Modular former for inner barrel assembly of pressurized water reactor

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. Attachment means secured to the surfaces of the plates extend beyond the respective outer arcuate edges thereof and through holes provided therefore in the cylindrical sidewall and are welded thereto from the exterior surface of the sidewall. One more banks of modular formers, as required, establish the proper pressure drop of the core output flow from the lower barrel assembly so as to approach an axial flow condition within the inner barrel assembly, reducing turbulance and minimizing vibration in operation.