METHOD OF CONTROL OF A NUCLEAR REACTOR BY MOVEMENT WITHIN THE CORE OF THIS REACTOR OF GROUPS OF CONTROL RODS

A nuclear reactor associated with a turbine is controlled by determining a control value of the diff. between turbine demand power and actual power produced by the core, determining the position of the value in a range straddling zero, and moving groups of control rods in given sequence in a direction determined by the sign of the value and at a proportional speed when the value is outside the range. Axial power distribution in the core is determined and movement of the control rod groups is further controlled in relation to this. Use of control rods is pref. accompanied by a system for controlling the content of soluble boron is coolant contacting fuel elements in the core.