US4913849A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for pretreatment of chromium-rich oxide surfaces prior to decontamination
Assignee: Individual
•
Filing: 1988-07-07
•
Granted: 1990-04-03
•
Expires: 2008-07-07
Abstract
Abstract A process for pretreatment of chromium-rich oxide surfaces of nuclear reactor cooling system components involves application of a dilute acidic reagent comprising potassium permanganate and chromic acid, at elevated temperatures.
Inventors
- 👤 Aamir Husain
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 16:12
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/02; C23G1/08; G; G21; G21F; G21F9/00; G21F9/001; G21F9/002; G21F9/004
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
56 words
A method of decontaminating stainless steel components of the cooling system of a nuclear reactor, comprising pretreating contaminated components with an aqueous acidic oxidizing solution consisting essentially of potassium permanganate and chromic acid as chromium (VI) oxide, at a temperature of about 50° C. or greater to solubilize chromium in surface oxide layers on said components.
Claim 2
Independent Claim
56 words
A method of decontaminating stainless steel components of the cooling system of a nuclear reactor, comprising pretreating contaminated components with an aqueous acidic oxidizing solution consisting essentially of potassium permanganate and chromic acid as chromium (VI) oxide, at a temperature of about 50° C. or greater to solubilize chromium in surface oxide layers on said components.
Claim 3
Dependent Claim
24 words
A method according to claim 1, wherein the pretreatment of the contaminated components is carried out at a temperature of 95° C. or greater.
Claim 4
Dependent Claim
45 words
A method according to claim 1 or claim 2, wherein said aqueous oxidizing solution contains potassium permanganate at a concentration between about 0.1% and about 0.2% by weight and chromic acid as CrO 3 at a concentration between about 0.005% and about 0.02% by weight.
Claim 5
Independent Claim
68 words
A method of decontaminating stainless steel components of the cooling system of a nuclear reactor, comprising the steps of contacting the components successively with: (a) a reducing agent in acidic aqueous solution; (b) an aqueous acidic oxidizing solution consisting essentially of potassium permanganate and chromic acid as chromium (VI) oxide, at a temperature of about 50° C. or greater; and (c) a reducing agent in acidic aqueous solution.
Claim 6
Independent Claim
68 words
A method of decontaminating stainless steel components of the cooling system of a nuclear reactor, comprising the steps of contacting the components successively with: (a) a reducing agent in acidic aqueous solution; (b) an aqueous acidic oxidizing solution consisting essentially of potassium permanganate and chromic acid as chromium (VI) oxide, at a temperature of about 50° C. or greater; and (c) a reducing agent in acidic aqueous solution.
Claim 7
Dependent Claim
20 words
A method according to claim 4, wherein step (b) is carried out at a temperature of 95° C. or greater.
Claim 8
Dependent Claim
49 words
A method according to claim 4, wherein the concentration of potassium permanganate in said aqueous acidic oxidizing solution is between about 0.1% and about 0.2% by weight and the chromic acid concentration corresponds to a concentration of added CrO 3 of between about 0.005% and about 0.02% by weight.
Claim 9
Dependent Claim
29 words
A method according to claim 4, claim 5 or claim 6, wherein said reducing agent comprises a mixture of oxalic acid, citric acid, ethylenediaminetetraacetic acid and a corrosion inhibitor.
References Cited (Backward Citations)
DE2358683A1
Cited
CA1062590A
Cited
US4226640A
Cited
US4287002A
Cited
US4731124A
Cited
US4481040A
Cited
CA1217412A
Cited
US4476047A
Cited
WO1984003170A1
Cited
US4685971A
Cited
US4704235A
Cited
US4686067A
Cited
US4839100A
Cited
EP0313843A1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-04-02 | 1993-10-02 | 1994-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-02 | 1997-10-02 | 1998-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-02 | 2001-10-02 | 2002-04-03 | $7700.00 | Window Closed / Lapsed |