Abstract: A method of manufacturing fuel channels made of zirconium-based alloy by combining heat treatment, warm forming and thermal sizing. Fuel channel strip material is heated to a temperature which initiates the transformation from a hexagonal close-packed to a body-centered cubic crystallographic phase and then quenched at a rate which initiates transformation to a hexagonal close-packed crystallographic phase having a texture factor f.sub.L =0.28-0.38. The heat-treated strips are formed into fuel channel components by bending at an elevated temperature sufficient to increase the ductility of the strip material. After the fuel channel components are welded together, the fuel channel is annealed by thermal sizing.

Abstract: A rectilinear sectioned water rod--preferably of square cross-section--is provided with horizontal grooves for keying to bands on the inner, water rod surrounding aperture of spacers. Each spacer is constructed preferably of Inconel and includes a specialized inner band for keying to the water rod. The inner spacer member includes an upper surrounding band, a lower surrounding band, and four connecting vertical members--one positioned at each corner of the water rod. Two adjacent vertical members are bent inward to contact one side of the water rod at spaced apart points on the corners of the water rod. The remaining two adjacent vertical members are bent inward to contact the remaining two corners at single points on each vertical member.

Abstract: In a boiling water nuclear reactor fuel bundle, a debris catching arrangement is disclosed for incorporation within the flow plenum up stream or below the rod supporting grid of the lower tie plate assembly. The device is preferably placed within the lower tie plate flow plenum between the fuel bundle inlet orifice and the rod supporting grid structure supporting the fuel rods; alternate placement can include any inlet channel upstream of the fuel rods including the fuel support casting. Paired plates defining offset holes and bosses are utilized. The bosses are supported at plate webbing between the respective holes. The holes are preferably square in plan with appropriately relieved and rounded corners defining the edges of the webbing. The bosses may be cylindrical, square or rectangular in cross-section. In confrontation of plates to form the debris catching grid, each boss from one plate confronts a hole from the remaining plate.

Abstract: A cross point spacer is provided with subchannel vertical tubes at the subchannel volumes, these tubes being supplied with an inner flow free cylindrical volume and an peripheral steam separator in the form of a surface which imparts a spiral flow pattern to steam/water mixture flowing peripherally upwardly within the subchannel tube. According to a first and preferred embodiment, the subchannel tube of the cross point spacer is provided with rifling. According to a second embodiment, twisted vanes are installed and fastened to the interior of the subchannel tube and drilled away at the central portion of the twisted vanes to leave strips of metal defining rifling like paths on the subchannel tube interior. In either case, the main and central portion of the subchannel volume through the spacer is provided with an unobstructed central portion for upward steam flow.

Abstract: An improved ferrule spacer for use with high density fuel rod arrays within boiling water reactor fuel bundles is disclosed. Ferrules are constructed in mating ferrule pairs. Each ferrule is divided into upper and lower ferrule halves. One ferrule half has sides thereof with the walls removed. The other ferrule half has its in place. The ferrule pairs are confronted with one ferrule inverted with respect to the other and with each complete ferrule wall of one ferrule half being juxtaposed to a ferrule half at a missing wall. Preferably, and at the point of tangency between the ferrule pairs, an aperture for receiving and confining an "H" type double loop spring is defined. The disclosure includes ferrules having a circular surround for the fuel rods and ferrules having an octagon sectioned surround for the fuel rods. Each member of the ferrule pair is symmetrical and completely interchangeable to provide for both convenient assembly and a small inventory of assembly parts.

Abstract: A method of manufacturing components made of zirconium-based alloy by combining heat treatment with thermal sizing. The heat treatment includes heating the component to a temperature which initiates the transformation from a hexagonal close-packed crystallographic phase of uniform texture to a body-centered cubic crystallographic phase and then quenching to a quench temperature at a rate which initiates transformation to a hexagonal close-packed crystallographic phase having a texture factor f.sub.L =0.28-0.38. The thermal sizing includes heating the component to a temperature less than the quench temperature, but sufficient to anneal the component, and then cooling. Preferably, the thermal sizing is performed twice: before and after the heat treatment.

Abstract: A fuel pellet retainer spring assembly is disclosed for insertion to the open unsealed end of a fuel rod. The assembly includes a locking sleeve having a normal radial diameter exceeding the inside radial diameter of the fuel rod cladding. This sleeve is compressed to a diameter less than the inside diameter of the fuel rod cladding. Thereafter, the sleeve is inserted. In the preferred embodiment, a washer and coil spring precedes the sleeve into the fuel rod. The sleeve is inserted and thereafter allowed to expand and frictionally hold to the inside wall of the cladding. When the sleeve is in place, the coil bears against the inside portion of the radial sleeve and forms the surface from which a fuel pellet biasing spring maintains fuel pellets within the unsealed fuel rod.

Abstract: In a fuel bundle for use in the core of a boiling water nuclear reactor, part length rods having a tendency to reduce pressure drop are used in combination with spacers and spacer attached devices tending to restore pressure drop to improve critical power. The addition of the part length rods has the advantage of lowering the pressure drop. Attached devices substantially recapture the pressure drop. Exemplary spacer attached mechanisms for the recapture of pressure drop are set forth including vanes--preferably swirl vanes on the spacers, decreasing the spacer pitch to increase the total number of spacers in the upper two phase region of the fuel bundle, increasing the vertical height of the spacers, and increasing the thickness of the metal from which the spacers are constructed. Two classes of separation devices are disclosed for placement in the volume overlying the end of the partial length fuel rods.

Abstract: An improved spacer is disclosed which contains an Inconel grid and a Zircaloy surrounding band. The Inconel grid can be fabricated from the extremely thin and highly elastic spring metal utilizing a modification of a prior art cell construction that includes paired inwardly bent vertical spring legs with cantilevered and rod encircling upper and lower arm pairs The spring legs extend at spaced apart locations between the upper and lower arm pairs and have a medial spring rod contacting portion for biasing the rods into stops on the rod encircling arm pairs. The springs at the upper and lower ends are provided with spring dimple stops to prevent over stressing of the spring during assembly or handling of the fuel bundle into which the spacer is incorporated. The rod encircling arm pairs have an offset from center where the two arms meet at their distal ends to complete encirclement of the rods. This offset from center enables the cells to be fastened in cell pairs at their respective embracing arms.

Abstract: A swirl vane is disclosed for addition to a spring metal grid spacer utilized with a conventional nuclear boiling water nuclear reactor. The spring metal spacer includes a matrix of fuel rod containing cells. Each cell has at least one spring leg and at least two fuel rod encircling arms. The spring leg functions to bias a fuel rod contained within the cell at the spacer to one side of the cell. The two rod encircling arms define stops against which the fuel rods are biased. The cells themselves are welded into a unitary matrix and preferably surrounded by a metallic band. The improved swirl vane of this invention includes an "I" shaped spring steel strip. This strip includes top and bottom tabs for engaging the respective top and bottom grid structure of the spacer. The "I" shaped strip is then twisted to provide the swirl vane surface, this twisting being preferably slightly less than or greater than the total twisting required.

Abstract: To provide quality assurance inspection of the dimensional characteristics of cells to be incorporated in spacers utilized in nuclear fuel bundles to establish critical spacings between fuel rods, a cell is placed in a fixture dimensioned to gauge the outer dimensions of the cell. A fuel rod-simulating pin is then inserted through the cell to rest on fuel rod-positioning stops formed on the cell. "Go, no go" feeler gauges then check the dimensions of the gaps between the fixture and pin.

Abstract: In a nuclear fuel bundle for a boiling water reactor, the prior art suggested concept of tapered fuel rods forming the bundle array is disclosed in a practical design including a fuel bundle and an improved associated spacer utilized in the upper two phase region of the fuel bundle. A tapered fuel rod is utilized having a large diameter bottom tube for holding corresponding large diameter fuel pellets at the fuel rod bottom, a smaller diameter top tube for holding correspondingly smaller diameter pellets at the top of the fuel rod, and a bell reducer situated between the large diameter lower fuel tube and the smaller diameter upper fuel tube. This bell reducer tapers from the large outside diameter of the lower fuel tube and the smaller outside fuel diameter of the upper fuel tube and forms a smooth transition between the large and small diameter sections of the fuel rod. An improved fuel rod spacer is disclosed for use with the upper and smaller tube portions of the fuel rods.

Abstract: A fuel bundle and fuel bundle assembly sequence utilizing a peanut sectioned large water rod is shown locking spacers into place along the axial length of the water rod. In a first embodiment, clearance is defined relative to tabs welded on the large water rod so that spacer assembly to the water rods can occur. In a second and preferred embodiment, spacers are individually equipped with springs locking into complimentary apertures in the peanut sectioned water rod. In both embodiments, the spacers are threaded onto the peanut sectioned water rod and locked into alignment for the receipt of the fuel rods. An improved suspension of the water rod relative to the lower tie plate is disclosed in which a transition piece connects the large water rod to a flexible rod which is threaded at its lower end. This rod is screwed into a threaded aperture in the lower tie plate.

Abstract: In a fuel bundle having a matrix of parallel side-by-side fuel rods supported between a lower tie plate and an upper tie plate, a new ferrule and spring construction for the required spacers used to maintain the fuel rods in their required precise side-by-side alignment is disclosed. Paired ferrules are each provided with apertures for capturing a single spring between the ferrules. The springs are provided with a continuously looping main body having protruding tabs on opposite sides of the springs. The paired ferrules are confronted at their respective apertures for the capture of the springs. The shape of the apertures permits insertion of the spring after the ferrules have been welded together. The springs are compressed while being inserted. After insertion the springs return to their original shape and are confined between the ferrules. After insertion of the fuel rods, the springs are compressed to an intermediate position, but are still confined within the ferrule apertures.

Abstract: A spacer for a fuel bundle is disclosed in which a grid type construction provides an approximation to a traditional ferrule spacer. First and second sets of diagonally extending strips of Zircaloy are utilized extending along opposite diagonals across a square sectioned spacer. One set of strips is disposed in a first parallel array along a first diagonal, with each strip of the set being spaced from other strips of the set at rod width spaced intervals along the second and remaining diagonal. The other set of strips is disposed in a second parallel array along an second diagonal, with each strip of the set being spaced from the other strips of the set at rod width spaced intervals along the first diagonal.

Abstract: An improved spacer is disclosed which contains an Inconel grid and a Zircaloy surrounding band. The Inconel grid can be fabricated from the extremely thin and highly elastic spring metal utilizing a modification of a prior art cell construction that includes paired inwardly bent vertical spring legs with cantilevered and rod encircling upper and lower arm pairs. The spring legs extend at spaced apart locations between the upper and lower arm pairs and have a medial spring rod contacting portion for biasing the rods into stops on the rod encircling arm pairs. The springs at the upper and lower ends are provided with spring dimple stops to prevent over stressing of the spring during assembly or handling of the fuel bundle into which the spacer is incorporated. The rod encircling arm pairs have an offset from center where the two arms meet at their distal ends to complete encirclement of the rods. This offset from center enables the cells to be fastened in cell pairs at their respective embracing arms.

Abstract: A spring-and-spacer assembly for maintaining fuel rods upright in a fuel assembly of a nuclear reactor core is provided. The spring is in the form of a continuous loop with first and second legs having mid-leg rod-contact regions. Bend regions are positioned on each side of each contact region extending toward the interior of the loop spring. In most positions, the spring is used to load two adjacent fuel rods. In configurations in which there is an unpaired fuel rod, a plate having a tab for contacting the spring is provided. The spring provides the desired force, such as about 2.5 pounds per fuel rod, in a small rod-to-rod spacing of less than about 0.14 inches.

Abstract: A spacer with a spring construction for the fuel bundle having matrix of parallel side by side fuel rods supported within a fuel channel between a supporting lower tie plate and holding upper tie plate is illustrated. The spacers each have a corresponding matrix of individual ferrules each surrounding the discrete fuel rods to be spaced within the matrix of fuel rods at any given elevation within the fuel bundle. Each of the individual ferrules surrounding the individual fuel rods are provided with stops against which the fuel rods are biased to ensure the required side-by-side spacing. Each ferrules must have at least one spring for forcing the fuel rods against the stops of its spacer ferrules to enable the spacer to assure required side-by-side alignment of the fuel rod. The springs are provided with a continuously looping main body having protruding tabs on opposite sides of the springs.

Abstract: An improved channel is disclosed which has a reduced average thickness in its upper portion. The lesser average thickness corresponds to a lower pressure difference acting on the channel sides, over the upper portion of the channel. The reduction in average thickness is accomplished by cutting flow trippers into the inner surface of the channel walls and/or cutting grooves into the outer surface of the channel. The axial variation of channel average thickness increases water volume adjacent to the upper part of the channel to provide increased neutron moderation, to minimize the steam void reactivity coefficient, and to provide a greater cold shutdown margin. The material removed to produce the flow trippers increases the cross-sectional area inside the channel and reduces pressure drop in the upper portion of the channel. The flow trippers divert water flowing on the channel walls to the fuel rods adjacent to the channel walls, permitting higher reactor power operation.

Abstract: In a channel contained fuel bundle for a boiling water nuclear reactor, an improved channel is disclosed. The channel contains a plurality of fuel rods held in spaced apart relation by at least upper and lower tie-plates and/or spacers. In the reactor, the channel contains fuel rods extending between a lower support plate and an upper support grid. When the reactor is operating, the channel confines water flow intimately about the rod bundle on the inside and assures steam generation in a predictable pattern. Water exterior of the channel is at a different and typically lower pressure. To accommodate control blades (which control the fission process) outside of the fuel bundles, the channel is provided with a polygon cross section, most typically a square cross section. In operation, the flat walls tend to bulge due to primarily pressure effects but also due to thermal and radiation effects.