United Kingdom Atomic Energy Authority

Secretary of State for United Kingdom Atomic Energy Authority

Robert Jolly

Colin E Butterfield

A nuclear reactor fuel of the kind comprising multi-pins (10) located in a hexagonal wrapper (11) and stabilized by a series of spacing grids (12) has an internal grid support cage (13) formed by six vertical limbs (20) inside the wrapper. The limbs of the cage have upturned parts (14) which engage into the cellular structure of the grids such as lying between two adjacent unit cells (16). The cells have tabs (21 in FIG. 3 and 52 in FIG. 5) which can be welded to the upturned parts.

Nuclear reactor fuel assemblies

Irradiated nuclear fuel pins (30) comprising metal-sheathed refractory pellets are rendered into short lengths by notching at a pair of notching wheels (14) and providing a deflector block (18) against which the notching wheels drive the notched pins to bend and brake them at the notches.

Machine and method for rendering irradiated nuclear fuel pins into short

A bracing grid (27) made from joggled strip (20) and which is one of a number of similar grids supporting fuel pins (26) in a fuel sub-assembly for a nuclear reactor is characterized in having the peripheries of the grids completed by unit edge cells (21). Where the periphery of the grids accommodate sub-assembly corner posts (30) the continuity of the unit edge cells is maintained around the corner posts.

Bracing grids for nuclear reactor fuel sub-assemblies

A fuel pin bracing grid for a nuclear fuel sub-assembly comprises a honeycomb array of unit cells formed from discrete strips. The cells are hexagonal, three alternate sides having windows and the remaining sides have linear groups of three embossments to provide guide pads for fuel pins. The openings provide a measure of compliancy for the grid to facilitate insertion and withdrawal of the pins. A fuel sub-assembly for a liquid metal cooled fast breeder nuclear reactor has a central fuel section with end extensions, the fuel section comprising a bundle of fuel pins in a hexagonal wrapper the pins being braced by a series of grids according to the invention. Reprocessing of the fuel is facilitated because the pins are withdrawable collectively from the compliant grids and wrapper combination merely by cutting an end extension from the wrapper.

Nuclear reactor with fuel pin bracing grid

A welding jig comprising a multiplicity of members which are right cylinders each stepped intermediately so as to have a major diameter at one end and a minor diameter at the other end, the members being freestanding on their ends of major diameter and so confined in a regular hexagonal array on a base plate that the major diameters determine the triangular pitch of the members.

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Freckleton, United Kingdom

Robert Jolly