Passively-cooled spent nuclear fuel pool system

Abstract

A passively-cooled spent nuclear fuel pool system in one embodiment includes a containment vessel comprising a thermally conductive shell and an annular reservoir surrounding the shell that holds a liquid coolant forming a heat sink. A spent fuel pool is disposed inside the containment vessel and includes a body of water in contact with a first peripheral sidewall of the fuel pool. At least one spent nuclear fuel rod submerged in the body of water heats the water. The first peripheral sidewall of the spent fuel pool is formed by a portion of the shell of the containment vessel adjacent to the fuel pool, thereby defining a shared common heat transfer wall. The heat transfer wall operates to transfer heat from the body of water in the spent fuel pool to the heat sink to cool the body of water. The heat transfer wall comprises metal in one embodiment.

What is claimed is: 
     
         1 . A passively cooled spent nuclear fuel pool system, the system comprising:
 a containment vessel comprising a thermally conductive cylindrical shell formed of metal;   an annular reservoir surrounding the cylindrical shell of the containment vessel, the annular reservoir holding a liquid coolant to form a heat sink; and   a spent fuel pool disposed inside the containment vessel, the fuel pool comprising:
 a floor and a first peripheral sidewall extending upwards from the floor that collectively define an interior cavity; 
 a body of water disposed in the interior cavity and having a surface level, the water being in contact with the first peripheral sidewall; and 
 at least one spent nuclear fuel rod submerged in the body of water that heats the body of water; 
   wherein the first peripheral sidewall of the fuel pool is formed by a portion of the cylindrical shell of the containment vessel adjacent to the spent fuel pool which defines a shared common heat transfer wall, the heat transfer wall operable to transfer heat from the body of water in the spent fuel pool to the heat sink for cooling the body of water.   
     
     
         2 . The system according to  claim 1 , wherein the annular reservoir contains water as the liquid coolant having a lower temperature than the body of water in the spent fuel pool. 
     
     
         3 . The system according to  claim 1 , wherein the heat transfer wall has an arcuate shape in top plan view. 
     
     
         4 . The system according to  claim 1 , further comprising a vertically oriented flow partition plate disposed in at least a portion of the annular reservoir adjacent the heat transfer wall, the flow partition plate spaced radially apart from the heat transfer wall and configured to define a first convective flow path that induces natural gravity circulation of the liquid coolant in the annular reservoir. 
     
     
         5 . The system according to  claim 4 , wherein the flow partition plate has substantially arcuate shape in top plan view. 
     
     
         6 . The system according to  claim 4 , wherein the flow partition plate includes a bottom spaced above a base mat of the annular reservoir and a top spaced apart below a top end of the annular reservoir such that a liquid coolant circulation flow path is formed over and under the flow partition plate. 
     
     
         7 . The system according to  claim 6 , wherein heated liquid coolant in the annular reservoir circulates vertically upward along the heat transfer wall between the flow partition plate, horizontally outward over a top of the flow partition plate, vertically downward along a side of the flow partition plate opposite the heat transfer wall, and horizontally inward beneath at least a portion of the flow partition plate back towards the heat transfer wall to complete the first convective flow path. 
     
     
         8 . The system according to  claim 7 , wherein water in the spent fuel pool cooled by exchanging heat through the heat transfer wall to the annular reservoir circulates vertically downward along the heat transfer wall in an opposite direction to the heated liquid coolant in the annular reservoir. 
     
     
         9 . The system according to  claim 8 , further comprising a vertically oriented flow partition wall disposed in the spent fuel pool between a spent fuel rack storage area on the floor and the heat transfer wall, the flow partition wall configured to define a second convective flow path that induces natural gravity circulation of the body of water in the fuel pool. 
     
     
         10 . The system according to  claim 9 , wherein the flow partition wall includes a bottom spaced above the floor of the spent fuel pool and a top spaced below the surface level of the body of water such that a water circulation flow path is formed over and under the flow partition wall. 
     
     
         11 . The system according to  claim 9 , wherein the flow partition wall in the spent fuel pool has an arcuate shape in top plan view. 
     
     
         12 . The system according to  claim 10 , wherein the flow partition wall spans horizontally between opposing second and third peripheral walls formed of concrete which intersect the heat transfer wall. 
     
     
         13 . The system according to  claim 1 , further comprising a vertically oriented flow partition wall disposed in the spent fuel pool between a spent fuel rack storage area on the floor and the heat transfer wall, the flow partition wall configured to define a convective flow path that induces natural gravity circulation of the body of water in the fuel pool. 
     
     
         14 . The system according to  claim 13 , wherein the flow partition wall is disposed proximally to the heat transfer wall. 
     
     
         15 . The system according to  claim 4 , further comprising a plurality of heat exchange fins extending radially outwards from cylindrical shell of the containment vessel into the annular reservoir, and wherein the flow partition plate is supported between a pair of the heat exchange fins. 
     
     
         16 . The system according to  claim 15 , wherein the flow partition plate is comprised of a plurality of segments each attached between a pair of heat exchange fins. 
     
     
         17 . The system according to  claim 1 , wherein the annular reservoir is vented to atmosphere for cooling the liquid coolant via evaporative loss. 
     
     
         18 . The system according to  claim 1 , wherein the annular reservoir is formed between the cylindrical shell of the containment vessel and a cylindrical shell of a containment enclosure surrounding the containment vessel. 
     
     
         19 . A passively cooled spent nuclear fuel pool system, the system comprising:
 a containment vessel comprising a thermally conductive cylindrical shell formed of metal;   an annular reservoir surrounding the cylindrical shell of the containment vessel, the annular reservoir holding a liquid coolant to form a heat sink; and   a spent fuel pool disposed inside the containment vessel, the fuel pool comprising:
 a floor formed of concrete; 
 a plurality of concrete peripheral sidewalls extending upwards from the floor that collectively define an interior cavity configured for holding at least one spent fuel rack comprising a plurality of nuclear spent fuel rods; 
 a shared common heat transfer wall formed by a portion of the metal cylindrical shell of the containment vessel and arranged between the spent fuel pool and the annular reservoir; 
 a body of water disposed in the interior cavity and having a surface level, the water being in contact with the common heat transfer wall; and 
 the spent nuclear fuel rods submerged in the body of water operable to heat the body of water; 
   a vertically oriented flow partition plate disposed in a portion of the annular reservoir adjacent to the common heat transfer wall, the flow partition plate spaced radially apart from the common heat transfer wall and configured to define a first convective flow path that induces natural gravity circulation of the liquid coolant in the annular reservoir along the common heat transfer wall;   wherein the common heat transfer wall is operable to conductively transfer heat from the body of water in the spent fuel pool to the heat sink for cooling the body of water.   
     
     
         20 . The system according to  claim 19 , wherein the flow partition plate is configured to create a liquid coolant circulation flow path over and under or through a bottom portion of the flow partition plate. 
     
     
         21 . The system according to  claim 20 , further comprising a vertically oriented flow partition wall disposed in the spent fuel pool between the at least one spent fuel rack and the heat transfer wall, the flow partition wall configured to define a convective flow path that induces natural gravity circulation of the body of water in the fuel pool along the common heat transfer wall. 
     
     
         22 . The system according to  claim 21 , wherein the flow partition wall is configured to create a liquid coolant circulation flow path over and under or through a bottom portion of the flow partition wall.