US3297543A

US3297543A - Plate-type nuclear fuel element

Info

Publication number: US3297543A
Application number: US380851A
Authority: US
Inventors: Nicholas C Jessen; William F Heer
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1964-07-07
Filing date: 1964-07-07
Publication date: 1967-01-10
Anticipated expiration: 1984-01-10
Also published as: GB1071363A

Description

Jan.;10; 1967 N. c. JESSEN ETAL 3,297,543

PLATE-TYPE NUCLEAR FUEL ELEMENT Filed July 7, 1964 FIG. 1

FIG.3

INVENTORS Nicholas C. Jessen By W|ll|am F. Heer ATTORNEY Whitedf States Patent This invention relates to plate-type nuclear fuel elements and more particularly, to such elements in which the fissile core material is arranged within a circumscribing frame member and encased by cover plates.

Inthe past it has been standard practice to manufacture uranium-aluminum alloy fuel plates by inserting the fissile core material into a frame member, cladding or covering both sides of the frame member and the core with plates, and roll bonding the assembly. However, one

, serious disadvantage stemming from the use of uraniumaluminum :alloy as thefuel has been its lack of homogeniety gwiththe consequent possibility of developing hot spots in the fuel plates. This necessitates reduction in the heat. output rate, and a corresponding reduction in the eflicjiency potential. Further, in such plate-type elements,

, as the uranium content of the alloy is increased, the workability of the core, particularly in the rolling operation, decreases. rapidly and poses a difficult manufacturing problem. This problem is furtheraggravated if boron is added :to the fuel alloy because its tendency to segregate is worse than that of uranium. To date it has been very diflicult to attain any degree of homogeneity in boronaluminum-uranium fuel alloys.

Toovercome this problem, a cermet, such as powdered aluminum. metal and uranium oxide, has been suggested as thefuel material. However, the powdered fuel, though satisfying the need for a homogeneous mass, has a tendency to squirt out of its frame member when pressure is applied during the roll bonding step in the assembly. This j is known as stringering and results in the dispersion of fuel outside of the desired location within the plate.

Itisa primary object of the present invention to provide .a plate-type fuel element construction which overcomes the objections just cited by assuring that the cermet core will remain intact and will be properly positioned within theelement.

Accordingly, the present invention provides a circumscribing frame member having an aperture extending between "its oppositely disposed faces. In the aperture a fuel core is positioned so that it is recessed with respect to both the upper and lower faces of the frame member. Core cover plates are fitted to and are in contact with the upper. and lower sides of the core, within the aperture. They are of a thickness such that they will be flush with the adjacent upper and lower faces of the frame member.

Next, a cover plate is placed on the upper and lower faces of the frame member covering its entire surface. The assembled: fuel element is then rolled to assure bonding between its various components.

.The core cover plates may be integrally attached to the framegmember, as by welding, prior to placing of the upper. and lower cover plates, to assure the maintenance of the core withinthe aperture.

Preferably, the fuel core comprises a cermet consisting of powdered aluminum metal and uranium oxide and in some instances, if required, boron.

The various features of novelty which characterize this invention are pointed out with particularity in the claims 3,297,543 Patented Jan. 10, 1967 Of the drawings:

FIG. 1 is an exploded perspective view of the fuel element embodying the present invention;

SIG. 2 is a perspective View of the assembled element; an

FIG. 3 is a cross section taken along line 33 in FIG. 1.

In FIG. 1 the various components of a plate-type fuel element 10 are illustrated in disassembled, exploded fashion, while assembly views are shown in FIGS. 2 and 3. Forming the center layer of the fuel element 10 is a rectangular frame member 12 having a rectangular aperture 14 extending through it between its upper and

lower faces

16 and 18 respectively. This aperture accommodates a fuel core 20 of a thickness relative to the frame 12 so that it may be positioned recessed from both the upper and

lower faces

16, 18 of the frame member. Additionally, the aperture accommodates a pair

ofcore cover plates

21, 22 which cover the upper and lower faces, respectively, of fuel core 20. These core cover plates are of a thicknesssuch that upon assembly of the components, they will be flush with the

corresponding faces

16, 18 of the frame member 12. To prevent any displacement of the fuel core material from within the aperture, the core cover plates are welded about their periphery to the frame member.

Cover plates

23, 24 are provided for the upper and

lower faces

16, 18, respectively, of the frame member 12, and the component assembly is then rolled to achieve bonding between the various cover plates and the frame member and to further compact the fuel core.

As mentioned previously, one of the problems faced in employing cermets is the possibility that the cermet core under pressure of rolling might squirt into the interfaces between the frame member and its cover plates. By utilizing core cover plates and welding them to the frame member, the retention of core material within the aperture is assured. This feature is especially important since proper location of the fuel is essential to the efficient use of fuel elements.

It will be appreciated that it would be equally advantageous to use core materials other than cermets in the construction disclosed by the present invention to achieve plate-type fuel elements in which the fuel is retained within a definite location.

Tests have indicated that both U 0 as well as U0 may be employed in the cermet, and there is some indication that the use of U 0 powder might be preferable in the present invention. Additionally, the present invention would be applicable for any powder metallurgy fuel cores.

While in accordance with the provisions of the statutes the invention has been illustrated and described in the best form and mode of operation of the invention now known, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered 'by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

1. A plate-type fuel element comprising:

(A) a frame member having a pair of oppositely disposed faces and an aperture in at least one of said faces,

(B) a core of fissile material disposed within said aperture and recessed from said face containing the aperture, the edges of said core being in substantial contact with the sides of said aperture, and

(C) a core cover plate superimposed upon said core and disposed within and filling said aperture.

2. A plate-type fuel element as set forth in claim 1 wherein the core cover plate is integrally attached to the frame member sealing the core within said aperture.

3. A plate-type fuel element comprising:

(B) .a core of fissile material having a thickness less than said frame member disposed within said aperture and recess from said face containing the aperture, the edges of said core being in substantial contact with the sides of said aperture,

(C) a core cover plate superimposed upon said core within said aperture and the edges of said core cover plate being in substantial contact with the sides of said aperture, and

(D) a frame member cover plate superimposed upon the face of said frame member having the aperture therein.

4. A plate-type element comprising:

(A) a frame member having a pair of oppositely disposed faces and an aperture extending therethrough between said faces,

(B) a core of fissile material having a thickness less than said frame member disposed within said aperture .and recessed from both faces of said frame member, the edges of said core being in substantial contact with the sides of said aperture,

(C) a core cover plate superimposed on each side of said core within said aperture and the edges of said core cover plate being in substantial contact with the sides of said .aperture, and

(D) a frame member cover plate superimposed upon each face of the frame member.

5. A plate-type fuel element comprising:

(A) a relatively thin frame member having a pair of oppositely disposed faces and a rectangular shaped aperture extending therethrough between said faces,

(B) a core of fissile material having a thickness less than said frame member disposed within said aperture and recessed from both faces of said frame member, the face of said core having the same dimensions and shape as said aperture and the edges of said core being in substantial contact with the sides of said aperture,

(C) a core cover plate having substantially the same face dimension and shape as said aperture and disposed therein on each face of said core, and

(D) a frame member cover plate superimposed upon each face of said frame member and said assembled fuel element rolled to provide bonding of the separate components.

6. A plate-type fuel element as set forth in claim 5 wherein the outer faces of said core cover plates are arranged flush with the corresponding faces of said frame member and are integrally attached thereto.

References Cited by the Examiner UNITED STATES PATENTS BENJAMIN R. PADGETT, Primary Examiner. L. DEWAYNE RUTIJEDGE, Examiner. I. V. MAY, M. J. SCOLNICK, Assistant Examiners.

Claims

1. A PLATE-TYPE FUEL ELEMENT COMPRISING: (A) A FRAME MEMBER HAVING A PAIR OF OPPOSITELY DISFACES, (B) A CORE OF FISSILE MATERIAL DISPOSED WITHIN SAID APERTURE AND RECESSED FROM SAID FACE CONTAINING THE APERTURE, THE EDGES OF SAID CORE BEING IN SUBSTANTIAL CONI TACT WITH THE SIDES OF SAID APERTURE, AND