GB2098642A - Radiation shield for a shelter - Google Patents

Abstract

A closure and radiation shield arrangement for an underground shelter includes a horizontally moveable radiation shield 15, 16 which is distanced above the habitable space 1 of the shelter and below a blast-proof, dust-proof outer cover 10. The shield may comprise a box 11 closed by bolted panels 14, containing a filling 15 eg. of coke with a concrete screed 16 and movable by sliding on castors 18. <IMAGE>

Description

SPECIFICATION Closure arrangement for the entrance to a habitable space The present invention relates to a closure arrangement for the entrance to a habitable space, and more particularly to a radiation shield arrangement for the entrance to a shelter and to an underground shelter having such an arrangement. The shelter can serve as a blast-proof shelter or a biological shelter, but it will also be a nuclear shelter. Various nuclear shelters are known, but reference can be made to the shelter described in British Patent Application 80 15277 for details of a suitable shelter.

Although it is conceivable that the arrangement of the invention could be applied to for instance a suitably constructed above-ground shelter or to a shelter having a horizontal entrance, the shelters in question are more particularly underground shelters having a generally vertical entrance shaft leading to a habitable space. The closure for the entrance has given considerable problems. The closure must provide blast protection (against the increase in atmospheric pressure), and thus must be sufficiently stout.

The closure must also provide a shield against radioactive emmision, and such a shield must be sufficiently thick and inherently heavy. The thickness of the shield means that the shield will require a relatively large amount of space, and it is desirable that this should not reduce the available size of the habitable space of the shelter. The weight of the shield makes it very difficult to manipulate, particularly if there is any debris or rubble, or if there have been severe ground shocks or distortion of the ground around the shelter; for instance, such distortion can jam the shield in the opening due to contact between the shield and the sides of the opening or could jam the shield by for instance by putting hinges out of alignment. It should also be noted that if there is a downwardly or upwardly hinging shield, considerable mechanical assistance would be required.

The invention provides radiation shield arrangements as set forth in Claims 1 and 7, and underground shelters as set forth in Claims 8 and 9. The remaining Claims set forth preferred features of the Invention.

The invention can solve the problems noted above in a simple and cheap manner. The radiation shield arrangement could be sold as a unit for use with any sort of shelter, whether a plastics shelter as in the Patent Application referred to above, or a conventional reinforced concrete or steel shelter.The horizontally-movable shield does not require very great mechanical assistance for its movement (though some mechanical assistance is preferably provided), and if (as is preferred) the shield is associated with an outer cover which is blast-proof (and preferably also dust-proof), there is no necessity to arrange that the shield should form a seal when it is closed, so that clear gaps can be left (at least on two non-opposite sides) for any distortion that may occur- in practice gaps can be left on all sides, though the shield may run up against a buffer on one side, which will tend to close that side.

The shield is preferably spaced below ground level (or entrance level) but above the habitable space. In this way, the shield can stop roughly vertical radiation passing down the entrance shaft, but is well protected from blast. At the same time, it does not infringe on the habitable space within the shelter and also allows for proper continuity of the structure of the habitable space - according to the proposal in the Patent Application referred to above, there is a concrete shell on top (at least) of the habitable space, and if the radiation shield is sufficiently far above the habitable space, this concrete shell can cover the whole of the top except the relatively small entrance shaft aperture.

It is impossible to provide for all circumstances, and should there be very severe ground shock, or ground distortion, or penetration of debris, there is a remote possibility that the shield could jam close.

Forthis reason, provision can be made for enabling the shield to be taken apart from the inside, by having the inner face of the shield openable and the major part of the thickness of the filling in the form of removable pieces.

Preferably, the removable pieces are immediately adjacent the openable face as this gives more confidence to those removing the filling, but it is desirable to have an impervious slab (normally of concrete) within the shield, and this can be on the top part of the shield. Suitable tools can be provided in the shelterto enable the concrete to be broken up.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevation (partly in section) of a shelter in accordance with the invention; Figure 2 is a vertical section along the line Il-Il in Figure 1; Figure 3 is a vertical section along the line Ill-Ill in Figures 4 and 5, through the closure arrangement of the shelter, on a larger scale; Figure 4 is a vertical section along the line IV-IV in Figures3 and 5; Figure 5 is a plan view (with the outer cover and associated parts removed) of the closure arrangement of Figures 3 and 4; and Figures 6 is an isometric view, in section (generally along the lineVI-VI in Figure 5) of the sliding shield and rails.

The habitable space of the shelter is formed by a generally cylindrical shell of glass-reinforced plastics 1 with a concrete surround 2. The shell 1 contains a light bulkhead 3 dividing the left-hand part of the habitable space (which can contain for instance storage or toilet facilities) from the main, right-hand part.

There is a escape tube 4 which can be filled with particulate material such as coke; the escape tube 4 is closed at the top in a suitable manner and is closed at the bottom by a hatch 5.

The drawings originally filed were informal and the print here reproduced is taken from a later filed formal copy. The shelter has a vertical, glass reinforced-plastics entrance shaft 6 whose lower part is integral with the shell 1 and which is also integral with the casing 7 of a radiation shield arrangement. As can be seen, the casing 7 is spaced about half way between ground level and the top ofthe habitable space (shell 1). The casing 7 is closed by a steel plate 8 which is welded to the upper, steel part 9 of the entrance shaft; the entrance shaft is closed by a pivoted blast-proof and dust-proof outer cover 10 provided with a spring stay 10' and a spring-loaded, camming locking lever 10" (see Figure 3). The cover 8, shaft part 9 and outer cover 10 are formed of steel to provide heat and fire protection.

The radiation shield is in the form of a sheet metal box 11 which has an opening 12 in its inner or lower face (see Figure 5.) The box 11 is contained in an angle-iron frame 13 which also supports two sliding, flanged plates 14 which close the opening 12 and which can be bolted together as indicated in Figure 3. The box 11 contains a filling in the form of suitable pieces which can be removed through the opening 12 once the plates 14 have been slid back; the filling could be for instance in the form of bricks, but the illustrated filling is a filling of coke 15. To stop the filling shifting excessively, there is a top screed 16 of concrete, and the box 11 with its frame 13 and other attached parts, and the filling, can weigh about half a ton. The concrete screed 16 can be of any suitable thickness, though about 50 millimetres is suggested.

The frame 13 carries gussetted brackets 17 mounting grooved wheels or castors 18. Looking at Figure 4 or 6, the right-hand castors 18 run on the base flange of an angle-section rail 19 while the left-hand castors 18 run on an up-turned angle-section rail 20.

The arrangement is such that the top-plate 8 pre vents the shield jumping so far that the right-hand castors rise above the inner lip of the rail 19; although lateral clearances are provided, they are not such that the left-hand castors will not re position themselves on the rail 20 after a severe shock (these large tolerances have the added advan tage that manufacturing is cheaper). It can be seen from Figure 5 that the rails 19, 20 are positioned on either side of the entrance shaft 6.

As a safety measure, to take shock loads along one horizontal axis (parallel to the direction of movement) and the vertical axis, the shield may be held closed by bolts 21 carried in lugs 22 fixed to the frame 13 and engaging in fixed lugs 23 (see Figure 6). If desired, one or two further bolts could be provided for taking shock loads along the transverse horizontal axis. A hammer or mallet can be retained in the shelter for opening the bolts 21.

When the horizontally-movable radiation shield is closed, there can be gaps all round, though small buffers 24 are provided. To provide some mechani cal advantage when opening and closing, there is a block-and-tackle arrangement with blocks 25 con nected to the housing 7, blocks 26 fixed to the shield frame 13, eyes fixed on the side of the shaft 6, and an endless line 27 which hangs in a loop in the entrance shaft 6.

Claims (9)

1. A radiation shield arrangement for the entrance to a shelter, comprising a generally horizontally movable radiation shield for moving across and shielding an entrance to the shelter.

2. The arrangement of Claim 1, and being for a generally vertical entrance shaft to the shelter, the arrangement comprising two spaced tracks on which the shield runs, so that the tracks can be positioned on either side of the entrance shaft.

3. The arrangement of Claim 1 or 2, wherein, when the shield is in its closed position, there are gaps on at least two non-opposite sides thereof.

4. The arrangement of any one of the preceding Claims, wherein the shield runs on a generally horizontal guide rail, some vertical and lateral movement being permitted between the shield and the guide rail, but abutments being provided to ensure that the shield cannot move laterally to such an extent that it does not reposition itself on the guide rail after a severe ground shock.

5. The arrangement of any one of the preceding Claims, wherein the shield contains a filling, the inner face of the shield being openable and the major part of the thickness of the filling being in the form of pieces which are removable through the open inner face.

6. The arrangement of any one of the preceding Claims, when associated with a blast-proof, dustproof, outer cover.

7. A radiation shield arrangementforthe entr ante so a shelter, substantially as herein described with reference to, and as shown in, the accompanying drawings.

8. An underground shelter comprising a habitable space, a generally vertical entrance shaft leading to the space, and the arrangement of Claim 6 or 7 for closing and shielding the entrance shaft, the radiation shield being spaced below ground level but above the habitable space.

9. An underground shelter, substantially as herein described with reference to, and as shown in, the accompanying drawings.