US4637900A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fabrication of high exposure nuclear fuel pellets
Assignee: United States Department of Energy
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Filing: 1984-01-13
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Granted: 1987-01-20
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Expires: 2004-01-13
Abstract
Abstract A method is disclosed for making a fuel pellet for a nuclear reactor. A mixture is prepared of PuO2 and UO2 powders, where the mixture contains at least about 30% PuO2, and where at least about 12% of the Pu is the Pu240 isotope. To this mixture is added about 0.3 to about 5% of a binder having a melting point of at least about 250 DEG F. The mixture is pressed to form a slug and the slug is granulated. Up to about 4.7% of a lubricant having a melting point of at least about 330 DEG F. is added to the granulated slug. Both the binder and the lubricant are selected from a group consisting of polyvinyl carboxylate, polyvinyl alcohol, naturally occurring high molecular weight cellulosic polymers, chemically modified high molecular weight cellulosic polymers, and mixtures thereof. The mixture is pressed to form a pellet and the pellet is sintered.
Inventors
- 👤 James R. Frederickson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 10:41
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
200 words
A method of making a fuel pellet for a nuclear reactor comprising (A) preparing a mixture of PuO 2 and UO 2 powders, said mixture containing at least about 30% PuO 2 , where at least 12% by weight of said Pu is Pu 240 ; (B) adding to said mixture about 0.3 to about 5% of a binder having a melting temperature of at least about 250 F. selected from a group consisting of fatty acid diamides, polyvinyl carboxylate, polyvinyl alcohol, naturally occurring high molecular weight cellulosic polymers, chemically modified high molecular weight cellulosic polymers, and mixtures thereof; (C) pressing said mixture at about 5000 to about 25,000 psi to form a slug; (D) granulating said slug; (E) adding to said granulated slug a positive amount up to about 4.7% of a lubricant having a melting point of at least about 330° F., selected from the group consisting of fatty acid diamides, polyvinyl carboxylate, polyvinyl alcohol, naturally occurring high molecular weight cellulosic polymers, chemically modified high molecular weight cellulosic polymers, and mixtures thereof; (F) pressing said granulated slug at about 20,000 to about 70,000 psi to form a pellet; and (G) sintering said pellet at about 1700° C.±200° C.
Claim 2
Independent Claim
200 words
A method of making a fuel pellet for a nuclear reactor comprising (A) preparing a mixture of PuO 2 and UO 2 powders, said mixture containing at least about 30% PuO 2 , where at least 12% by weight of said Pu is Pu 240 ; (B) adding to said mixture about 0.3 to about 5% of a binder having a melting temperature of at least about 250 F. selected from a group consisting of fatty acid diamides, polyvinyl carboxylate, polyvinyl alcohol, naturally occurring high molecular weight cellulosic polymers, chemically modified high molecular weight cellulosic polymers, and mixtures thereof; (C) pressing said mixture at about 5000 to about 25,000 psi to form a slug; (D) granulating said slug; (E) adding to said granulated slug a positive amount up to about 4.7% of a lubricant having a melting point of at least about 330° F., selected from the group consisting of fatty acid diamides, polyvinyl carboxylate, polyvinyl alcohol, naturally occurring high molecular weight cellulosic polymers, chemically modified high molecular weight cellulosic polymers, and mixtures thereof; (F) pressing said granulated slug at about 20,000 to about 70,000 psi to form a pellet; and (G) sintering said pellet at about 1700° C.±200° C.
Claim 3
Dependent Claim
22 words
A method according to claim 1 wherein said binder is N, N'-disteroyl ethylene diamine, polyvinyl alcohol, or methyl cellulose or mixtures thereof.
Claim 4
Dependent Claim
12 words
A method according to claim 1 wherein said lubricant is methyl cellulose.
Claim 5
Dependent Claim
12 words
A method according to claim 1 wherein said lubricant is polyvinyl alcohol.
Claim 6
Dependent Claim
14 words
A method according to claim 1 wherein said lubricant is a fatty acid diamide.
Claim 7
Dependent Claim
11 words
A sintered pellet prepared according to the method of claim 1.
Claim 8
Dependent Claim
22 words
A method according to claim 1 wherein said slug is granulated to a particle size of about -10 to about -60 mesh.
Claim 9
Dependent Claim
28 words
A method according to claim 1 wherein said pellet has a diameter of about 0.15 to about 0.5 inches and a length to diameter ratio of about 1.25:1.
Claim 10
Dependent Claim
31 words
A method according to claim 1 wherein said sintering is performed for about 4 to about 10 hours in a reducing atmosphere that keeps the oxygen to metal ratio below 2.
Claim 11
Dependent Claim
17 words
A method according to claim 1 wherein said binder and said lubricant each comprise N,N'-disteroyl ethylene diamine.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-01-19 | 1990-07-21 | 1991-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-19 | 1994-07-21 | 1995-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-19 | 1998-07-21 | 1999-01-20 | $7700.00 | Window Closed / Lapsed |