Patent Number: 058621954
Section: description

DETAILED DESCRIPTION OF THE INVENTION After service in power plant nuclear reactor spent fuel rods 1 which can no longer heat to efficiently make steam are put into the power plants water storage pool 2 for about five years or more of further radioactive decay or heat reduction. After time, clusters of the typically fourteen foot long spent fuel rods 1 are put into cylindrical canisters 3, "MPC"s 3, for transport and dry storage. Fuel rods 1 are typically loaded into "MPC"s 3 under the pool water 2 where the canister 3 loading has the shielding of the water 2 during this operation. "MPC" 3 is a term or name for a popular design called a multi-purpose-canister 3 where the "MPC" 3 is used for both the transport of the fuel rods 1 and storage of the fuel rods 1. A proposed "MPC" 3 has shielding on its top to shield operators making its closure. "MPC"s 3 are usually standing vertical, an exception is when they lay horizontal during transport. For interplant transfer from the wet to the dry storage the inventors preferred design is to keep the "MPC" 3 vertical. Loaded and sealed "MPC"s 3 are crane 4 lifted from the plant's water storage pool 2, carried through a shielded corridor 6, placed into a transporter 7 which rides on a RR-track 8 or roadway. The transporter 7 has walls and floor with radiation shielding 9 to confine radiation when the transporter 7 is outside in the open 11 between the wet pool 2 storage and dry-pool 12 storage. The "MPC" 3 containing transporter 7 enters the storage field area 13 which has radiation shielding 14 by either strategically placed panels 14, or storage casks 16 themselves, or the building 17 over the dry-pool which may be the primary shield for the entire storage site 13. The transporter 7 enters on tracks 8 extending from the load out at the plant water pool 2. At the field 13 or in the building 17 other tracks 18 carry a bridge crane 19 which picks an "MPC" 3 from the transporter 7. Doors 21 in the transporter 7 shielding 9 allows a horizontal exodus of the "MPC" through a shielded corridor 22 to an entrance 23 of the dry-pool 24. Walls 26 of an on plane dry-pool 27 provide shielding to move the "MPC" to the its storage spot 28. Once in position a seismic brace 29 hinged to the wall 26 secures the "MPC" 3 standing vertical. In a submerged dry-pool 31 a vertical chase 32 provides a falling floor 33 so as the "MPC" 3 is lowered to the dry-pool 31 floor 34 should the "MPC" 3 be dropped, it would fall less than eighteen inches to an impact. The falling floor 33 is a mechanically moving device which would move with the "MPC" 3. A most simple form of a hydraulic device is simply a pool of water 36 confined by water lock gates 37. The lock water 36 surface would provide a cushioned fall and only an obvious and massive leak would foil the safety process. When the "MPC" 3 gets to the dry-pool 31 floor 34 the water lock gates 37 are opened and the bridge crane 19 then carries the "MPC" 3 to its selected storage spot 28. As described before, again, a hinged seismic brace 29 secures the top of the "MPC" 3 to the dry-pool 31 walls 26. At the storage spot 28 around the perimeter of the standing "MPC" 3 vertical holes 38 communicated with a horizontal pipe 39 which brings in outside air 41 for cooling the surface of the standing "MPC" 3. In the on plane dry-pool 27 configuration the horizontal pipe 39 may extend directly out to the outside air atmosphere 41 without a basin 42. In the submerged dry-pool configuration 31 an outside basin 42 extends down from the ground surface 43 where the sub-floor 34 horizontal pipe 39 extends horizontally to into the outside air entrance basin 42 so outside air 41 can sink into the basin 42, then proceed under the dry-pool 31 floor 34, then proceed up the circumferential holes 38 to cool surface of the "MPC" 3. The cooling air 41 would then be vented back to the atmosphere 41 by exiting to the outside of the building 17. In the submerged dry-pool configuration 31, if additional shielding should be desired, then the dry-pool 31 could be filled with water 44 which would then provide shielding typical of the wet pool 2 configuration. Then, again, by draining the water 44 out the dry-pool 31 it would return to its dry configuration. After such an exercise, it would be well to check the "MPC"s 3 for water leakage from the pool into the vessels. A building 17 having a thick concrete roof 46 and thick concrete walls 47 combined with vertical shielding 14 will shield the ambient atmosphere 48 from outward radiation 49 but still allow a transporter 7 and the servicing bridge crane 19 to freely enter and exit the storage field 13 or storage building 17. The field 13 and storage building 17 are un-manned and the storage operation is orchestrated from an off-site control center 51.