Method for protecting components of a primary system of a boiling water reactor in particular from stress corrosion cracking

Abstract

A method for protecting the components of the primary system of a boiling water reactor, especially against stress cracking corrosion, includes feeding a reducing agent into the primary coolant in order to reduce the number of substances having a oxidizing effect or in order to modify the electrochemical potential of the component surfaces covered with an oxide layer to negative values. An alcohol that can be oxidized in the conditions of a reactor is fed in as a reducing agent, preferably in a liquid form, into the primary coolant. The component surfaces are provided with a blank coating or a single intrinsic oxide coating.

1 . A method for protecting components of a primary system of a boiling water reactor having a pressure vessel and a feedwater line opening out into the pressure vessel, the method which comprises: 
 providing an alcohol that is oxidizable under operating conditions of the primary system;    feeding the alcohol into a primary coolant to establish an alcohol concentration of from 0.1 to less than 10 μmol/kg (≈0.0032 to less than 0.32 ppm for methanol) in a downcomer, the downcomer extending downward at an opening of the feedwater line, with surfaces of the components still being bright or covered only by a native oxide layer.    
   
   
       2 . (canceled)  
   
   
       3 . The method according to  claim 1 , which comprises protecting the components against stress corrosion cracking.  
   
   
       4 . The method according to  claim 1 , which comprises feeding the alcohol into a condensate or feedwater system and carrying the alcohol into the primary system with the feedwater.  
   
   
       5 . The method according to  claim 1 , wherein the alcohol is selected from the group consisting of methanol, ethanol, and propanol.  
   
   
       6 . The method according to  claim 1 , which comprises doping the component surfaces with a precious metal.  
   
   
       7 . The method according to  claim 6 , wherein the component surfaces are doped with platinum.