US3770583A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fuel assembly hold-down device
Assignee: Combustion Engineering Inc
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Filing: 1971-05-20
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Granted: 1973-11-06
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Expires: 1991-05-20
Abstract
Abstract The invention provides a hold-down device which maintains a net downward force on a fuel assembly in a nuclear reactor under all thermal and hydraulic conditions in the reactor core region. The hold-down device is particularly applicable in reactors having stainless steel support barrels and Zircaloy guide tubes.
Inventors
- 👤 R Klumb
- 👤 J Hutchinson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:38
CPC Classifications
G; G21; G21C; G21C3/00; G21C3/30; G21C3/32; G21C5/00; G21C5/02; G21C5/06; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
191 words
In a nuclear fuel assembly including, longitudinally extending rigid support means; upper and lower end fittings supported by said support means at opposite ends thereof; a plurality of elongated fuel elements in parallel relationship and extending substantially between said upper and lower end fittings and supported by said support means, hold-down apparatus for said fuel assembly in which said upper end fitting comprises: an end plate supported by said support means against downward motion relative thereto and extending transversely thereof; alignment means projecting longitudinally upward from and supported against upward motion relative to said end plate, said alignment means having an outwardly enlarged shoulder affixed thereto and spaced upwardly from said end plate; force transmitting means slidably mounted on said alignment means and movable therealong between said shoulder and said end plate and having a portion thereof extending laterally beyond said shoulder for receiving a downward force applied to said portion; and spring means interposed between said force transmitting means and said end plate for biasing said force transmitting means upwardly from said plate whereby a said downward force on said force transmitting means is yieldably transmitted to said fuel assembly.
Claim 2
Dependent Claim
191 words
In a nuclear fuel assembly including, longitudinally extending rigid support means; upper and lower end fittings supported by said support means at opposite ends thereof; a plurality of elongated fuel elements in parallel relationship and extending substantially between said upper and lower end fittings and supported by said support means, hold-down apparatus for said fuel assembly in which said upper end fitting comprises: an end plate supported by said support means against downward motion relative thereto and extending transversely thereof; alignment means projecting longitudinally upward from and supported against upward motion relative to said end plate, said alignment means having an outwardly enlarged shoulder affixed thereto and spaced upwardly from said end plate; force transmitting means slidably mounted on said alignment means and movable therealong between said shoulder and said end plate and having a portion thereof extending laterally beyond said shoulder for receiving a downward force applied to said portion; and spring means interposed between said force transmitting means and said end plate for biasing said force transmitting means upwardly from said plate whereby a said downward force on said force transmitting means is yieldably transmitted to said fuel assembly.
Claim 3
Dependent Claim
57 words
The apparatus of claim 1 wherein said force transmitting means comprise a hold-down plate having at least one hub portion; an aperture in and extending through said hub portion for relative slidable passage therethrough of said alignment means; and leg means extending substantially radially outward from said hub portion beyond said enlarged shoulder on said alignment means.
Claim 4
Dependent Claim
75 words
The apparatus of claim 2 wherein said alignment means comprise a plurality of cylindrical posts extending upwardly from said end plate and symmetrically disposed about the vertical axis passing through the center of gravity of said fuel assembly; and said hold-down plate includes said same plural number of apertured hub portions for relative insertion therethrough of said alignment posts, said hub portions being joined and positioned relative to one another and by said leg means.
Claim 5
Dependent Claim
26 words
The apparatus of claim 1 wherein said spring means comprise a coil spring, said coil spring being in compression and coaxially disposed about said alignment means.
Claim 6
Dependent Claim
28 words
The apparatus of claim 3 wherein said spring means comprise coil springs, said coil springs being in compression and coaxially disposed about a plurality of said alignment posts.
Claim 7
Dependent Claim
71 words
The apparatus of claim 1 wherein said fuel assembly includes a hollow tube open at its upper end and extending at least the full extent of said fuel elements parallel thereto and in vertical alignment with said alignment means; and said alignment means and said end plate include a passageway extending vertically therethrough in registry with said hollow tube whereby a control element may be inserted therewithin into said fuel assembly.
Claim 8
Dependent Claim
67 words
The apparatus of claim 3 wherein said fuel assembly includes hollow tubes open at their upper ends and extending at least the full extent of said fuel elements thereto and in vertical alignment with alignment posts; and said alignment posts and said end plate include passageways extending vertically thereto in registry with said hollow tubes whereby a control element may be inserted therewithin into said fuel assembly.
Claim 9
Dependent Claim
20 words
The apparatus of claim 7 wherein said hollow tubes comprise said support means extending between said fuel assembly end fittings.
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) | 1976-11-05 | 1977-05-07 | 1977-11-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-05 | 1981-05-07 | 1981-11-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-05 | 1985-05-07 | 1985-11-06 | $7700.00 | Window Closed / Lapsed |