EMERGENCY TRANSFER TUBE CLOSURE FOR SEALING TRANSFER TUBE UNDER EMERGENCY CONDITIONS

Abstract: An emergency transfer tube closure for a fuel transfer tube of a nuclear containment comprises elongated, vertically-extending, U-shaped guides disposed on opposite sides of the transfer tube, with a closure plate supported between the guides and having rollers thereon riding within the guides permitting movement of the closure plate downwardly into sealing engagement with the transfer tube under emergency conditions.

Description: This invention relates to an emergency transfer tube closure for a nuclear reactor wherein, a closure plate is with guide rollers rotatably mounted on each side thereof and disposed in guides is adapted to ride downwardly into sealing engagement with the transfer tube. In nuclear reactor generating plants there is a large reactor well structure and a spent fuel storage pool structure adjacent thereto. The latter is typically filled with a fluid, such as water, to isolate the spent fuel from the surrounding environment and to serve as a protective outer structure for the spent nuclear fuel. The reactor well contains a fuel transfer tube through which fresh fuel is brought into the reactor well during refueling operations. Normally, the fuel transfer tube is maintained in its closed position by means of a plate valve therein that extends across the opening therein. During refueling operations, the plate valve is lifted up out of position, by any suitable means, to permit entry therein. In the event the reactor cavity seal fails during the refueling operation, and water from the spent fuel storage pool structure begins to flow through the fuel transfer tube into the reactor well, it is absolutely necessary to stop the flow of water into the reactor well as quickly as possible. The normal plate valve is hand operated and cannot be closed quickly in such emergency. The novel fuel transfer device claimed herein will quickly and effectively stop the flow of water from the spent fuel storage pool into the reactor well in such emergency conditions. Afterwards, the normal plate valve can be moved into closed position and the emergency transfer tube closure claimed herein can be removed into its storage position. Means for maintaining sealing means between adjacent structures in nuclear reactor plants are known. Garin in U.S. Patent No. 4,078,969, disclosed a flexible metal seal attached to a component of a nuclear reactor closure head capable of being drawn substantially tightly against another such component by an activating mechanism located on one of the components for sealing the annulus between the components under severe reactor conditions while allowing rotation of these components under normal reactor conditions. In U.S. Patent No. 4,355,000 Lumelleau discloses sealing means operable to provide a fluid-tight seal between a gate and the wall of a reactor well which comprises a beam structure having a generally U-shaped I-beam, a gate with support elements engageable with the transverse members of the beam structure to support the beam on the gate, and a plurality of inflatable sealing elements arranged along the entire length of the U-shaped beam which are inflated after the gate is closed to form the desired leak-tight seal. Starr et al., in U.S. Patent No. 4,375,104, disclose a device for sealing a gateway between interconnectable pools in a nuclear facility comprising a liquid impermeable, pliant sheet sealed to the frame of the sealing device and an inflatable sealing tube mounted in a channel about the periphery of the frame. Stenabaugh in U.S. Patent No. 4,436,692, discloses apparatus for plugging a nozzle in a boiling water reactor comprising a disc-shaped plug movable into position by means of cables. In U.S. Patent No. 4,470,946, Vassalotte et al. disclose a plugging device for pressure testing a steam pipeline in a boiling water reactor comprising an inflatable annular member and radially movable shoes for holding the plug in place. Vertically movable gate assembly closures are also known. Whipps in U.S.-A-4,028,896, discloses a sluice gate assembly comprising a frame, gate disc guides mounted on the frame, and a gate disc slidably supported by the gate disc guides for vertical movement of the gate. Dreyer et al., in US-A-4,474,205, disclose a conduit closure apparatus comprising a first frame and a second frame slidably fitting vertically within the channels of the first frame. Document US-A-4 235 256 discloses a conduit closure apparatus comprising vertically extending U-shaped guides defining tracks and rollers on which a closure plate could slide. It is the principal object of the present invention to provide a transfer tube closure for the fuel channel of a nuclear reactor wall which can be rapidly operated and, which is adapted to assume its closed position without requiring power for its operation. With this object in view, the present invention resides in an emergency closure arrangement for the transfer tube of a nuclear reactor well, or the like, said transfer tube having a circumferential flange extending outwardly laterally therefrom, and an emergency transfer tube closure adapted to engage said flange for closure of said tube, wherein elongated, vertically-extending U-shaped guides are disposed on each side of said transfer tube in spaced parallel relationship, with their open ends facing each other, a closure plate having a surface facing said circumferential flange greater in area than the area circumscribed by the outer circumference of said circumferential flange is disposed between said U-shaped guides, normally in an essentially vertical plane extending slightly in front of the plane of said circumferential flange, with two pairs of rollers, one pair of which is rotatably mounted on each side of said closure plate adjacent said U-shaped guides, riding on the inner portion of each of said flanges of each of said U-shaped guides, characterized in that each of said U-shaped guides is provided with a pair of spatially disposed openings on a flange thereof adjacent the wall of said nuclear fuel reactor well, each of said pairs of openings being disposed on each of said U-shaped guides a distance equal to the distance between the center lines of the corresponding pair of rollers riding within said U-shaped guides, each of said openings being sufficiently large to receive a corresponding roller of said pairs of rollers in said U-shaped guides, and that one roller in each pair of rollers is not in vertical alignment with the other roller in said pair of rollers so that each pair of rollers can enter only the pair of openings adapted to receive them, said openings being spaced on said flanges of said U-shaped guides so that when said pairs of rollers are disposed therein, the face of said closure plate will be in sealing engagement with said circumferential flange of said transfer tube and that further the inner surface of said laterally extending flange of each of said U-shaped guides remote from said wall of said nuclear fuel reactor is provided with a wedge adjacent the base thereof for moving said closure plate toward said circumferential flange when said pair of rollers are positioned in said pair of openings. The invention will become more readily apparent from the following description of a preferred embodiment thereof shown, by way of example only, in the accompanying drawings, wherein: Figure 1 is a perspective view, partially cut away, showing a portion of a nuclear reactor facility embodying the novel emergency transfer tube closure herein; Figure 2 is an elevational view, partially cut away, of the novel emergency fuel transfer tube closure claimed herein prior to emergency use; Figure 3 is an elevational view of the novel emergency fuel transfer tube closure in its emergency, operative state sealing the transfer tube; Figure 4 is a section taken along the line 4-4 of Figure 2 illustrating mounting means of the first pair of rollers on the closure plate; Figure 5 is a section taken along the line 5-5 of Figure 2 illustrating mounting means of the second pair of rollers on the closure plate; Figure 6 is a section taken along the line 6-6 of Figure 2 showing that the closure plate is normally disposed in a vertical plane just slightly in front of the plane of the circumferential flange of the closure tube; and Figure 7 is a section taken along the lines 7-7 of Figure 3 showing the closure plate in sealing engagement with the circumferential flange of the closure tube. Referring to Figure 1, there is shown the emergency fuel transfer tube closure 2, securely mounted by means not shown, on a wall 4 of a nuclear reactor well, or similar facility. Also shown in Figure 1, is a transfer tube closure 6 that is also in place, also securely mounted by means not shown, to the wall 4 of the nuclear reactor well, provided with means to move a closure plate 8 downwardly into fuel transfer tube 10 to close the same or to move the closure plate 8 upwardly out of transfer tube 10 to open the same. The means employed to operate such closure 6 are not critical and can include, for example, an elongated shaft 12, means, such as a wheel 14, attached thereto for rotating shaft 12, and well-known, suitable means not shown, within housing 16, that will translate rotation of shaft 12 into the desired vertical movement of closure plate 8. The transfer tube closure 6 is normally used to open and close fuel transfer tube 10 and the novel emergency transfer tube closure claimed herein is used only under emergency conditions when closure of fuel transfer tube 10 is desired much more quickly than would be obtainable, or possible, using normal transfer tube closure 6. As shown in Figures 1 and 2, the emergency fuel transfer tube closure 2 includes a pair of elongated, vertically-extending, U-shaped guides 18 and 20 securely mounted, by means not shown, on the wall 4 of the nuclear reactor well. One U-shaped guide is disposed laterally on each side of the fuel transfer tube 10 having a circumferential flange 22 extending outwardly laterally therefrom at the outer edge thereof. Each of U-shaped guides 18 and 20 comprises a base 24 and laterally-extending flanges 26 and 28. The U-shaped guides 18 and 20 have their open ends facing each other. A rectangular closure plate 30, having a surface on the side facing said circumferential flange 22 greater in area that the area circumscribed by the outer circumference of circumferential flange 22 on said fuel transfer tube 10, is vertically disposed between said U-shaped guides 18 and 20. As shown in Figures 6, closure plate 30 is mounted, before emergency use, vertically above said fuel transfer tube 10 so that its inner face is in a vertical plane just slightly in front of the plane of the outer face of circumferential flange 22. The distance between the two planes is defined by the distance "t" in Figure 6. Two pairs of rollers 32 and 34, and 36 and 38, are provided, one pair of which is rotatably mounted on each side of the closure plate 30 adjacent U-shaped guides 18 and 20, respectively, that ride on the inner portions of each of flanges 26 and 28 of the respective U-shaped guides 18 and 20. In a preferred embodiment, in order to prevent binding of closure plate 30 within U-shaped guides 18 and 20 and to facilitate downward movement of closure plate 30 within U-shaped guides 18 and 20, two additional pairs of rollers 40 and 42, and 44 and 46, are also provided, one pair of which is also rotatably mounted on each side of the closure plate 30, adjacent U-shaped guides 18 and 20, respectively, so as to extend laterally outwardly from the said closure plate (30) and ride on the inner portions of the base 24 of the respective U-shaped guides 18 and 20. Each of U-shaped guides 18 and 20 is provided with a pair of spatially disposed, vertically elongated openings 48 and 50, and 52 and 54, respectively, on each flange 26. Openings 48, 50, 52 54, spatially surround fuel transfer tube 10 and each has a length greater than the diameter of rollers 32, 34, 36 and 38, respectively. The distance between the center lines of openings 48 and 50 is equal to the distance between the center lines of rollers 32 and 34, and similarly, the distance between the center lines of openings 52 and 54 is equal to the distance between the center lines of rollers 36 and 38, so that when closure plate 30 moves downwardly into sealing engagement with circumferential flange 22 on fuel transfer tube 10, rollers 32 and 34 will move into openings 48 and 50, respectively, and rollers 36 and 38 will move into openings 52 and 54, respectively. Thus, each of said openings is spatially disposed to correspond to the spatial disposition of each of said first pairs of rollers. The openings are made large enough to enable the closure plate 30 to move toward circumferential flange 22 in its operative, emergency mode the distance "t", defined above. Thus, closure plate 30 can move downwardly, in operation, safely past circumferential flange 22, but just as it is facing circumferential flange 22 and the rollers move into their respective openings in flanges 26, the closure plate 30 will move toward circumferential flange 22 the distance "t", bringing it into sealing engagement with circumferential flange 22, as shown in Figure 7. As shown in Figure 2, upper rollers 32 and 36 preferably are not in vertical alignment with lower rollers 34 and 38, respectively. Similarly, upper openings 48 and 52 are not in vertical alignment with lower openings 50 and 54, respectively. This is done so that rollers 34 and 38 will not engage slots 48 and 52 as the closure plate 30 moves downward, approaching the closed position. When rollers 32, 34, 36 and 38 are engaged within openings 48, 50, 52 and 54, respectively, the closure plate will be maintained in its closed or sealed position. Closure plate 30 is normally maintained in its ready state, prior to emergency operation, as shown in Figure 1, in a vertical position vertically above fuel transfer line 10 in any suitable manner, for example, by cable 56 secured to closure plate 30 at one end, as shown, and secured to fixed means at the other end, not shown. The rollers on closure plate 30 can be mounted thereon in any suitable manner. As shown in Figure 4, roller 32, and similarly rollers 34, 36 and 38, can be rotatably mounted on a shaft 58, firmly positioned in closure plate 30, so that it extends laterally outwardly from the vertical edge of closure plate 30. In Figure 5, a preferred mounting for roller 42, and similarly rollers 40, 44 and 46, is shown. Thus, a vertical edge of closure plate 30 is provided with a recess 60 in which a shaft 62 is firmly positioned and upon which roller 42 is rotatably mounted. The roller 42 extends outwardly from the vertical edge of closure plate 30 so that it rides on the inner surface of the base 24 of the U-shaped guide. To provide a more effective seal between closure plate 30 and circumferential flange 22, in use, the inner surface 64 of closure plate 30 can be provided with at least one circumferential dovetail slot 66, as shown in Figures 4 and 5, containing a resilient material 68 such as rubber. The dovetail slot 66 is positioned on closure plate 30 so that it faces the outer surface or face of circumferential flange 22 when the closure plate 30 and the circumferential flange 22 are in sealing engagement. If desired, corresponding dovetail slots carrying a resilient material, could be mounted on the outer surface of circumferential flange 22, instead of closure plate 30. In order to bring the closure plate 30 to a controlled stop in use, a shock absorber 70 (Figure 1) is securely mounted, by means not shown, between U-shaped guides 18 and 20 below openings 50 and 54, extending across the path of closure plate 30, to be in abutting relation with the lower edge 72 of closure plate 30 when each of rollers 32, 34, 36 and 38 is in engagement with openings 48, 50, 52 and 54, respectively. Shock absorber 70 can be made of two horizontal metal plates 74 and 76 between which metallic tubular members 78 are laterally disposed. Wedges 80 (Figures 6 and 7) tapering inwardly and upwardly toward flange 28 can be securely mounted, by means not shown, on the underside of each other flange 28 of each of U-shaped guides 18 and 20, just above shock absorber 70, to firmly force closure plate 30 against circumferential flange 22. Fluid pressure on the exposed sealing area will force the closure plate against the transfer tube flange, thus compressing the seals which contact the face of the transfer tube flange when the four rollers are aligned with their respective slots or openings. The operation of the novel emergency fuel transfer tube closure e device is as follows. As pointed out hereinabove, the arrangement in Figure 2 is the arrangement wherein the closure plate 30 is positioned vertically above the fuel transfer tube 10 ready for use in an emergency situation. When an emergency occurs, that is, when transfer tube closure 6 is open and fuel transfer tube 10 must be closed quickly, cable 56 is quickly released from its secured position, by means not shown, and closure plate 30 then moves downwardly within the path defined by U-shaped guides 18 and 20 until rollers 32, 34, 36 and 38 come into engagement with openings 48, 50, 52 and 54. As shown in Figure 7, when this occurs, the inner surface 64 of closure plate 30 moves inwardly toward the outer surface of circumferential flange 22 of fuel transfer tube 10 by an amount defined by the distance "t", defined hereinabove, creating an effective seal therebetween. Thus, no movement of liquid through fuel transfer tube 10 is possible. When the emergency is over, closure plate 30 can be lifted vertically by cable 56 out of engagement with circumferential flange 22 and maintained in such position for further possible emergency use.

Claims: An emergency closure arrangement for the transfer tube of a nuclear reactor well, or the like, said transfer tube (10) having a circumferential flange (22) extending outwardly laterally therefrom, and an emergency transfer tube closure (2) adapted to engage said flange for closure of said tube (10), wherein elongated, vertically-extending U-shaped guides (18, 20) are disposed on each side of said transfer tube in spaced parallel relationship, with their open ends facing each other, a closure plate (30) having a surface facing said circumferential flange (22) greater in area than the area circumscribed by the outer circumference of said circumferential flange is disposed between said U-shaped guides (18, 20), normally in an essentially vertical plane extending slightly in front of the plane of said circumferential flange (22), with two pairs of rollers (32, 34, 36, 38), one pair of which is rotatably mounted on each side of said closure plate (30) adjacent said U-shaped guides (18, 20), riding on the inner portion of each of said flanges (26, 28) of each of said U-shaped guides, characterized in that each of said U-shaped guides (18, 20) is provided with a pair of spatially disposed openings (48, 50, 52, 54) on a flange (26) thereof adjacent the wall of said nuclear fuel reactor well, each of said pairs of openings (45, 50, 52, 54) being disposed on each of said U-shaped guides a distance equal to the distance between the center lines of the corresponding pair of rollers (32, 34, 36, 38) riding within said U-shaped guides, each of said openings (45, 50, 52, 54) being sufficiently large to receive a corresponding roller of said pairs of rollers (32, 34, 36, 38) in said U-shaped guides, and that one roller (32, 36) in each pair of rollers is not in vertical alignment with the other roller (34, 38) in said pair of rollers so that each pair of rollers can enter only the pair of openings adapted to receive them, said openings being spaced on said flanges of said U-shaped guides so that when said pairs of rollers are disposed therein, the face of said closure plate (30) will be in sealing engagement with said circumferential flange (22) of said transfer tube (10) and that further the inner surface of said laterally extending flange (28) of each of said U-shaped guides (18, 20) remote from said wall of said nuclear fuel reactor is provided with a wedge (80) adjacent the base thereof for moving said closure plate (30) toward said circumferential flange (22) when said pair of rollers are positioned in said pair of openings. An arrangement according to claim 1, characterized in that said closure plate (30) is provided with two additional pairs of rollers (40, 42, 44, 46), one pair of which is rotatably mounted on each side thereof adjacent said U-shaped guides (18, 20) that ride on the inner portion of said base (24) of each of said U-shaped guides. An arrangement according to claim 1 or 2, characterized in that said closure plate (30) is provided on said face (64) thereof facing said circumferential flange with circumferential slots (66) in which a resilient material (68) is mounted, said circumferential slots (66) being positioned on said closure plate (30) so that they face the outer surface of said circumferential flange (22) when said closure plate (30) is in sealing engagement with said circumferential flange (22). An arrangement according to any of claims 1 to 3, characterized in that a shock absorber (70) is mounted between said U-shaped guides (18, 20) extending across the path of said closure plate (30) and in abutting relationship with the lower end (72) of said closure plate (30) when said rollers are positioned in said openings.

Inventors: HARDIN, ROY TYLER, JR., MARSHALL, JAMES RICHARD
Applicants: WESTINGHOUSE ELECTRIC CORPORATION
Application year: 1986
Main classification: G21C13
IPC codes: G21C19, F16K3, G21C13