Conditioning of nuclear reactor fuel
AssigneeGeneral Electric Company
InventorsJohn Robert Thompson, Trevor Cartwright Rowland, Richard Alan Proebstle, Edward Rosicky, Thoma Mees van't Hoff Snyder
Life of this patent
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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.
Claims15
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.
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).sup.3 /D.sub.n.sup.3 times T.sub.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).sup.3 /D.sub.n.sup.3 times T.sub.n /0.032 kw/ft/hr where D.sub.n is the diameter of the fuel pellets and T.sub.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.
Dependencies are inferred from the claim text.