GB934612A - Improvements in or relating to heterogeneous liquid moderated nuclear reactors - Google Patents

Abstract

934,612. Nuclear reactors; handling radio-active materials. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. June 26, 1962 [July 10, 1961], No. 24851/61. Class 39 (4). A liquid moderated nuclear reactor comprises a container for liquid moderator and means for locating a plurality of frames in planes parallel to one another within the container, each of the frames being adapted to releasably retain nuclear fuel bodies. In Fig. 1 the reactor core is housed in a tank 1 containing liquid moderator, and nuclear fuel rods 2 are mounted in a series of frames 3 arranged in parallel planes within the tank. The frames 3 are provided at their upper comers with sockets 3a, which engage pins 4 mounted on the tank, and at their lower corners with projections 3b which engage with slots in the rack 5 to maintain the frames in parallel vertical planes. Each pin 4 is tubular, as shown in Fig. 2, and is supported by a bracket 7 which also supports a mounting for a latch 8 provided with a bolt portion 9 which can engage a laterally-extending plate 3c carried by the frame 3. Guide rods 6 for use during loading and unloading are provided with spigots 12 which are inserted in the pins 4, each spigot being provided with a portion 12c of square section which engages a square section aperture in the latch 8; a plate 10 provided with a square section aperture prevents the rod 6 from being withdrawn unless the latch is in the locked position. The top corner of each frame 3 is yoked at 14, the arms of the yoke being joined by a cross-pin 15 adapted to be engaged by a latch provided on a transport beam 13. Fig. 4 shows a part of the top of the tank fitted with a slidable lid 20 provided with three slots 21 (of which only one is shown), sealing between the lid and a fixed containment structure 22 being provided by an inflatable seal member 23. Each of the slots 21 is framed by an upwardly-projecting beading 24 retaining a further inflatable tubular seal 25. When there is a risk of contamination of the atmosphere round the core during loading or unloading, the frame containing fuel elements is enclosed in a collapsible cover 26 comprising rigid top and base plates and side walls 29 of concertina form made of synthetic plastic material. In use the cover encloses the loading beam 13 and the fuel frame 3 and the whole assembly is brought into position above the lid by a gantry crane. The detachable bottom plate 28a is removed and the bottom skirt 28b of the cover is attached in sealing engagement with the beading 24 and the seal 25 is inflated. The frame 3 is then lowered through the slot and the cover side walls 29 are allowed to collapse.