Patent Number: 047284854
Section: description

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT In FIG. 2 the measuring signal of the water level in the pressurizer, taken at 19, is applied to the regulator 18 of the charging valve 17 through a switch 30. In the same way, the regulation loop 12 of the discharging valve 10, from the pressure detector 11, passes through a switch 31 which receives an another stud the output signal of a comparator 33. The comparator 33 receives the signal from a pressure detector 34, mounted directly in the primary circuit of the reactor; a signal representing a reference pressure is applied through 35 to the comparator 33. In addition, the regulating valve 23 for the sprinkling flow rate is controlled through a regulator 36 which, through a switch 37, receives the output signal from a comparator 38. The comparator 38 receives the signal from a flow rate detector 40 located downstream of the valve 10 in the discharge line, and the signal from a flow rate detector 41 located downstream of the valve 17 in the charging line; an increaser-decreaser 42 is inserted between the detector 41 and the comparator 38. When the three switches 30, 31 and 37 have swung to the left, the reverse of that which is shown in FIG. 2, all the regulation circuits are in the same state as in FIG. 1. It is under these conditions that the first phase of cooling the primary circuit is effected, with continuous sprinkling from the primary circuit, regulation of the discharge flow rate as a function of the pressure taken downstream of the high pressure expansion orifices 9, and regulation of the charging flow rate as as function of the water level in the pressurizer. When the water level reaches the upper part of the pressurizer, and it is no longer possible to follow its development exactly, the switches are swung over to the position of FIG. 2, which permits the automatic resorption of the bubble by the bringing into action of two regulating circuits coupled and having different reaction speeds. The charging flow rate is kept constant through the valve 17 whose regulator 18 is isolated from the measurement 19. The comparison, at 33, of the actual primary pressure measured at 34, with a reference pressure set by 35, controls through the high reaction speed regulator 12 the opening of the discharge valve 10 and creates a discharging flow rate. This discharging flow rate is measured at 40, and compared at 38 with a developed reference flow rate, by decrease at 42, from the charging flow rate measured at 41. The signal resulting from this comparison is applied to the lower speed reaction regulator 36 which controls the opening of the valve 23 and results in sprinkling of the pressurizer. This sprinkling results in a condensation of vapor and reduction in the primary pressure; the primary pressure drop is immediately reflected by the circuit 34-33-12 in a reduction in the opening of the discharge valve 10, and the sprinkling is maintained until the reduction of the discharging flow rate to its reference value. This operation is repeated until the action on the decreaser 42 no longer has an effect on the discharge flow rate. It is then certain that the bubble has been resorbed. At this time there is in fact no longer condensation of steam requiring replacement by an equivalent volume of water, but all proceeds as if all the charging flow rate were directly introduced into the piping of the primary circuit, without by-pass to the sprinkling of the pressurizer; the only effect of the sprinkling is then that of cooling the pressurizer and homogenizing the temperature of the latter with that of the circuit. After disappearance of the bubble, the cooling can continue with regulation of the pressure through the discharge valve. It is also possible to provide still more complete automation by causing the development through a mini-computer of the switching functions of the regulation modes before complete collapse of the vapor bubble and of the sprinkling control functions for the end of resorption of the bubble through successive levels, or continuously. It will also be noted that these regulating circuits can also, on the contrary, be used to pass from a mono-phase state to a bi-phase state, if a regulator homologous with the regulator 36 is used for controlling the vaporization heating rods in the pressurizer. Then there is developed for the comparator 38, a reference signal increased at 42 with respect to the measuring signal of the charging flow rate at 41, and the process is then the reverse of that which was described above when the signal from 41 was decreased at 42. The regulating method can be carried out manually by proceeding with successive sprinklings by direct action on the valve 23, and by detecting by a simple measurement of the flow rate at 40 if this sprinkling has resulted in a condensation of vapor, hence a drop in the primary pressure and an immediate variation in the discharge flow rate.