US4729855A
Expired / Lapsed
US
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Method of decontaminating radioactive metal surfaces
Assignee: Westinghouse Electric Co LLC
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Filing: 1985-11-29
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Granted: 1988-03-08
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Expires: 2005-11-29
Abstract
Abstract Disclosed is a method of decontaminating metal surfaces contaminated with a radioactive deposit by passing over the coating an aqueous solution of a water soluble condensation reaction product of (1) a hydrazine compound having the general formula ##STR1## where each R group is independently selected from hydrogen and alkyl to C 4 and (2) a water soluble aliphatic polycarboxylic acid. The method includes the additional last steps of passing an aqueous oxidizing solution over the deposit followed by passing a decontamination solution over the deposit a second time. The solution is circulated through a cationic exchange column which can be preloaded with hydrazine ion. The decontamination solution can be decomposed by the addition of an oxidant to form nitrogen, carbon dioxide, and water.
Inventors
- 👤 Alexander P. Murray
- 👤 Clifton G. Slater
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:56
CPC Classifications
G; G21; G21F; G21F9/00; G21F9/001
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
80 words
A method of decontaminating metal surfaces contaminated with a radioactive deposit, comprising circulating between said deposit and a cationic ion exchange column an aqueous solution of a water soluble condensation reaction product of (1) a hydrazine compound having the general formula ##STR3## where each R is independently selected from hydrogen and alkyl to C 4 ; and (2) a water-soluble aliphatic polycarboxylic acid selected from the group consisting of oxalic acid, tartaric acid, citric acid, succinic acid, and mixtures thereof.
Claim 2
Independent Claim
80 words
A method of decontaminating metal surfaces contaminated with a radioactive deposit, comprising circulating between said deposit and a cationic ion exchange column an aqueous solution of a water soluble condensation reaction product of (1) a hydrazine compound having the general formula ##STR3## where each R is independently selected from hydrogen and alkyl to C 4 ; and (2) a water-soluble aliphatic polycarboxylic acid selected from the group consisting of oxalic acid, tartaric acid, citric acid, succinic acid, and mixtures thereof.
Claim 3
Dependent Claim
15 words
A method according to claim 1 wherein said water-soluble aliphatic polycarboxylic acid is oxalic acid.
Claim 4
Dependent Claim
22 words
A method according to claim 1 wherein one mole of said hydrazine compound is reacted with one equivalent of said polycarboxylic acid.
Claim 5
Dependent Claim
31 words
A method according to claim 1 wherein the concentration of said condensation reaction product in said aqueous solution is about 0.05 to about 10% by weight, based on total solution weight.
Claim 6
Dependent Claim
20 words
A method according to claim 1 wherein the temperature of said aqueous solution is about 80° to about 125° C.
Claim 7
Dependent Claim
19 words
A method according to claim 1 including the additional last step of adding an oxidant to said aqueous solution.
Claim 8
Dependent Claim
26 words
A method according to claim 1 wherein said R group is H and said cationic exchange resin is loaded with N 2 H 5 + .
Claim 9
Dependent Claim
23 words
A method according to claim 1 wherein said cationic ion exchange column is preloaded with the cationic moiety of said condensation reaction product.
Claim 10
Dependent Claim
15 words
A method according to claim 1 wherein said water-soluble aliphatic polycarboxylic acid is citric acid.
Claim 11
Dependent Claim
15 words
A method according to claim 1 wherein said water-soluble aliphatic polycarboxylic acid is tartaric acid.
Claim 12
Dependent Claim
15 words
A method according to claim 1 wherein said water-soluble aliphatic polycarboxylic acid is succinic acid.
Claim 13
Dependent Claim
11 words
A method according to claim 1 wherein each R is hydrogen.
Claim 14
Dependent Claim
15 words
A method according to claim 12 wherein said water-soluble aliphatic polycarboxylic acid is oxalic acid.
Claim 15
Dependent Claim
32 words
A method according to claim 1 including the additional last steps of passing an aqueous oxidizing solution over said deposit, followed by passing said aqueous solution iover said deposit a second time.
Claim 16
Dependent Claim
23 words
A method according to claim 14 wherein said oxidizing solution is a solution of an alkali metal hydroxide and an alkali metal permanganate.
Claim 17
Independent Claim
102 words
A method of decontaminating a metal surface having a deposit thereon that contains radioactive elements, comprising (1) preloading a cationic ion exchange column with N 2 H 5 + ; (2) circulating between said deposit and said cationic exchange column, an aqueous solution iof dihydrazine oxalate, at a concentration of about 0.05 to about 10% by weight, based on solution weight, heated to about 870° to about 125° C.; (3) passing an oxidizing solution over said deposit; (4) repeating step (2); and (5) adding an oxidant to said aqueous solution, whereby said dihydrazine oxalate is oxidized to nitrogen, carbon dioxide, and water.
Claim 18
Independent Claim
102 words
A method of decontaminating a metal surface having a deposit thereon that contains radioactive elements, comprising (1) preloading a cationic ion exchange column with N 2 H 5 + ; (2) circulating between said deposit and said cationic exchange column, an aqueous solution iof dihydrazine oxalate, at a concentration of about 0.05 to about 10% by weight, based on solution weight, heated to about 870° to about 125° C.; (3) passing an oxidizing solution over said deposit; (4) repeating step (2); and (5) adding an oxidant to said aqueous solution, whereby said dihydrazine oxalate is oxidized to nitrogen, carbon dioxide, and water.
Claim 19
Dependent Claim
12 words
A method according to claim 16 wherein said oxidant is hydrogen peroxide.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-08 | 1991-09-07 | 1992-03-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-08 | 1995-09-07 | 1996-03-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-08 | 1999-09-07 | 2000-03-08 | $7700.00 | Window Closed / Lapsed |