Patent Number: 055925200
Section: summary

TECHNICAL FIELD The present invention relates to a latch handle for use in a control rod in a nuclear reactor and particularly relates to a latch handle which may be readily and easily installed in the control rod and which does not require any welding, machining or additional parts for retention by the control rod and service to release the control rod drive. BACKGROUND As well known, control rods in nuclear reactors form dual functions of power distribution shaping and reactivity control. The rods enter from the bottom of the reactor and are typically connected to bottom mounted, hydraulically actuated drive mechanisms which allow either axial positioning for reactivity regulation or rapid scram insertion. The control rod to control rod drive connection permits each control rod to be attached and detached from its drive during an outage, for example, for refueling, without disturbing the remainder of the control system for the control rod. The control rods are generally cruciform in cross-sectional shape with each blade of the rod containing tubes filled with boron carbide. The bottom of the control rod tube includes rollers for guidance of the rod during insertion and withdrawal as well as a velocity limiter. Each control rod when inserted into the core of the nuclear reactor has a fuel bundle in each of its quadrants. Each control rod typically includes at its lower end below the velocity limiter a coupling socket and a lock plug. The lock plug is mounted on an actuating shaft which passes upwardly coaxially along the control rod to a window in which is mounted a latch handle connected to the shaft. The coupling socket and lock plug are releasably attached to a coupling spud on the control rod drive by operation of the latch handle. Thus, the lock plug and socket receive the coupling spud and lock the control rod to the control rod drive. During an outage, when it is desirable to remove the control rod while leaving the control rod drive intact, and after removal of the fuel bundles, the latch handle is displaced upwardly displacing the lock plug from its locked condition with respect to the socket and coupling spud whereby the control rod is released from the control rod drive and may be removed. Conventional latch handles for control rods have laterally projecting tongues which engage in slots formed along side edges of the window of the control rod. Typically, these slots require either four strips which are welded in place to the control rod or two slots machined into the edges of a thin plate with an overlying strip to capture the latch handle. Welding of strips to the control rod is necessary in these prior art handles to capture the handle in the control rod. Substantial labor is involved in welding the necessary strips to form the slots and, in general, to locate the latch in the control rod window. DISCLOSURE OF THE INVENTION According to the present invention, there is provided a latch handle which performs the same function as latch handles of the prior art, i.e., to releasably lock the control rod and the control rod drive to one another yet which does not require welding or substantial labor to locate the handle in the window of the control rod. To accomplish this, the window in the control rod is formed with flanges projecting from its opposite sides. The latch handle is generally rectilinear in configuration with opposite sides defining slots for receiving the flanges along the opposite sides of the window. The latch handle, however, is sized and configured so that, in a first rotational orientation, the latch handle lies within the peripheral confines of the window and, upon rotation of the latch handle into a second angular orientation, the slots of the latch handle receive the flanges of the window sides. The latch handle in its second orientation is attached to the shaft mounting the lock plug. Hence, by sliding the latch handle in a vertical direction, the lock plug cooperates with the socket and spud to detach or attach the control rod and control rod drive relative to one another. It will be appreciated that the slots on the latch handle and the flanges on the window can be reversed with the flanges lying on the latch handle and the slots along the sides of the window. In a preferred embodiment according to the present invention, there is provided a control rod for a nuclear reactor comprising a control rod body having a plurality of blades projecting generally at right angles to one another, the body having a window defined by a plurality of generally linearly extending sides, a latch handle for connection to the control rod body and location in the window, the latch handle having a plurality of linearly extending sides, at least a pair of sides of one of the window and the latch handle having retaining slots and at least a pair of sides of another of the window and the latch handle having flanges for engaging in the slots, the sides of the latch handle and the window being configured so that the latch handle, in a first rotational orientation relative to the window, is receivable within the peripheral confines of the window and, upon rotation thereof into a second rotational orientation relative to the window, engages the periphery of the window with slots and flanges of the pairs of sides of the window and the latch handle engaging one another, respectively, to retain the latch handle in the window, the pairs of sides engaging one another in the second orientation of the latch handle relative to the window to enable sliding movement of the latch handle in at least one linear direction relative to the window. In a further preferred embodiment according to the present invention, there is provided a control rod for a nuclear reactor comprising a control rod body having an elongated axis and a plurality of laterally projecting blades, the body having a generally rectangular window defined by upper and lower edges and opposite sides, the window lying along the axis, a generally rectangular latch handle for connection to the control rod body and location in the window, the latch handle having a pair of opposite sides, the opposite sides of one of the window and the latch handle having retaining slots and the opposite sides of another of the window and the latch handle having flanges for engaging in the slots, the latch handle and the window being configured so that the latch handle, in a first rotational orientation relative to the window, is receivable within the window with the latch handle sides lying generally in opposition to the upper and lower edges of the window and, upon rotation thereof into a second rotational orientation relative to the window, has the sides thereof engaging with the opposite sides of the window, respectively, with the slots and flanges engaging one another to retain the latch in the window, the opposite sides of the latch handle and the opposite sides of the window engaging one another in the second orientation of the latch handle to enable sliding movement of the latch handle in at least one linear direction relative to the window and along the axis. In a still further preferred embodiment according to the present invention, there is provided a control rod for a nuclear reactor comprising a control rod body having a plurality of laterally projecting blades angularly related to one another, the body having a window with spaced edges, a latch handle for connection to the control rod body and location in the window, the latch handle having spaced edges, at least a pair of edges of one of the window and the latch handle having retaining slots and at least a pair of edges of another of the window and the latch handle having flanges for engaging in the slots, the edges of the latch handle and the window being configured so that the latch handle, in a first rotational orientation relative to the window, is receivable within the peripheral confines of the window and, upon rotation thereof into a second rotational orientation relative to the window, engages the periphery of the window with slots and flanges of the edges engaging one another, respectively, to retain the latch handle in the window, the slots and the flanges engaging one another in the second orientation of the latch handle relative to the window to enable sliding movement of the latch handle in at least one linear direction relative to the window. Accordingly, it is the primary object of the present invention to provide a novel and improved latch handle for a control rod which is readily and easily mounted within the window of the control rod without welding and reduced labor.