Evaluation of the influence which the position of regulating elements has upon nuclear reactor stability

The present paper consists of two parts. The first part deals with a general method of calculating the degree of stability of nuclear power assemblies and an analysis of their internal safety. The second part presents an example of using the proposed method for calculating the influence which the position of regulating elements, the parameters of the internal feedback and the characteristics of the control system have upon the degree of reactor stability. The following conclusions can be drawn from the results of this work: (1) A method of calculating the degree of stability of nonlinear reactor systems has been developed; the method facilitates the determination of the greatest external effects which can be handled by the control system without emergency situations developing. (2) It was shown by way of a model problem that one can quantitatively analyze the change of the degree of reactor stability when the control elements are moved and also when the parameters of the internal negative feedback and the characteristics of the control system fluctuate. (3) This method makes it possible to determine rules for activating overcompensation which ensures a given reserve of reactor stability; the method can also be used for the operational determination of the degree of stability of a nuclear power assembly and for the analysis of its internal safety