1497910 Neutron shield assemblies COMMISSARIAT A L'ENERGIE ATOMIQUE 3 June 1975 [11 June 1974] 23956/75 Heading G6C The lateral neutron shield assembly of a fast reactor comprises a support structure which is generally annular in plan view and whose internal contour coincides with the external contour of the reactor core, the support structure being constituted by a plurality of layers of metal plates maintained in relative positional relation by means of clamping members, said structure being penetrated by vertical bores receiving the bottom end-connectors 22a, 22b of elements constituting the shield. The metal plates of each layer are arranged in end-to-end relation to form the annular structure, the plates of successive layers being relatively staggered; thus, the plate 18a 1 (Fig. 4) overlies half of the plate 18b 1 and half of the plate 18b2 of the next layer. The clamping members are preferably tie rods. In one embodiment (Fig. 2, not shown), the layers are held in contiguous relationship. In another embodiment (Fig. 3), the layers 30 are held in spaced relation by means of spacing washers 32 through which the tie rods 34 pass. Coolant can enter each shield element not only via a main orifice 42SP1/SP in the lowermost plate 30SP1/SP, but also through lateral orifices 46 connecting their interiors with the spaces 38 between the plates 30. In one arrangement, the shield element end-connector 22a is received in a bore 40 formed through all the plates 30 except the lowermost plate 30SP1/SP. In another arrangement, the shield element end connector 22b has a shouldered portion 44 which rests on the uppermost plate 30, the bore 40 in the support structure being formed through all of the plates 30, 30SP1/SP. Stellited surfaces are formed where the end connectors and plates come into mutual contact.
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