Ball valve assemblies are conventionally used to control the flow of gases or liquids.

The applicants have found that there are significant problems with existing ball valve assembly designs used to handle powders in the nuclear fuel manufacturing industry.

The invention has amongst its aims the provision of a blockage free and/or reliable ball valve assembly suitable for handling nuclear fuel materials in powder form.

According to a first aspect of the invention we provide a ball valve assembly, the ball valve assembly including a ball valve housing and a ball valve mounted in the ball valve housing, the ball valve having a through aperture, the aperture having an inlet profile and an outlet profile, at least one of the inlet or outlet profiles corresponding to the adjoining profile of the pipe connected to the ball valve assembly in use.

Preferably both the inlet and outlet profiles correspond to their respective adjoining profile of the pipe connected to the ball valve assembly in use. Preferably the inlet and outlet profiles are the same. Preferably the inlet and outlet profiles are circles.

Preferably the intervening profiles of the aperture are the same. Preferably the aperture is defined by a cylinder.

The pipe connected to the ball valve assembly may be provided within 5mm of the ball valve inlet and/or outlet profile, measured with the ball valve in the fully opened position. The pipe connected to the ball valve assembly may contact, ideally abut, the ball valve housing at least at one end. The pipe connected to the ball valve assembly may contact, ideally abut, the seat component of the ball valve assembly, at least at one end The first aspect of the invention may include one or more of the features, options or possibilities set out elsewhere in this document, including in the other aspects of the invention and the options, features and possibilities therefore.

According to a second aspect of the invention we provide a ball valve assembly, the ball valve assembly including a ball valve housing and a ball valve mounted in the ball valve housing, the ball valve having a through aperture, the aperture having an inlet profile and an outlet profile, wherein at least one end of the ball valve assembly is connected to a pipe, the end profile of the pipe being provided within 5mm of the opposing inlet or outlet profile of the ball valve with the ball valve in the open position..

Preferably only one end of the ball valve assembly is connected to a pipe. The end profile is preferably a circle, most preferably a circle of equivalent diameter to the diameter of the through aperture.

The second aspect of the invention may include one or more of the features, options or possibilities set out elsewhere in this document, including in the other aspects of the invention and the options, features and possibilities therefore.

According to a third aspect of the invention we provide a ball valve assembly, the ball valve assembly including a ball valve housing and a ball valve mounted in the ball valve housing, the ball valve having a through aperture, one end of the ball valve assembly being at least in part within a process vessel.

Preferably the one end of the ball valve assembly is planar. Preferably the ball valve housing at least in part defines the one end. Preferably the seat component at least in part defines the one end. The ball valve may define a part of the one end when in the open position.

Preferably the end part of the ball valve housing and/or the end part of the seat component and/or the end part of the ball valve in the open position are flush with one another. Preferably the end part of the ball valve housing and/or the end part of the seat component and/or the end part of the ball valve in the open position are flush with the internal surface of the process vessel adjoining the ball valve assembly.

The third aspect of the invention may include one or more of the features, options or possibilities set out elsewhere in this document, including in the other aspects of the invention and the options, features and possibilities therefore.

According to a fourth aspect of the invention we provide a ball valve assembly, the ball valve assembly including a ball valve housing and a ball valve mounted in the ball valve housing, wherein the rotatable ball valve is formed of stainless steel.

Preferably the ball valve is a hollow ball. Preferably the ball valve includes a hollow cylindrical component, ideally a right cylinder. Preferably the axial extent of the cylinder is less than the axial extent of the ball valve housing and/or assembly. The ball valve and/or ball valve housing and/or ball valve assembly preferably has an axis which corresponds to the direction of flow through the valve. Preferably the axis coincidences with the centre line of the cylinder. Preferably the ball valve includes two components which are hemispherical. One and preferably both of the hemispheres may be hollow, in addition to the hollow cylindrical component. The hemispherical parts may extend through a 180° arc, at least in part, particularly about the axis of the ball valve assembly. The hemispherical parts may extend through an arc of 100°or less, at least in part, particularly about the centre point on the axis of the ball valve assembly. The junctions between different components of the ball valve may be welded.

One or more locations on the periphery of the ball valve may be provided with a recessed portion. Preferably the recessed portion engages with a fluid supply component.

Preferably a 90°turn of the fluid supply component results in a 90° rotation of the ball valve. Preferably the 90° rotation of the ball valve results in closure of the valve.

Preferably the ball valve housing is formed of aluminium. The ball valve housing preferably has a cylindrical exterior profile. One or more components related to the fluid supply may extend outward from the profile. Preferably the ball valve housing has a planar end face and preferably two planar end faces. Preferably the two end faces are parallel to one another. Preferably one end face of the ball valve housing is provided with an aperture of equivalent diameter to the internal diameter. Preferably one end face of the ball valve housing is provided with an aperture of equivalent diameter to the external diameter of the seat component. The aluminium housing may include one or more seals. Preferably the seals are at least partially recessed into the ball valve housing. Preferably the ball valve housing is provided with one or more screw threaded bores, ideally which accommodate releasable fasteners which also engage one or more components to which the ball valve assembly is attached.

The seat component for the ball valve may be mounted on the aluminium of the ball valve housing. The ball valve housing may extend over at least part of one end of the seat component. The seat component may include an aperture, preferably connected to one or more of the fluid supply connections or accommodating the fluid supply components.

The connection between the fluid supply and the recess in the ball valve is preferably formed of one or more stainless steel components.

The fourth aspect of the invention may include one or more of the features, options or possibilities set out elsewhere in this document, including in the other aspects of the invention and the options, features and possibilities therefore.

According to a fifth aspect of the invention we provide a ball valve assembly, the ball valve assembly including a ball valve housing and a ball valve mounted in the ball valve housing through opposing contact surfaces, the contact surface of the ball valve housing, at least in part, being formed of polyetheretherketone.

The contact surface of the ball valve housing may be the inside surface of a seat component. The contact surface may be a part of a sphere, preferably a sphere with at least two opposing part hemispheres removed, ideally also with a aperture. The seat component may be formed fully of the polyetheretherketone. The seat component may have a cylindrical exterior profile, ideally with an axis corresponding to the axis of the ball valve assembly. The seat component may have a shorter axial extent than the ball valve housing and/or assembly. Preferably one end surface of the seat component is flush with the end surface of the ball valve housing at the same end. The seat component may include one or more seals, preferably at least partially recessed in the seat component.

The fifth aspect of the invention may include one or more of the features, options or possibilities set out elsewhere in this document, including in the other aspects of the invention and the options, features and possibilities therefore.

An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying figures in which:- Figure 1 is a cross sectional side view through a ball valve assembly according to the present invention ; Figure 2 is an end view of the ball valve assembly of Figure 1.

Existing ball valve assembly designs if considered for the handling of powdered nuclear fuel materials, such as plutonium dioxide or uranium dioxide (instead of their conventional use for gases or liquids) have been determined by the applicant to face a number of significant design problems.

To address these issues ball valve assemblies according to the present invention have been designed as exemplified by the ball valve assembly which will now be described.

The cross sectional view in Figure 1 illustrates the aluminium housing 2 of the assembly, the housing being attached in use to the pipe, not shown, leading to the ball valve assembly, and the pipe, not shown, leading from the ball valve assembly by captive bolt fasteners 4 and 6 respectively. Within the housing 2 is mounted the seat components 8 which receive the ball valve 10 of the ball valve assembly. The seat components are made of wear resistant plastics material, preferably polyetheretherketone, which has been determined by the applicants to offer sufficient wear resistance to the nuclear fuel powders which have been determined by the applicant to be extremely abrasive, particularly in the case of plutonium dioxide. A series of O-ring seals 12 and 14 are provided to effect the seal in use between the ball valve assembly 1 and the pipe to which it is connected.

The ball valve itself 10 is constructed of a series of stainless steel components, namely a stainless steel cylinder 16 and partial hemispherical structures 18, 20 which form the overall ball valve 10 and cooperate with the wear resistant seat components 8 in practice. The hemispherical portion is provided with a recess 22, the function of which is explained in more detail below.

Significantly, the diameter of the cylindrical section 16 matches the diameter of the pipes, not shown, to which the ball valve assembly is attached. In this way the exposure of the wear resistant seat components to the powder flow is minimised, reducing abrasion, and furthermore the capacity for powder to accumulate on the lead or trailing faces of the ball valve assembly is minimised. This feature is most important for material accountancy purposes as in the nuclear fuel processes industry it is imperative to known where the nuclear fuel material being processed is, and the quantity present at any location.

The provision of the cylindrical bore 16 through the valve as being of equivalent diameter to the pipe bore leading to it is also advantageous in avoiding potential blockage by means of the powder bridging the bore. Uranium dioxide in particular is a hydrophilic material which can be prone to clumping together and blockages result.

The fact that the cylinder 16 of the ball valve 10 lies wholly within the profile of the body 2 in the open state also means that the ball valve assembly 1 can be incorporated directly into the processing vessel body without any intervening pipe length. This is also advantageous in minimising the locations at which unknown, potentially variable with time, amounts of nuclear fuel material could accumulate.

The construction of the housing from aluminium lined with 321 stainless steel and the ball valve 10 from 321 stainless steel is particularly advantageous in achieving a ball valve assembly of practical more mass. A ball valve assembly with a through bore diameter of 3 inches according to the present invention weighs approximately 1 lkg as compared with the weight of 80 kilos for an equivalent ball valve assembly manufactured according to prior art designs.

The ball valve is controlled in practice by the introduction of fluid into the recess 22 in the hemispherical portion 18 via stem 24 which is connected using a nut 26 to the gland 28 on the body 2. Intervening washers 32 are provided and seals 34 are deployed within the body 2. In operation rotation of component 24 through 90° results in a rotation of the ball valve through 90° and hence closure of the aperture through the ball valve assembly. Reversing the rotation of stem 24 reverses the process.