Westinghouse Electric Corporation

Donald G Sherwood

James E Gillett

Arthur W Kramer

John F Wilson

Daniel C Garner

Anoop Kapoor

Frederick J Ellingson

Luciano Veronesi

Robert E Meuschke

Bruce W Bevilacqua

Ronald J Hopkins

Robert B Salton

Douglas E Ekeroth

Terry L Schulz

Larry A Shockling

Thomas R Freeman

Denis J Altman

David A Altman

Leonard J Balog

Bernard L Silverblatt

Alan Savinell

Allen L Morris

Charles H Boyd

Brian H Alsop

Albert C Davidson

Eric D Rinker

John V Miller

Howard F Fensterer

Glenn E Bost

James E Kimbrell

Steven J Lovasic

William R Snyder

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

A system and a method for removing and consolidating the spent fuel rods of a fuel assembly is disclosed herein. The system comprises a pushing assembly having a push rod for pushing a selected fuel rod out of a fuel assembly, a fuel assembly positioner including an elevator for conveniently positioning a fuel assembly within the spent fuel pool of a nuclear facility, a rod catching grid for preventing the pushed-out fuel rods from falling to the bottom of the pool and a transition cannister for funneling the rods into a consolidated arrangement within a storage cannister. In operation, the push rod is positioned over and engaged against the upper end of a fuel rod to be removed from the assembly. Thus engaged, the push rod is inserted through the cells in the grids of the fuel assembly that surround the selected fuel rod, thereby pushing it out of the fuel assembly. Thus the grid cells are used as an alignment means for the push rod during the rod-pushing operation.

System and method for removing and consolidating the fuel rods of a

A method and system for removing fuel rods from a fuel assembly having top and bottom nozzles that are removed and a plurality of grids for uniformly spacing apart the fuel rods is disclosed. The system includes a rod pushing mechanism which pushes a first end of a selected fuel rod such that a second end of the fuel rod extends out of the fuel assembly. The system also includes a removal device adjacent the second end of the selected fuel rod. The removal device engages and pulls the fuel rod completely from the fuel assembly when the second end of the fuel rod extends out of the fuel assembly a distance sufficient to engage the removal device. The method includes the following steps. First, a first end of a selected fuel rod is pushed such that a second end of the fuel rod extends out of the fuel assembly. Then, the second end of the selected fuel rod is engaged with a removal device. Finally, the selected fuel rod is pulled completely from the fuel assembly with the removal device.

Method and apparatus for removing the fuel rods of a nuclear fuel

A system and a method for removing and consolidating the spent fuel rods of a fuel assembly is disclosed herein. The sytem comprises a pushing assembly having a push rod for pushing a selected fuel rod out of a fuel assembly, a fuel assembly positioner including an elevator for conveniently positioning a fuel assembly within the spent fuel pool of a nuclear facility, a rod catching grid for preventing the pushed-out fuel rods from falling to the bottom of the pool and a transition cannister for funneling the rods into a consolidated arrangement within a storage cannister. In operation, the push rod is positioned over and engaged against the upper end of a fuel rod to be removed from the assembly. Thus engaged, the push rod is inserted through the cells in the grids of the fuel assembly that surround the selected fuel rod, thereby pushing it out of the fuel assembly. Thus the grid cells are used as an alignment means for the push rod during the rod-pushing operation.

System and method for removing and consolidation fuel rods of a nuclear

Modular neutron reflector assemblies removably insertable into the irregular space in a nuclear reactor between a generally cylindrical array of square fuel assemblies comprising the core and the cylindrical core barrel surrounding the core, include an elongated enclosure having a strongback adjacent the core barrel and flat plates adjacent the fuel assemblies. The strongback is thicker than the steel plates by an amount which results in the strongback and plates reaching approximately the same temperature to minimize thermal stresses despite the 8 to 20 times greater nuclear heating at the core side of the enclosure as opposed to that at the core barrel side. The enclosure is suspended by a single point mounting on the core barrel which permits vertical, radial, and circumferential expansion but a pin depending from the lower end of the enclosure slides in a vertical bore in the reactor lower core support plate to limit lateral movement while allowing unrestrained vertical expansion and contraction. A separately removable reflector unit in each enclosure comprises a bundle of closely packed stainless steel circular rods with smaller diameter rods inserted in the interstices between the larger rods to generate a 0.90-0.92% volume fraction of stainless steel while also providing a distributed array of small longitudinal passages for reactor coolant. Selected rods are suspended from a cover plate on the module with the remaining rods suspended from a horizontal plate which is in turn, suspended from the selected rods so that the rods are all free to expand and contract vertically.

Modular radial neutron reflector

The mechanical spectral shift reactor comprises a reactive core having fuel assemblies accommodating both water displacer elements and control rods for selectively changing the volume of water-moderator in the core. The fuel assemblies are arranged in alternating fashion so that one drive mechanism may move displacer elements in more than one fuel assembly without interfering with the movement of control rods or the corresponding control rod drive mechanisms.

Mechanical spectral shift reactor

A vent system for controlling hydraulically actuated drive means for selectively moving pluralities of rod clusters respectively connected to the plurality of drive means between fully inserted positions within the lower barrel assembly of the vessel in telescoping relationship with fuel rod assemblies contained therein, and a fully withdrawn position. Each drive means responds to the reactor coolant fluid pressure and includes a leakage passage and an outlet channel through which a leakage flow may pass under control of the vent system, the latter comprising a valve arrangement, flow restrictors and a common orifice through which the outlet channels are selectively connected to essentially ambient pressure, for establishing a pressure differential within each drive means producing a net force for moving the drive rods and associated clusters to the withdrawn position at which the drive means mechanically latch the fully withdrawn clusters for mechanically supporting same in the fully withdrawn position. The valve arrangement may be selectively actuated to reestablish the pressure differential within each drive means thereby to raise the associated drive rods and release same from the mechanically latched positions, after which the valve arrangement is selectively operated to establish pressure equilibrium within the drive means to permit the corresponding drive rods and associated control rod clusters to fall by force of gravity to the fully inserted positions thereof. Display indications and control panel operation provide for operator sensing of the rod cluster positions and control of the valve arrangement.

Vent system for displacer rod drive mechanism of pressurized water

A radial neutron reflector is disclosed for a light water nuclear reactor. The irregular space between the core periphery and the core barrel surrounding the core is filled with a structure comprising material other than hydrogen such as zirconia or stainless steel so as to displace the reactor water coolant in this region. The structure is provided with appropriately sized flow holes to pass reactor coolant therethrough and to balance the pressure within the structure to substantially coincide with the axial pressure profile at the core periphery.

Radial neutron reflector

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.

Wear resistant zirconium base alloy article for water reactors

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. Both the end closure and the cylindrical sidewalls of the fixed cylindrical support and the interior surface of the sleeve are configured so as to correspond to the perimeter of flow holes disposed in a symmetrical array about the associated depending extension, to permit unimpeded passage therethrough of the core outlet flow.

Top end support for water displacement rod guides of pressurized water

The mechanical spectral shift reactor comprises apparatus for inserting and withdrawing water displacer elements from the reactor core for selectively changing the water-moderator volume in the core thereby changing the reactivity of the core. The apparatus may include drive mechanisms for moving the displacer elements relative to the core and guide mechanisms for guiding the displacer rods through the reactor vessel. An array of tubes may be disposed between the guide mechanisms and the fuel assemblies for guidance and minimization of flow induced vibrations of the displacer elements.

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. The respective top support plates of the first and second different types have mating, respective exterior and interior vertices for assemblage of same in an array of interdigitated, respective matrices. A flexible linkage is connected between each top plate of the first type and the respective surrounding and contiguous, interdigitated top plates of the second type, thereby interconnecting all of the top plates of the array in a concatenated arrangement. Stop pins received in aligned bores and extending between the interdigitized top plates limit the extent of load that can be applied to the linkage, and the ultimate extent of possible relative movement therebetween. Central recesses in top plates of the second type receive extensions from the lower calandria plate which establish basic alignment of the concatenated and interleaved matrices of top plates. Leaf springs secured to the calandria bottom plate engage and exert a downward force, at their outer ends, on the surfaces of the top plates of the second type for establishing a frictional force opposing lateral movement of the top plates of the second type and, correspondingly, through the concatenated and interleaved arrangement, the top plates of the first type, thereby opposing lateral movement while permitting restrained axial displacement of the individual rod guides.

Flexible rod guide support structure for inner barrel assembly of

To preclude failure of components of control-rod assemblies or of unprotected control rods (WDRC's) a calandria is provided above the upper internals. The calandria includes hollow tubes through which the drive rods for the various control rods pass and which protect the drive rods. The guides for the control rods are closed except at the top so that the coolant flows vertically through the guides into the calandria. In the calandria, the coolant flows transversely to the hollow tubes and out through the outlet nozzle. The tubes have a mass and stiffness and strength such that they resist failure by reason of the transverse flow of the coolant to which they are subjected.

Nuclear reactor

The hydraulic drive mechanism comprises an hydraulically actuated rod drive mechanism that cooperates with a pivotable latching mechanism. The pressurized reactor coolant is utilized to raise the drive rod into contact with and to pivot the latching mechanism so as to allow the drive rod to pass the latching mechanism. The pressure in the housing is then equalized which allows the drive rod to move downwardly into contact with the latching mechanism but remain in a raised position with respect to the reactor core. Once again, the reactor coolant pressure may be utilized to raise the drive rod and thus pivot the latching mechanism so that the drive rod passes above the latching mechanism. Again, the mechanism pressure can be equalized which allows the drive rod to fall and pass by the latching mechanism so that the drive rod approaches the reactor core.

Hydraulic drive mechanism

A quick opening hatch for use on a transfer tube of a nuclear reactor plant that is adapted to replace the conventional hatch on the transfer tube. A locking ring is provided with a plurality of screw openings that is adapted for connection to the transfer tube, and a hatch cover fitably received within the locking ring for closing-off the transfer tube. To lock the cover to the ring, latches are movably connected with the cover for locking engagement with the locking ring, and a sprocket with a plurality of crank arms is movably connected with the cover and the latches for movement thereof into locking engagement with a latch housing on the locking ring for locking the cover to the ring and out of engagement with the latch housing for releasing the cover from the locking ring so as to permit removal of the hatch cover from the locking ring to provide access to the transfer tube. A davit assembly is provided which is connected with the transfer tube and the hatch cover to move the cover away and to provide guidance for closing-off the transfer tube. The locking ring and hatch cover also include cooperating keys and keyways for alignment when closing the transfer tube. The cover is provided with sealing rings and the latch housing and latches include cooperating cam surfaces to provide a tight locking engagement by compressing the sealing rings between the transfer tube and the hatch cover.

Growing community of inventors

Monroeville, PA, United States of America

Donald G Sherwood