US3976540A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic latch trigger for inherent shutdown assembly
Assignee: Energy Research and Development Administration ERDA
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Filing: 1975-04-03
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Granted: 1976-08-24
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Expires: 1995-04-03
Abstract
Abstract An inherent shutdown assembly for a nuclear reactor is provided. A neutron absorber is held ready to be inserted into the reactor core by a magnetic latch. The latch includes a magnet whose lines of force are linked by a yoke of material whose Curie point is at the critical temperature of the reactor at which the neutron absorber is to be inserted into the reactor core. The yoke is in contact with the core coolant or fissionable material so that when the coolant or the fissionable material increase in temperature above the Curie point the yoke loses its magnetic susceptibility and the magnetic link is broken, thereby causing the absorber to be released into the reactor core.
Inventors
- 👤 Edmund S. Sowa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 12:40
CPC Classifications
G; G21; G21C; G21C9/00; G21C9/02; G21C9/027; G21C17/00; G21C17/10; G21C17/12; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
241 words
In a nuclear reactor, an inherent shutdown assembly for releasing a neutron absorber into the core region of the reactor with the density of neutron flux of the core region at a critical level, comprising: support means adjacent the core region capable of supporting an object coupled thereto, a neutron absorber, a fissionable material exposed to the neutron flux of the core region so that as the density of said flux varies the temperature of said fissionable material varies proportionally, and a magnetic latch including a magnet and a ferromagnetic link in contact with said fissionable material so that the temperature of said link varies proportionally with the temperature of said fissionable material and thereby with the density of said flux, said latch being coupled to said support means and said absorber so that with the density of neutron flux below the critical level said link is attracted to said magnet to form a completed magnetic circuit of sufficient attractive force between said link and said magnet to couple the absorber to said support means whereby the absorber is held in a position adjacent the core region, and so that with the density of neutron flux at least equal to the critical level the magnetic permeability of said link being of such value that the attractive force between said link and said magnet is insufficient to couple said absorber to said support thereby allowing said absorber to enter said core region.
Claim 2
Dependent Claim
241 words
In a nuclear reactor, an inherent shutdown assembly for releasing a neutron absorber into the core region of the reactor with the density of neutron flux of the core region at a critical level, comprising: support means adjacent the core region capable of supporting an object coupled thereto, a neutron absorber, a fissionable material exposed to the neutron flux of the core region so that as the density of said flux varies the temperature of said fissionable material varies proportionally, and a magnetic latch including a magnet and a ferromagnetic link in contact with said fissionable material so that the temperature of said link varies proportionally with the temperature of said fissionable material and thereby with the density of said flux, said latch being coupled to said support means and said absorber so that with the density of neutron flux below the critical level said link is attracted to said magnet to form a completed magnetic circuit of sufficient attractive force between said link and said magnet to couple the absorber to said support means whereby the absorber is held in a position adjacent the core region, and so that with the density of neutron flux at least equal to the critical level the magnetic permeability of said link being of such value that the attractive force between said link and said magnet is insufficient to couple said absorber to said support thereby allowing said absorber to enter said core region.
Claim 3
Dependent Claim
32 words
The assembly of claim 1 wherein the reactor core region coolant is in contact with said link so that as the temperature of said coolant increases the temperature of said link increases.
Claim 4
Dependent Claim
28 words
The assembly of claim 2 further including a power source, and electrical connections coupling said power source to said link thereby allowing said link to be resistance heated.
Claim 5
Dependent Claim
28 words
The assembly of claim 3 further including at least one additional magnetic latch with all said magnetic latches arranged in a stack with said absorber atop said stack.
Claim 6
Dependent Claim
70 words
The assembly of claim 4 wherein said shutdown assembly enters the reactor core by descending therein and wherein the reactor core region includes subassemblies of particular shape, and wherein at least one of said subassemblies is adapted to receive said descending shutdown assembly, said one subassembly includes means to stop the descent of said shutdown assembly so that the absorber is positioned in a predetermined manner within the core region.
Claim 7
Dependent Claim
47 words
The device of claim 5 further including means for resetting said shutdown assembly so that with said shutdown assembly having descended into the core region said means for resetting is capable of raising said assembly to allow for recoupling of said magnetic latches to said support structure.
References Cited (Backward Citations)
GB890661A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-24 | 1980-02-23 | 1980-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-24 | 1984-02-23 | 1984-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-24 | 1988-02-23 | 1988-08-24 | $7700.00 | Window Closed / Lapsed |