EP0355628B1
Expired / Lapsed
EP
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Process for chemically decontaminating the surface of a metallic construction element of a nuclear power plant
Assignee: Areva GmbH
•
Filing: 1989-08-11
•
Granted: 1993-11-10
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Expires: 2009-08-11
Abstract
No abstract record available.
Inventors
- 👤 Rainer Dr. Gassen
- 👤 Klaus Dipl.-Ing. Zeuch (Fh)
- 👤 Horst-Otto Bertholdt
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-24 15:59
CPC Classifications
G; G21; G21F; G21F9/00; G21F9/28; G21F9/001; G21F9/002; G21F9/004
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
74 words
Process for the chemical decontamination of the surface of a metal component of a nuclear reactor plant, characterised in that the surface is treated in a single-stage process with an aqueous solution which is free from the carboxylic acid oxalic acid and contains another carboxylic acid (3, 6, 8, 11, 12) which is converted by a chemical or heat process (7, 9, 10, 13, 14) into a further carboxylic acid (3, 8, 11, 12).
Claim 2
Dependent Claim
16 words
Process according to claim 1, characterised in that the aqueous solution contains a ketocarboxylic acid (3).
Claim 3
Dependent Claim
15 words
Process according to claim 2, characterised in that the aqueous solution contains mesoxalic acid (3).
Claim 4
Dependent Claim
23 words
Process according to one of claims 1 to 3, characterised in that the aqueous solution contains a hydroxycarboxylic acid (6, 8, 11, 12).
Claim 5
Dependent Claim
15 words
Process according to claim 4, characterised in that the aqueous solution contains dihydroxytartaric acid (6).
Claim 6
Dependent Claim
19 words
Process according to one of claims 4 or 5, characterised in that the aqueous solution contains tartronic acid (8).
Claim 7
Dependent Claim
19 words
Process according to one of claims 1 to 6, characterised in that the aqueous solution contains a complexing agent.
Claim 8
Dependent Claim
20 words
Process according to claim 7, characterised in that the aqueous solution contains a pyridine carboxylic acid as the complexing agent.
Claim 9
Dependent Claim
26 words
Process according to one of claims 7 or 8, characterised in that the aqueous solution contains ethylene diamine tetra acetic acid (EDTA) as the complexing agent.
Claim 10
Dependent Claim
20 words
Process according to one of claims 1 to 9, characterised in that the aqueous solution contains hydrogen peroxide or hypophosphite.
Claim 11
Dependent Claim
39 words
Process according to one of claims 5 to 10, characterised in that an aqueous solution containing dihydroxytartaric acid (6) is brought into contact with the surface, and in that the solution is then heated to form tartronic acid (8).
Claim 12
Dependent Claim
30 words
Process according to one of claims 6 to 11, characterised in that the aqueous solution contains tartronic acid (8) which has been formed previously from dihydroxytartaric acid (6) by heating.
Claim 13
Dependent Claim
29 words
Process according to one of claims 5 to 12, characterised in that dihydroxytartaric acid (6) is produced from one of its salts, in particular from its sodium salt (4).
Claim 14
Dependent Claim
29 words
Process according to one of claims 3 to 13, characterised in that mesoxalic acid (3) is produced from one of its salts, in particular from its sodium salt (1).
Claim 15
Dependent Claim
26 words
Process according to claims 13 or 14, characterised in that the acid (3, 6) is produced from one of its salts (1, 4) by ion exchange.
Claim 16
Dependent Claim
42 words
Process according to one of claims 6 to 15, characterised in that an aqueous solution containing tartronic acid (8) is brought into contact with the surfaces, and in that hydrogen peroxide is added (9) to the solution to form mesoxalic acid (3).
Claim 17
Dependent Claim
35 words
Process according to one of claims 3 to 16, characterised in that the aqueous solution contains mesoxalic acid (3) which has been previously formed by a reaction (9) of tartronic acid (8) and hydrogen peroxide.
Claim 18
Dependent Claim
57 words
Process according to one of claims 5 to 17, characterised in that an aqueous solution containing dihydroxytartaric acid (6) is brought into contact with the surfaces, in that the aqueous solution is then heated (7) to form tartronic acid (8), and in that hydrogen peroxide is then added (9) to the solution to form mesoxalic acid (3).
Claim 19
Dependent Claim
33 words
Process according to one of claims 1 to 18, characterised in that an oxidation step, carried out in an acidic or alkaline medium, precedes the treatment of the surface with the aqueous solution.
Claim 20
Dependent Claim
19 words
Process according to claim 19, characterised in that the oxidation step is carried out in the presence of permanganate.
Claim 21
Dependent Claim
34 words
Process according to one of claims 19 or 20, characterised in that several oxidation steps are carried out alternately in an acidic and alkaline medium before treatment of the surfaces with the aqueous solution.
Claim 22
Dependent Claim
45 words
Process according to one of claims 19 to 21, characterised in that when the oxidation step has been carried out the oxidation solution is destroyed and neutralised with a carboxylic acid (3, 6, 8, 11, 12), which is a component of the aqueous decontamination solution.
Claim 23
Dependent Claim
30 words
Process according to one of claims 1 to 22, characterised in that solution containing radioactive materials is delivered to an evaporator after treatment of the surface of the metal component.
Claim 24
Dependent Claim
31 words
Process according to one of claims 1 to 22, characterised in that solution containing radioactive substances is delivered to an ion exchanger after treatment of the surface of the metal component.
Claim 25
Dependent Claim
30 words
Process according to claim 23, characterised in that dicarboxylic acid (3, 6, 8) contained in the solution is thermally broken down in the evaporator to form monocarboxylic acid (11, 12).
Claim 26
Dependent Claim
44 words
Process according to one of claims 1 to 25, characterised in that during the treatment of the surface of the metal component, which is a component of the system to be decontaminated, the aqueous solution is recirculated in the system through a cleaning device.
Claim 27
Dependent Claim
45 words
Process according to one of claims 1 to 25, characterised in that during the treatment of the surface of the metal component, which is put in a container of a decontamination system, the aqueous solution is recirculated in the decontamination system through a cleaning device.
Claim 28
Dependent Claim
19 words
Process according to one of claims 26 or 27, characterised in that the cleaning device is an ion exchanger.
Claim 29
Dependent Claim
18 words
Process according to one of claims 26 to 28, characterised in that the cleaning device is a filter.
Claim 30
Dependent Claim
29 words
Process according to one of claims 26 to 29, characterised in that the cleaning device is arranged in a by-pass line of the system or of the decontamination system.
References Cited (Backward Citations)
No citation records indexed.
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