Patent Number: 051924943
Section: claims

1. An arrangement for protecting the integrity of a nuclear reactor containment, the arrangement comprising: the nuclear reactor containment including a reactor vessel for containing a nuclear reactor core, a pool beneath the reactor vessel for receiving molten core material from the vessel, the pool being adapted to be filled with water to cool and granulate molten core material which may descend from the reactor vessel during a core meltdown to form a granulate bed of the core material in a lower part of the pool;  a tubular surface penetrating into the pool of the nuclear reactor containment and below the reactor vessel;  a pipe around the tubular surface and being so sized and separated from the tubular surface as to define a gap between them for the pipe to protect the tubular surface from the effects of the core meltdown; the pipe having an upper end and a first opening in the pipe at the upper end, the first opening being located below the height of the surface of water that will enter the pool on a meltdown and above the highest level in the pool which the granulate bed could be expected to reach; the pipe having a lower end and a second opening at the lower end, the second opening being located at the height in the pool as to be in the granulate bed, and the second opening communicating with the lower part of the pool so that water flowing into the gap through the first opening flows through the gap around the tubular surface and out through the second opening into the granulate bed to cool the granulate bed. 2. The arrangement according to claim 1, further comprising a screen device at the first opening of the pipe to prevent granulate material from entering the pipe. 3. The arrangement according to claim 2, further comprising a screen device at the second opening the pipe to prevent granulate material from entering the pipe. 4. The arrangement according to claim 2, wherein the pool further has a bottom wall which would support the granulate bed, and the tubular surface comprises a penetration through the bottom wall of the pool into the pool. 5. The arrangement according to claim 2, wherein the pool further has a side wall and the tubular surface comprises a penetration through the side wall of the pool into the pool. 6. The arrangement according to claim 2, wherein the tubular comprise the side wall of the pool. 7. The arrangement according to claim 6, further comprising a first perforated bottom wall which is above and separated from a second bottom wall to define a bottom wall gap, the first bottom wall being adapted for supporting the granulate bed, while the perforations in the first bottom wall form outlet from the bottom wall gap into the granulate bed so that water flowing into the gap through the first opening in the pipe flows through the gap between the tubular surface and the pipe and then into the bottom wall gap and into the granulate bed.