GB1209953A - Hydraulically operated control rod drive system for pressurised water and boiling water reactors - Google Patents

Abstract

1,209,953. Controlling reactors. MASCHINENFABKIK AUGSBURG - NURNBERG A.G. 30 Jan., 1968, No. 4762/68. Heading G6C. An hydraulic control rod drive system for a pressurized water or boiling water reactor normally derives its pressurized water from an auxiliary source but, alternatively, may utilize the pressurized water in the reactor. The system ensures that should a breakdown occur in the auxiliary source the reactor may still be controlled both for normal operation and scram operation of the control rod. As shown, a housing 2 attached to the reactor pressure vessel 1 encloses a cylinder having a smaller diameter section 6 and a larger diameter section 7, the cylinder receiving pistons 10, 12 interconnected by a rod 11 and controlling the movement of a reactor control rod 9. A valve 15 comprising a cylindrical shell 16 is biased by a spring 23 so that when there is no pressure acting on the lower end of the valve due to absence of pressurized liquid in pipe 4 or pipe 14 the valve has the position shown, Fig. 1, in which it is free from the seat 8 at the end of cylinder 7. Thus the valve 15 takes this position in the event of a breakdown in the auxiliary source of pressurized water connected to the pipes 4, 14 and in this position pressurized water from the reactor in the annular space 5 acts on the underside of the piston 12. To permit movement of the piston 12 to drive the control rod 9 into the reactor the water between the pistons 10, 12 is discharged by opening a valve 34<SP>1</SP> in pipe 34 or valve 35<SP>1</SP> in pipe 35, the smaller pipe 34 serving for normal rod insertion and the larger pipe 35 for scram operation. The rod 9 is returned by admitting pressurized water to the pipe 34 and opening a valve in a discharge pipe 33. For normal operation, pressurized water from the auxiliary source is supplied through pipe 14 for normal control rod insertion and through pipe 4 for scram operation. In these conditions, valve 15 is lifted against the seat 8 and a valve 19 biased by a spring 21 within the valve 15 is lifted from its seat 26, Fig. 2, to permit the pressurized water to act on the piston 12.