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US3923933A
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Process for preparing sintered uranium dioxide grains
Assignee: General Electric Co
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Filing: 1973-10-09
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Granted: 1975-12-02
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Expires: 1993-10-09
Abstract
Abstract Uranium dioxide powder is prepared for use as fuel in nuclear reactors by forming it into compacts of any convenient size, and sintering these compacts at a temperature of at least about 1900*C until grains of the desired size are formed in the compacts. The heating is carried out in an atmosphere of dry hydrogen having a dewpoint sufficient to produce substoichiometric uranium dioxide. The sintered compacts are then cooled in an atmosphere of hydrogen at a rate sufficient to precipitate uranium on the grain boundaries. The precipitated uranium reacts with the hydrogen in the atmosphere to form uranium hydride, causing a significant volume increase which disintegrates the compacts into substantially the grains formed therein.
Inventors
- 👤 Kenneth W Lay
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 01:28
CPC Classifications
G; G21; G21C; G21C3/00; G21C3/42; G21C3/58; G21C3/62; G21C3/623; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
150 words
A PROCESS OF PREPARING FREE-FLOWING SUBSTANTIALLY EQUIAXED URANIUM DIOXIDE NUCLEAR FUEL GRAINS OF CONTROLLED SIZE WHICH COMPRISES PRESSING POWDER CONSISTING ESSENTIALLY OF URANIUM DIOXIDE OR AMMONIUM DIURANATE INTO COMPACTS, SINTERING SAID COMPACTS AT A TEMPERATURE OF AT LEAST ABOUT 1900*C UNTIL GRAINS OF URANIUM DIOXIDE OF THE DESIRED SIZE ARE FORMED THEREIN, SAID SINTERING BEING CARRIED OUT IN AN ATMOSPHERE OF DRY HYDROGEN HAVING A DEWPOINT SUFFICIENT TO PRODUCE SUBSTOICHIOMETRIC URANIUM DIOXIDE, AND COOLING SAID SINTERED COMPACTS IN AN ATMOSPHERE OF HYDROGEN AT A RATE OF ABOUT 100 TO 300 CENTIGRADE DEGREE PER MINUTE TO PRECIPITATE METALLIC URANIUM SUBSTANTIALLY AT THE BOUNDARIES OF THE GRAINS, AND REACTING SAID PRECIPITATED METALLIC URANIUM WITH HYDROGEN DURING SAID COOLING AT TEMPERATURES BELOW ABOUT 400*C TO FORM URANIUM HYDRIDE AND THEREBY CAUSING SAID SINTERED COMPACTS TO DISINTEGRATE SUBSTANTIALLY ALONG THE GRAIN BOUNDARIES FORMING SUBSTANTIALLY EQUIAXIAL GRAINS OF URANIUM DIOXIDE OF SUBSTANTIALLY THE SAME SIZE.
Claim 2
Dependent Claim
150 words
A PROCESS OF PREPARING FREE-FLOWING SUBSTANTIALLY EQUIAXED URANIUM DIOXIDE NUCLEAR FUEL GRAINS OF CONTROLLED SIZE WHICH COMPRISES PRESSING POWDER CONSISTING ESSENTIALLY OF URANIUM DIOXIDE OR AMMONIUM DIURANATE INTO COMPACTS, SINTERING SAID COMPACTS AT A TEMPERATURE OF AT LEAST ABOUT 1900*C UNTIL GRAINS OF URANIUM DIOXIDE OF THE DESIRED SIZE ARE FORMED THEREIN, SAID SINTERING BEING CARRIED OUT IN AN ATMOSPHERE OF DRY HYDROGEN HAVING A DEWPOINT SUFFICIENT TO PRODUCE SUBSTOICHIOMETRIC URANIUM DIOXIDE, AND COOLING SAID SINTERED COMPACTS IN AN ATMOSPHERE OF HYDROGEN AT A RATE OF ABOUT 100 TO 300 CENTIGRADE DEGREE PER MINUTE TO PRECIPITATE METALLIC URANIUM SUBSTANTIALLY AT THE BOUNDARIES OF THE GRAINS, AND REACTING SAID PRECIPITATED METALLIC URANIUM WITH HYDROGEN DURING SAID COOLING AT TEMPERATURES BELOW ABOUT 400*C TO FORM URANIUM HYDRIDE AND THEREBY CAUSING SAID SINTERED COMPACTS TO DISINTEGRATE SUBSTANTIALLY ALONG THE GRAIN BOUNDARIES FORMING SUBSTANTIALLY EQUIAXIAL GRAINS OF URANIUM DIOXIDE OF SUBSTANTIALLY THE SAME SIZE.
Claim 3
Dependent Claim
36 words
A process according to claim 1 wherein a grain growth accelerator in an amount ranging from about 0.1 to 1% by weight of the powder is added to said powder before it is compressed into compacts.
Claim 4
Dependent Claim
27 words
A process according to claim 2 wherein said grain growth accelerator is selected from the group consisting of aluminum oxide, magnesium oxide, beryllium oxide and titanium dioxide.
Claim 5
Dependent Claim
24 words
A process according to claim 1 wherein uranium is admixed with the uranium dioxide or ammonium diuranate powder before it is pressed into compacts.
Claim 6
Dependent Claim
22 words
A process according to claim 4 wherein a grain growth accelerator is added to said mixture before it is pressed into compacts.
Claim 7
Dependent Claim
23 words
A process according to claim 1 wherein said compacts are cooled initially in an atmosphere of an inert gas until above about 400*C.
Claim 8
Dependent Claim
32 words
A NUCLEAR FUEL COMPRISED OF SINTERED URANIUM DIOXIDE HAVING AN OXYGEN TO URANIUM RATIO OF ABOUT 2.00 AND BEING IN THE FORM OF WHOLE, SINTER-GROWN GRAINS WHICH ARE FREE-FLOWING AND SUBSTANTIALLY EQUIAXED.
Claim 9
Dependent Claim
32 words
A NUCLEAR FUEL COMPRISED OF SINTERED URANIUM DIOXIDE HAVING AN OXYGEN TO URANIUM RATIO OF ABOUT 2.00 AND BEING IN THE FORM OF WHOLE, SINTER-GROWN GRAINS WHICH ARE FREE-FLOWING AND SUBSTANTIALLY EQUIAXED.
Claim 10
Dependent Claim
19 words
A nuclear fuel according to claim 7 wherein said grains range in size from about 60 to 320 microns.
Claim 11
Dependent Claim
11 words
A sealed metal tube packed with the product of claim 7.
References Cited (Backward Citations)
US3573036A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |