Decontamination process

Claim 2

A process for decontaminating metal surfaces of coolant circuits of nuclear reactors and associated equipment with surfaces are contaminated with radioactive contaminants, which comprises the steps of: contacting the contaminated metal surface with an aqueous solution consisting essentially of a 0.001 to 1.0 molar solution of at least one water-soluble cerium(IV) salt in water, at a temperature in the range of from the freezing point to the boiling point of the solution, and thereby dissolving the contaminants in said solution; then removing said solution from contact with said surface and then washing said surface with water to remove residues of said solution therefrom.

Claim 3

A process according to claim 1 wherein the temperature is in the range of from 20° C. to 90° C.

Claim 4

A process according to claim 1 wherein said solution contains an effective amount of a corrosion inhibitor for inhibiting dissolution of metal from areas which have been freed from contaminants.

Claim 5

A process according to claim 3 wherein after the washing step, said surface is contacted with a reducing or complex-forming solution, at a temperature in the range of from the freezing point to the boiling point of the reducing or complex-forming solution.

Claim 6

A process according to claim 4 in which said reducing or complex-forming solution is an aqueous solution of a citrate, oxalate or ascorbate.

Claim 7

A process according to claim 1 wherein after the washing step, said surface is contacted with a reducing or complex-forming solution, at a temperature in the range of from the freezing point to the boiling point of the reducing or complex-forming solution.

Claim 8

A process according to claim 6 in which said reducing or complex-forming solution is an aqueous solution of a citrate, oxalate or ascorbate.

Claim 9

A process according to claim 1 in which said cerium salt is cerium(IV) nitrate.

Claim 10

A process for decontaminating metal surfaces of coolant circuits of nuclear reactors and associated equipment which surfaces are contaminated with radioactive contaminants, which comprises the steps of: contacting the contaminated metal surface with an aqueous solution consisting essentially of a 0.001 to 1.0 molar solution of at least one water-soluble cerium(IV) salt in water containing acid in a concentration of up to 5 molar, at a temperature in the range of from the freezing point to the boiling point of the solution, and thereby dissolving the contaminants in said solution; then removing said solution from contact with said surface and then washing said surface with water to remove residues of said solution therefrom.

Claim 11

A process for decontaminating metal surfaces of coolant circuits of nuclear reactors and associated equipment which surfaces are contaminated with radioactive contaminants, which comprises the steps of: contacting the contaminated metal surface with an aqueous solution consisting essentially of a 0.001 to 1.0 molar solution of at least one water-soluble cerium(IV) salt in water containing acid in a concentration of up to 5 molar, at a temperature in the range of from the freezing point to the boiling point of the solution, and thereby dissolving the contaminants in said solution; then removing said solution from contact with said surface and then washing said surface with water to remove residues of said solution therefrom.

Claim 12

A process according to claim 9 wherein the temperature is in the range of from 20° C. to 90° C.

Claim 13

A process according to claim 9 wherein said solution contains an effective amount of a corrosion inhibitor for inhibiting dissolution of metal from areas which have been freed from contaminants.

Claim 14

A process according to claim 11 wherein after the washing step, said surface is contacted with a reducing or complex-forming solution, at a temperature in the range of from the freezing point to the boiling point of the reducing or complex-forming solution.

Claim 15

A process according to claim 12 in which said reducing or complex-forming solution is an aqueous solution of a citrate, oxalate or ascorbate.

Claim 16

A process according to claim 9 wherein after the washing step, said surface is contacted with a reducing or complex-forming solution, at a temperature in the range of from the freezing point to the boiling point of the reducing or complex-forming solution.

Claim 17

A process according to claim 14 in which said reducing or complex-forming solution is an aqueous solution of a citrate, oxalate or ascorbate.

Claim 18

A process according to claim 9 in which said acid is a mineral acid.

Claim 19

A process according to claim 9 in which said acid is nitric acid or sulfuric acid.

Claim 20

A process according to claim 17 in which said cerium salt is cerium(IV) nitrate.

Claim 21

A process according to claim 9 in which the concentration of said acid is at least 0.1 molar.