Patent ID: 8654916
Filing Date: 2014-02-18
Classification: G21C,G21D,Y02E

Abstract:
1. A method for regulating operational parameters of the core of a pressurized water nuclear reactor, the nuclear reactor having: a core which is divided into an upper zone and a lower zone, and produces thermal power; a plurality of groups of rods for controlling the reactivity of the core, each of which occupies, in the core, a plurality of insertion positions which are stepped vertically starting from an upper position; means for inserting each group of rods in the core vertically; a primary circuit which assures the circulation of a primary cooling fluid through the core; means for adjusting the concentration of a neutron-absorbent component in the primary cooling fluid; and means for acquiring values which are representative of the conditions of operation of the core of the reactor, wherein the regulation method comprises: a step of acquiring values representative of (1) thermal power produced in the upper and lower zones of the core, (2) temperatures of hot and cold branches, and (3)flow of primary cooling fluid, which are representative of the conditions of operation of the core of the reactor; a step of evaluation of actual values of (i) mean temperature of the primary cooling fluid in the core, (ii) axial distribution of thermal power between the upper and lower zones of the core, and (iii) a parameter representative of capacity to increase power of the reactor corresponding to the thermal power which is produced by the core when the groups of rods are raised to the vicinity of the upper position, which values (i)-(iii) are collectively the operational parameters, this evaluation being performed at least as a function of the values acquired; a step of selection of either a first control law or a second control law to control (a) the concentration of the absorbent component, and (b) positions of insertion of the groups of rods, the first control law being different from the second control law, wherein the first control law is selected as soon as at least one group of rods is in an insertion position lower than a predetermined position, and the second control law is selected as soon as all the groups of rods are in respective insertion positions above said predetermined position; a step of calculating set points of the operational parameters at least as a function of control set points; and a step of regulation of the operational parameters as a function of set points relating to said parameters and of the actual values evaluated, by means of the selected control law, modifying the positions of insertion of the groups of rods as a function of the deviation of the mean temperature of the primary cooling fluid in the core with regard to its set point, in order to regulate the mean temperature of the primary cooling fluid in the core to its set point; modifying the positions of insertion of the groups of rods as a function of the deviation of the axial distribution of power with regard to its set point, in order to regulate the axial distribution of power to its set point; and adjusting the concentration of the neutron-absorbent component in the primary cooling fluid as a function of the deviation from its set point of the parameter which is representative of the capacity to increase power of the reactor corresponding to the thermal power produced by the core when the groups of rods are raised to the vicinity of the upper position, which is representative of the capacity to increase the power of the reactor to its set point, in order to regulate the said increase power capacity to its set point; and wherein the second control law comprises the following steps, in any order: modifying the positions of insertion of the groups of rods as a function of the deviation of the mean temperature of the primary cooling fluid in the core with regard to its set point, in order to regulate the mean temperature of the primary cooling fluid in the core to its set point; adjusting the concentration of the neutron-absorbent component in the primary cooling fluid as a function of the deviation of the axial distribution of power with regard to its set point, in order to regulate the axial distribution of power to its set point; and modifying the positions of insertion of the groups of rods as a function of the deviation from its set point of the parameter which is representative of the capacity to increase power of the reactor corresponding to the thermal power produced by the core when the groups of rods are raised to the vicinity of the upper position, which is representative of the capacity to increase the power of the reactor to its set point, in order to regulate the said increase power capacity to its set point.