US3666846A
Expired / Lapsed
US
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Process of forming an isotopic heat source
Assignee: United States Atomic Energy Commission
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Filing: 1969-04-11
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Granted: 1972-05-30
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Expires: 1989-04-11
Abstract
Abstract A process of encapsulating an alpha-emitting isotope to form an isotopic heat source. Microspheres are prepared, each containing its own helium gas plenum, an alpha-emitting isotope, and containment cladding. These microspheres are sealed in a capsule with or without a metal matrix.
Inventors
- 👤 Kenneth R Sump
- 👤 Ramon K Robinson
- 👤 Boyd D Howard
- 👤 Kirk Drumheller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 04:43
CPC Classifications
G; G21; G21G; G21G4/00; G21G4/04; G21G4/06
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
31 words
A process according to claim 1 wherein the refractory metal of the microspheres and the compatible cladding is tungsten and the material containing an alpha-emitting isotope is a rare earth polonide.
Claim 2
Dependent Claim
28 words
A process according to claim 2 wherein the coated microspheres are further coated with a different metal to provide strength to the microspheres and with an oxidation-resistant material.
Claim 3
Dependent Claim
38 words
A process according to claim 3 wherein the solid microspheres are formed of magnesium, tungsten is deposited on the microspheres by chemical vapor deposition, nd the magnesium is removed by heating the coated microspheres at about 1,500* C.
Claim 4
Dependent Claim
66 words
A method according to claim 4 wherein a water-cooled plate is disposed above the tungsten-clad microspheres as they are being heated to about 1,500* C. whereby a large button of magnesium forms on the water-cooled plate, the system being cooled after the button of magnesium forms, the magnesium button then being removed and the system being rEheated to a temperature between 1, 000* and 1,500* C.
Claim 5
Dependent Claim
34 words
A process according to claim 1 wherein the material containing an alpha-emitting isotope is deposited on the hollow microsphere by depositing a rare earth metal on the microspheres and reacting this metal with polonium-210.
Claim 6
Dependent Claim
29 words
A process according to claim 5 wherein gadolinium is deposited on the microspheres by vacuum vaporization and the gadolinium layer is reacted with polonium vapor at about 850* C.
Claim 7
Dependent Claim
40 words
A process according to claim 7 wherein the gadolinium-coated microspheres are reacted with hydrogen for two hours prior to reacting it with polonium and the polonium is pretreated by heating it at about 800* C. in the presence of tantalum.
Claim 8
Independent Claim
47 words
A method of coating hollow refractory metal microspheres with an alpha-emitting heat source comprising exposing the microspheres to vapor of a rare earth metal until a layer of a rare earth metal is deposited on the microspheres and reacting the said rare earth metal with polonium vapor.
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) | 1975-05-30 | 1975-11-29 | 1976-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-30 | 1979-11-29 | 1980-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-30 | 1983-11-29 | 1984-05-30 | $7700.00 | Window Closed / Lapsed |