GB1528012A - Nuclear reactor refuelling system - Google Patents

Abstract

1528012 Fuelling reactors UNITED KING- DOM ATOMIC ENERGY AUTHORITY 7 June 1976 [7 July 1975] 28532/75 Heading G6C A handling system for fuel element assemblies of a liquid metal cooled nuclear reactor comprises a transfer bucket and ramp means for guiding the bucket for lifting or lowering in a direction inclined to the vertical, a branch of the ramp means causing a change of attitude of the bucket between parallelism with the ramp means and a vertical attitude. As shown, the ramp means comprises two pairs of inclined parallel rails 10, 11 (only one rail of each pair being shown), the inner pair 11 having a branch in the lower end region which is inclined at a steeper angle than the parent rails, and the transfer bucket 2 has two longitudinally spaced pairs of trunnions 6, 7 of which the upper pair 6 are in engagement with the outer rails 10 whilst the lower pair 7 project less than the upper pair 6 so that they are capable of engaging only the inner rails 11. At the exchange position 1, a fuel element assembly can be manipulated by a charge/discharge machine (not shown) into and out of the transfer bucket 2 within a pool 4 of molten sodium, the upper end of which bucket 2 abuts a pad 8 on the vertical surface 3 of the reactor core vessel whilst its tapering lower end 5 fits within a socket 9. The interior of the socket 9 tapers in complementary manner to the lower end 5 of the bucket 2 and provides an opening 13 at its upper end which is wider than the bucket 2. The socket 9 is mounted on a shock absorber 12, which absorbs energy should a fuel element assembly be inadvertently dropped into the bucket 2, or should the bucket 2 be released inadvertently to run out of control down the rails 10, 11. The bucket 2 may be drawn along the rails 10, 11 by a chain drive (not shown) extending parallel with the rails 10, 11 and attached to the trunnions 6. Although not shown in the drawing, the upper region of a duct 14 housing the rails 10, 11 is surrounded by an annular coaxial duct whereby argon cooling gas can be passed through the inner duct 14 in heat exchange with the bucket 2 and returned through the outer duct to gas circulating means situated outside the reactor vault.