US4172762A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High exposure control rod finger
Assignee: Combustion Engineering Inc
•
Filing: 1978-01-20
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Granted: 1979-10-30
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Expires: 1998-01-20
Abstract
Abstract A nuclear reactor control rod containing a stack of B 4 C absorber pellets in which the pellets in the lower end have a radius smaller than that of the other pellets and are wrapped with a sleeve having a linear compressibility sufficient to accommodate exposure-induced radial expansion of the end pellets without producing excessive clad strain and having a thermal conductivity sufficient to keep the centerline temperature of the end pellets below the melting point of B 4 C. One such sleeve material is a type 347 stainless steel having 22.5% theoretical density.
Inventors
- 👤 Andrew J. Anthony
- 👤 Malcom D. Groves
- 👤 Richard H. Young
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:41
CPC Classifications
G; G21; G21C; G21C7/00; G21C7/06; G21C7/08; G21C7/10; Y; Y02; Y02E; Y02E30/00; Y02E30/30
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
90 words
In a nuclear reactor control rod having a sealed cylindrical cladding of inside radius R1 within which are stacked a plurality of poison absorber pellets having outside radius R2 substantially equal to R1, wherein the improvement comprises: at least one of the pellets at the leading end of the rod having a radius R3 less than R2; and a sleeve circumferentially wrapped around said end pellets, said sleeve having a thickness substantially equal to R2 minus R3 and a minimum linear compressibility of 1.0 percent per 1,000 psi continuous load.
Claim 2
Dependent Claim
90 words
In a nuclear reactor control rod having a sealed cylindrical cladding of inside radius R1 within which are stacked a plurality of poison absorber pellets having outside radius R2 substantially equal to R1, wherein the improvement comprises: at least one of the pellets at the leading end of the rod having a radius R3 less than R2; and a sleeve circumferentially wrapped around said end pellets, said sleeve having a thickness substantially equal to R2 minus R3 and a minimum linear compressibility of 1.0 percent per 1,000 psi continuous load.
Claim 3
Dependent Claim
11 words
The control rod of claim 1 wherein said sleeve is integral.
Claim 4
Dependent Claim
16 words
The control rod of claim 1 wherein said end pellets are made of B 4 C.
Claim 5
Dependent Claim
56 words
The control rod of claim 3 wherein said sleeve has a thermal conductivity sufficient to keep the centerline temperature of said end pellets below the melting point of B 4 C when said end pellets are located in a thermal reactor spectrum steady state total neutron flux of 3.0×10 14 neutrons per second per square centimeter.
Claim 6
Dependent Claim
25 words
The control rod of claim 3 wherein said sleeve has a minimum thermal conductivity of 3.0 BTU per hour per square foot per degree F.
Claim 7
Dependent Claim
24 words
The control rod of claim 3 wherein said sleeve material is type 347 stainless steel having a density between 15% and 30% of theoretical.
Claim 8
Dependent Claim
24 words
The control rod of claim 6 wherein said sleeve material is type 347 stainless steel having a density of approximately 22.5 percent of theoretical.
References Cited (Backward Citations)
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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) | 1982-10-29 | 1983-04-30 | 1983-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-10-29 | 1987-04-30 | 1987-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-10-29 | 1991-04-30 | 1991-10-30 | $7700.00 | Window Closed / Lapsed |