US3762996A
Expired / Lapsed
US
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Nuclear reactor fuel element assembly
Assignee: United Kingdom Atomic Energy Authority
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Filing: 1971-03-25
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Granted: 1973-10-02
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Expires: 1991-03-25
Abstract
Abstract A spacer grid for a nuclear reactor fuel element assembly in which a number of fuel pins are supported in a bundle with their longitudinal axes parallel and spaced transversely one from another. The grid structure is of cellular form being made up of cojoined tubular ferrules or intersecting strips defining cells each one of which is penetrated by a fuel pin. Resilient leaf members extend longitudinally in the cells of the grid structure and contact the fuel pins. The back faces of the free ends of the leaf members overlie but are spaced by a small clearance from stop members projecting inside the cells of the grid structure. The resilient leaf members are of low spring rating so as to allow freedom of lateral vibraton of the fuel pin within the cells of the grid structure whilst remaining in contact with the fuel pins. The limits of lateral vibration of the fuel pins is governed by tapping of the back faces of the resilient leaf members on the stop members.
Inventors
- 👤 G Milburn
- 👤 J Chetter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:19
CPC Classifications
G; G21; G21C; G21C3/00; G21C3/30; G21C3/32; G21C3/34; G21C3/344; G21C3/356; G21C3/3563; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
123 words
A nuclear reactor fuel element assembly as claimed in claim 1 wherein the grid structure comprises a plurality of cojoined tubular ferrules, a fuel pin extending through each ferrule, the ferrules being longitudinally slotted and shaped to define the resilient leaf members extending longitudinally inside the ferrules, the fuel pin extending through each ferrule being engaged by the free ends of the resilient leaf members in the ferrule, each ferrule being formed with outwardly extending rigid stop means, each corresponding to a resilient leaf member in an adjacent ferrule, the stop means extending to a point adjacent but spaced by a small clearance from the back faces of the ends of the resilient members which contact the fuel pins in the adjacent ferrules.
Claim 2
Dependent Claim
97 words
A nuclear reactor fuEl element assembly as claimed in claim 2 wherein the resilient leaf members in each ferrule alternately extend in opposite longitudinal directions in the ferrule, the resilient leaf members in the ferrules each corresponding with a resilient leaf member extending in the opposite direction in an adjacent ferrule, said stop means extending outwardly from the ferrules at the bases of the resilient leaf members of the ferrules, the stop means at the base of each resilient member in the ferrules being associated with the oppositely extending corresponding resilient leaf member in an adjacent ferrule.
Claim 3
Dependent Claim
121 words
A nuclear reactor fuel element assembly as claimed in claim 1 wherein the grid structure comprises two longitudinally spaced grid members each formed from intersecting strips defining cells in the grid members, each fuel pin extending longitudinally through a pair of corresponding cells in the two grid members, resilient leaf members extending longitudinally from the edges of the cell in one of the grid members, the free ends of the resilient leaf members contacting the fuel pin within the corresponding cell in the second of the grid members, said ends of the resilient leaf members overlying but spaced by a small clearance from rigid stop means projecting inwardly from the faces of the cell in the second of the grid members.
Claim 4
Dependent Claim
134 words
A nuclear reactor fuel element assembly as claimed in claim 4 wherein a first set of resilient leaf members extends longitudinally from the edges of alternate cells in the one grid member, the free ends of the first set of resilient leaf members contacting the fuel pins and overlying the stop means in the corresponding cells of the second of the grid members and wherein a second set of resilient leaf members extends longitudinally from the edges of the other cells in the second of the grid members in the opposite direction to which the first set of resilient leaf members extends, the free ends of the second set of resilient leaf members contacting the fuel pins and overlying the stop means in the corresponding other cells of the first of the grid members.
Claim 5
Dependent Claim
205 words
A nuclear reactor fuel element assembly as claimed in claim 1 wherein the grid structure comprises three parallel grid members formed from rigid intersecting strips defining cells in each grid member, each fuel pin extending through three corresponding cells of the three grid members, a first set of resilient leaf members extending longitudinally from the edges of the cell of one of the outer grid members, the free ends of the first set of resilient leaf members contacting the fuel pin within the corresponding cell of the centre grid member, said ends of the first set of resilient leaf members overlying but spaced by a small clearance from stop means projecting inwardly from the faces of the cell of the centre grid member, a second set of resilient leaf members extending longitudinally from the edges of the cell of the centre grid member, the free ends of the second set of resilient leaf members contacting the fuel pin within the corresponding cell of the second of the outer grid members, the free ends of the second set of resilient leaf members overlying, but spaced by a small clearance from stop means projecting inwardly from the faces of the cell of said second outer grid member.
Claim 6
Dependent Claim
115 words
A nuclear reactor fuel element assembly as claimed in claim 1 wherein the grid structure comprises two longitudinally spaced grid members each formed from intersecting strips defining cells in the grid members, each fuel pin extending longitudinally through a pair of corresponding cells in the two grid members, resilient leaf members extending longitudinally from the edges of the cell in one of the grid members, the fuel pin being contacted by the resilient leaf members at a point intermediate the ends of the resilient leaf members, the free ends of the resilient leaf members facing but spaced by a small clearance from the faces of the corresponding cell in the second of the grid members.
Claim 7
Dependent Claim
21 words
A nuclear reactor fueL element assembly as claimed in claim 1 wherein the stop means are permanently of substantially rigid form.
Claim 8
Dependent Claim
41 words
A nuclear reactor fuel element assembly as claimed in claim 1 wherein the stop means are of semi resilient form and arranged so as to be initially flexible under load but so as to become substantially rigid under an optimum loading.
Claim 9
Dependent Claim
72 words
A nuclear reactor fuel element assembly as claimed in claim 9 wherein the stop means comprises stop members separately attached to the grid structure and comprising resilient strip material formed into a curved bridge part with flat angled end parts, the stop members being attached to the grid structure at the ends of the flat angled end parts which hold the bridge part of the stop members away from the grid structure.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-01 | 1977-04-02 | 1977-10-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-01 | 1981-04-02 | 1981-10-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-01 | 1985-04-02 | 1985-10-02 | $7700.00 | Window Closed / Lapsed |