Protection of aluminum during a loss-of-coolant accident

Abstract

A method for reducing corrosion of an aluminum or aluminum alloy material by contacting the surface of the material with an aqueous solution comprising silicon dissolved therein. The aqueous solution can be reactor containment pool cooling water following a loss-of-coolant accident or an aqueous pretreatment solution. The dissolved silicon can comprise a dissolvable compound of silicon and oxygen, such as a silicate compound.

1 . A method for reducing corrosion of a material comprised of aluminum or aluminum alloy, comprising contacting a surface of the material with an aqueous solution comprising silicon dissolved therein. 
   
   
       2 . The method of  claim 1  wherein the aqueous solution comprises reactor cooling water following a loss-of-coolant accident. 
   
   
       3 . The method of  claim 1  wherein the aqueous solution comprises a pretreatment solution. 
   
   
       4 . The method of  claim 1  wherein the aqueous solution comprises a pH in the range of about 7 to about 11. 
   
   
       5 . The method of  claim 4  wherein the aqueous solution comprises borate. 
   
   
       6 . The method of  claim 5  wherein the aqueous solution comprises borate in a concentration of about 2000 to about 2800 mg/L as B. 
   
   
       7 . The method of claim I wherein the silicon comprises a water-dissolvable compound of silicon and oxygen. 
   
   
       8 . The method of  claim 4  wherein the compound comprises a silicate compound. 
   
   
       9 . The method of  claim 1  wherein the aqueous solution comprises greater than zero to not exceeding 1000 mg/L as Si. 
   
   
       10 . The method of  claim 9  wherein the aqueous solution comprises greater than zero to not exceeding 500 mg/L as Si. 
   
   
       11 . The method of  claim 10  wherein the aqueous solution comprises about 20 to about 100 mg/L as Si. 
   
   
       12 . The method of  claim 11  wherein the aqueous solution comprises about 45 to about 100 mg/L as Si. 
   
   
       13 . A method for reducing corrosion of a material comprised of aluminum or aluminum alloy exposed to reactor cooling water following a loss-of-coolant-accident, comprising providing a corrosion-inhibiting agent comprising silicon in the cooling water and contacting a surface of the material the cooling water. 
   
   
       14 . The method of  claim 13  wherein the cooling water has a pH in the range of about 7 to about 11 and includes borate. 
   
   
       15 . The method of  claim 13  wherein the cooling water includes borate in a concentration of about 2000 to about 2800 mg/L as B. 
   
   
       16 . The method of  claim 13  wherein the corrosion-reducing agent comprises a dissolvable compound of silicon and oxygen. 
   
   
       17 . The method of  claim 16  wherein the compound comprises a silicate compound. 
   
   
       18 . The method of  claim 13  wherein the agent is provided in the cooling water by introducing it into emergency cooling water spray, by introducing it into a cooling water pool, and/or by exposing the agent to spilled cooling water. 
   
   
       19 . The method of  claim 13  wherein the cooling water comprises greater than zero to not exceeding 1000 mg/L as Si. 
   
   
       20 . The method of  claim 19  wherein the cooling water comprises greater than zero to not exceeding 500 mg/L as Si. 
   
   
       21 . The method of  claim 20  wherein the cooling water comprises about 20 to about 100 mg/L as Si. 
   
   
       22 . The method of  claim 21  wherein the cooling water comprises about 45 to about 100 mg/L as Si. 
   
   
       23 . A method of pretreating aluminum or aluminum alloy, comprising contacting a surface of the aluminum or aluminum alloy with an aqueous solution that includes silicon therein in a manner to form a layer on the surface. 
   
   
       24 . The method of  claim 23  wherein the aqueous solution comprises a pH in the range of about 7 to about 11. 
   
   
       25 . The method of  claim 23  wherein the silicon comprises a water-dissolvable compound of silicon and oxygen. 
   
   
       26 . The method of  claim 25  wherein the compound comprises a silicate compound. 
   
   
       27 . The method of  claim 23  wherein ionic species H 3 SiO 4   −  reacts with the surface to form a layer of insoluble Al 2 OSiO 4 . 
   
   
       28 . The method of  claim 27  wherein said layer inhibits oxidation reactions from removing aluminum from the solid surface. 
   
   
       29 . The method of  claim 23  including immersing an aluminum or aluminum alloy material, structure or component in the aqueous solution containing silicon. 
   
   
       30 . The method of  claim 23  including spraying an aluminum or aluminum alloy material, structure or component with the aqueous solution containing silicon. 
   
   
       31 . The method of  claim 23  wherein the aqueous solution comprises greater than zero to not exceeding 1000 mg/L as Si. 
   
   
       32 . The method of  claim 31  wherein the aqueous solution comprises greater than zero to not exceeding 500 mg/L as Si. 
   
   
       33 . The method of  claim 32  wherein the aqueous solution comprises about 20 to about 100 mg/L as Si. 
   
   
       34 . A chemically treated aluminum or aluminum alloy material having a layer comprising silicon thereon. 
   
   
       35 . The material of  claim 34  having a layer comprising aluminum and silicon. 
   
   
       36 . The material of  claim 35  having an insoluble aluminosilicate coating. 
   
   
       37 . The material of  claim 34  which comprises a subsurface marine material, water quality treatment material, a chemical processing material, a mining material, drilling material, an aviation construction material, an automotive construction material, a pipe material, or pump material.