IMPROVEMENTS IN DEVICES FOR PROVIDING SHIELDING FROM RADIOACTIVE RADIATION

1,201,258. Shielded enclosures. COMMISSARIAT A L'ENERGIE ATOMIQUE. 14 May, 1969 [17 May, 1968], No. 24597/69. Heading B4Q. An aperture 12 through a shielding wall 8 may be opened or closed by a sphere 1 of shielding material pivoted at 9 and having a passage 11 which may be aligned with the aperture. To provide adequate shielding thickness when the sphere is in the closed position, shown, the passage 11 is blocked by an axially movable mandrel 13 of shielding material driven through a rack and pinion gearing 15, 16 by a motor 17. The mandrel 13 is withdrawn from the passage 11 when it is required to rotate the sphere 1 to the open position. In another embodiment (Fig. 2, not shown) in which the sphere 1 opens or closes the entry to a shielded transport flask, the mandrel is in two halves which meet at the centre of the sphere and are withdrawn in opposite directions when it is required to rotate the sphere to the open position.