Abstract: An advanced overfire air system for NO.sub.x control designed for use in a firing system of the type that is particularly suited for use in fossil fuel-fired furnaces and a method of operating such a furnace which embodies an advanced overfire air system. The advanced overfire air system for NO.sub.x control includes multi-elevations of overfire air compartments consisting of a plurality of close coupled overfire air compartments and a plurality of separated overfire air compartments. The close coupled overfire air compartments are supported at a first elevation in the furnace and the separated overfire air compartments are supported at a second elevation in the furnace so as to be spaced from but aligned with the close coupled overfire air compartments.

Abstract: A retainer is for retaining a grid on a fuel assembly. The retainer has at least one aperture at one end thereof for receiving a shoulder on a guide control tube and legs on the other end thereof for welding to the grid. The one end of the retainer is captured between the shoulder and a surface on the bottom nozzle of the fuel assembly when the guide tube is attached to the bottom nozzle. The retainer reduces the rotation of the guide tube resulting from torquing of the screws which connect the guide tube to the bottom nozzle thereby increasing the integrity of the assembly.

Abstract: Apparatus for sensing and transmitting a signal indicative of the position of a movable ferromagnetic member relative to a fixed structure within which the member moves. The apparatus includes a plurality of magnetic circuit arrangements arranged uniformly along the outside of the fixed structure. Each magnetic circuit arrangement includes a pair of magnets and a pair of arcuate-shaped magnetic path elements extending circumferentially about the fixed structure. A plurality of magnetic field responsive position transmitters are positioned adjacent the magnetic circuit arrangements for sensing the presence of the movable ferromagnetic member at predetermined positions within the fixed structure. The apparatus is particularly useful for monitoring the position of control rods in a nuclear reactor because the monitoring is done from outside the sealed structure.

Abstract: A non-intrusive method for timing the full operational motion of a valve plug (26) in an electrically actuated, pneumatically operated valve (10). An actuation signal is sent to the valve actuator (54). A coil of wire (68) around the valve actuator solenoid (56), an accelerometer (70) on the solenoid slug (64), or a connection to a permanent pressure sensor (72), non-intrusively senses arrival of the actuation signal at the valve. The time measuring equipment (12) begins timing when the actuation signal is sensed. A laser valve motion sensor (74) then non-intrusively senses when the valve plug reaches a limit of motion. The time measuring equipment ends timing when the valve plug reaches a limit of motion. The time measuring equipment then records the elapsed time from the sensing of the arrival of actuation signal to the final limit of motion of the valve plug.

Abstract: A grid strip (10) for a fuel rod support grid of a nuclear fuel assembly is cold-formed from a flat annealed plate having length, height, and width dimensions. A plurality of slots (12,14) extend along the height dimension at regular intervals along the length dimension, thereby defining successive cell walls (16,18,20) between successive slots along the length dimension. Each cell wall has upper, central, and lower regions (28,30,32) along the height dimension, each region including a substantially flat base area (34,36,38) and fuel rod support structure (22,24,26) projecting integrally from the base area along the width dimension of the strip. The support structure in each of the upper and lower regions includes a relatively stiff, arched stop (22,26) which projects in a first direction and the support structure in the central region includes a relatively soft, arched spring (24) which projects in a second direction opposite the first direction.

Abstract: A latch tool features two elongate arms which extend down along either side of a control rod. Rotatable actuating rods are mounted on the arms. The upper ends of the actuating rods are provided with cranks which engage in slots formed in an actuating disc. As the disc is rotated, the cranks rotate the actuating rods and swing cam-like members, which are fixed to the rods, into position under an unlatching handle. In the preferred embodiments, the actuating disc is threaded onto the exterior of a rotatable input member, so that after the cam-like members are swung into position, the actuating disc threads its way up the input member in a manner which pulls the cam-like members upwardly and pulls the unlatching handle. In addition to the cam-like members which actuate the unlatching handle, lifting cam-like members may additionally be provided to fit in under a lifting handle of the control rod, and facilitate lifting of the control rod out of its position.

Abstract: In order to reduce the time and difficulty of disassembling a seal arrangement which includes a Grayloc flange, in a cramped radioactive environment, the Grayloc hub is modified to include a step bore which receives a seal arrangement and a retaining nut which presses the seal into engagement with an inner wall portion of the hub and outer wall portion of an ICI (in core instrument) supporting column. A loading ring is threaded onto a portion of the column. Bolts associated with the ring are screwed down onto a belleville washer which is disposed between the loading ring and the top of the retaining nut for maintaining a desired amount of load on the seals irrespective of thermal variations.

Abstract: A boiling water reactor control rod drive housing support bars having wing assemblies to limit the travel of a control rod in the event that a control rod housing is ruptured. The wing assemblies are placed on support bars located in rows on opposing sides of the control rod drives. Each wing on the wing assemblies supports a quadrant of a control rod drive. The wing assemblies may be rotated from an operation position to a service position to allow replacement of the control rod drives.

Abstract: A liquid-vapor separator for two-phase fluids in general and specifically a steam-water separator in a steam drum of a steam generator includes axial or radial spinner blades to create a centrifugal motion which causes liquid to be forced outward against the outer wall and the vapor to be concentrated in the center. Conical extraction skimmers systematically extract and discharge the liquid outwardly and downwardly through the side walls such that it impinges on an optional discharge screen surrounding the skimmers. The vapor flows out the top through a central opening and enters a secondary separator packed with crimped wire mesh encased in a perforated enclosure. The conical extraction skimmers include an outwardly protruding rim portion which forms an enlarged annular chamber between the rim and the underlying conical extraction skimmer. This forms a converging-diverging flow path out between skimmer sections and an outwardly extending ring forms a tortuous path.

Abstract: A boiling water reactor control rod drive housing support bars having radiation shields to limit the travel of a control rod in the event that a control rod housing is ruptured and protect persons working under the reactor vessel from radiation exposure. The radiation shield includes radiation shield cups for surrounding the bottom portion of a control rod drive. The radiation shield cups are placed on support bars located in rows on opposing sides of the control rod drives. The radiation shield may be easily raised and lowered automatically by the control rod drive installation/removal machine.

Abstract: It has now been found that these and other objects of the invention may be attained in a vapor generation apparatus which includes a tube wall and an elongated first horizontal buckstay disposed at a first elevation. The apparatus also includes coupling means coupling the first horizontal buckstay to the tube wall, an elongated second horizontal buckstay disposed at an elevation that is higher than the first elevation. The apparatus also includes means for coupling the second horizontal buckstay to the tube wall. A first elongated vertical buckstay member has first and second ends and also includes for securing one end of the first elongated vertical buckstay members to one of the horizontal buckstay members.

Abstract: A fuel element for a nuclear reactor is described having a zirconium alloy cladding tube, with a thin coating of a metal silicate and particles of enriched boron-containing compound burnable-poison particles, such as ZrB.sub.2, deposited from a liquid suspension which includes a polymer binder material and water and/or alcohol as a diluent.

Abstract: A composite holddown spring for applying an axial force to a fuel pellet stack in a nuclear reactor fuel rod. The composite holddown spring comprises a shape-memory alloy spring portion and a conventional metal spring portion. The shape-memory alloy spring portion has a two-way memory characteristic such that it contracts to a low temperature configuration at ambient temperatures wherein the axial force exerted by the shape-memory alloy spring portion is minimized and expands to a high temperature configuration at operating conditions wherein the axial force exerted by the shape-memory alloy spring portion is maximized. Somewhat conversely, the conventional metal spring portion weakens and contracts at operating temperature and strengthens and expands at atmospheric temperature.

Abstract: A tool system features an EDM crack removal head which can be positioned within a nozzle/thermal sleeve and then oscillated in a vertical and horizontal directions to enable precise material removal, leaving the surface free of cracks and in a condition for rewelding if required. If a crack is found in a surface which is covered by a thermal sleeve, then a small specialized EDM cutting head, which can be delivered from the under side of the reactor head and has an ability to pass through the ID of the thermal sleeve, is used. The head enables the sleeve to be cut and allow a portion of the sleeve to be removed. The crack can then be removed using a crack removal type of head.

Abstract: An integrated low NO.sub.x tangential firing system (12) that is particularly suited for use with pulverized solid fuel-fired furnaces (10), and a method of operating a pulverized solid fuel-fired furnace (10) equipped with an integrated low NO.sub.x tangential firing system (12). The integrated low NO.sub.x tangential firing system (12) when so employed with a pulverized solid fuel-fired furnace (10) is capable of limiting NO.sub.x emissions therefrom to less than 0.15 lb./10.sup. 6 BTU, while yet maintaining carbon-in-flyash to less than 5% and CO emissions to less than 50 ppm. The integrated low NO.sub.x tangential firing system (12) includes pulverized solid fuel supply means (62), flame attachment pulverized solid fuel nozzle tips (60), concentric firing nozzles, close-coupled overfire air (98,100), and multi-staged separate overfire air (104,106).

Abstract: A device 20 for cleaning threaded studs 14 securing the dome-shaped head of a nuclear reactor pressure vessel to the vessel body 10 comprises a cylindrical brush holder 24 rotatably carried in a housing 22. An annular steel wire brush 28, disposed on the inner surface of the brush holder 24, is adapted to fit over and engage the threaded portion 14a of a stud 14. An electric motor 26 mounted on the housing 22 rotates the brush holder 24 as it is lowered onto an upstanding stud 14. A vacuum source connected to the housing 22 captures any particulate matter removed from the stud 14.

Abstract: A nuclear fuel assembly grid (100) made from a plurality of interlaced corrugated metal strips (102-116) forming an egg-crate configuration so as to define plurality of four-walled cells (118) for receiving respective individual fuel rods (120). The spaced apart vertical bend lines (160,162) of the currugation define vertices (130,132) and consecutive body panels (164,166) which alternate generally inwardly and outwardly between consecutive bend lines. A vertical slot (168) extending from one of the strip upper or lower edges (176) into each panel midway between consecutive bend lines, and overlapping a slot from an interlaced strip to form an hourglass-shaped cell having opposed convex walls and opposed concave walls and four 90 degree corners (150). Spring (148) and stop (153) structure projects from each wall of a cell, for centering and supporting the fuel rod within the cell.

Abstract: The grids (14) of a nuclear fuel assembly (10) include an outer strip, or perimeter plate (100), having outwardly projecting formations (104,106) spaced from the side edges (110) of the internal grid strips (108), for resiliently absorbing lateral forces before such forces are transferred directly to the internal strips. The load dissipating feature of the present invention can be enhanced by providing orifices (552) in the substantially flat, central region (502) of each perimeter plate. This produces an hydraulic damping effect that can be pre-established by selecting the orifice sizes for a given set of impact load conditions.

Abstract: A vapor generation apparatus which includes a furnace, having a tube wall and at least one vertical buckstay member disposed proximate to the outer face of the spiral tube wall. The apparatus includes a stirrup for transmitting forces between the spiral tube wall and the vertical buckstay member. The stirrup includes a U-shaped plate and a cylindrical member, apparatus for mounting the cylindrical member on the vertical buckstay member including first and second lugs fixed to the vertical buckstay member in spaced relationship. The cylindrical member is fixed between the first and second lugs in spaced relation to the vertical buckstay member. The apparatus also includes apparatus for mounting the U-shaped plate on the tube wall.

Abstract: The method of repairing in situ a damaged or malfunctioning electrical connector (10) of a safety related nuclear reactor instrument (14) and its associated sheathed cable (18) wherein the damaged or malfunctioning connector portion (20) is cut from its associated cable (18) and replaced by a new connector portion. The wires of the cut cable are connected with the replacement connector portion and are suitably insulated. The cut cable and new connector portion are then secured together by a special alloy coupling (34) which is positioned in spanning relation with the cut cable (18) and the replacement connector portion (20). This special alloy has the property that it can be expanded within limits and upon being heated above a critical temperature will return to its original dimension. The tubular coupling accordingly has an expanded diameter slightly larger than that of the replacement connector portion and the sheath of the cut cable but an original inner diameter slightly smaller.