US4057466A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Conditioning of nuclear reactor fuel
Assignee: General Electric Co
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Filing: 1976-02-23
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Granted: 1977-11-08
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Expires: 1996-02-23
Abstract
Abstract A method of conditioning the fuel of a nuclear reactor core to minimize failure of the fuel cladding comprising increasing the fuel rod power to a desired maximum power level at a rate below a critical rate which would cause cladding damage. Such conditioning allows subsequent freedom of power changes below and up to said maximum power level with minimized danger of cladding damage.
Inventors
- 👤 John Robert Thompson
- 👤 Trevor Cartwright Rowland
- 👤 Richard Alan Proebstle
- 👤 Edward Rosicky
- 👤 Thoma Mees van't Hoff Snyder
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:22
CPC Classifications
G; G21; G21C; G21C3/00; G21C3/02; G21C3/04; G21C3/06; G21C7/00; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
263 words
In a fuel core of a nuclear reactor wherein said fuel consists of a plurality of cylindrical pellets of fuel in oxide form of about 0.49 inches in diameter contained in a plurality of elongated zirconium alloy cladded tubular fuel elements with a cladding thickness of about 0.032 inches and having a range of power output and a maximum power rating, a method of conditioning said fuel elements to withstand subsequent rapid power changes without cladding failure comprising: (1) increasing the power produced by said fuel elements through a fuel pellet-cladding interaction range of power wherein expansion of said pellets and consequent pellet-cladding interaction causes said pellets to exert forces upon said cladding to a selected power level no greater than said maximum power level at a first rate of power increase below a critical rate which causes cladding damage due to said fuel pellet-cladding interaction, said critical rate being about 0.125 kw/ft/hr, and stepwise increases in power at said first rate comprising steps no greater than about 0.5 kw/ft, whereby said fuel elements are conditioned for subsequent rapid power changes up to said desired power level with minimized danger of cladding damage; (2) decreasing the power produced by said fuel elements from said selected power level to a lower power level; and (3) subsequently increasing the power produced by said fuel elements over any portion of the power range of said fuel elements up to said selected power level at a second rate of power increase greater then said critical rate, said second rate of power increase being at least 16 kw/ft/hr.
Claim 2
Dependent Claim
263 words
In a fuel core of a nuclear reactor wherein said fuel consists of a plurality of cylindrical pellets of fuel in oxide form of about 0.49 inches in diameter contained in a plurality of elongated zirconium alloy cladded tubular fuel elements with a cladding thickness of about 0.032 inches and having a range of power output and a maximum power rating, a method of conditioning said fuel elements to withstand subsequent rapid power changes without cladding failure comprising: (1) increasing the power produced by said fuel elements through a fuel pellet-cladding interaction range of power wherein expansion of said pellets and consequent pellet-cladding interaction causes said pellets to exert forces upon said cladding to a selected power level no greater than said maximum power level at a first rate of power increase below a critical rate which causes cladding damage due to said fuel pellet-cladding interaction, said critical rate being about 0.125 kw/ft/hr, and stepwise increases in power at said first rate comprising steps no greater than about 0.5 kw/ft, whereby said fuel elements are conditioned for subsequent rapid power changes up to said desired power level with minimized danger of cladding damage; (2) decreasing the power produced by said fuel elements from said selected power level to a lower power level; and (3) subsequently increasing the power produced by said fuel elements over any portion of the power range of said fuel elements up to said selected power level at a second rate of power increase greater then said critical rate, said second rate of power increase being at least 16 kw/ft/hr.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein said second rate of power increase is at least 15 percent of said maximum power rating per minute.
Claim 4
Dependent Claim
28 words
The method of claim 2 wherein power increases at said first rate toward said selected power level are made at a rate no greater than about 0.1 kw/ft/hr.
Claim 5
Dependent Claim
27 words
The method of claim 2 wherein power increases at said first rate toward said selected power level are made at a rate of 0.08 - 0.1 kw/ft/hr.
Claim 6
Dependent Claim
52 words
The method of claim 2 wherein power increases at said first rate toward said selected power level are made as a series of step increases in power and each of said steps is no greater than about 0.1 kw/ft with a time of no less than 1 hour between said step increases.
Claim 7
Dependent Claim
276 words
In a fuel core of a nuclear reactor wherein said fuel consists of a plurality of cylindrical pellets of fuel in oxide form contained in a plurality of elongated zirconium alloy cladded tubular fuel elements having a range of power output and a maximum power rating, a method of operating said fuel elements comprising: (1) increasing the power produced by said fuel elements through a fuel pellet-cladding interaction range of power wherein expansion of said pellets and consequent pellet-cladding interaction causes said pellets to exert forces upon said cladding to a selected power level no greater than said maximum power level at a first rate of power increase below a critical rate which causes cladding damage due to said fuel pellet-cladding interaction, said critical rate being about 0.125 (0.49) 3 /D n 3 times T n /0.032 kw/ft/hr and stepwise increases in power at said first rate comprising steps no greater than about 0.5 (0.49) 3 /D n 3 times T n /0.032 kw/ft/hr where D n is the diameter of the fuel pellets and T n is the thickness of the cladding, whereby said fuel elements are conditioned for subsequent rapid power changes up to said selected power level with minimized danger of cladding failure; (2) decreasing the power produced by said fuel elements to a lower power level below said selected power level; and (3) subsequently increasing the power produced by said fuel elements over any portion of the power range of said fuel elements up to said selected power level at a second rate of power increase above said critical rate, said second rate of power increase being at least about 16 kw/ft/hr.
Claim 8
Dependent Claim
276 words
In a fuel core of a nuclear reactor wherein said fuel consists of a plurality of cylindrical pellets of fuel in oxide form contained in a plurality of elongated zirconium alloy cladded tubular fuel elements having a range of power output and a maximum power rating, a method of operating said fuel elements comprising: (1) increasing the power produced by said fuel elements through a fuel pellet-cladding interaction range of power wherein expansion of said pellets and consequent pellet-cladding interaction causes said pellets to exert forces upon said cladding to a selected power level no greater than said maximum power level at a first rate of power increase below a critical rate which causes cladding damage due to said fuel pellet-cladding interaction, said critical rate being about 0.125 (0.49) 3 /D n 3 times T n /0.032 kw/ft/hr and stepwise increases in power at said first rate comprising steps no greater than about 0.5 (0.49) 3 /D n 3 times T n /0.032 kw/ft/hr where D n is the diameter of the fuel pellets and T n is the thickness of the cladding, whereby said fuel elements are conditioned for subsequent rapid power changes up to said selected power level with minimized danger of cladding failure; (2) decreasing the power produced by said fuel elements to a lower power level below said selected power level; and (3) subsequently increasing the power produced by said fuel elements over any portion of the power range of said fuel elements up to said selected power level at a second rate of power increase above said critical rate, said second rate of power increase being at least about 16 kw/ft/hr.
Claim 9
Dependent Claim
24 words
The method of claim 6 wherein said second rate of power increase is at least 15 percent of said maximum power rating per minute.
Claim 10
Dependent Claim
14 words
The method of claim 7 wherein said maximum power rating is about 16 kw/ft.
Claim 11
Dependent Claim
22 words
The method of claim 6 wherein said critical rate is about 0.125 kw/ft/hr for fuel pellets of about 0.49 inches in diameter.
Claim 12
Dependent Claim
28 words
The method of claim 8 wherein power increases at said first rate toward said selected power level are made at a rate no greater than about 0.1 kw/ft/hr.
Claim 13
Dependent Claim
27 words
The method of claim 8 wherein power increases at said first rate toward said selected power level are made at a rate of 0.08 - 0.1 kw/ft/hr.
Claim 14
Dependent Claim
52 words
The method of claim 8 wherein power increases at said first rate toward said selected power level are made as a series of step increases in power and each of said steps is no greater than about 0.1 kw/ft with a time of no less than 1 hour between said step increases.
Claim 15
Dependent Claim
36 words
The method of claim 6 wherein power increases at said first rate toward said selected power level are made at a rate no greater than 0.1 (0.49) 3 /D n 3 times T n /0.032 kw/ft/hr.
Claim 16
Dependent Claim
36 words
The method of claim 6 wherein power increases at said first rate toward said selected power level are made at a rate of (0.08 to 0.1) (0.49) 3 /D n 3 times T n /0.032 kw/ft/hr.
Claim 17
Dependent Claim
61 words
The method of claim 6 wherein power increases at said first rate toward said selected power level are made as a series of step increases in power and each of said steps is no greater than about 0.1 (0.49) 3 /D n 3 times T n /0.032 kw/ft with a time of no less than 1 hour between said step increases.
References Cited (Backward Citations)
US3926721A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-11-07 | 1981-05-09 | 1981-11-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-11-07 | 1985-05-09 | 1985-11-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-11-07 | 1989-05-09 | 1989-11-08 | $7700.00 | Window Closed / Lapsed |