Patent Number: 
Section: claims

1. A method for chemically decontaminating a radioactive material comprising iron, comprising:contacting at least one surface of the radioactive material with a reducing decontamination liquid comprising formic acid and oxalic acid;wherein mole fraction of the formic acid in the reducing decontamination liquid is 0.9 or more;contacting the at least one surface of the radioactive material with an oxidizing decontamination liquid comprising at least one oxidizer;separating and removing Fe2+ ions and Fe3+ ions, which have eluted into the reducing decontamination liquid, with at least one cation resin;decomposing the formic acid with a hydrogen peroxide solution; anddecomposing the oxalic acid with the oxidizing decontamination liquid. 2. The method of claim 1, wherein:the radioactive material comprises stainless steel; andwherein the contacting at least one surface of the radioactive material with a reducing decontamination liquid comprising formic acid and oxalic acid further comprises lowering the potential of the radioactive material by applying direct current to the radioactive material. 3. The method of claim 2, further comprising repeating, at least one time,the contacting at least one surface of the radioactive material with a reducing decontamination liquid comprising formic acid and oxalic acid; andthe contacting the at least one surface of the radioactive material with an oxidizing decontamination liquid comprising at least one oxidizer. 4. The method of claim 3, wherein the oxidizer is selected from the group consisting of ozone, permanganic acid, permanganate, and combinations thereof. 5. The method of claim 2, wherein the oxidizer is selected from the group consisting of ozone, permanganic acid, permanganate, and combinations thereof. 6. The method of claim 1, further comprising repeating, at least one time, the contacting at least one surface of the radioactive material with a reducing decontamination liquid comprising formic acid and oxalic acid; andthe contacting the at least one surface of the radioactive material with an oxidizing decontamination liquid comprising at least one oxidizer. 7. The method of claim 6, wherein the oxidizer is selected from the group consisting of ozone, permanganic acid, permanganate, and combinations thereof. 8. The method of claim 1, wherein the oxidizer is selected from the group consisting of ozone, permanganic acid, permanganate, and combinations thereof.