US4704235A
Expired / Lapsed
US
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Decontamination of pressurized water reactors
Assignee: Studsvik Energiteknik AB
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Filing: 1985-02-05
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Granted: 1987-11-03
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Expires: 2005-02-05
Abstract
Abstract A method of decontaminating radionuclide-contaminated acid insoluble corrosion products from primary system surfaces in pressurized water reactors by oxidation and concurrent dissolution in an acidic decontamination solution of the corrosion products which have been made acid-soluble by the oxidation. The characterizing feature of the method is that the oxidation is carried out at relatively low temperatures with a water-based oxidation agent having a pH below 7 and containing cerium nitrate, chromic acid and ozone.
Inventors
- 👤 Jan Arvesen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:08
CPC Classifications
G; G21; G21F; G21F9/00; G21F9/001; G21F9/002; G21F9/004
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
70 words
A method of decontaminating radionuclide-contaminated acid-insoluble corrosion products from primary system surfaces in pressurized water reactors comprising contacting the contaminated surfaces with an oxidation agent in an acidic solution and dissolving the corrosion products which have been made acid-soluble by the oxidation, the oxidation being performed with a water-based oxidation agent having a pH below 7 and containing 0.01-50 g/l cerium nitrate, 0.01-50 g/l chromic acid and 0.001-1 g/l ozone.
Claim 2
Independent Claim
70 words
A method of decontaminating radionuclide-contaminated acid-insoluble corrosion products from primary system surfaces in pressurized water reactors comprising contacting the contaminated surfaces with an oxidation agent in an acidic solution and dissolving the corrosion products which have been made acid-soluble by the oxidation, the oxidation being performed with a water-based oxidation agent having a pH below 7 and containing 0.01-50 g/l cerium nitrate, 0.01-50 g/l chromic acid and 0.001-1 g/l ozone.
Claim 3
Dependent Claim
30 words
A method according to claim 1 wherein the oxidation agent is an acidic aqueous solution of cerium nitrate and chromic acid and ozone in a saturated solution and dispersed form.
Claim 4
Dependent Claim
35 words
A method according to claim 1 wherein the oxidation agent is a two-phase ozone gas-aqueous mixture, where ozone in gaseous form has been dispersed in an acidic aqueous solution of cerium nitrate and chromic acid.
Claim 5
Dependent Claim
19 words
A method according to claim 1 wherein the oxidation and dissolution are performed in one and the same step.
Claim 6
Dependent Claim
21 words
A method according to claim 1 wherein the oxidation and dissolution are carried out at a temperature below about 60° C.
Claim 7
Dependent Claim
18 words
A method according to claim 1 wherein the water-based oxidation agent has been made acidic with nitric acid.
Claim 8
Dependent Claim
22 words
A method according to claim 6 wherein the water-based oxidation agent has been made acidic to a pH value of about 1.
Claim 9
Dependent Claim
32 words
A method according to claim 1 wherein the concentration of cerium nitrate is 0.5-2 g/l, the concentration of chromic acid is 0.05-0.2 g/l, and the concentration of the ozone is 0.005-0.015 g/l.
Claim 10
Dependent Claim
19 words
A method according to claim 2 wherein the oxidation and dissolution are performed in one and the same step.
Claim 11
Dependent Claim
19 words
A method according to claim 3 wherein the oxidation and dissolution are performed in one and the same step.
Claim 12
Dependent Claim
21 words
A method according to claim 2 wherein the oxidation and dissolution are carried out at a temperature below about 60° C.
Claim 13
Dependent Claim
21 words
A method according to claim 3 wherein the oxidation and dissolution are carried out at a temperature below about 60° C.
Claim 14
Dependent Claim
21 words
A method according to claim 4 wherein the oxidation and dissolution are carried out at a temperature below about 60° C.
Claim 15
Dependent Claim
21 words
A method according to claim 9 wherein the oxidation and dissolution are carried out at a temperature below about 60° C.
Claim 16
Dependent Claim
18 words
A method according to claim 2 wherein the water-based oxidation agent has been made acidic with nitric acid.
Claim 17
Dependent Claim
18 words
A method according to claim 3 wherein the water-based oxidation agent has been made acidic with nitric acid.
Claim 18
Dependent Claim
18 words
A method according to claim 4 wherein the water-based oxidation agent has been made acidic with nitric acid.
Claim 19
Dependent Claim
31 words
A method according to claim 2 wherein the concentration of cerium nitrate is 0.5-2 g/l, the concentration of chromic acid is 0.05-02 g/l, and the concentration of ozone is 0.005-0.015 g/l.
Claim 20
Dependent Claim
31 words
A method according to claim 3 wherein the concentration of cerium nitrate is 0.5-2 g/l, the concentration of chromic acid is 0.05-02 g/l, and the concentration of ozone is 0.005-0.015 g/l.
Claim 21
Dependent Claim
31 words
A method according to claim 4 wherein the concentration of cerium nitrate is 0.5-2 g/l, the concentration of chromic acid is 0.05-0.2 g/l, and the concentration of ozone is 0.005-0.015 g/l.
Claim 22
Dependent Claim
21 words
A method according to claim 5 wherein the oxidation and dissolution are carried out at a temperature below about 25° C.
Claim 23
Dependent Claim
14 words
A method according to claim 21 wherein the temperature is below about 20° C.
Claim 24
Dependent Claim
21 words
A method according to claim 11 wherein the oxidation and dissolution are carried out at a temperature below about 25° C.
Claim 25
Dependent Claim
14 words
A method according to claim 23 wherein the temperature is below about 20° C.
Claim 26
Dependent Claim
21 words
A method according to claim 12 wherein the oxidation and dissolution are carried out at a temperature below about 25° C.
Claim 27
Dependent Claim
14 words
A method according to claim 25 wherein the temperature is below about 20° C.
Claim 28
Dependent Claim
21 words
A method according to claim 13 wherein the oxidation and dissolution are carried out at a temperature below about 25° C.
Claim 29
Dependent Claim
14 words
A method according to claim 27 wherein the temperature is below about 20° C.
Claim 30
Dependent Claim
21 words
A method according to claim 14 wherein the oxidation and dissolution are carried out at a temperature below about 25° C.
Claim 31
Dependent Claim
14 words
A method according to claim 29 wherein the temperature is below about 20° C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-11-02 | 1991-05-04 | 1991-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-02 | 1995-05-04 | 1995-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-02 | 1999-05-04 | 1999-11-03 | $7700.00 | Window Closed / Lapsed |