System and method for reclaiming energy from heat emanating from spent nuclear fuel

Abstract

The present invention provides a system and method for reclaiming energy from the heat emanating from spent nuclear fuel contained within a canister-based dry storage system. The inventive system and method provides continuous passive cooling of the loaded canisters by utilizing the chimney-effect and reclaims the energy from the air that is heated by the canisters. The inventive system and method, in one embodiment, is particularly suited to store the canisters below-grade, thereby utilizing the natural radiation shielding properties of the sub-grade while still facilitating passive air cooling of the canisters. In another embodiment, the invention focuses on a special arrangement of the spent nuclear fuel within the canisters so that spent nuclear fuel that is hotter than that which is typically allowed to be withdrawn from the spent fuel pools can be used in a dry-storage environment, thereby increasing the amount energy that can be reclaimed.

What is claimed is: 
     
         1 . A method for reclaiming energy from spent nuclear fuel comprising:
 positioning at least one canister containing spent nuclear fuel emanating heat in each of a plurality of storage cavities having substantially vertical axes and arranged in a spaced-apart side-by-side manner;   heating air within each of the storage cavities via the canisters which rises to a top portion of the storage cavities;   collecting the heated air from the top portions of the storage cavities with an air outlet manifold forming a first portion of an air outlet passageway, the air outlet manifold fluidly interconnecting each of the top portions of the storage cavities together; and   flowing the collected heated air through the air outlet passageway into a common energy reclamation chamber of an energy reclamation unit.   
     
     
         2 . The method according to  claim 1 , wherein the top portions of the storage cavities form a second portion of the air outlet passageway, the top portions of each storage cavity and air outlet manifold collectively forming an entirety of the air outlet passageway fluidly coupling each top portion of the storage cavities to the common energy reclamation chamber. 
     
     
         3 . The method according to  claim 2 , wherein the heated air flowing through the air outlet passageway en route to the common energy reclamation chamber flows through the air outlet manifold and the top portions of at least some of the storage cavities. 
     
     
         4 . The method according to claim to  claim 1 , wherein the flowing step comprises flowing the heated air from at least one storage cavity through the top portion of at least one other storage cavity to the common energy reclamation chamber. 
     
     
         5 . The method according to  claim 1 , wherein the common energy reclamation chamber is fluidly coupled directly to at least one of the top portions of one of the storage cavities. 
     
     
         6 . The method according to  claim 5 , wherein the common energy reclamation chamber is fluidly coupled directly to at least two of the top portions of the storage cavities. 
     
     
         7 . The method according to  claim 6 , wherein the common energy reclamation chamber is fluidly coupled directly to three top portions of the storage cavities. 
     
     
         8 . The method according to  claim 2 , wherein each storage cavity is defined by an elongated storage shell extending along the vertical axis of the storage cavity. 
     
     
         9 . The method according to  claim 8  wherein the storage shells are arranged in a rectilinear grid array comprising a plurality of parallel rows of spaced apart storage shells. 
     
     
         10 . The method according to  claim 9 , wherein the air outlet manifold comprises a plurality of perpendicularly arranged piping segments which fluidly couple to top portions of the storage cavities together. 
     
     
         11 . The method according to  claim 10 , wherein a first group of piping segments are arranged parallel to a centerline defined by each row of storage shells and a second group of piping segments arranged perpendicularly to the first group and the centerlines of the rows. 
     
     
         12 . The method according to  claim 1 , wherein the top portions of the storage cavities are only fluidly connected to ambient atmosphere through the common energy reclamation chamber. 
     
     
         13 . The method according to  claim 1 , further comprising reclaiming energy from the heated air in the common energy reclamation chamber via the energy reclamation unit. 
     
     
         14 . The method according to  claim 13 , wherein the reclaiming step includes the energy reclamation unit extracting heat from the heat air in the common energy reclamation chamber and transferring the extracted heat to a secondary working fluid flowing through the energy reclamation unit. 
     
     
         15 . The method according to  claim 14 , wherein the energy reclamation unit is a heat exchanger comprising tubes which carry the secondary working fluid. 
     
     
         16 . The method according to  claim 1 , further comprising a vertically oriented air intake shell fluidly coupled to ambient atmosphere and arranged among the storage cavities, the air intake shell fluidly coupled to bottom portions of each of the storage cavities. 
     
     
         17 . The method according to  claim 16 , further comprising a step of drawing ambient cooling air into air intake shell and distributing the cooling air to the bottom portions of each storage cavity via an air inlet manifold fluidly interconnecting the bottom portions and the air intake shell. 
     
     
         18 . A method for reclaiming energy from spent nuclear fuel comprising:
 providing a vertically oriented air intake shell fluidly coupled to ambient atmosphere and a plurality of vertically oriented storage shells each defining a storage cavity, the air intake shell and storage shells being spaced apart in a grid array;   and arranged among the storage cavities, the air intake shell fluidly coupled to bottom portions of each of the storage cavities.   positioning at least one canister containing spent nuclear fuel emanating heat in each of the storage cavities;   drawing ambient cooling air into air intake shell and distributing the cooling air to bottom portions of each storage cavity via an air inlet manifold, the bottom top portions of each storage cavity and air inlet manifold collectively forming an air inlet passageway;   heating air within each of the storage cavities via the canisters which rises to a top portion of the storage cavities;   collecting the heated air from the top portions of the storage cavities with an air outlet manifold fluidly coupled to and fluidly interconnecting each of the top portions together, the top portions of each storage cavity and air outlet manifold collectively forming an air outlet passageway; and   flowing the collected heated air through the air outlet passageway into a common energy reclamation chamber of an energy reclamation unit;   extracting heat from the heated air using the energy reclamation unit which cools the heated air; and   discharging the cooled air to ambient atmosphere from the common energy reclamation chamber.   
     
     
         19 . The method according to  claim 18 , wherein the air outlet manifold and air inlet manifold each comprise a plurality of perpendicularly arranged piping segments which fluidly couple to top portions and the bottom portions of the storage cavities together, respectively. 
     
     
         20 . The method according to  claim 18 , wherein the cooling air flows from ambient atmosphere vertically downwards in the air intake shell, horizontally through the air inlet manifold into the bottom portion of the storage shells, vertically upwards through storage shells to the top portions, and horizontally from the top portions through the air outlet manifold to the common energy reclamation chamber and then back to ambient atmosphere.