dynamic period equation. Both controllers use the `Reactivity Constraint Approach´ which is a general methodology for the digital control of power in nuclear reactors that can be described using point kinetics. The standard formulation is the basis of the MIT-CSDL Non-Linear Digital Controller, a technique that has been licensed by the U. S. Nuclear Regulatory Commission for general use on the 5 MWt MIT Research Reactor. The alternate controller is newly developed. A principal strength of both controllers is that they address the time-delayed nature of reactor dynamics. The experiments show that while the overall response of the alternate controller is slower than that of its standard counterpart, the two do have comparable 80% rise times. Also, it is noted that there are certain advantages to use of the alternate formulation. Specifically, the derivation of the alternate dynamic period equation does not require the making of any assumptions, each of the alternate equation´s component terms can be accurately measured on-line in real time, and no approximations are required in the development of the associated reactivity constraints.