Thermal load reducing system for nuclear reactor vessel

Abstract

In a reactor vessel thermal load reducing system near the surface level of a coolant, the present invention is characterized in that a heat conductive member is installed not contacting the reactor vessel ( 1 ) wall in an area above and below the coolant liquid surface, and the heat conducting member is a guard vessel ( 2 ) made of good heat conductivity, or a heat conductive plate ( 20 ) made of good heat conductivity.

1 . A reactor vessel thermal load reducing system comprising: 
 a reactor vessel having at least one wall and being partially filled with liquid coolant to an operating coolant liquid surface level between a bottom and a top of said reactor vessel wall, wherein said reactor vessel wall has the following vertically defined points: 
 Point A at said bottom of the wall,  
 Point C at said operating coolant liquid surface level,  
 Point E at said top of the wall,  
 Point B between Point A and Point C, and  
 Point D between Point C and Point E; and  
   a reactor vessel wall temperature difference minimizing means, said means comprising 
 a heat conductive member as a guard vessel wall located directly adjacent to said reactor vessel wall;  
 heat insulation material distributed on the inside of said reactor vessel wall from point D to point C but not from point B to point A;  
 heat insulation material distributed on the outside of said heat conductive member from point B to point D;  
 wherein during steady state operation of said reactor, said heat conductive member receives a net amount of heat radiation from said reactor vessel wall from point B to point C, and said heat conductive member radiates a net amount of heat to said reactor vessel wall from point C to point D.  
   
   
   
       2 . The reactor vessel thermal load reducing system according to  claim 1 , wherein said heat conductive member has a higher heat conduction coefficient than said reactor vessel wall.  
   
   
       3 . The reactor vessel thermal load reducing system according to  claim 2 , wherein said heat conductive member is 12% Cr steel.  
   
   
       4 . The reactor vessel thermal load reducing system according to  claim 3 , wherein said heat conductive member is 12% Cr steel.