Patent Number: 048636789
Section: claims

1. A pressurized water reactor vessel, the vessel defining a predetermined axial direction of the flow of coolant therewithin and having plural spider assemblies supporting, for vertical movement within the vessel, respective clusters of rods in spaced, parallel axial relationship, parallel to the predetermined axial direction of coolant flow, and a rod guide for each spider assembly and respective cluster of rods, the rod guide having horizontally oriented support plates therewithin, each plate having an interior opening for accommodating axial movement therethrough of the spider assembly and respective cluster of rods, the opening defining plural radially extending channels and corresponding parallel interior wall surfaces of the support plate, the spider assembly comprising: a hub of elongated configuration and defining a central axis, for positioning parallel to the predetermined axial direction of coolant flow;  control rod mounts for the respectively corresponding control rods of the cluster; and  a vane assembly integrally connecting the control and mounts to the hub, the vane assembly comprising plural, planar vane elements, at least a predetermined number thereof being affixed to and extending radially from the hub and oriented so as to be received through respectively corresponding channels in each support plate, each said radially extending vane element having parallel, spaced major planar surfaces which are contiguous to the respective interior wall surfaces of the support plate defined by the radially extending channels when the vane element is received therewithin, said parallel, spaced major planar surfaces defining a plane of symmetry therebetween parallel to the central axis of the hub and each said vane element having a leading edge and a trailing edge relative to and extending transversely of the axial direction of coolant flow, the leading edge having a cross-sectional configuration in a plane perpendicular to the major parallel planar surfaces which is non-symmetrical relative to the plane of symmetry, the respective flow stagnation lines of the radially extending vane elements being off-set from the respective planes of symmetry thereof in a commonly oriented direction and producing in response to the coolant flow thereover a torsional load bias on the hub in a predetermined orientation for engaging the commonly oriented, spaced, major planar surfaces of the plural radially extending vanes against the respective, commonly oriented and contiguous interior wall surfaces of the support plate defined by the corresponding channels. 2. A pressure vessel having plural spider assemblies as recited in claim 1, wherein the trailing edge of each vane element of each spider assembly is of square cross-sectional configuration in a plane transverse to the major planar surfaces thereof and parallel to the direction of coolant flow. 3. A pressure vessel having spider assemblies as recited in claim 1, wherein each vane element leading edge of each spider assembly is of a non-symmetrical, convex cross-sectional configuration. 4. A pressure vessel having spider assemblies as recited in claim 1, wherein each vane element leading edge of each spider assembly cross-section defines a single acute angle with respect to one of the major planar surfaces thereof. 5. A pressure vessel having spider assemblies as recited in claim 1, wherein each vane element leading edge of each spider assembly cross-section defines double acute angles with respect to the respective planar surfaces. 6. A pressure vessel having spider assemblies as recited in claim 1, wherein each vane element leading edge of each spider assembly cross-section defines a truncated acute angle with respect to one of the major planar surfaces thereof.