Patent Number: 044903286
Section: claims

1. A gas cooled, high temperature nuclear reactor installation comprising: a prestressed concrete pressure vessel having a reactor cavity;  a steel liner for said reactor cavity attached to said pressure vessel, said steel liner having a bottom member; and  a bottom shield mounted on said bottom member of said liner wherein said bottom shield comprises:  first means for spacing said first plate from said second plate coaxially thereto; and  second means for spacing said second plate member above said bottom member of said liner.  a supporting ring formed of a plurality of interconnected supporting ring members, said supporting ring circumferentially surrounding said lower circular plate. 2. A nuclear reactor installation as claimed in claim 1 in which said upper circular plate is thinner than said lower circular plate. 3. A nuclear reactor installation as claimed in claim 2 in which said lower circular plate is provided with passage orifices to permit cooling gas to flow into the space created by said first spacing means and onto said upper circular plate. 4. A nuclear reactor installation as claimed in claim 3 wherein said first and second spacing means comprise a plurality of bearing supports. 5. A nuclear reactor installation as claimed in claim 4 further comprising: 6. A nuclear reactor installation as claimed in claim 5 wherein said.interconnecting plate members are secured by means of pins in said overlapping radial portions. 7. A nuclear reactor installation as claimed in claim 6 further comprising a plurality of sheet metal plates secured in spaced relation to one another on the upper surface of said upper circular plate by means of pins, thereby forming a plurality of expansion gaps. 8. A nuclear reactor installation as claimed in claim 7 wherein said upper circular plate has a waffle-like pattern on its upper surface. 9. A nuclear reactor installation as claimed in claim 8 wherein said upper circular plate has a ribbed lower surface. 10. A nuclear reactor installation as claimed in claim 9 wherein said distances between said bearing supports for said upper circular plate are smaller than the distances between said bearing supports for said lower circular plate.