Patent US3713974A successfully refreshed from Google Patents.
US3713974A
Expired / Lapsed
US
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Nuclear reactor fuel elements
Assignee: Fiat TTG SpA
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Filing: 1969-12-10
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Granted: 1973-01-30
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Expires: 1989-12-10
Abstract
Abstract A nuclear reactor fuel element has a number of fuel rods arranged in a metallic sheath, the rods being spaced by a number of axially spaced apart grids. Some grids are fixed relative to the sheath while others can slide axially therein, and each fuel rod is frictionally connected to all the slidable grids but to some only of the fixed grids, said fuel rod passing freely through the other fixed grids. The fixed and slidable grids alternate in the central part of the fuel element, and in consequence the loading of the sheath as a result of differential thermal expansion is minimized.
Inventors
- 👤 G Previti
- 👤 P Roncarolo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 11:51
CPC Classifications
G; G21; G21C; G21C3/00; G21C3/30; G21C3/32; G21C3/34; G21C3/356; G21C3/3566; G21C3/33; G21C3/332; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
114 words
Nuclear reactor fuel element comprising in combination: a. a plurality of fuel rods arranged parallel to each other; b. a plurality of grids spacing and stabilizing the fuel rods; c. an external sheath enclosing the fuel rods; d. each of said grids being disposed parallel to and spaced from each other along the length of said rods with every other one of said grids being rigidly secured to said external sheath; e. grid connecting means frictionally connecting the remaining grids to said sheath for limited axial sliding movement relative to said sheath, and f. interconnecting means frictionally connecting each rod to one rigidly secured grid and to each of the remaining axially movable grids.
Claim 2
Dependent Claim
114 words
Nuclear reactor fuel element comprising in combination: a. a plurality of fuel rods arranged parallel to each other; b. a plurality of grids spacing and stabilizing the fuel rods; c. an external sheath enclosing the fuel rods; d. each of said grids being disposed parallel to and spaced from each other along the length of said rods with every other one of said grids being rigidly secured to said external sheath; e. grid connecting means frictionally connecting the remaining grids to said sheath for limited axial sliding movement relative to said sheath, and f. interconnecting means frictionally connecting each rod to one rigidly secured grid and to each of the remaining axially movable grids.
Claim 3
Dependent Claim
114 words
Nuclear reactor fuel element comprising in combination: a. a plurality of fuel rods arranged parallel to each other; b. a plurality of grids spacing and stabilizing the fuel rods; c. an external sheath enclosing the fuel rods; d. each of said grids being disposed parallel to and spaced from each other along the length of said rods with every other one of said grids being rigidly secured to said external sheath; e. grid connecting means frictionally connecting the remaining grids to said sheath for limited axial sliding movement relative to said sheath, and f. interconnecting means frictionally connecting each rod to one rigidly secured grid and to each of the remaining axially movable grids.
Claim 4
Dependent Claim
114 words
Nuclear reactor fuel element comprising in combination: a. a plurality of fuel rods arranged parallel to each other; b. a plurality of grids spacing and stabilizing the fuel rods; c. an external sheath enclosing the fuel rods; d. each of said grids being disposed parallel to and spaced from each other along the length of said rods with every other one of said grids being rigidly secured to said external sheath; e. grid connecting means frictionally connecting the remaining grids to said sheath for limited axial sliding movement relative to said sheath, and f. interconnecting means frictionally connecting each rod to one rigidly secured grid and to each of the remaining axially movable grids.
Claim 5
Dependent Claim
67 words
Fuel element according to claim 1, including means defining flow passages for coolant fluid between the fuel rods and the grids, the frictional interconnecting means between the fuel rods and the grids being so distributed along the length of the fuel element to cause transverse deflection of coolant fluid flowing along said flow passages whereby to enhance thermal exchange between the fuel rods and the coolant fluid.
Claim 6
Dependent Claim
37 words
Fuel element according to claim 3, wherein slidable grids are arranged at the opposite ends of the fuel element while the fixed grids are arranged in the central part of the fuel element, alternating with slidable grids.
Claim 7
Dependent Claim
23 words
Fuel element according to claim 3, wherein the fixed grids arranged in the central part of the fuel element are three in number.
Claim 8
Dependent Claim
76 words
Fuel element according to claim 4, wherein the guide means comprise axially extending fillets provided at opposite ends with flanges fixed to the inner surface of the external sheath, the part of each fillet between said flanges being spaced from the said inner surface of the sheath, and including laminar peripheral walls on each slidable grid interposed between the fillets and the external sheath and permitting relative axial sliding movement between the sheath and said grid.
Claim 9
Dependent Claim
31 words
Fuel element according to claim 6, further comprising a metallic comb-shaped strip, said fillets cooperating with each side of the sheath being formed as part of said respective metallic comb-shaped strip.
Claim 10
Dependent Claim
31 words
Fuel element according to claim 6, wherein each comb-shaped strip carrying the fillets adjacent each respective side of the sheath has a shorter length than that of the respective said side.
Claim 11
Dependent Claim
47 words
Fuel element according to claim 6, wherein the fillets of each comb-shaped strip are each formed with axially elongated openings and the laminar peripheral walls of each sliding grid are formed with spring elements which enter respective said elongated openings to support the grid from the strip.
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) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |