Patent Number: 048448575
Section: summary

The invention relates to a pressurized water reactor and, more particularly, to a reactor with a primary circuit including therein a reactor pressure vessel, a steam generator and a main coolant pump, and with an auxiliary system having high-pressure pumps for feeding water into the primary circuit, the auxiliary system being connected with the reactor pressure vessel through a line extending from the upper side of the latter and having at least one shut-off or isolating valve therein. In installations of the afore-described type, cold water was heretofore introduced into the reactor pressure vessel, to condense steam which may be present therein as a result of a leak. This requires pumps with a feed pressure higher than the steam pressure in the reactor pressure vessel. The cold water serving to effect the condensation can lead to thermal stresses, however, which are all the more undesirable whenever there is a failure. It is accordingly an object of the invention to provide a pressurized water reactor which, in case of a power failure, when the main cooling pumps do not operate, and cooling of the reactor pressure vessel has broken down, removes hot cooling liquid in the upper part of the reactor pressure vessel without introducing cold water into the reactor pressure vessel by means of strong pumps. With the foregoing and other objects in view, the invention which utilizes a technique exactly opposite that used in the heretofore known state of the art provides for a pressurized water reactor with a primary circuit including therein a reactor pressure vessel, a steam generator and a main coolant pump, and with an auxiliary system having high pressure pumps for feeding water into the primary circuit, comprising a line extending from an upper side of the pressure vessel and having at least one shut-off valve therein, the line connecting the reactor pressure vessel and a part of the auxiliary system wherein a lower pressure prevails than in the reactor pressure vessel. With such construction, an outlet for the hot coolant is created, and the hot coolant is cooled outside of the reactor pressure vessel. In accordance with another feature of the invention, the line is connected to the suction side of a water-jet pump, which is supplied and operated with the water of the auxiliary system as the working or driving fluid. The water-jet pump effects an intimate mixing with the colder water of the auxiliary system. Furthermore, a defined negative pressure can thereby be generated. In accordance with a further feature of the invention, the auxiliary system used a volume control system of the pressurized water reactor, because the volume control system already had adequately dimensioned pumps for feeding water into the primary circuit. With these pumps, the coolant can be returned to the primary circuit, so that the liquid level therein is not reduced. In accordance with an alternate feature of the invention, the auxiliary system is a boron-addition system of the pressurized water reactor, which is likewise provided with high pressure pumps. Furthermore, the auxiliary systems, regardless of the construction thereof, can be connected with the reactor pressure vessel by a motor-driven pump, for example, a centrifugal pump, in order to remove coolant by suction in a metered or dosed manner. In accordance with an added feature of the invention, a temperature measuring station is provided in the line, so that the temperature of the discharging coolant can be used for controlling the quantitative discharge flow hereof, or the like. In accordance with a concomitant feature of the invention, the pressure vessel has a conventional cover closing the top thereof, and the line extends from the cover of the pressure vessel. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a pressurized water reactor, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit or the invention and within the scope and range of equivalents of the claims. The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which: