REMOVAL OF BLOCKAGES FROM PIPEWORK
(19)AUSTRALIAN PATENT OFFICE(54)TitleREMOVAL OF BLOCKAGES FROM PIPEWORK (51)6 International Patent Classification(s) G21F 009/00 (21) Application No: 2003229887(22) Application Date: 2003.04.07(87) WIPONo: WO03/088268 (30) Priority Data (31) Number (32) Date 0207876.4 2002.04.05(33) Country GB(43) Publication Date : 2003.10.27(43) Publication Journal Date : 2003.12.04(71)Applicant(s)BRITISH NUCLEAR FUELS PLC(72)Inventor(s)DENNIS, lain, Stewart; MAYHEW, Phillip Antony (H) Application NoAU2003229887 A1(19)AUSTRALIAN PATENT OFFICE(54)TitleREMOVAL OF BLOCKAGES FROM PIPEWORK (51)6 International Patent Classification(s) G21F 009/00 (21) Application No: 2003229887(22) Application Date: 2003.04.07(87) WIPONo: WO03/088268 (30) Priority Data (31) Number (32) Date 0207876.4 2002.04.05(33) Country GB(43) Publication Date : 2003.10.27(43) Publication Journal Date : 2003.12.04(71)Applicant(s)BRITISH NUCLEAR FUELS PLC(72)Inventor(s)DENNIS, lain, Stewart; MAYHEW, Phillip Antony The invention provides a method for the removal of contaminating materials from pipework, the contaminating materials comprising deposits on the pipework which cause a reduction in the effective internal diameter of the pipes and thereby effect a reduction in the rate of flow of a fluid through the pipework, the method comprising treating the contaminating materials with at least one carbamate salt. The methods is also suitable for the treatment of contaminating materials which have a particularly deleterious effect on fluid flow and comprise partial or total blockages of the pipework. The carbamate is preferably in the form of an aqueous solution, and a preferred carbamate salt is ammonium carbamate. The treatment may be carried out in the presence of an additive such as caesium carbonate or ammonium bicarbonate. Optionally the treatment may be accompanied by a pre-treatment or post-treatment with aid, this being followed by a water wash. The method finds particular application in the nuclear processing industry. A method for the removal of contaminating materials from pipework, said contaminating materials comprising deposits on the pipework which comprise inorganic salts having low solubility levels which are deposited from solutions or suspensions in contact with the pipework, wherein said contaminating materials cause a reduction in the effective internal diameter of the pipes and thereby effect a reduction in the rate of flow of a fluid through the pipework, the method comprising treating said contaminating materials with at least one carbamate salt. A method as claimed in claim 1 wherein said inorganic salts comprise phosphate, alkylphosphate, molybdate and phosphomolybdate salts. A method as clamed in claim 2 wherein said salts comprise the phosphate, butylphosphate, molybdate and phosphomolybdate salts of zirconium, tellurium, gadolinium, caesium, iron and uranium. A method as claimed in claims 1, 2 or 3 wherein said contaminating materials comprise partial or total blockages of the pipework. A method as claimed in any one of claims 1 to 4 wherein said carbamate salt comprises an aqueous solution of a carbamate salt. A method as claimed in any preceding claim wherein said carbamate salt comprises ammonium carbamate. A method as claimed in any one of any preceding claim wherein said treatment is carried out at a temperature in the range of from 40°C to 60°C. A method as claimed in claim 7 wherein said temperature is in the region of 60°C. A method as claimed in any preceding claim wherein said treatment is continued for an extended period of time. A method as claimed in claim 9 wherein said treatment is continued for at least 2 hours. A method as claimed in any preceding claim wherein the concentration of said carbamate in aqueous solution is in the range of from 0.3M to 6.0M. A method as claimed in claim 11 wherein said concentration is between 1.0M and 3.0M. A method as claimed in any preceding claim wherein said treatment is carried out in the presence of at least one additive. A method as claimed in claim 13 wherein said additive comprises a carbonate or bicarbonate salt. A method as claimed in claim 14 wherein said carbonate or bicarbonate salt comprises caesium carbonate or ammonium bicarbonate. A method as claimed in any preceding claim wherein said treatment is preceded by pre-treatment with acid and washing with water. A method as claimed in claim 16 wherein said pre-treatment and washing is carried out at room temperature. A method as claimed in any one of claims 1 to 15 wherein said treatment is followed by post-treatment with acid and washing with water. A method as claimed in claim 18 wherein said post-treatment and washing is carried out at room temperature. A method as claimed in any one of claims 16 to 19 wherein said acid comprises nitric acid. A method as claimed in any preceding claim whenever applied to the removal of contaminating materials from pipework in the nuclear processing industry. A method as claimed in claim 21 which comprises the treatment of pipework used in the processing of Highly Active Liquor with an aqueous solution comprising 0.3-1.0M ammonium carbamate and 0.2M caesium carbonate at 60°C for 2 hours. A method as claimed in claim 21 which comprises the treatment of pipework used in the processing of Highly Active Liquor as follows:
(a) treatment with 2.0M nitric acid at room temperature; followed by (b) washing with water at room temperature; followed by (c) treatment with 1.0M or 3.0M aqueous ammonium carbamate solution at 60°C for 2 hours. A method as claimed in claim 21 which comprises the treatment of pipework used in the processing of Highly Active Liquor as follows:
(a) Treatment with 1.0M or 3.0M aqueous ammonium carbamate solution at 60°C for 2 hours; followed by (b) Treatment with 2.0M nitric acid at room temperature; followed by (c) Washing with water at room temperature.