The present invention relates to a passive shutdown sealing device (20) for a reactor coolant pump unit comprising: a split sealing ring (23) having an inactivated position in which a leakage flow is permitted and an activated position in which said ring stops said leakage flow; at least one piston (22) designed to position said split sealing ring (23) in its activated position; locking/unlocking means (25) designed to lock said at least one piston (22) in its inactivated position when the temperature of said locking/unlocking means is below a temperature threshold and to release said at least one piston (22) when the temperature of said locking/unlocking means is above said temperature threshold; elastic means (24) designed to move said at least one piston (22) when said piston is released, so as to position said sealing ring (23) in its activated position.

The present invention relates to a passive shutdown sealing device (20) for a reactor coolant pump unit comprising: a split sealing ring (23) having an inactivated position in which a leakage flow is permitted and an activated position in which said ring stops said leakage flow; at least one piston (22) designed to position said split sealing ring (23) in its activated position; locking/unlocking means (25) designed to lock said at least one piston (22) in its inactivated position when the temperature of said locking/unlocking means is below a temperature threshold and to release said at least one piston (22) when the temperature of said locking/unlocking means is above said temperature threshold; elastic means (24) designed to move said at least one piston (22) when said piston is released, so as to position said sealing ring (23) in its activated position.

A canned rotodynamic flow machine (1) configured for operating with a working fluid such as molten salt of a molten salt nuclear reactor. The stator windings are formed by one or more electrically conductive solid bars (12).

One or more embodiments of the present invention relate to a pump/heat exchanger assembly of a nuclear reactor, in particular a liquid metal cooled nuclear reactor, the pump being characterized in that the shaft for driving the impeller is inserted in an shell inside the heat exchanger and has a smaller cross section at the bottom part of the tube bundle of the heat exchanger and a cross section that gradually increases up to a widest cross section at the top part of the tube bundle of the heat exchanger. The resulting axial profile of the impeller's shaft is, at the same time, designed to uniformly distribute the flow of the primary fluid inside the tube bundle of the heat exchanger and to provide high mechanical inertia to the pump.

One or more embodiments of the present invention relate to a pump/heat exchanger assembly of a nuclear reactor, in particular a liquid metal cooled nuclear reactor, the pump being characterized in that the shaft for driving the impeller is inserted in an shell inside the heat exchanger and has a smaller cross section at the bottom part of the tube bundle of the heat exchanger and a cross section that gradually increases up to a widest cross section at the top part of the tube bundle of the heat exchanger. The resulting axial profile of the impeller's shaft is, at the same time, designed to uniformly distribute the flow of the primary fluid inside the tube bundle of the heat exchanger and to provide high mechanical inertia to the pump.

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.

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.

The present invention relates to a rotary machine (10), comprising a casing (32) delimiting an oil compartment (31), a shaft (33), a bearing (22, 23, 24), an oil sealing device (35) located between the rotary portion (360) and the upper portion (320) of the casing (32), characterised in that the oil sealing device (35) comprises at least one groove (52) for drawing in external air in the direction (S) of rotation of the shaft (33), the groove (52) being located in the rotary portion (360) and/or in the upper portion (320) of the housing (32), the rotary portion (360) not being in contact with the upper portion (320), the groove (52) for drawing in external air being configured to draw air from the upstream end (521) to the downstream end (522) towards the compartment (31) when the shaft (33) rotates in the direction (S).

The present invention relates to a rotary machine (10), comprising a casing (32) delimiting an oil compartment (31), a shaft (33), a bearing (22, 23, 24), an oil sealing device (35) located between the rotary portion (360) and the upper portion (320) of the casing (32), characterised in that the oil sealing device (35) comprises at least one groove (52) for drawing in external air in the direction (S) of rotation of the shaft (33), the groove (52) being located in the rotary portion (360) and/or in the upper portion (320) of the housing (32), the rotary portion (360) not being in contact with the upper portion (320), the groove (52) for drawing in external air being configured to draw air from the upstream end (521) to the downstream end (522) towards the compartment (31) when the shaft (33) rotates in the direction (S).

A motor-driven centrifugal pump for circulating a coolant in a primary circuit of a nuclear reactor comprises a sealed motor unit, a hydraulic part and a shaft which is immersed in the coolant, turned by the sealed motor unit and pumping the coolant by means of an impeller of the hydraulic part secured to the shaft; the motor unit comprising a dry stator and an immersed rotor mounted securely on the shaft. The motor-driven pump also comprises an immersed flywheel mounted securely on the shaft between the rotor of the motor unit and the impeller of the hydraulic part, allowing a minimum slowing-down time after the electrical power supply is cut; the flywheel comprising a vaned wheel generating a circulation of the coolant to cool the motor unit.