Induced nuclear reactions: processes – systems – and elements – Handling of fission reactor component structure within... – Storage container systems for new and/or irradiated core...
Patent
1980-02-01
1982-09-07
Walsh, Donald P.
Induced nuclear reactions: processes, systems, and elements
Handling of fission reactor component structure within...
Storage container systems for new and/or irradiated core...
2505061, G21C 1900
Patent
active
043483526
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a rack for intermediate storage of nuclear reactor fuel element bundles.
Racks for intermediate storage of new fuel element bundles or of bundles removed from nuclear reactors according to the head concept of the above claim 1 are known, where the receiving tubes stand loosely on a bottom plate of a tank and are braced laterally by a structure which is firmly connected with the bottom plate and is braced laterally against the tank walls. Since for safety reasons--in view of earthquakes--considerable horizontal accelerations must be expected, the supporting structure, to be designed for buckling, becomes very massive if the intermediate storage areas are large. Thus, there result relatively large distances between the individual receiving tubes.
It is an object of the invention to provide an intermediate storage rack which at equal earthquake safety has smaller receiving tube distances, so that it is possible to lodge a given number of tube bundles in a smaller water tank or, in a water tank of given size, a larger number of fuel element bundles.
Briefly, the invention provides a storage rack for fuel element bundles. The rack is comprised of a bottom plate, a plurality of vertically disposed square receiving tubes each of which has an inwardly directed flange resting on the bottom plate and which defines a bore for centering a fuel element bundle and screws passing through each flange and into the bottom plate to secure the tubes to the plate. This construction not only requires less space than previously known racks, but also eliminates, either entirely or partly, any need for lateral bracing of a support sturcture against a tank wall. Thus, continuous channels disposed laterally of the rack for transfer of the fuel element bundles from the reactor safety tank and/or for manipulating the fuel element bundles can remain free.
The bottom plate may also be provided with passage openings aligned with each bore so that a first circulation path for the water cooling the fuel element in natural circulation is provided.
A plurality of ribs may also be secured to the underside of the plate to stiffen the plate. The ribs which extend at least in the direction of the longer dimension of the rack, provide a certain carrying capacity against buckling with a smaller thickness of the bottom plate and hence lower cost of material.
Vertically adjustable screws may also be secured to the above plate for vertically adjusting the plate. In this way, by an exact leveling of the bottom plate, not only are difficulties in applying the manipulator avoided, but moreover the danger of the bottom plate buckling in case of earthquakes is reduced.
Each tube may also be provided with lateral inlet openings for the passage of circulating water. This opens up additional paths for natural circulation of the water cooling the fuel elements. The cooling is thereby made more uniform and intensified.
A cover plate may also be mounted over the tubes with square openings coaxially of the tubes with a depending frame secured to the plate and vertical angle sections securing the frame to the bottom plate. This cover plate reduces by its damping the ability of the system to swing in case of earthquakes. Besides, it permits a simple lateral bracing of the rack elements in the region of the upper ends of the receiving tubes, whether against each other or against the tank wall.
Diagonally disposed flat rods may also be secured at each end to a respective end of an adjacent pair of angle sections. In this way, the cover plate is able to absorb higher transverse forces.
The rack may also be sub-divided into a plurality of units with connecting elements screwed into the cover plates to secure adjacent units together. In addition, the cover plates are rigidly connected with one another also in the direction of traction.
The connecting elements may also function as guides for installation and removal of the fuel element bundles. By transferring the guide function to the connecting elements, the cover plate is saved from addition
REFERENCES:
patent: 4042828 (1977-08-01), Rubinstein
patent: 4088897 (1978-05-01), Soot
patent: 4248668 (1981-02-01), Dixon
Sulzer Brothers Limited
Walsh Donald P.
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