US4355002A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nuclear fuel assembly
Assignee: Hitachi Ltd
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Filing: 1977-10-13
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Granted: 1982-10-19
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Expires: 1997-10-13
Abstract
Abstract First nuclear fuel elements in which a fissionable material in which a burnable poison is incorporated is loaded and second nuclear fuel elements in which a fissionable material in which no burnable poison is incorporated is loaded are disposed in a nuclear fuel assembly. Content of the fissionable material in the first nuclear fuel element is less than about 72% of that of the fissionable material in the second nuclear fuel element adjacent to the first nuclear fuel element.
Inventors
- 👤 Takanori Hosokawa
- 👤 Hideo Maki
- 👤 Katsutoshi Shinbo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:41
CPC Classifications
G; G21; G21C; G21C3/00; G21C3/30; G21C3/32; G21C3/326; G21C3/328; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
98 words
In a nuclear fuel assembly including first nuclear fuel elements containing fissionable material and a non-fissionable burnable poison, and second adjacent nuclear fuel elements containing the same fissionable material as contained in said first nuclear fuel elements but being free of said non-fissionable burnable poison, the improvement comprising the enrichment of said fissionable material in said first nuclear fuel elements at zero megawatt.day/ton burn-up being less than the enrichment of said same fissionable material in said second adjacent nuclear fuel elements at zero megawatt.day/ton burn-up, whereby the danger of damage to said first nuclear fuel elements is reduced.
Claim 2
Dependent Claim
98 words
In a nuclear fuel assembly including first nuclear fuel elements containing fissionable material and a non-fissionable burnable poison, and second adjacent nuclear fuel elements containing the same fissionable material as contained in said first nuclear fuel elements but being free of said non-fissionable burnable poison, the improvement comprising the enrichment of said fissionable material in said first nuclear fuel elements at zero megawatt.day/ton burn-up being less than the enrichment of said same fissionable material in said second adjacent nuclear fuel elements at zero megawatt.day/ton burn-up, whereby the danger of damage to said first nuclear fuel elements is reduced.
Claim 3
Dependent Claim
40 words
A nuclear fuel assembly according to claim 1, wherein the enrichment of said fissionable material in said first nuclear fuel elements is less than about 72% of the enrichment of said fissionable material in said second adjacent nuclear fuel elements.
Claim 4
Dependent Claim
58 words
A nuclear fuel assembly according to claim 2, wherein said nuclear fuel elements are in the form of axially elongated rods, and wherein the enrichment of fissionable material in the axially middle portions of said first nuclear fuel elements is less than the enrichment of fissionable material in the same portion of said second adjacent nuclear fuel elements.
Claim 5
Dependent Claim
46 words
A nuclear fuel assembly according to claim 3, wherein the enrichment of fissionable material in said axially middle portions of said first nuclear fuel elements is less than the enrichment of the same fissionable material in the axially end portions of said first nuclear fuel elements.
Claim 6
Dependent Claim
43 words
A nuclear fuel assembly according to claim 3, wherein the enrichment of fissionable material in said axially middle portions of said first nuclear fuel elements is less than about 72% of the enrichment of fissionable material in said second adjacent nuclear fuel elements.
Claim 7
Dependent Claim
46 words
A nuclear fuel assembly according to claim 5, wherein the enrichment of fissionable material in said axially middle portions of said first nuclear fuel elements is less than the enrichment of the same fissionable material in the axially end portions of said first nuclear fuel elements.
Claim 8
Dependent Claim
45 words
A nuclear fuel assembly according to claim 3, wherein said fissionable material contained in said first and second nuclear fuel elements is present in pellets of UO 2 , and wherein said non-fissionable burnable poison contained in said first nuclear fuel elements is gadolinium oxide.
Claim 9
Dependent Claim
19 words
A nuclear fuel assembly according to claim 1, wherein said first nuclear fuel elements contain a single fissionable material.
Claim 10
Dependent Claim
59 words
A nuclear fuel assembly according to claim 1, wherein said nuclear fuel elements are in the form of axially elongated rods, and wherein the enrichment of said fissionable material in the axially middle portions of said first nuclear fuel elements is less than the enrichment of said fissionable material in identical portions of said second adjacent nuclear fuel elements.
Claim 11
Dependent Claim
41 words
A nuclear fuel assembly according to claim 9, wherein the enrichment of said fissionable material in the axially middle portions of said first nuclear fuel elements is less than about 72% of the enrichment of said second adjacent nuclear fuel elements.
Claim 12
Dependent Claim
26 words
A nuclear fuel assembly according to claim 1, wherein said second adjacent nuclear fuel elements are arranged adjacently surrounding each of said first nuclear fuel elements.
Claim 13
Dependent Claim
45 words
A nuclear fuel assembly according to claim 1, wherein said fissionable material contained in said first and second nuclear fuel elements is present in pellets of UO 2 , and wherein said non-fissionable burnable poison contained in said first nuclear fuel elements is gadolinium oxide.
Claim 14
Dependent Claim
40 words
A nuclear fuel assembly according to claim 12, wherein the enrichment of said fissionable material in said first nuclear fuel elements is less than about 72% of the enrichment of said fissionable material in said second adjacent nuclear fuel elements.
Claim 15
Dependent Claim
21 words
A nuclear fuel assembly according to claim 1, wherein said nuclear fuel elements are in the form of axially elongated rods.
Claim 16
Dependent Claim
23 words
A nuclear fuel assembly according to claim 1, wherein said non-fissionable burnable poison is a material having a high thermal neutron absorption cross-section.
Claim 17
Dependent Claim
31 words
A nuclear fuel assembly according to claim 15, wherein said non-fissionable burnable poison is a material containing at least one of boron, cadmium, erbium, europium, hafnium, samarium, and chemical compounds thereof.
Claim 18
Dependent Claim
120 words
In a nuclear fuel assembly including first nuclear fuel elements containing fissionable material and a non-fissionable burnable poison, and second adjacent nuclear fuel elements containing the same fissionable material as contained in said first nuclear elements but being free of said non-fissionable burnable poison, a method for preventing failure of said first nuclear fuel elements comprising the step of loading fissionable material in said first nuclear fuel elements so that the enrichment of the fissionable material in said first nuclear fuel elements at zero megawatt.day/ton burn-up is less than the enrichment of the same fissionable material in said second adjacent nuclear fuel elements at zero megawatt.day/ton burn-up, whereby the danger of damage to said first nuclear fuel elements is reduced.
Claim 19
Dependent Claim
120 words
In a nuclear fuel assembly including first nuclear fuel elements containing fissionable material and a non-fissionable burnable poison, and second adjacent nuclear fuel elements containing the same fissionable material as contained in said first nuclear elements but being free of said non-fissionable burnable poison, a method for preventing failure of said first nuclear fuel elements comprising the step of loading fissionable material in said first nuclear fuel elements so that the enrichment of the fissionable material in said first nuclear fuel elements at zero megawatt.day/ton burn-up is less than the enrichment of the same fissionable material in said second adjacent nuclear fuel elements at zero megawatt.day/ton burn-up, whereby the danger of damage to said first nuclear fuel elements is reduced.
Claim 20
Dependent Claim
37 words
A method according to claim 17, wherein the enrichment of fissionable material loaded in said first nuclear fuel elements is less than about 72% of the enrichment of fissionable material in said second adjacent nuclear fuel elements.
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) | 1985-10-18 | 1986-04-19 | 1986-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-18 | 1990-04-19 | 1990-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-18 | 1994-04-19 | 1994-10-19 | $7700.00 | Window Closed / Lapsed |