Westinghouse Electric Corporation

Ronald J Hopkins

John T Land

Craig H Popalis

Bruce W Bevilacqua

Donald G Sherwood

Ralph W Tolino

Arthur W Kramer

Douglas E Ekeroth

Franklin D Obermeyer

Leonard J Balog

Daniel E Ford

Daniel C Garner

Ray L Congleton

Michael C Misvel

Jose M Martinez

An apparatus and method are provided for replacing the existing lower internal components in a nuclear reactor vessel with new components. The alignment of the new lower internals to the pressure vessel and the existing upper internals is achieved by customizing the new lower internals on-site based on alignment measurements obtained by gages installed on the new core barrel and the existing upper core plate. The gages allow the custom machining of radial support keys on the lower portion of the new core barrel and the custom drilling of upper core plate alignment pin holes in the new core barrel.

Apparatus and method for replacing internal components in a nuclear

Self-locking alignment pin and method for aligning a nuclear fuel assembly with respect to a core plate disposed in a nuclear reactor pressure vessel. The fuel assembly has a top nozzle having a first bore formed therein. The core plate has a second bore alignable with the first bore. The second bore has first threads of a first predetermined pitch and second threads of a second predetermined pitch. The alignment pin further includes a shaft that has an end portion having third threads of the first predetermined pitch for threadably engaging the first threads of the second bore. A flange, which has a plurality of recesses in the underside surface thereof, surrounds the shaft and is integrally attached thereto. A locking member surrounds the flange and has exterior fourth threads of the predetermined second pitch for threadably engaging the second threads of the second bore. The locking member also has deformable portions adapted to engage respective ones of the recesses for locking the locking member to the flange. The flange and the shaft are prevented from disengaging the bore in the core plate because the first and third threads have a pitch different than the pitch of the second and fourth threads.

Alignment pin and method for aligning a nuclear fuel assembly with

Extrusion-resistant seal assembly for sealing a gap defined between a first structure spaced-apart from a second structure, which first structure and second structure may be an annular first flange and an annular second flange belonging to an instrumentation column of the kind typically found penetrating nuclear reactor pressure vessels. The seal assembly includes an annular retainer disposed in a gap defined between the first flange and the second flange, the first flange and the second flange capable of being moved into close proximity to reduce the gap therebetween. The retainer includes a first surface thereon having a first recess extending therearound. The retainer also has a second surface thereon having a second recess extending therearound. An annular first gasket is retained in the first recess and an annular second gasket is retained in the second recess. The first gasket intimately engages the first flange as the second gasket intimately engages the second flange to seal the gap when the first and second flanges are brought into close proximity and clamped together. The first and second gaskets resist extrusion as they are compressed between the flanges and as they are subjected to high fluid pressure because the gaskets are constrained within their respective recesses and because the retainer bears the compressive load. In this manner, the seal assembly seals the gap as the first and second flanges are brought into close proximity and clamped together.

Extrusion-resistant seal assembly

A nuclear reactor reflector is disclosed that comprises a stack of reflector blocks with vertical water flow passages to cool the reflector. The interface between blocks is opposite support points for reactor fuel rods. Water flows between the reflector and the reactor barrel from passages in a bottom block. The top block contains a flange to limit this flow and the flange has a slot to receive an alignment pin that is welded to the barrel. The pin is held in the slot by two removable shims. Alignment bars extend the length of the stack in slots machined in each block when the stack is assembled.

Nuclear reactor reflector

An apparatus and method are provided for suppressing the formation of vortices in circulating coolant fluid of a nuclear reactor. A vortex-suppressing plate having a plurality of openings therein is suspended within the lower plenum of a reactor vessel below and generally parallel to the main core support of the reactor. The plate is positioned so as to intersect vortices which may form in the circulating reactor coolant fluid. The intersection of the plate with such vortices disrupts the rotational flow pattern of the vortices, thereby disrupting the formation thereof.

Apparatus for suppressing formation of vortices in the coolant fluid of

A guide tube insert assembly for receiving and guiding a control rod assembly through mutually aligned apertures formed in an upper support plate and an upper core plate of a nuclear reactor is disclosed. The guide tube insert assembly includes a plurality of guide plates with each guide plate including a plurality of bores with respective bores of each of the guide plates being axially aligned with one another so as to form a plurality of axial passages for conducting rodlets of the control rod assembly into and out of the fuel rod assemblies of a nuclear reactor. A plurality of tie rods are provided and extend between an uppermost guide plate and a lowermost guide plate, the tie rods being concentrically surrounded by a plurality of spacer sleeves of a predetermined length, with the spacer sleeves being positioned between adjacent guide plates so as to space the guide plates a predetermined distance from one another. The guide tube insert assembly further includes nuts which threadingly engage opposing ends of the tie rods so as to generate a compressive force between the lowermost and the uppermost guide plates to maintain the guide plates in their predetermined positions with respect to one another. The tie rods thereby maintain the predetermined spacing between each of the plurality of guide plates and allow the plurality of guide plates to be simultaneously removed from within a guide tube extending between the upper core plate and the upper support plate within the upper internals of a nuclear reactor.

Guide tube insert assembly for use in a nuclear reactor

A mounting system for removably mounting the lower flange of a control rod guide tube over an opening in the upper core plate of a nuclear reactor includes support pins having first and second pin portions. The first pin portion passes through the guide tube flange and has an externally threaded section. The second pin portion is secured within the bore of the upper core plate and has a solid body section and a split-leaf section. The solid body section has an outer diameter which is accommodated in the bore by a close clearance fit. The split-leaf section has a split intermediate section and a split end section. The split intermediate section extends from the solid body section, has an outer diameter which is less than the outer diameter of the solid body section, and tapers uniformly between the solid body section and the split end section to form a conical shape. The split end section biasingly engages at least a portion of the bore wall. A locking nut threadedly engages an externally threaded section of the first pin portion. A washer is disposed around the first pin portion between the locking nut and the control rod guide tube flange and includes a concave spherical upper surface which is shiftable during mounting of the locking nut to compensate for nonperpendicular alignment between the support pin and the control rod guide tube flange.

Tapered leaf support pin for operating plant guide tubes

A combined support and guide tube member for use in a nuclear reactor is disclosed which both suspends an upper core plate from an upper support plate and receives and guides a control rod assembly through mutually aligned apertures in the support and core plates. The tube member generally comprises an elongated tubular body having an upper and lower mounting assembly for detachably mounting the upper and lower ends of the body around selected, aligned apertures in the support plate and core plate, respectively. The upper mounting assembly includes four mounting lugs disposed 90 degrees around the upper edge of the tubular body, as well as mounting bolts for detachably connecting the mounting lugs around an aperture in the support plate. The support plate aperture includes four cloverleaf cutouts which are complementary in shape to the four mounting lugs of the upper mounting assembly so that the entire support and guide tube member may be easily removed from the nuclear reactor by merely aligning the lugs with the cloverleaf cutouts, and withdrawing the tube member through the selected aperture. The tubular body of the tube member includes an array of flow ports for uniformly discharging pressurized water flowing out of the upper core plate in such a manner so as to avoid localized water jets which can vibrate and fret the rodlets forming the control rod assemblies. Finally, the combined support and guide tube member is formed from the same type of stainless steel forming the support and core plates to minimize stresses caused by differential thermal expansion.

Combined support column and guide tube for use in a nuclear reactor

A support pin system which is a non-welded system for fastening a first structural member, such as a nuclear reactor control rod guide tube flange, to a second structural member, such as nuclear reactor upper core plate, includes a support pin and nut. A first pin portion passes through the first member and has a threaded section which mates with the nut. A second pin portion has a solid body section and a split-leaf base section which biasingly engages a bore in the second member. The solid body section is accommodated by a close clearance fit. The split-leaf base section has an intermediate diameter which is less than the diameter of the solid body section. Thus, loads applied transversely to the system are reacted substantially in pure shear through the solid body section. The nut may be a locking nut having a crimpable cylindrical section integrally connected to an internally threaded section. The crimpable section is crimped to engage recesses provided in the pin whereby relative rotation therebetween is positively prevented. A locking nut retainer may optionally be provided for positively retaining the nut in position around the support pin which has a crimpable split cylindrical wall portion and an axial slot, and tabs. The retainer is compressed for insertion into a bore in a structural member, the bore having an annular recess for accommodating the tabs whereby the retainer is positively retained in the structural member and the wall portion is crimped to engage the nut.

Support pin system and locking nut retainer

A support pin system (10) for fastening nuclear reactor guide tube flanges (14) to a nuclear reactor upper core plate (12) includes a support pin (16) having a lower portion (20) frictionally disposed within the upper core plate (12), while an upper section (24) is disposed within a through-bore (22) of the guide tube flange (14). The support pin (16) includes a threaded region (30) upon which is threadedly mounted a nut (32). In order to prevent retrograde rotation of the nut (32) relative to the support pin (16), a locking cap (46) is mounted upon the nut (32) and support pin (16) such that first crimped sections (48) are engaged within apertures (44) defined within the nut (32), while second crimped sections (54) are engaged within longitudinal grooves (50) defined upon the external surface of the support pin (16).

Replacement support pin for guide tubes in operating plants

A gauge plate for use in customizing replacement upper core plate inserts of a nuclear reactor which comprises: a circular metal plate of a known diameter corresponding to that of the upper core plate of the nuclear reactor to be gauged; a plurality of U-shaped gauging slots of known size formed in the peripheral surface of the gauge plate at locations corresponding to the locations of the guide pins for the lower internals of the reactor; an arrangement for positioning the gauge plate within the core barrel at the normal elevation of the upper core plate inserts and the guide pins; and devices, disposed on the gauge plate, for positioning the gauge plate relative to the reactor baffle plate arrangement; and, for determining the actual position of the gauge plate relative to the baffle plate arrangement. The gauge plate is positioned in a core barrel containing a baffle plate arrangement but no upper internals so that the gauge plate rests on the upper end of the baffle plates with the guide pins extending into the gauging slots and with the gauge plate properly positioned relative to the baffle plates; the clearances between the gauge plate and the inner surface of the core barrel, and between the three sides of a gauging slot and the adjacent sides of the associated guide pin are measured at each gauging slot; and, the actual position of the gauge plate relative to the baffle plates is determined by gauging devices.

Gauge plate for use in customizing a replacement upper core plate in a

The invention comprises a core barrel plug capable of being remotely installed in a port of a core barrel of a pressurized water nuclear reactor for converting the reactor from a by-pass downflow configuration to a by-pass upflow configuration. The plug comprises a body having an expandable cylindrical portion with a movable mandrel disposed in the body. Remote fluid pressurization causes the mandrel to be advanced thus expanding the body into contact with the port. The plug also comprises a locking mechanism to prevent inadvertent release of the plug.

Growing community of inventors

Pensacola, FL, United States of America

Ronald J Hopkins