The shaft sealing structure includes a seal ring that has abutment portions formed by dividing the seal ring along the axial direction and that is provided around a main shaft in a ring-like manner; a support member that is provided in the seal ring along the circumferential direction of the main shaft; and a thermoswitch that is connected to the support member between the abutment portions and that presses the support member toward the center of the main shaft when the temperature rises to a temperature higher than that during normal operation, in which the seal ring is fixed at a position separated from the main shaft during the normal operation and is moved by the support member toward the center of the main shaft when the temperature rises to a temperature higher than that during the normal operation.

Arrangements for promoting the restriction of fluid flow along a shaft via providing a deformable ring member in an annulus between the shaft and housing. In an initial general condition, the deformable ring member permits free fluid flow in a general direction along the shaft while in a second, constricted condition, the deformable ring closes or blocks a gap or clearance normally conducive to free fluid flow to thereby restrict fluid flow. An actuation medium, which can take any of a very wide variety of forms, preferably promotes constriction of the deformable ring member directly or indirectly.

Embodiments include an apparatus and techniques for operating an electromagnetic cartridge seal. Embodiments include operating a cartridge seal in one of a plurality of modes, and receiving a signal at a force applying mechanism of the cartridge seal, the force applying mechanism being coupled to a primary sealing component of the cartridge seal. Embodiments also include controlling the force applying mechanism based at least in part on the received signal.

A shaft bearing device for a pump includes an antifriction bearing, which can be connected to an axially displaceable pump shaft. A spring is arranged at the antifriction bearing in such a way, that a spring force can be transmitted to an outer ring of the antifriction bearing by the spring in a mounting condition of the shaft bearing device. A lifting element attached to the pump shaft and a corresponding counter element are separated from each other by the spring force in a starting state and/or in a shutdown state of the pump.

A shaft sealing structure for a rotation shaft, includes a sealing ring having ends formed by removal of its part. The ends abutting each other are continuous in the circumferential direction when the sealing ring is reduced in diameter to a radially inner side. The sealing ring is provided along the circumferential direction of the rotation shaft so as to be contactable with an outer peripheral surface of the rotation shaft. The structure also includes a pressing member configured to be movable between a pressing position and a retracted position; an elastic member configured to bias the pressing member toward the pressing position by elastic force; and a support member configured to support the pressing member at the retracted position against the elastic force, and to allow the pressing member to move to the pressing position at a predetermined temperature.

A thermal actuator for a rotating shaft shutdown seal that has a piston with a portion of its axial length enclosed within a chamber shell with a material that expands upon a rise in temperature. The portion of the actual length of the piston within the chamber has at least two different diameters with the larger diameter leading in the direction of travel of the piston. Upon a rise in temperature, expansion of the material surrounding the piston within the chamber creates a force on the piston in the desired direction of travel. Below a preselected temperature the piston is positively locked with a passive release when the preselected temperature is reached.

A method for carrying out emergent shaft sealing for a reactor coolant pump and a shaft sealing assembly is provided. The method comprises the steps that a passive stopping sealing member is arranged in a first sealing assembly and forms an opening under the normal operation condition, without affecting the first sealing assembly using a liquid film formed by fluid static pressure to prevent reactor coolant from leaking along a pump shaft; under the station blackout condition, after sensing high-temperature fluid flowing into the first sealing assembly, the passive stopping sealing member is closed and holds the pump shaft of the reactor coolant pump tightly, the gap between the first sealing assembly and the pump shaft of the reactor coolant pump is blocked, and therefore the reactor coolant is prevented from leaking along the pump shaft.

A thermal actuator for a rotating shaft shutdown seal that has a piston with a portion of its axial length enclosed within a chamber shell with a material that expands upon a rise in temperature. The portion of the actual length of the piston within the chamber has at least two different diameters with the larger diameter leading in the direction of travel of the piston. Upon a rise in temperature, expansion of the material surrounding the piston within the chamber creates a force on the piston in the desired direction of travel. Below a preselected temperature the piston is positively locked with a passive release when the preselected temperature is reached.

A thermal actuator for a rotating shaft shutdown seal that has a piston with a portion of its axial length enclosed within a chamber shell with a material that expands upon a rise in temperature. The portion of the actual length of the piston within the chamber has at least two different diameters with the larger diameter leading in the direction of travel of the piston. Upon a rise in temperature, expansion of the material surrounding the piston within the chamber creates a force on the piston in the desired direction of travel. Below a preselected temperature the piston is positively locked with a passive release when the preselected temperature is reached.