There is disclosed a containment system for a nuclear plant, the containment system comprising a pressure vessel defining a containment space for containing nuclear plant structures, a working floor extending from within the containment space to outside the pressure vessel, an access opening in the pressure vessel for providing access from the working floor outside the pressure vessel to the working floor in the containment space, and an access door provided within the pressure vessel. The access door is configured to slidably move downwardly with respect to the pressure vessel from a closed position in which it closes the access opening to seal the pressure vessel, and an open position in which it reveals the access opening and is received in a door space in the working floor. The access door comprises a first integral floor plug which is configured to plug the door space in the working floor when the access door is in the open position, to provide a substantially continuous working floor surface from outside the pressure vessel to within the containment space.

A pressure vessel includes a pressure vessel body provided with a flow channel through which a fluid is caused to flow, having a rectangular cross-sectional shape, and formed to extend in a direction of flow of the fluid, a body flange provided at at least one end side of the pressure vessel body in a longitudinal direction and having a circular cross-sectional shape, and a connecting member connecting the pressure vessel body and the body flange to each other, and the connecting member has a body-flange connected portion connected to the body flange, having a circular cross-sectional shape, and formed in a cylindrical shape, a pressure-vessel-body connected portion connected to the pressure vessel body, being larger in outer shape than the body-flange connected portion, and formed in a cylindrical shape, and a connecting portion connecting the body-flange connected portion and the pressure-vessel-body connected portion to each other and formed in a cylindrical shape with a shape changing to be gradually smaller from the pressure-vessel-body connected portion toward the body-flange connected portion.

A nuclear reactor comprises a nuclear reactor core disposed in a pressure vessel. An isolation valve protects a penetration through the pressure vessel. The isolation valve comprises: a mounting flange connecting with a mating flange of the pressure vessel; a valve seat formed into the mounting flange; and a valve member movable between an open position and a closed position sealing against the valve seat. The valve member is disposed inside the mounting flange or inside the mating flange of the pressure vessel. A biasing member operatively connects to the valve member to bias the valve member towards the open position. The bias keeps the valve member in the open position except when a differential fluid pressure across the isolation valve and directed outward from the pressure vessel exceeds a threshold pressure.

A nuclear reactor comprises a nuclear reactor core disposed in a pressure vessel. An isolation valve protects a penetration through the pressure vessel. The isolation valve comprises: a mounting flange connecting with a mating flange of the pressure vessel; a valve seat formed into the mounting flange; and a valve member movable between an open position and a closed position sealing against the valve seat. The valve member is disposed inside the mounting flange or inside the mating flange of the pressure vessel. A biasing member operatively connects to the valve member to bias the valve member towards the open position. The bias keeps the valve member in the open position except when a differential fluid pressure across the isolation valve and directed outward from the pressure vessel exceeds a threshold pressure.

A pressure vessel comprises a pressure vessel body having a rectangular cross-sectional shape and formed to extend in the direction of flow of fluids, and the pressure vessel body includes a first flow channel which is formed in the longitudinal direction of the pressure vessel body and through which a first fluid is caused to flow, a second flow channel which is formed in the longitudinal direction of the pressure vessel body and through which a second fluid is caused to flow, a first-fluid inlet-outlet port which is provided in one longitudinal end surface of the pressure vessel body and connects with the first flow channel and through which the first fluid is caused to flow in or out, a second-fluid inlet-outlet port which is provided in the other longitudinal end surface of the pressure vessel body and connects with the second flow channel and through which the second fluid is caused to flow in or out, an opening portion which is provided in the one longitudinal end surface of the pressure vessel body and connects with the second flow channel, and a closing member which closes the opening portion in a demountable manner.

An electrical penetration assembly for a nuclear reactor vessel, mountable in an aperture of a nuclear reactor vessel, includes a penetration body including first and second ends to be positioned, respectively, inside and outside the vessel; a sealed electrical connector providing a first seal for the electrical penetration assembly, the sealed connector insulating the penetration body at the first end; a feed-through carrier flange having a plurality of unitary electrical feed-throughs, each unitary feed-through allowing a single electrical conductor to pass therethrough, thereby ensuring continuity of the electrical connections, each unitary feed-through being individually insulated by an individual insulator providing a second seal, the unitary feed-throughs insulating the penetration body at the second end; and an anti-ejection device formed by the engagement between a narrowed portion provided at each unitary feed-through and a shoulder that is larger than the narrowed portion and provided on each of the electrical conductors.

Pressure vessels have full penetrations that can be opened and closed with no separate valve piping or external valve. A projected volume from the vessel wall may house valve structures and flow path, and these structures may move with an external actuator. The flow path may extend both along and into the projected volume. Vessel walls may remain a minimum thickness even at the penetration, and any type of gates may be used with any degree of duplication. Penetrations may be formed by installing valve gates directly into the channel in the wall. The wall may be built outward into the projected volume by forging or welding additional pieces integrally machining the channel through the same volume and wall. Additional passages for gates and actuators may be machined into the projections as well. Pressure vessels may not require flanges at join points or material seams for penetration flow paths.

A containment seal seals a cable or tube to an opening accessing a containment vessel. The containment seal includes a lower body that attaches over the opening into the containment vessel. The cable or tube is inserted through a hole that extends axially through an upper body of the containment seal. Compression fittings are attached to the top and bottom ends of the upper body sealing the cable inside of the upper body. The cable sealed inside of the upper body in inserted through the lower body and into the opening accessing the containment vessel and a lower portion of the upper body is seated into the opening formed in the lower body. A retaining device compresses the upper body down against the lower body forming a seal between the upper body and lower body.

A pressure vessel includes a pressure vessel body provided with a flow channel through which a fluid is caused to flow, having a rectangular cross-sectional shape, and formed to extend in a direction of flow of the fluid, a body flange provided at at least one end side of the pressure vessel body in a longitudinal direction and having a circular cross-sectional shape, and a connecting member connecting the pressure vessel body and the body flange to each other, and the connecting member has a body-flange connected portion connected to the body flange, having a circular cross-sectional shape, and formed in a cylindrical shape, a pressure-vessel-body connected portion connected to the pressure vessel body, being larger in outer shape than the body-flange connected portion, and formed in a cylindrical shape, and a connecting portion connecting the body-flange connected portion and the pressure-vessel-body connected portion to each other and formed in a cylindrical shape with a shape changing to be gradually smaller from the pressure-vessel-body connected portion toward the body-flange connected portion.

A pressure vessel comprises a pressure vessel body having a rectangular cross-sectional shape and formed to extend in the direction of flow of fluids, and the pressure vessel body includes a first flow channel which is formed in the longitudinal direction of the pressure vessel body and through which a first fluid is caused to flow, a second flow channel which is formed in the longitudinal direction of the pressure vessel body and through which a second fluid is caused to flow, a first-fluid inlet-outlet port which is provided in one longitudinal end surface of the pressure vessel body and connects with the first flow channel and through which the first fluid is caused to flow in or out, a second-fluid inlet-outlet port which is provided in the other longitudinal end surface of the pressure vessel body and connects with the second flow channel and through which the second fluid is caused to flow in or out, an opening portion which is provided in the one longitudinal end surface of the pressure vessel body and connects with the second flow channel, and a closing member which closes the opening portion in a demountable manner.