Means for supporting nuclear fuel components in moderator channel

摘要

978,220. Nuclear fuel elements. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Feb. 11,1963.[Feb. 15,1962], No. 5818/62. Heading G6C. A nuclear reactor coolant channel 2 contains tubular fuel elements 3 in superposition with castellated guide means allowing relative longitudinal displacement between the elements. A location means 5 (Figs. 1,1A) comprises a split ring with three radial splines 6, the upper surfaces of which support a fuel element 3, and axial projections 7a, 7b which extend in opposite directions and form the castellated guide means referred to above. With a number of fuel elements, as shown, each element is supported on its lower end face and permitted axial displacement, radial restraint being maintained at both ends by the axial projections 7a, 7b. The location means 5 are located in grooves 4 between adjacent moderator blocks 1. In another embodiment (Figs. 2, 2A, not shown), the location means is a split ring with three radial splines and the adjacent ends of the fuel tubes are castellated to form, in co-operation with the splines, the castellated guide means; while in yet another embodiment (Figs. 3, 3A, not shown), each fuel tube is supported intermediate its ends by means of a ring in three segments, each having a radial projection which extends inwardly through a hole in the fuel tube, the ends of adjacent fuel tubes being castellated and inter-engaging to provide the castellated guide means. In the embodiment shown in Fig. 4, the location means is a ring 15, the upper portion of which has four grooves 16 for receiving the projections 17 of the castellated end of the upper fuel tube. The lower portion has an internal shoulder 15d and a skirt 15e which together present an annylar groove to the lower fuel tube and form a means of attachment therewith through an intermediate ring 18 formed by an inner sleeve and an outer split bush which is an interference fit in the skirt 15e. The clearance X between the lower end face of the upper fuel tube and the upper face of the shoulder 15d allows for longitudinal growth of the fuel tube whilst radial displacement is restrained at each end. Locating pins 15c hold the ring 15 in position. In a similar embodiment (Figs. 5, 5A and 5B, not shown), the lower free ends of the fuel tubes are allowed radial displacement.