Patent Number: 054003741
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates an example of the bellows type arrangement 100 which characterizes the present invention. As shown, this arrangement includes an annular buoyant member 102 formed at the upper end of an extendible flexible corrugated tube portion 104 which defines the main body of the bellows. A sleeve 106 is formed at the lower end of the corrugated tube 104. This sleeve 106 is arranged to enable the bellows arrangement 100 to be installed at the upper end of a rigid tubular extension 108 which is provided at the top of, or which forms part of, a conventional crane hook box 110, in a manner which forms a water-tight seal. The combination of the hook box, tubular extension and bellows arrangement provides a water-tight enclosure about a hook block 112 and cables 114 commonly associated with the type of overhead traveling crane 116 (schematically illustrated in FIG. 3) which is used in a boiling water reactor. The hook box 110, which is of a size to receive hook 118, is detachably secured to the hook 118 by two parallel, transversely disposed pins 120. The hook box 110 is engageable with a load to be handled by the crane 116. For purposes of illustration, the hook box 110 is shown in association with a conventional strongback 121, which may be integrally formed with the hook box 110. The rigid tubular extension 108 is fixedly connected to the top of the hook box 110 in a manner which establishes a water-tight seal. The sleeve 106 of the bellows arrangement is of course connected to the tubular extension 108 in a manner which provides a water-tight seal. In FIGS. 2 to 4, the watertight enclosure 100 is shown in use within the reactor cavity of a boiling water reactor (BWR). In this instance the apparatus which is being removed from a pressure vessel P/V and moved to a separator pool 121 is, merely by way of example, a steam separator 122. As will be appreciated from these figures, it is necessary to lift the steam separator 122 up out of the pressure vessel P/V, carry it over the separator pool threshold 123 and then lower it into the separator pool 121 until it rests on the pool floor. It will be appreciated that this problem is complicated by the comparatively low maximum travel height of the overhead crane 116 and the desire to avoid wetting the crane hook 118, hook block 112 and cables 114 with contaminating radioactive water. With the provision of the tubular extension 108 and the bellows arrangement 100 in accordance with the present invention, as the hook 118 and hook block 112 are lowered down into the reactor cavity and reach a given depth below the water level, the buoyant member floats 102 on the surface of the water and produces sufficiently lift to induce the corrugated tube portion 104 of the bellows arrangement 100 to extend as the hook 118 and hook box 112 continue to sink below the surface of the water, and assume the condition illustrated in FIG. 2. As will be appreciated, with the bellows arrangement 100 extended in this manner, the radioactive water is prevented from contacting the hook 118, hook block 112 and portion of the cables 114 which are below water level, hence preventing contamination of these components. After the appropriate connection is established and the steam separator 122 is lifted out of the pressure vessel P/V and raised to a level wherein it can be carried over a separator pool threshold 123 (such as illustrated in FIG. 3), the corrugated tube portion 104 is compressed under the weight of the buoyant member 104 and assumes a non-extended condition such as illustrated in FIGS. 3 and 4. When the steam separator 122 is lowered into the separator pool 121 and comes to rest on the floor of the pool (see FIG. 4), the hook box 110 is still above the level of the water in the reactor cavity and the bellows arrangement 100 remains in its non-extended state. When it is time to return the steam separator 122 to the pressure vessel P/V, the device lifted up out of the separator pool 121, moved over the separator pool threshold 123 and lowered back down into its operative position in the reactor pressure vessel P/V. Again as the hook 118 and hook box 110 are lowered sufficiently below the level of the water, the bellows 100 arrangement elongates due to the floatation of the buoyant member on the water and any contaminating contact between the water and the hook 118 and associated pieces of apparatus is prevented. The present invention is particularly useful in situations wherein the bellows arrangement 100 is required to undergo a relative short amount extension. The bellows is preferably made of plastic or rubber and provided with reinforcing rings or a springy helical coil so as increase the resistance the force produced by the water pressure acting on the external surface of the corrugated tube portion 104. The bellows arrangement which characterizes the present invention is relatively simple, cheap, readily replaceable and expands and contracts automatically in response to immersion. Accordingly, the need for a remote controlled servo device is eliminated and the crane operations are simplified in that the expansion and contraction of the bellows is totally automatic and does not require any operator intervention. Although the invention has been described by reference to only a single embodiment, it is to be understood that various changes and modifications may be effected without departing from the scope of the invention which is intended to be limited only the appended claims.