Patent Number: 
Section: claims

1. Process for the radioactive decontamination of a surface, which involves bringing the surface to be decontaminated into contact with a foam prepared with an aqueous solution which comprises, per liter of solution:0.2 to 2% by weight of a foaming organic surface-active agent or of a mixture of foaming surface-active agents,from 0.1 to 1.5% by weight of a gelling agent, wherein the gelling agent is an organic thickening agent exhibiting a rheological behaviour of pseudoplastic type, and, optionally,0.2 to 7 mol of an inorganic acid or oxalic acid or inorganic base for radioactive decontamination or of a mixture of inorganic acids or inorganic acid(s) and oxalic acid or of inorganic bases for radioactive decontamination. 2. Process according to claim 1, in which the surface-active agent is a foaming nonionic surfactant. 3. Process according to claim 1, in which the surface-active agent is a foaming nonionic surfactant chosen from the family of the alkylpolyglucosides or alkylpolyetherglucosides. 4. Process according to claim 1, in which the surface-active agent is an amphoteric surfactant. 5. Process according to claim 1, in which the surface-active agent is an amphoteric surfactant chosen from the family of the sulphobetaines, from the family of the alkyl amidopropyl hydroxysulphobetaines or from the family of the amine oxides. 6. Process according to claim 1, in which the acid is chosen from the group consisting of hydrochloric acid, nitric acid, sulphuric acid, phosphoric acid and oxalic acid or is a mixture of acids from this group. 7. Process according to claim 1, in which the acid is in an amount of 0.3 to 7 mol. 8. Process according to claim 1, in which the acid is in an amount of 1 to 4 mol. 9. Process according to claim 1, in which the base is chosen from the group consisting of sodium hydroxide, potassium hydroxide and sodium carbonate or is a mixture of bases from this group. 10. Process according to claim 1, in which the base is in an amount of less than 2 mol. 11. Process according to claim 1, in which the base is in an amount of 0.5 to 1.5 mol. 12. Process according to claim 1, in which the gelling agent is chosen from the group consisting of a water-soluble polymer, a hydrocolloid and a heteropolysaccharide or from the group consisting of cellulose derivatives. 13. Process according to claim 1, in which the gelling agent is chosen from the group consisting of heteropolysaccharides chosen from the family of the polyglucoside polymers comprising trisaccharide branched chains; and cellulose derivatives, such as carboxymethylcellulose or a polysaccharide comprising glucose as sole monomer. 14. Process according to claim 1, in which the gelling agent is xanthan gum. 15. Process according to claim 1, in which the surface to be decontaminated is brought into contact with the foam for 1 to 10 hours. 16. Process according to claim 15, additionally comprising, after the operation of bringing the surface to be decontaminated into contact with the foam, rinsing the surface using a rinsing solution.