Patent Number: 050930729
Section: claims

1. Process for the radioactive decontamination of metal surfaces, particularly portions of primary circuits of water-cooled nuclear reactors, comprising the steps of contacting said surfaces during an oxidizing pretreatment with a solution of KMnO.sub.4 and nitric acid and then rinsing said surfaces with demineralized water, and then contacting said surfaces during a reducing treatment in a basic medium with an alkali metal gluconate solution of formula HOH.sub.2 C--CHOH--CHOH--CHOH--CHOH--COOM, in which M is an alkali metal chosen from among Na and K, and NaOH, said oxidizing pretreatment solution having a molar composition of KMnO.sub.4 between 0.006 and 0.1 M. and a molar composition of nitric acid HNO.sub.3 between 0.035 and 0.1 M., said metal surfaces being contacted with said oxidizing pretreatment solution at a temperature of approximately 80.degree. C. for approximately 24 hours, said alkali metal gluconate solution having a molar composition of alkali metal gluconate between 0.05 and 1 M. and a molar composition of NaOH between 0.1 and 1 M., the temperature of the solution being approximately 80.degree. C. and its pH approximately 11. 2. Decontamination process according to claim 1, characterized in that the reducing treatment in the basic medium is performed with the aid of a solution having a molar composition of sodium gluconate close to 0.5 M. and a molar composition of NaOH close to 0.1 M., the temperature of the solution being approximately 80.degree. C. and its pH close to 11.