Patent Number: 055925200
Section: description

BEST MODE FOR CARRYING OUT THE INVENTION Referring now to the drawings, particularly to FIG. 1, there is illustrated a control rod constructed in accordance with the prior art and generally designated 10. The control rod includes a control rod body 12 which is generally cruciform in cross section to define laterally projecting blades 14 disposed generally at right angles relative to one another. The blades contain neutron absorber rods for power distribution shaping and reactivity control in the nuclear reactor. The control rod body 12 also includes a velocity limiter 16, rollers 18 which facilitate removal and insertion of the control rod in the reactor vessel, and a window 20 for receiving a latch handle 22 for releasably attaching the control rod to a control rod drive. As will be appreciated, the control rod drive lies below the control rod and serves to raise and lower the control rod within the core of the nuclear reactor. The control rod drive terminates at its upper end in a coupling spud 24 which is releasably coupled in a conventional manner by a socket 26 and a lock plug 28 to latch handle 22 by way of a shaft 30. That is, the opposite ends of the shaft 30 carry the lock plug 28 and a connection to the latch handle 22, for example, a threaded nut and bolt arrangement. Thus, the control rod 10 may be detached from the control rod drive by raising the handle 22 which in turn raises the locking plug to release the coupling spud 24 from the socket 26, all as conventional. Referring to FIGS. 2 and 3, the prior art latch handle 22 is generally rectangular in shape and has a pair of laterally projecting flanges 32. To capture the handle 22 within the window 20, elongated strips 34 are provided along the opposite faces of the window 22 and welded to the body of the control rod after the latch handle 22 has been inserted within the peripheral confines of the window. In this manner, the latch handle 22 is locked in the window and is enabled for vertical sliding movement within the window whereby the shaft 30 coupled to the latch handle 22 by a nut and threaded end of shaft 30 can be raised and lowered to operate the latching mechanism between the control rod and control rod drive. The latch handle and window arrangement according to the present invention is illustrated in FIGS. 4-8. In FIG. 4, a latch handle 40 according to the present invention has a plurality of generally linearly extending sides. Particularly, latch handle 40 is generally rectangular in cross section with the corners removed. Handle 40 has a central opening 42 and the lower leg 44 of handle 40 mounts a laterally projecting hub 46 for receiving the threaded end of the shaft 30. In a preferred form of the present invention, the opposite sides 48 of handle 40 are provided with marginal grooves. As illustrated in FIG. 4, the base 50 of each marginal groove extends linearly along each side 48 and has an end portion 52 which is curved or set back from any extension of the linear base 50. The set back or curved portions 52 on opposite sides of the handle lie diagonally opposite one another. Referring to FIG. 6, the opening 54 in the control rod has upper and lower edges 56 and 58, respectively, as well as side edges 60. The side edges 60 are formed to provide side flanges or tongues 62 opposite one another. As will appreciated from a review of FIG. 6, the latch handle 40 is sized and configured in a first angular orientation to lie wholly within and spaced from the peripheral confines of the window 54. That is, as illustrated in FIG. 6, the opposite sides 48 of latch handle 40 lie in spaced opposition to the upper and lower edges 56 and 58, respectively, of window 54, while the upper and lower legs 55 and 57 of handle 40 lie in spaced opposition to opposite side edges 60 of window 54. Upon rotation of the latch handle 40 while within the peripheral confines of window 54 into a second angular orientation as illustrated in FIG. 7, the slots 50 in the sides 48 of the latch handle 40 receive the flanges 62 of the sides of the window 54. Consequently, upon rotation of the latch handle a full 90.degree. between the angular orientations illustrated upon comparison of FIGS. 6 and 7, the flanges 62 are engaged in the slots 50 of the latch handle 40 thereby capturing the latch handle within the window. In the second angular orientation illustrated in FIG. 7, it will be appreciated that the latch handle is free for vertical sliding movement within the confines of the window 54. Once the latch handle has been oriented as illustrated in FIG. 7, the shaft 30 may be inserted through the opening in hub 46 and a nut 66 applied about the threaded end of the shaft to secure the latch handle and shaft to one another. To facilitate the rotation of the latch handle between the two angular orientations illustrated in FIGS. 6 and 7, respectively, the bases 52 of the slots 50 are arcuate adjacent diagonally opposite end portions of the sides of the latch handle. This facilitates rotation of the latch handle so that the latch handle does not bind up along the margins of the window upon rotation from the first orientation (FIG. 6) to the second orientation (FIG. 7). It will also be appreciated from the foregoing that while slots are preferably provided in the sides of the latch handle and flanges along the opposite sides of the window, the slots and the flanges can be reversed with the slots lying along the opposite sides of the window and the flanges lying along opposite sides of the latch handle. The flanges in the latter configuration have curved end portions similarly as the bases 52 of the slots to facilitate rotation of the latch handle between its angular orientations illustrated in FIGS. 6 and 7, respectively. Thus, it will be appreciated that the latch handle can be disposed within the window without welding strips to the control rod as in the prior art after the latch handle has been disposed in the window. This, of course, facilitates the construction and reduces the labor involved in applying the latch handle to the control rod. No additional elements need to be attached to the window or the latch handle to provide for capture of the latch handle within the window while still providing for vertical linear sliding movement of the latch handle along the window. Note also that the latch handle can be removed without any deleterious effects on the major components of the control rod. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.