GB1032396A - Improvements in or relating to liquid moderated nuclear reactors - Google Patents

Abstract

1,032,396. Reactors. SOC ANGLO-BELGE VULCAIN S.A. Nov. 13, 1963 [Nov. 19, 1962], No. 43616/62. Heading G6C. A liquid moderated nuclear reactor has a core formed of elongate fuel rod assemblies between which are spaces which accommodate hollow slab-shaped control members. The moderator, which also acts as coolant, is preferably pressurized water, and the hollow control members are open at both ends so as to enclose a volume of moderator when inserted in the core. The reactor described is suitable for marine use, and comprises a core of fuel assemblies 2a, each formed of a number of parallel fuel rods, supported on a bottom plate 3 suspended by a lower tubular member 5 which is attached to an upper tubular member 8 attached to the wall 1 of the pressure vessel. Water enters through a port 13 and passes downwards on both sides of the lower tubular member 5, and upwards through the core, via passages 19, 20. The core is surrounded by a zircalloy lining 17 (see also Fig. 2) held in position at its base by engaging a correspondingly shaped hole in a plate 3a, and at its upper end by an identically shaped flange 18. The lining 17 is freely supported so as to move radially and axially. The fuel element assemblies are suspended from tubular extensions 26 by means of an extension rod 22 and an abutment plate 24. The plate 24 is resiliently urged downwards on to an abutment plate fixed to the extension tube 26. The core section (Fig. 2) includes fixed guide surfaces integral with the bottom core plate, namely, the lining 17 and lattice plates 27. The lattice plates are in the form of parallel shallow troughs so that two such members joined face to face define a series of narrow channels; these channels accommodate hollow control rod members 28. The spaces between the control member channels are cross subdivided by plates 27b to form a number of channels, each of which contains a fuel element assembly. In a first modification (Fig. 4, not shown), the fuel element assemblies are of right triangular cross-section and are placed in pairs to form squares of which the control member channel is a diagonal. A second modification (Fig. 5, not shown), is very similar to that shown in Fig. 2, except that each control member channel is of unitary construction.