Abstract: A method for sputtering coating the inside surface of a fuel assembly tubular component (10,200,400,700) with absorber material such as a burnable poison or getter. The steps include supporting the e.g., cladding tube (10) in a fixture (12,14) and supporting a source tube (100) of e.g., burnable poison material coaxially within the cladding tube, thereby defining a cylindrical annulus (24) between the tubes. The annular space is evacuated and backfilled with an inert working gas (26) such as argon, to a pressure sufficient to sustain a plasma discharge. The cladding tube is positively biased (36) as an anode, and the source tube is negatively biased (34) as a cathode, such that a plasma of the working gas is established in the annular space. A circumferential magnetic field is generated around the source tube to confine and shape the plasma whereby the source tube is bombarded with ions from the plasma substantially uniformly over the length of the source tube.

Abstract: A valve test unit (100) for attachment to a value (12) having a fluidly operated stem actuator (20a) responsive to a positioner device (24a). The unit includes a first input port (102) connectable to a source (104) of fluid pressure, a second input port (106) connectable to a source (108) of electrical power, a first output port (110) fluidly connected to the first input port, for delivering a controlled fluid pressure from the unit, and a second output port (114) electrically connected to the second input port, for delivering a controlled electrical signal from the unit. Test programs (118) are provided for converting fluid pressure, at the first input port, into a controlled, time dependent fluid pressure at the first output port and converting electrical power at the second input port into a controlled, time dependent electrical signal at the second output port.

Abstract: A nuclear fuel perimeter strip grid corner-piece (12) of increased flatness having at least two flat side sections (18,20) on either side of a transverse bend line (22) is provided. The flat side section (20) or sections (20 and 32) which have small cut-outs for arches (34), as opposed to large spring (36) cut-outs, as the fuel support features adjacent to the bend line (22) of variable radii at portions (24 and 26) are stress-relieved by means of slots (30) of length equal to 1/2 to 1/3 of the width of the flat section. The slot (30) is of a width less than twice the material thickness, so as not to weaken the structure near bend (22).

Abstract: A holddown leaf spring for a nuclear fuel assembly (10) with an upper end fitting (12) having spring retaining slots (30). Two spring stacks (20, 24 and 22, 26), respectively, are made up of unitary elongated metal bar springs having two substantially tapered width leg portions (20a, 20b, etc.) joined by an arcuate transition portion (28) therebetween. The wider opposite end portions (20c, 20d, etc.) are received in slots (30) of end fitting (12) and retained by welded pins (or capped screws) (not shown). The tapered width distributes localized stresses and may be horizontal or vertical. Less chance of debris exists due to retained spring ends. Flow at two opposite corners is opened up by the taper and by transition portion (28) being spaced from the nozzle openings (32 and 34). The assembly requires fewer parts and less machining.

Abstract: In a method for fabricating an end fitting (12,200) for a nuclear fuel assembly (10), wherein the end fitting includes at least one spring member (24,202) having an active external surface (32,206) for contacting rigid core support structure (100) in the nuclear reactor, the improvement comprising applying a coating to the active surface of the spring member. The coating is selected from the group consisting of nitrides, Cr, TiC, CrC, ZrC and NiTaB. The spring member is preferably Inconel and the coating is one of ZrN or TiN. Each spring member can be formed by nesting a plurality of spring elements (28,34,36 or 208,210) so that the spring elements are in contact with each other and the method includes applying said coating to each of the spring elements at least where they contact each other.

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 for enhancing the wear resistance of a tubular component (62) of a nuclear fuel assembly, including the first steps of supporting the component in an implantation chamber (16), removing ambient air from the chamber such as by a pump (56) and generating a plasma plume (28) of positively charged metal source material by establishing an electrical discharge arc which travels from a cathode (18) of said source material to an anode (24) of a different material. At least a portion of the plasma plume is passed through an electromagnetic duct (14) which filters constituents other than free, high energy source material ions out of the plume. The high energy source material positive ions are directed through the chamber onto the negatively charged component. The chamber can be backfilled with a reactive gas such as nitrogen which forms an ionic compound with the source material ions such as Zr or Ti, and the ionic compound such as ZrN or TiN implants in the component.

Abstract: Apparatus for sealing a joint between an inclined base surface having a leak path and a mating end surface of a hollow body surrounding the leak path. Compression gasket means receive an asymmetric preload force applied through the hollow body from an environmental pressure preloading element having a variable spring constant in register with the joint. The preloading element is a ring-shaped body of a given thickness of an asymmetric radial structure defined by a plurality of unlike radially inwardly directed through slots open to its periphery and axially stacked.

Abstract: A burnable-absorber-containing zirconium alloy is described for application to the inside surface of cladding tubes for light water nuclear reactors. The alloy comprises naturally occurring erbium in a range from a measurable amount up to about 20 wt. % or isotopically purified erbium-167 in a range from a measurable amount up to about 5 wt. %; tin in a range from a measurable amount up to about 0.5 wt. %; iron in a range from a measurable amount up to about 0.2 wt. %; chromium in a range from a measurable amount up to about 0.1 wt. %; niobium in a range from a measurable amount up to about 0.1 wt. %; silicon in a range from about 50 to about 120 parts per million ("ppm"); oxygen in a range from a measurable amount up to about 800 ppm; and the balance zirconium. Such an alloy provides an effective absorber material for reactor control, while providing adequate mechanical properties and corrosion resistance for the intended application.

Abstract: A zirconium alloy absorber material is described which can be used in structural components in light water nuclear reactors. The zirconium alloy absorber material includes a zirconium alloy material, such as Zircaloy-2 or Zircaloy-4, which has been modified by the addition of isotopically pure erbium-167 in an amount ranging from about 0.1 to about 0.4 wt. %, and preferably about 0.2 wt. %.

Abstract: A nuclear fuel assembly grid (1) has a plurality of flat strips (10,12) that are orthogonally interlaced along vertical slots (38,60) through their upper or lower edges and welded together to form an egg crate-like array of four-walled cells (14) for receiving respective fuel rods (16), each cell including springs (20,30) and arches (32,34) projecting from the walls for contacting and supporting a respective fuel rod in the interior of the cell. At least some of the cells having flow deflection vanes (36,56) projecting integrally from a cell wall into the interior of the cell without contacting the fuel rod. Preferably, the vane is bent along a bend line (52) that is parallel to the upper edge (24) of the strip, into the interior of the cell, thereby forming an angle of between about 15 degrees and 30 degrees relative to the plane defined by the body, or plate portion of the strip.

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: An improved short-term autoclave (10) test for ex-reactor evaluation of in-reactor corrosion resistance of zirconium alloy members (16) for use in pressurized water reactors and pressurized heavy water reactors by:providing a heat flux to initiate hydride precipitation close to the metal-oxide interface of the tube outside surface by means of a resistance heater (20) and a directed flow of aqueous coolant in the water phase to only the outside surface which is one of two specimen (16) opposed surfaces; providing the inside surface with access to the coolant from the flow but not in the flow; reducing the distance between the opposed surfaces of specimen (16);regulating coolant flow from inlet port (12) to outlet port (14) and power of autoclave (10) to optimum saturation condition of 360.degree. C..+-. 5.degree. C. and pressure 2700 p.s.i..+-. 100 p.s.i.;providing a coolant chemistry which simulates a rector's;removing most of the oxygen from the coolant.

Abstract: A method and apparatus for inspecting the profile of the inner wall of a conduit, such as a heat exchanger in a steam generator by a probe body that includes eddy current sensing coils. The number of eddy current sensing coils is increased for more completely sensing the conduit surface without a corresponding increase in coaxial cables by the use of a bank switch which switches respective banks of coils to existing conduits.

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: An improved lower end fitting 10 (L.E.F.) having a bell mouth multistage type of flow jet diffuser 30 with stages 31, 31' decreases pressure drop 15-20% over a single stage bell mouth diffuser and more evenly distributes flow and adds strength. It includes neutron thimble flux impingement shield 50 of instrument and/or cable. Each diffuser stage 31, 31' is S.S., of circular cross-sect. and parabolic to optimize diffusion. The multistage shape is based on lower core plate 20 flow hole 24 geometry, L.E.F. design and reactor flow rate. Thinner L.E.F. legs 36, smaller L.E.F. gussets 38 and thinner L.E.F. flow plates 22 are possible.

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.