Reactor Core

Abstract

A reactor core, comprising: an outermost region; a core region surrounded by said outermost region; a plurality of fuel support members, each of which is disposed at a lower end portion of said outermost region and said core region; and a plurality of fuel assemblies loaded in said outermost region and said core region and supported by said fuel support members, wherein a plurality of fuel assemblies disposed in said core region include a plurality of first fuel assemblies, each of which is inserted into a first coolant passage which is formed in said fuel support member and has a first resistor having an opening, and a plurality of second fuel assemblies, each of which is individually inserted into each of second coolant passage which is formed in said fuel support member and has a second resistor having an opening and a larger pressure loss than that of said first resistor; and, four fuel assemblies, each of which is adjacent to each of four lateral sides of each of a plurality of first fuel assemblies, include either three or four second fuel assemblies.

1 . A reactor core, comprising:
 an outermost region;   a core region surrounded by said outermost region;   a plurality of fuel support members, each of which is disposed at a lower end portion of said outermost region and said core region; and   a plurality of fuel assemblies loaded in said outermost region and said core region and supported by said fuel support members,   wherein a plurality of fuel assemblies disposed in said core region include a plurality of first fuel assemblies, each of which is inserted into a first coolant passage which is formed in said fuel support member and has a first resistor having an opening, and a plurality of second fuel assemblies, each of which is individually inserted into each of second coolant passage which is formed in said fuel support member and has a second resistor having an opening and a larger pressure loss than that of said first resistor; and,   four fuel assemblies, each of which is adjacent to each of four lateral sides of each of a plurality of first fuel assemblies, include either three or four second fuel assemblies.   
   
   
       2 . The reactor core according to  claim 1 ,
 wherein when said four fuel assemblies adjacent to said four lateral sides include three said second fuel assemblies, other fuel assembly among said four fuel assemblies is said first fuel assembly.   
   
   
       3 . The reactor core according to  claim 1  or  claim 2 ,
 wherein said first fuel assemblies, each of which is adjacent to either three or four said second fuel assemblies, account for more than half of said first fuel assemblies arranged in said core region.   
   
   
       4 . The reactor core according to  claim 1 ,
 wherein when distance between a center of said core region and an axis of said fuel assembly located at the furthest position from said center of said core region within the core region is represented as L, said core region includes an inner region wherein said fuel assemblies, each of which has said axis on an inner side of a L/√{square root over (2)} position in a radial direction of said core region from said center of said core region, are loaded, and an outer region surrounding said inner region; and   said first fuel assemblies and said second fuel assemblies are arranged in said inner region, and said second fuel assemblies are arranged in said outer region including no said first fuel assemblies.   
   
   
       5 . The reactor core according to  claim 1 ,
 wherein when distance between a center of said core region and an axis of said fuel assembly located at the furthest position from said center of said core region within said core region is represented as L, said core region includes an inner region wherein fuel said assemblies, each of which has said axis on an inner side of a L/√{square root over (2)} position in a radial direction of said core region from said center of said core region, are loaded, and an outer region surrounding the inner region, and   said first fuel assemblies and said second fuel assemblies are arranged in said inner region and said outer region.   
   
   
       6 . The reactor core according to  claim 4 ,
 wherein said first fuel assemblies, each of which is adjacent to either three or four said second fuel assemblies, are all of said first fuel assemblies arranged in said inner region.   
   
   
       7 . The reactor core according to  claim 5 ,
 wherein said first fuel assemblies, each of which is adjacent to either three or four said second fuel assemblies, are all of said first fuel assemblies arranged in said inner region, and also account for more than half of said first fuel assemblies arranged in said outer region.   
   
   
       8 . A reactor core, comprising:
 an outermost region;   a core region surrounded by said outermost region;   a plurality of fuel support members, each of which is disposed at a lower end portion of said outermost region and said core region; and   a plurality of fuel assemblies loaded in said outermost region and said core region and supported by said fuel support members,   wherein a plurality of said fuel assemblies disposed in said core region include a plurality of first fuel assemblies, each of which is inserted a first coolant passage which is formed in said fuel support member and has a first resistor having an opening, and a plurality of second fuel assemblies, each of which is inserted into each of second coolant passage which is formed in said fuel support members and has a second resistor having an opening and a larger pressure loss than that of said first resistor; and,   when distance between a center of said core region and an axis of said fuel assembly located at the furthest position from said center of said core region within said core region is represented as L, said core region includes an inner region wherein said fuel assemblies, each of which has said axis on an inner side of a L/√{square root over (2)} position in a radial direction of said core region from said center of said core region, are loaded, and an outer region surrounding said inner region, and   when a number of said first fuel assemblies among four said fuel assemblies separately adjacent to four lateral sides of each of said first fuel assemblies is represented as α, an average number α in said inner region is 1 or less.   
   
   
       9 . The reactor core according to  claim 8 ,
 wherein said four fuel assemblies adjacent to said four lateral sides include either three or four said second fuel assemblies.   
   
   
       10 . The reactor core according to  claim 8 ,
 wherein said second fuel assemblies are arranged in said outer region including no said first fuel assemblies.   
   
   
       11 . The reactor core according to  claim 8 ,
 wherein said first fuel assemblies and said second fuel assemblies are arranged in said outer region; and   four said fuel assemblies adjacent to said four lateral sides of each of at least a part of said first fuel assemblies located in said outer region include either three or four said second fuel assemblies.   
   
   
       12 . The reactor core according to  claim 4 ,
 wherein said first fuel assemblies, each of which is adjacent to either three or four said second fuel assemblies, are all of said first fuel assemblies arranged in said inner region.   
   
   
       13 . The reactor core according to  claim 8 ,
 wherein said average number α of said fuel assemblies in said inner region is 0.   
   
   
       14 . The reactor core according to  claim 1 ,
 wherein said first fuel assembly is fuel assembly, in-core fuel dwelling time of which is shorter than that of core average.