General Electric Company

Robert C Dixon

Gerald A Deaver

James R Punches

John Geddes Erbes

Henry Peter Offer

James E Cearley

Guy E Singleton

James Edward Charnley

Louis L Aiello

Gerald M Gordon

Paul Van Diemen

James A Mees

Edwin D Sayre

Richard W Perry

Jaime A Zuloaga, Jr

David L Faulstich

Kenneth R Izzo

David L Rousar

John C Carruth

Bob Y Okashima

Walter A Graf, Jr

Bradley G Stoll

David R Sponseller

Ronald D Poland

Stephanie S Spencer

John Chang

In a boiling water nuclear reactor having its core, fuel support casting, and control rod guide tubes removed to expose the core plate, a method for the submerged welding repair and replacement of the control rod drive housing at the bottom extremity of the reactor vessel is disclosed. An alignment device registers to a hole in the core plate and its corresponding guide pin. A control rod drive housing mating fixture on the depending extremity of the shaft of the alignment device precisely fits and mates to the top of the control rod drive housing. The alignment device includes cross electronic levels sealed for submersion which levels remotely transfer through attached wiring the precise angularity between the top of the control rod drive housing on one hand and the corresponding and overlying hole in the core plate on the other hand. For the welding repair process herein, a welding cylinder apparatus fits over the depending end of the shaft of the alignment device. This welding cylinder protrudes downwardly and around the control rod drive housing mating to the stub tube through which the control rod drive housing is inserted. In the embodiment here illustrated, a rotating raceway is provided interior of the chamber for permitting TIG welding unit to traverse around a path for weldment defined at the side of the control rod drive housing and at the top of the stub tube.

Control rod housing alignment and repair method

A refueling mast for a reactor complex includes four generally cylindrical tubes. Each inner tube has vertical grooved tracks formed therein. Each outer tube has a guide roller mounted thereon with grooves which mate with track grooves of a respective track on the adjacent inner tube. Track grooves are cold formed moving a roller die tool up and down each inner tube, while increasing pressure on the incorporated die rollers. This process flattens the inner tube where the tracks are being formed. The grooved tracks and the associated flattening provide the torsional rigidity required on the mast tubes for precise positioning and orientation of fuel elements.

Cylindrical refueling mast with longitudinal guide grooves

In a boiling water nuclear reactor having its core, fuel support casting, and control rod guide tubes removed to expose the core plate, an apparatus and method for the submerged welding repair and replacement of the control rod drive housing at the bottom extremity of the reactor vessel is disclosed. The apparatus registers to a hole in the core plate and its corresponding guide pin. A mating fixture on the depending extremity of the shaft of the apparatus precisely fits and mates to the top of the control rod drive housing. The alignment device includes cross electronic levels sealed for submersion which levels remotely transfer through attached wiring the precise angularity between the top of the control rod drive housing on one hand and the corresponding and overlying hole in the core plate on the other hand. For the welding repair process herein, a welding cylinder apparatus fits over the depending end of the shaft of the alignment device. This welding cylinder protrudes downwardly and around the control rod drive housing mating to the stub tube through which the control rod drive housing is inserted. A rotating raceway is provided interior of the cylinder for permitting TIG welding unit to traverse around a path for weldment defined at the side of the control rod drive housing and at the top of the stub tube.

Control rod housing alignment and repair apparatus

In a boiling water nuclear reactor having its core, fuel support casting, and control rod guide tubes removed to expose the core plate, an apparatus for the repair and replacement of the control rod drive housing at the bottom extremity of the reactor vessel is disclosed. The apparatus registers to a hole in the core plate and its corresponding guide pin. A mating fixture on the depending extremity of the shaft of the apparatus precisely fits and mates to the top of the control rod drive housing. The alignment device includes cross electronic levels sealed for submersion which levels remotely transfer through attached wiring the precise angularity between the top of the control rod drive housing on one hand and the corresponding and overlying hole in the core plate on the other hand.

Control rod housing alignment apparatus

An apparatus and process for the construction of a cruciformed section control rod is disclosed. The control rod is characterized by having square exterior sectioned tubes with central cylindrical volumes for the containment of neutron absorbing poisons. In the process, these tubes are welded together at the corners of the square sections to form the planar members of the cruciformed shaped rods. An apparatus and process is disclosed in which the rods are all held by a jig in the same configuration as is ultimately fabricated. Thereafter, the jig is drawn through fixtures, which fixtures accurately guide the rods to be joined by welding past paired and opposed laser welding heads. By the expedient of positioning the laser and rapidly drawing the braced together tubes by the laser, control rod fabrication occurs. There results a solid, integral control rod constituting a suitable pressure vessel for neutron absorbers for control of nuclear reactions.

Control rod absorber section fabrication by square tube configuration

In a boiling water nuclear reactor having its core, fuel support casting, and control rod guide tubes removed to expose the core plate, an apparatus and method for the repair and replacement of the control rod drive housing at the bottom extremity of the reactor vessel is disclosed. The apparatus registers to a hole in the core plate and its corresponding guide pin. A mating fixture on the depending extremity of the shaft of the apparatus precisely fits and mates to the top of the control rod drive housing. The alignment device includes cross electronic levels sealed for submersion which levels remotely transfer through attached wiring the precise angularity between the top of the control rod drive housing on one hand and the corresponding and overlying hole in the core plate on the other hand.

Control rod housing alignment

An apparatus and process for control rod assembly and construction for a nuclear reactor is disclosed wherein the control rod is of cruciform configuration having a plurality of and preferably four flat planar members. Each planar member is made up with an assembly of square cross sectioned tubular members. Each square cross sectioned tubular member includes a defined cylindrical center and a constant thickness surrounding tubular metallic shell to provide the contained neutron absorbing materials in a cylindrically shaped pressure vessel. The constant thickness surrounding tubular shell constituting the cylindrical shaped pressure vessel has four corner sections added to generate a modified square exterior profile. These added four corner sections comprise an addition to the tubular side wall thickness of the shell. Appropriate chamfers and rounding are provided to the square profile to impart both stress relief and convenient points for automated welding between side-by-side square sections. The square cross sectioned tubular members when welded together extend axially and longitudinally the length of the control rod in the direction of control rod movement and fluid flow. The square cross sectioned tubular members are filled with a neutron absorbing material, plugged at both ends, and fastened by welding in side-by-side relation to form the planar control rod members of the required cruciform shape. These square cross sectioned tubular members as welded in side-by-side relation are in integral portion of the longitudinal support structure of the control rod and fasten and interconnect the handle at the top of the control rod and a conventional velocity limiting device at the bottom of the control rod. The fastening of the handles and velocity limiting device at the respective top and bottom provides a secondary and supplemental seal to primary plugs containing the neutron absorbing material. If needed for enhanced life, provision is made for the incorporation of a hafnium plate in a rectangular sectioned tube adjacent the handle at upper end of the control rod, this tip being variable in length dependent upon individual control rod requirements. Thus square sectioned tubular members form an improved poison containing cylindrical volume for providing resultant improved control rod worth and increased in service life time in moderating and shutting down nuclear reactions. Consequently, the disclosed construction can be used both for conventional control rods as well as for control rod configured for control cell locations.

Control rod

An apparatus and process for control rod assembly and construction for a nuclear reactor is disclosed wherein the control rod is of cruciform configuration having a plurality of and preferably four flat planar members. Each planar member is made up with an assembly of square cross sectioned tubular members. Each square cross sectioned tubular member includes a defined cylindrical center and a constant thickness surrounding tubular metallic shell to provide the contained neutron absorbing materials in a cylindrically shaped pressure vessel. The constant thickness surrounding tubular shell constituting the cylindrical shaped pressure vessel has four corner sections added to generate a modified square exterior profile. These added four corner sections comprise an addition to the tubular side wall thickness of the shell. Appropriate chamfers and rounding are provided to the square profile to impart both stress relief and convenient points for automated welding between side-by-side square sections. The square cross sectioned tubular members when welded together extend axially and longitudinally the length of the control rod in the direction of control rod movement and fluid flow. The square cross sectioned tubular members are filled with a neutron absorbing material, plugged at both ends, and fastened by welding in side-by-side relation to form the planar control rod members of the required cruciform shape. These square cross sectioned tubular members as welded in side-by-side relation are an integral portion of the longitudinal support structure of the control rod and fasten and interconnect the handle at the top of the control rod and a conventional velocity limiting device at the bottom of the control rod. The fastening of the handles and velocity limiting device at the respective top and bottom provides a secondary and supplemental seal to primary plugs containing the neutron absorbing material. If needed for enhanced life, provision is made for the incorporation of a hafnium plate in a rectangular sectioned tube adjacent the handle at upper end of the control rod, this tip being variable in length dependent upon individual control rod requirements. Thus square sectioned tubular members form an improved poison containing cylindrical volume for providing resultant improved control rod worth and increased in service life time in moderating and shutting down nuclear reactions. Consequently, the disclosed construction can be used both for conventional control rods as well as for control rod configured for control cell locations.

A restraint to enable temporary bracing and operation of a thermally cracked sparger nozzle mounted from a sparger manifold at the end of a pipe elbow is disclosed. The restraint includes a second and surrounding restraint elbow which is fitted over and captures the sparger elbow. The restraint elbow has a saddle surface baseplate communicated to the lower end which rest on the sparger manifold to form a substantially water tight base for the restraint. The nozzle end of the restraint elbow is fitted with a nozzle aperture plate for surrounding the outside of the sparger nozzle again in substantially water tight relation. The plate is mounted for movement on the end of the restraint elbow for conforming threading of the restraint at the plate over the sparger nozzle. The restraint can be rapidly mounted (in less than a minute), tack welded at the aperture and seat tensioning bold (in less than 4 minutes) and left in the reactor for a complete fuel cycle. With the restraint mounted, cracked and defective sparger nozzles are restrained in place while a replacement sparger is fabricated.

Feedwater sparger restraint

In a control rod construction for moderating and controlling a reaction of a nuclear reactor, a control rod structure is disclosed in which hafnium is welded to stainless steel. Typically, the control rod is confined for movement axially along its length into and out of the reactor. The hafnium is surrounded in the control rod structure by a sheath of stainless steel to inhibit movement relative to the control rod structure other than in the axial direction of control rod movement. The hafnium is friction welded to the stainless steel of the control rod so as to stress the weld in either tension or compression due to dynamic loading occurring from control rod movement. The stainless steel to which the hafnium is welded is in turn conventionally welded or mechanically connected to the remaining steel components of the control rod. There results a secure control rod structure having welded hafnium that can withstand the dynamic loadings of fast insertion of control rods such as those loadings which commonly occur under rapid control rod acceleration and deceleration due to SCRAM of a reactor.

Hafnium stainless steel absorber rod for control rod

Repair apparatus and a method of repair utilized for securing pressure sensing lines to jet pump diffusers in boiling water nuclear reactors is disclosed. Conventional access is made to the reactor with removal of the jet pump inlet mixer to expose the upwardly disposed frustum-shaped diffuser. The diffuser includes a pressure sensing line mounted by a stand off block. It has been found that this pressure sensing line becomes separated from the diffuser due to vibration and accompanying metal fatigue. A repair is effected by introduction of an arcuate beam configured for live support at each end. This pressure sensing line and stand off block is bracketed by the upper end of a beam to register the line to the stand off block. The lower end of the beam brackets the line and stands off from the diffuser at a second introduced stand off block. The line is provided with two points of support to prevent further dislodging vibration. The beam is in turn captured by an elliptical ring clamp encircling the essentially circular section of the diffuser between the beam and its captured line. A saddle on the elliptical ring opposite the clamped beam tensions the ring diameter. The ring clamp fits in a preformed notch on the beam and is disposed normally to the surface of the diffuser from the saddle. This disposition of the ring urges the beam upwardly in latched engagement with the stand off block so as to position the line at the upper end of the beam to the stand off block. A universal beam holder for the remote clamping and release of the beam as well as universal manipulation of the beam in pitch, yaw and azimuth is disclosed. This universal beam holder enables positioning of the beam in the submerged radio-active environment of the reactor. The clamp also enables the beam to be maintained in position with the line and stand off block while the ring clamp captures the beam. When the ring clamp is fastened to the beam by securing of a wedge fitting at the saddle, the universal beam holder releases the beam and is withdrawn. Clamping of the pressure sensing line at two spaced apart points secures against both initial detachment and further vibration damage.

Jet pump beam holder/positioner tool

A velocity limiting device providing greater resistance to motion through a fluid in one direction than in the opposite direction. The device includes a toroidally shaped control member having a smooth generally conical surface on one side for low resistance movement through the fluid in the one direction. On its opposite side the control member is formed with at least one groove providing a concave surface spaced from which is an arrangement of vanes forming a jet for directing a stream of fluid into the groove upon movement in the opposite direction whereby the resultant increase in fluid turbulence increases resistance to rapid movement in this opposite direction.

Control rod velocity limiter

A jet pump plug for a multi-nozzle jet pump is disclosed wherein the nozzles are accessible through a relatively small opening in the pump structure. The plug comprises a plurality of sections, each including a closure plate and a lever coupled thereto. Each plug section is constructed so as to allow that section to be separately introduced into the opening to the vicinity of the nozzles from a location which may be remote from the pump. The closure plates are manipulated through their attached levers from a remote location to the end of sealing the nozzles with them. The first plug section introduced through the opening includes means for alignment relative to the jet pump structure so as to orient its closure plate with respect to the nozzles. The remaining plug section is supported by the first plug section upon being introduced into the opening. The orientation of the closure plate of the latter plug section relative to the nozzles is effected with reference to the first introduced plug section which serves as a support therefor.

Jet pump plug

A storage module or rack is disclosed for storage of nuclear fuel assemblies in a water-filled pool comprising an array of storage tubes arranged in a checkerboard pattern and attached to one another along their corners. Each tube thus forms a storage cell for a fuel assembly and the spaces between each four adjacent tubes form intermediate fuel assembly storage cells. The storage tubes are formed with spaced double walls between which is contained a layer of neutron absorbing material to assure that the array of stored fuel assemblies remains subcritical. Provision is made for free circulation of water through the storage cells to extract heat from the stored assemblies. The storage module maximizes the number of fuel assemblies that can be stored in a given space while minimizing the material used in its construction.

Growing community of inventors

Morgan Hill, CA, United States of America

Robert C Dixon