Dispositif pour commander le déplacement d'une barre de pilotage dans un réacteur nucléaire

1,003,020. Controlling reactors. COMMISSARIAT A L'ENERGIE ATOMIQUE. June 20, 1962 [June 27, 1961], No. 23791/62. Heading G6C. [Also in Division F2] A nuclear reactor control rod operating device comprises, in combination, a control differential gear having an output element which produces the displacements of the control rod, a first input element adapted to be rotated in both directions, preferably at different speeds, by a power unit, and a second input element adapted to be rotated in the direction that moves the control rod towards its shut-down position by an actuating device, preferably of the spring type. Referring to Fig. 3, the output element consists of a first ring gear 42 producing the displacement of a control rod through a rack 44 with which it meshes, the control rod being supported from an operating bar 45 carrying the rack 44; the first input element consists of a shaft 48 carrying a planet wheel carrier 49b, a wheel 49 of which meshes with the ring gear 42; and the second input element consists of a ring gear 57 meshing with a wheel 49a of the planet wheel carrier 49b and being fixed on a sleeve 58 carrying a pinion 59 rotatable so as to move the control rod to its shut-down position by an actuating device 60 (Fig. 4). The power unit 50 (Fig. 3) comprises two electric motors 66, 67 (one of which is reversible) co-operating with differential gears 70 and 77 so as to rotate an intermediate shaft 77a to drive the input shaft 48 of the control differential gear 41 and hence the control rod, the latter downwardly at a medium speed (e.g. 1 mm./sec.) and upwardly at a slow speed (e.g. 0.1 mm/sec). In case of failure of the motors 66, 67, the shaft 77a may be rotated manually by means of a crank 87 and spring-loaded clutch 89. The position of the control rod is indicated by two selsyn transmitters 95a, 96a of fine and coarse adjustment, respectively, driven by two pairs of pinions 87a, 88a transmitting the rotation of the ring gear 42 to a toothed wheel 89a connected to the transmitters by gear transmissions 90a, 92a. The device 60 which produces the shutdown movement of the control rod comprises springs 61 (only one shown in Fig. 4) compressed between a fixed top plate 102 and a sliding bottom plate 103 which carries on one side a rack 62 and on the other side a rod 104 surrounded by the springs 61. The rack 62 actuates pinion 59 through toothed wheels 63, 64 and 65. The rod 104 carries a head 105 which, in the withdrawn position of the control