Abstract: An array of plural rod guides each housing therewithin corresponding pluralities of rods, as disposed in parallel axial relationship within the cylindrical sidewall of the inner barrel assembly of a pressurized water reactor, defines a plurality of peripheral regions between the inner circumferential surface of the cylindrical sidewall and the peripheral edges of the array. A plurality of modular formers is installed within the respective plurality of peripheral regions, at each of one or more banks of predetermined, respective elevations within the inner barrel assembly. Each modular former comprises a pair of parallel former plates having arcuate outer edges corresponding to the interior circumference of the cylindrical sidewall and chordlike inner edges contoured to correspond to the juxtaposed peripheral edge of the array, and a vertical column extending between and rigidly interconnecting the associated plates of a pair.

Abstract: A vibration arrestor for use in combination with the support structure for the upper ends of rod guides disposed in parallel axial relationship in an inner barrel assembly of a pressurized water reactor vessel, the rod guides being supported between a first, lower plate and a second, upper plate with their respective top ends disposed adjacent the second plate. At least for a selected type of rod guides and associated top plates, apertures provided in the top plates receive therein corresponding extensions which depend from the second plate.

Abstract: Slender water displacer rods for use in water reactors are provided with rings of a wear resistant coating spaced along the length of the rod. Each coating contains Cr.sub.2 C.sub.3 and is metallurgically applied and bonded to the zirconium base alloy forming the outer portion of the rod by electrospark-deposition (ESD) technique.

Abstract: A top end support for rod guides disposed in closely spaced, parallel axial relationship within an inner barrel assembly of a pressurized water reactor vessel includes, in telescoping relationship, a generally cylindrical support having an end closure with a central aperture therein for receiving a downwardly depending extension from a lower calandria plate and a sleeve having an outer periphery corresponding in cross-section to that of said rod guide and affixed thereto at its lower end, the sleeve having an interior, generally cylindrical surface for receiving the cylindrical support in close engagement therein. The telescopingly engaged, generally cylindrical surfaces of the cylindrical support and the sleeve provide substantial area to function as a long-life wear couple.

Abstract: The inner barrel assembly of a pressurized water reactor includes an array of interleaved first and second matrices of respective first and second pluralities of rod guides of corresponding first and second different types, disposed in parallel axial relationship, the bottom ends of the guides being affixed to the top core plate of a lower barrel assembly. A flexible support structure connects the top ends of the rod guides to a lower calandria plate and particularly includes corresponding first and second pluralities of top support plates respectively connected to the rod guides of the first and second different types and having outer peripheries generally corresponding to the respective first and second types of rod guides and inner openings for permitting axial passage therethrough of corresponding, first and second different types of rod clusters.

Abstract: Improvements in the design of internal components of J-shaped steam generators for liquid metal fast breeder reactors. Complex design improvements have been made to the internals of J-shaped steam generators which improvements are intended to reduce tube vibration, tube jamming, flow problems in the upper portion of the steam generator, manufacturing complexities in tube spacer attachments, thermal stripping potentials and difficulties in the weld fabrication of certain components.

Abstract: A jacking mechanism for raising the upper internals structure of a liquid metal nuclear reactor which jacking mechanism uses a system of gears and drive shafts to transmit force from a single motor to four mechanically synchronized ball jacks to raise and lower support columns which support the upper internals structure. The support columns have a pin structure which rides up and down in a slot in a housing fixed to the reactor head. The pin has two locking plates which can be rotated around the pin to bring bolt holes through the locking plates into alignment with a set of bolt holes in the housing, there being a set of such housing bolt holes corresponding to both a raised and a lowered position of the support column. When the locking plate is so aligned, a surface of the locking plate mates with a surface in the housing such that the support column is then supported by the locking plate and not by the ball jacks.