US4461650A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for removing scale from nuclear fuel rods
Assignee: Toshiba Corp
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Filing: 1981-11-19
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Granted: 1984-07-24
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Expires: 2001-11-19
Abstract
Abstract A neclear fuel rod assembly used in a nuclear reactor and deposited with radioactive scale is taken out of a fuel pool and disposed in a substantially sealed vertical casing, while the scale is still wetted by water. Gas in the casing is heated to a temperature higher than room temperature by the heat of nuclear fission or an electric heater to dry and peel off the scale. A mixture of the scale and water collected in a bottom portion of the casing is sent to a waterscale separator. To rapidly and perfectly remove the scale, after completing the step described above, water is sprayed onto the fuel rod assembly to wet remaining scale. Then, the drying of the scale with hot gas is repeated again.
Inventors
- 👤 Tamotsu Ozawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:09
CPC Classifications
G; G21; G21F; G21F9/00; G21F9/001
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
75 words
A method of removing scale deposited on a nuclear fuel rod assembly during operation thereof in a boiling water type nuclear reactor, comprising the steps of disposing said nuclear fuel rod assembly in a substantially sealed chamber while said scale is wet with water, and drying said wet scale by circulating a gas in the chamber heated to a temperature higher than room temperature, thus peeling off dried scale from said nuclear fuel rod assembly.
Claim 2
Independent Claim
75 words
A method of removing scale deposited on a nuclear fuel rod assembly during operation thereof in a boiling water type nuclear reactor, comprising the steps of disposing said nuclear fuel rod assembly in a substantially sealed chamber while said scale is wet with water, and drying said wet scale by circulating a gas in the chamber heated to a temperature higher than room temperature, thus peeling off dried scale from said nuclear fuel rod assembly.
Claim 3
Dependent Claim
36 words
The method according to claim 1 wherein a nuclear fuel assembly which has been utilized in a nuclear reactor core and deposited with scale is taken out from a fuel pool and deposited in said chamber.
Claim 4
Dependent Claim
24 words
The method according to claim 1 wherein said gas in said chamber is heated by heat of nuclear fission of said nuclear fuel rod.
Claim 5
Dependent Claim
16 words
The method according to claim 1 wherein said gas is introduced into said chamber from outside.
Claim 6
Dependent Claim
24 words
The method according to claim 4 wherein said gas is heated to a temperature above room temperature before it is introduced into said chamber.
Claim 7
Dependent Claim
26 words
The method according to claim 1 which further comprises the step of applying vibration to said nuclear fuel rod assembly while said scale is being dried.
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) | 1987-07-24 | 1988-01-23 | 1988-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-24 | 1992-01-23 | 1992-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-24 | 1996-01-23 | 1996-07-24 | $7700.00 | Window Closed / Lapsed |