Patent Number: 044407190
Section: summary

BACKGROUND This invention relates to the steam-driven injection of water into a vessel and more particularly relates to the cooling of water subject to multiple-stage steam-driven injection into the pressure vessel of a nuclear system. Pressure vessels in nuclear reactors may operate at pressures in excess of 1,000 psi in the course of generating steam for power production. It is desirable to employ the steam generated within the pressure vessel to insure the presence of an ample supply of cooling water in the core of the nuclear system. Presently, as for example shown in U.S. Pat. No. 3,431,168 (which relates to an invention by J. E. Kjemtrup, was issued on Mar. 4, 1969, and is expressly referred to and incorporated herein, a sufficient water level within the pressure vessel is insured by employing a turbine-driven pump which is an expensive and complex assembly of components including a steam-driven turbine rotating a shaft for driving the pump. In other arrangements, the pump is driven by an electric motor which requires substantial active controls and depends upon electrically operated speed governing equipment for operation. The pump is accordingly subject to failure during a loss of electric power. In the past, and as shown in U.S. Pat. No. 722,696, issued to W. W. Green on Mar. 17, 1903, a form of multiple-stage steam-driven injection of water into vessels has been accomplished. However, in such kinds of steam-driven water injection, irrespective of whether the stages are arranged in series or parallel or combinations thereof, the output of each stage produces heated water, which reduces the efficiency of subsequent stages. OBJECTS OF THE INVENTION Accordingly, it is an object of this invention to provide a passive, or non-electrically operated multi-stage steam-driven water injection system for supplying water to the pressure vessel of a nuclear system that is not subject to electrical failure, since it can be selectively and manually controlled. Another object of the instant invention is to cool the water departing from selected steam-driven stages of a multiple-stage water injection system. It is a further object of the present invention to supply water to the pressure vessel of a nuclear system by employing an injection or water supply system that is inexpensive, uncomplicated, and simple to maintain. SUMMARY The invention calls for stepwise increasing the pressure level of cooling water available from one or more of various containers such as for example the fuel pool, the suppression pool, or the condensate tank of a nuclear system. The increased pressure level is required to overcome the back pressure of the pressure vessel into which the water is sought to be injected and which operates at pressures of about 1,000 psi or above. The desired output pressure level of the injection system is attained in stages by employing steam generated in the pressure vessel itself. Two steam-driven water injectors are arranged in series with a cooling device such as for example a heat exchanger cooling the water flowing therebetween. A jet pump initially receives the water from one or more of the containers to which reference has already been made. Feedback water from the output of the first steam-driven water injector is cooled and propels the input water through the jet pump and into the first steam injector.