HYDRAULIC CONTROL ROD ACTUATOR
An investigation was made of the conceptual feasibility and production of a prototype model of a Hydraulic Control Rod Drive Mechanism that utilizes primary reactor water as the hydraulic fluid and is sealed within the reactor pressure vessel. It is capable of controlling 2300-pound rods such as might be used in large pressurized-water reactors. By utilizing hydraulic feedback in a closed loop contained within the power unit itself, mechanical and/or electrical external feedback linkages are eliminated. The initial design embodied a large control sleeve surrounding the power cylinder. Rotational positioning of this control sleeve by the command signal, would allow selective porting along the length of the power cylinder to alter the hydraulic force in the system. Since the hydraulic feedback continuously acts to maintain equalization of the load and hydraulic forces, the position of the power piston is thus controlled. This method of control, however, was found to be not feasible due to excessive binding of the control sleeve. A new control method was established which eliminated the objectionable characteristics of the initial design without changing the basic concept of balancing the load and hydraulic forces. This new design employs a servo mechanism which operates in the hydraulic feedback loop of the system. The servo is equipped with a small control sleeve which, when positioned by the commsmd signal, will alter the hydraulic force in the system. This change in hydraulic force causes power piston motion which, through feedback coupling, actuates the servo to re-establish equalization of the load and hydraulic forces; thus, control of piston position is achieved. Scram is initiated by a low level signal which causes release of the high pressure water below the power piston allowing control rod insertion by gravity. A built-in snubbing mechanism, which also uses primary water, decelerates the piston and rod in the last few inches of travel to insure a soft stop at rod bottom'' position. A single electrical harness connects the actuator to its control console. Rod position is continuously indicated on the control panel by a digital display of inches in 1/4 inch increments. (auth)
- Research Organization:
- American Bosch Arma Corp. American Bosch Div., Springfield, Mass.
- NSA Number:
- NSA-17-038436
- OSTI ID:
- 4657968
- Report Number(s):
- NYO-10027
- Country of Publication:
- United States
- Language:
- English
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