Patent GB-935025-A (GB)
Title: Improvements in or relating to apparatus for releasably suspending a nuclear fuel element
Inventor: METCALFE GEORGE RALPH ANTHONY
IPC: G21C19/10
Filed: 1960-08-11
Abstract: 935,025. Reactors; servicing reactors. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Aug. 4, 1961 [Aug. 11, 1960], No. 27906/60. Class 39 (4). A fuel element for the reactor of a nuclearpowered ship is releasably suspended from a support disposed above the core by means of a body part carrying the fuel element and engageable with the support by latch members, the body part carrying the fuel element between shock absorbing springs. As shown in Figs. 1A, 1B, the fuel element 1 comprises one hundred fuel members 8 separated by plates 10 into four groups within a box-like housing 9. The lower end of the fuel element has a tubular extension 13 received in an aperture in a locating plate 57 beneath the reactor core 56, Fig. 6, the extension also serving as an inlet for the coolant. The coolant passes upwardly through a tubular extension 14 of the housing 9, a sampling duct 16 permitting coolant monitoring, a flange 15 on the extension 14 being slidably mounted within a tubular body part 2 by shock absorber springs 20, 21. The body part 2 has three equi-spaced latches 3 pivoted at 26 in slots 25 and controlled by a sleeve-like actuator 5 biased by a spring 6 towards a flange 19 on the interior of the body part 2, slots 27 in the upper end of the actuator 5 receiving projections 28 on the latches. The fuel element 1 is suspended within the core 56 by a support plate 4 having apertures 42, a stop 44 on the body part 2 engaging the upper surface of the plate. The fuel element is lowered into the core by a grab 39 having retractable pegs 40 engaging a groove 36 in the actuator 5, the weight of the element compressing the spring 6 so that face 33 of the actuator engages stepped portions 30 of the latches 3, whereby projections 38 on the latches are held in their inner position away from the walls of the aperture 42, Fig. 2. The grab is still lowered after the stop 44 has engaged the plate 4 so that the actuator 5 engages stepped portions 32 on the latches and the projections 38 are moved into a groove 43 in the aperture 42, Fig. 4. The pegs 40 are now retracted and the grab withdrawn. Thus should the ship capsize the engagement of the projections 38 in the groove 43 prevents dropping out of the fuel element. The reactor is enclosed in a pressure vessel 52 filled with an organic liquid moderator and coolant, " Santowax R," the vessel being lined with a thermal shield 71 and divided into upper and lower regions 53, 54 by an annular baffle plate 55. Further shielding is provided by spaced plates 58, 59 and a tubular baffle 60, the baffle 60 defining an annular space accommodating heat-exchangers 62 having superheater sections 63 and evaporator sections 64. The coolant is circulated by pumps 66 having inlets 67 and outlets 68, the coolant flowing up through the core 56 and baffle 60 and down over the exchangers 62 to enter inlets 67. From the outlets 68 the coolant has two paths, one path being through the plates 58 and apertures 72, the other path being through apertures 72<SP>1</SP>, the space between the outermost plate 58 and shield 71 and up through holes 74 in the plates 59.