Abstract: A stabilized alpha metal matrix provides an improved ductility, creep strength, and corrosion resistance against irradiation in a zirconium alloy containing tin in a range of 0.45 to 0.75 wt. %, and typically 0.6 wt. %; iron in a range of 0.4 to 0.53 wt. %, and typically 0.45 percent; chromium in a range of 0.2 to 0.3 wt. %, and typically 0.25 percent; niobium in a range of 0.3 to 0.5 wt. %, and typically 0.45 wt. %; nickel in a range of 0.012 to 0.03 wt. %, and typically 0.02 wt. %; silicon in a range of 50 to 200 ppm, and typically 100 ppm; and oxygen in a range 1,000 to 2,000 ppm, and typically 1,600 ppm, with the balance zirconium. The addition of iron and niobium improves mechanical properties of the alloy with its lower level of tin, while corrosion resistance is addressed by having an iron level of 0.45 wt. % and an iron/chromium ratio on the order of 1.5. The addition of niobium also counters the effect of higher iron on the hydrogen absorption characteristics of the alloy.

Abstract: Equipment for acquiring diagnostic data from a valve train parameter that changes as a result of the operation of a valve (14) in a process plant is positioned as an auxiliary data acquisition unit (200) in the vicinity of the valve train. A plurality of sensor lines (P3, P4) are connected between the auxiliary unit and locations in the valve train where the parameter changes. The valve is operated so as to generate parameter signals manifested in a first physical form in the sensor lines. In the auxiliary unit, the physical form of the parameter signals is converted into diagnostic signals (E10, E11) having a different physical form. The diagnostic signals are transmitted to a base data acquisition unit (100) that is physically distinct from the auxiliary unit.

Abstract: A vent tube (66) and housing nut (62) replace the original housing plug (52) on a pressurized water nuclear reactor. The vent tube engages the installed vent stem (38) cross-slot (48) with a cross-shaped projection (70). During operation, the vent tube (66) is pushed down to engage the vent stem (38) and rotated to allow vented air to travel through stem (38) and tube (66). After venting, the vent stem is rotated back and tightened. The invention provides visual indication of a leaking ball (32) since any leakage lifts vent tube (66). Time required for venting is reduced and no removal of installed ball seal (32,34), a proven primary seal, is required.

Abstract: By using AVLIS or other methods capable of providing a depleted isotopic mixture, troublesome isotopes such as Gd.sup.154, Gd.sup.156 and Er.sup.166 are selectively removed from naturally occurring isotopic mixtures, while avoiding the additional costs associated with complete fractionation of the mixture. Such mixtures can be used to provide a burnable nuclear fuel absorber having a selectively depleted isotope or isotopes. In particular, the invention concerns burnable absorbers containing erbium with a depleted 166 isotope, gadolinium with a depleted 156 isotope or with depleted 154 and 156 isotopes, and methods for making such absorbers.

Abstract: A zirconium alloy which imparts good creep strength, while also providing favorable neutron cross section, improved corrosion resistance, low hydrogen uptake and good fabricability is described which contains vanadium in a range of from an amount effective to indicate its greater-than-trace presence up to 1.0 wt %, wherein either limit is typical; niobium in a range of from an amount effective to indicate its greater-than-trace presence up to 1.0 wt %, wherein either limit is typical; antimony in a range of from an amount effective to indicate its greater-than-trace presence up to 0.2 wt %, wherein either limit is typical; tellurium in a range of from an amount effective to indicate its greater-than-trace presence up to 0.2 wt %, wherein either limit is typical; tin in a range of from an amount effective to indicate its greater-than-trace presence up to 0.5 wt %, wherein either limit is typical; iron in a range of 0.2 to 0.5 wt %, typically 0.35 wt %; chromium in a range of from 0.1 to 0.4 wt %, typically 0.

Abstract: A plug assembly for plugging the flow hole of a core support barrel employs an offset arm for securing the plug to the core support barrel above the flow hole and the adjacent thermal shield. The disclosed embodiments do not require the cutting of an access opening through the thermal shield.

Abstract: A fuel assembly grid (10) in which the height dimension of the grid strips (A,B,C,D) varies along the strip length, so that channels or cells (24',28) immediately surrounding the guide tube (30) define a relatively longer flow path, than channels that are relatively remote from the guide tube. In particular, the grids have a first plurality of four-walled first cells (24) for receiving and supporting respective fuel rods (26) and a second plurality of four-walled second cells (28) that are larger in cross-sectional area than, and interspersed among, the first cells, for receiving respective guide tubes (30). The improvement according to the present invention, provides that the height dimension (H2) of each strip (C) that defines walls of particular first and second cells is greater at the walls of the particular second cells, than at the walls of at least some of the particular first cells.

Abstract: A fuel element (10) for a nuclear reactor having a zirconium-tin alloy cladding tube (20), with a thin coating (30) of a burnable poison consisting of an enriched boron particles sealed in a boron-containing glass or glass compound deposited from a liquid sol-gel.

Abstract: A fuel rod capturing support grid having a spring and arch design which provides performance improvements over current or previous designs by decreasing fuel rod fretting wear. The disclosed spring and arch designs follow the contour of the fuel rod, thus providing an increased, substantially arc-shaped area of contact between the fuel rod and the spring tabs and arches.

Abstract: A burnable absorber controls axial power peaking or moderator temperature coefficient while additional elements are added to improve strength and/or corrosion resistance in a zirconium alloy containing erbium in a range of from about 0.05 to 2 wt. % selected from the group consisting of a naturally occurring distribution of isotopically enriched erbium-167 and a combination thereof; in a range of from a measurable amount up to 1.4% tin; from 0.2 to 0.5 wt. % iron; from 0.07 to 0.25 wt. % chromium; in a range of from a measurable amount up to 0.6 wt. % niobium; in a range of from a measurable amount up to 0.5 wt. % vanadium; 50-120 ppm silicon; 1000-2200 ppm oxygen and a balance of zirconium. Alternatively, the erbium can be replaced by gadolinium in a range of from about 0.05 to 6 wt. % selected from the group consisting of a naturally occurring distribution of gadolinium isotopes, isotopically enriched gadolinium-157 and a combination thereof.

Abstract: A nozzle damper assembly (10) for installation in a duct (12) operative for measuring and controlling the flow of a gaseous medium through the duct (12). The subject nozzle damper assembly (10) includes enclosure means (24) cooperatively associated with the duct (12), shaft means (26) suitably supported from the sidewalls (32, 34, 36, 38) of the enclosure means (24), damper blade means (16,18) rotatable mounted on the shaft means (26) for movement within the enclosure means (24), damper blade operating means (28) operative for purposes of effecting the movement of the damper blade means (16,18) within the enclosure means (24), and flow measurement means (20,22) supported at a first location and at a second location relative to in lieu thereof the damper blade means (16,18) and operative to measure the flow of the gaseous medium through the nozzle damper assembly (10) such that control may be exercised over the flow of the gaseous medium through the duct (12) based on such measurements.

Abstract: The displacement of a valve stem (16) is measured during diagnostic testing by temporarily mounting a laser head (112) on the valve body (18) or yoke (20), for generating a source laser beam (118) that reflects from a target (120) that moves with the stem. The timing of the reflected beam (132) returning to the head (112) relative to the projection of the source beam, gives an indication of the displacement of the stem.

Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: A corrosion resistant metallic coating (60) of zirconium nitride is applied to the cladding tube (40) of a nuclear fuel rod (20). The zirconium nitride is reactively deposited on a zirconium-alloy cladding tube by a cathodic arc plasma deposition process. The zirconium nitride coating provides superior wear test results and enhances the corrosion resistance of the cladding tube.

Abstract: An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually.

Abstract: A method of removing in-core instruments and dry tubes from a boiling water reactor during a refueling outage wherein a pair of temporary storage containers are provided in the reactor core. A remotely operated cutting device is superposed on the first temporary storage container. An instrument is suspended by an end, with the in-core part uppermost, and lowered until a portion of the out-of-core part is within the first temporary storage container. The cutting device is then operated to sever the instrument portion within the temporary storage container. The instrument is repeatedly lowered, and portions severed, until all of the out-of-core part of the instrument is in the first temporary container. The in-core part of the instrument is then lowered into the second temporary container and the two temporary containers are removed from the reactor cavity using the existing equipment-handling crane.

Abstract: A plurality of neutron flux sensors (44,46,48,50) and a corresponding plurality of gamma flux sensors (62,64,66,68) are distributed throughout axial zones (24,26,28,30) of the core (14) at the same or closely proximate locations. A steady state comparison, or bias, between the signals of a given neutron/gamma sensor pair are monitored (314, 316), and a divergence (or convergence) can readily be detected through simple signal filtering, to detect a shift in the bias. The pattern of significant convergence and divergence throughout the core, is indicative of the thermal hydraulic stability of the core.

Abstract: An electron discharge machining tool (10) for removal of conductive material from a workpiece such as a plug (28) in a nuclear steam generator tube (26) is an end effector connected to a remotely operated manipulator arm by a mount (56). A piston (47) drives a hollow conductive rod (44) with a graphite electrode cutter (30) in reciprocating motion through receptacle (14) having a restrictive drain (37) and containing deionized water. The reciprocation of rod (44) is controlled by power supply (50) sensing the electrical potential and signalling valve (48) which controls hydraulic flow in conduits (54a, 54b) communicated to opposite sides of the piston (47). A TV camera (32) and a light (34) mounted behind a lens (36) are used to monitor the machining.

Abstract: An apparatus for monitoring the position of the shaft of a coolant circulating pump of a nuclear steam generating system comprising light source for directing a light beam at a number of reflecting surfaces on the shaft and a pair of spaced apart light receiving devices adapted to receive light beams reflected off the reflecting surface. Light from the receiving devices is conveyed, by fiber optic cables, to intensity measuring devices which measure the intensity of the two light beams on a time-dependent basis. A processor calculates the shaft rotational speed and the magnitude of the shaft wobble as functions of the time-dependent intensity measurements of the pair of reflected light beams.

Abstract: A stabilized alpha metal matrix provides an improved ductility, creep strength, and corrosion resistance under neutron irradiation environment in a zirconium alloy containing tin in a range of 0.8 to 1.2 percent; iron in a range of 0.2 to 0.5 percent, and typically 0.35 percent; chromium in a range of 0.1 to 0.4 percent, and typically 0.25 percent; niobium in a range of from a measurable amount up to 0.6 percent, and typically 0.30 percent; silicon in a range of 50 to 200 ppm, and typically 100 ppm; and oxygen in a range 900 to 1800 ppm, typically 1600 ppm. The silicon is added as an alloying element to reduce hydrogen absorption by the alloy and to reduce variations in the corrosion resistance with variations in the processing history of the alloy.