Patent Number: 039792579
Section: claims

1. A boiling-water reactor comprising a reactor pressure vessel having an inside and an outside and upper and lower ends, a reactor core in the inside of said vessel and positioned adjacent to said lower end, a steam dome in the inside of said vessel above said core, said vessel and steam dome forming a steam space above the steam dome inside of the vessel, said vessel having means for feeding feed water to below said steam dome and means for discharging steam from said space, at least one water separator positioned inside said vessel above said steam dome, at least one control rod drive on the outside of said vessel, a control rod drive shaft extending from said drive through said vessel into the vessel's inside, and at least one control rod insertable in said core and connected to said drive shaft, at least one standpipe extending upwardly from said steam dome into said space and having a lower end fixed to the steam dome and opening from said core, said standpipe conducting steam from below said steam dome to said steam space and having an upper portion connected with and supporting said water separator and the standpipe having an upper end opening into the water separator, said standpipe having an inside, said control rod drive being positioned above the pressure vessel's said upper end and said control rod drive shaft extending downwardly from said drive through the vessel's said upper end and said water separator and having a lower end in said inside of said standpipe, said control rod having an upper end connected to the control rod drive shaft's said lower end and said control rod depending from the lower end of said drive shaft and extending below the standpipe's said lower end below said steam dome and being insertable downwardly into said core and withdrawable upwardly from said core, and guide means for guiding said control rod vertically slidably in said inside of said standpipe. 2. The reactor of claim 1 in which said core has an upper end and a space is formed between the core's said upper end and below said steam dome, said control rod depending through said space to the core's said upper end, and the control rod has guide means formed by tracks fixed to and depending from said steam dome for slidingly guiding the control rod against deflection throughout at least a substantial portion of said space between the core's said upper end and said steam dome. 3. The reactor of claim 2 in which said control rod is shorter than the combined extents of both of said guide means so that the control rod can be completely withdrawn upwardly from said core. 4. The reactor of claim 3 having means for absorbing shock from said control rod when the control rod is dropped to a fully inserted position in said core, from a higher position.