Emergency shut-off valve for nuclear reactors

Claim 2

In a nuclear reactor pressure vessel for containing coolant fluid under high pressure and having means defining a coolant fluid opening by which said coolant fluid flows between the interior of said vessel and an exteriorly located pipe circuit, the improvement comprising a normally-open emergency shutoff valve located interiorly of said vessel adjacent to said coolant fluid opening for closing the latter by excessive differential hydraulic force generated upon a rupture of said pipe circuit, said shutoff valve comprising fixed support means adjacent to said coolant fluid opening, a valve seat surrounding said coolant fluid opening, a valve disc having a valve closure face for engaging said valve seat to close said valve, and means mounting said disc on said fixed support means in a valve-open normal position axially aligned with and spaced from said valve seat, said mounting means comprising means movable in response to said differential hydraulic force to permit said disc to move in axial direction to a valve-closed position whereat its said closure face is against said valve seat.

Claim 3

In a nuclear reactor pressure vessel for containing coolant fluid under high pressure and having means defining a coolant fluid opening by which said coolant fluid flows between the interior of said vessel and an exteriorly located pipe circuit, the improvement comprising a normally-open emergency shutoff valve located interiorly of said vessel adjacent to said coolant fluid opening for closing the latter by excessive differential hydraulic force generated upon a rupture of said pipe circuit, said shutoff valve comprising fixed support means adjacent to said coolant fluid opening, a valve seat surrounding said coolant fluid opening, a valve disc having a valve closure face for engaging said valve seat to close said valve, and means mounting said disc on said fixed support means in a valve-open normal position axially aligned with and spaced from said valve seat, said mounting means comprising means movable in response to said differential hydraulic force to permit said disc to move in axial direction to a valve-closed position whereat its said closure face is against said valve seat.

Claim 4

In a nuclear reactor pressure vessel for containing coolant fluid under high pressure and having means defining a coolant fluid opening by which said coolant fluid flows between the interior of said vessel and an exteriorly located pipe circuit, the improvement comprising a normally-open emergency shutoff valve located interiorly of said vessel adjacent to said coolant fluid opening for closing the latter by excessive differential hydraulic force generated upon a rupture of said pipe circuit, said shutoff valve comprising fixed support means adjacent to said coolant fluid opening, a valve seat surrounding said coolant fluid opening, a valve disc having a valve closure face for engaging said valve seat to close said valve, and means mounting said disc on said fixed support means in a valve-open normal position axially aligned with and spaced from said valve seat, said mounting means comprising means movable in response to said differential hydraulic force to permit said disc to move in axial direction to a valve-closed position whereat its said closure face is against said valve seat.

Claim 5

The improvement according to claim 1 wherein at least the periphery of said valve disc is exposed to permit accumulation of coolant fluid behind said valve disc during and after its movement to its said valve-closed position.

Claim 6

The improvement according to claim 1 wherein said nuclear reactor pressure vessel contains a core barrel, and said fixed support means comprises said core barrel.

Claim 7

The improvement according to claim 1 wherein said valve disc mounting means comprises spring means attached between said fixed support means and said valve disc and biasing said valve disc torward its said valve-open position, the bias of said spring means being less than said excessive differential hydraulic force.

Claim 8

The improvement according to claim 4 wherein said spring means comprises a plurality of folded leaf springs disposed in annularly and equally spaced apart relation around said valve disc, each said leaf spring being folded in substantially overlapping relation providing a folded end and a pair of free ends, one of said free ends of each said leaf spring being attached to said fixed support means, and the other of said free ends of each said leaf spring being attached to said valve disc.

Claim 9

The improvement according to claim 5 wherein said free ends of each said leaf spring are angularly spaced apart a distance of substantially eighteen degrees (18*) with respect to each other, the rearward surface of said valve disc being recessed to receive the overlapping portion of each said leaf spring.

Claim 10

The improvement according to claim 4 wherein said valve disc mounting means further comprises tension bolt means retaining said valve disc in its said valve-open position, the bias of said spring means and the tensile strength of said tension bolt means together being less than said excessive differential hydraulic force.

Claim 11

In a nuclear reactor pressure vessel in which high pressure coolant fluid is circulated and which has means defining a coolant fluid inlet opening and a coolant fluid outlet opening to each of which exteriorly located coolant fluid piping is attached, the improvement comprising a normally open emergency shutoff valve adjacent to each of said coolant fluid inlet and outlet openings, each said emergency shutoff valve being situated inside of said pressure vessel and being closable by hydraulic force exerted thereon upon occurrence of a predetermined pressure differential between the fluid in said pressure vessel and the fluid in said piping attached to that opening with which the valve is associated, and each said valve comprising fixed valve support means adjacent to its said associated coolant fluid opening, a substantially concave spherical-sector shaped valve seat surrounding said associated coolant fluid opening, a valve disc having a substantially convex spherical-sector shaped valve closure face for engaging said valve seat and closing said valve, and means mounting said valve disc on said fixed support means in a valve-open position wherein its said valve closure face is spaced away from, and aligned with the axis of said valve seat and its associated opening, said valve disc being linearly moveable to a valve-closed position wherein its said valve closure face so engages said valve seat, the periphery of said valve disc being exposed to permit accumulation of coolant fluid behind said valve disc during and after its movement to its said valve-closed position, said valve disc mounting means comprising a plurality of folded leaf springs disposed in annularly and equally spaced apart relation around said valve disc, each said leaf spring being folded in substantially overlapping relation providing a folded end facing towards the center of said valve disc and a pair of free ends adjacent to the periphery of said valve disc, one of said free ends of each of said leaf spring being attached to said fixed support means, and the other of said free ends of each said leaf spring being attached to said valve disc.

Claim 12

In a nuclear reactor pressure vessel in which high pressure coolant fluid is circulated and which has means defining a coolant fluid inlet opening and a coolant fluid outlet opening to each of which exteriorly located coolant fluid piping is attached, the improvement comprising a normally open emergency shutoff valve adjacent to each of said coolant fluid inlet and outlet openings, each said emergency shutoff valve being situated inside of said pressure vessel and being closable by hydraulic force exerted thereon upon occurrence of a predetermined pressure differential between the fluid in said pressure vessel and the fluid in said piping attached to that opening with which the valve is associated, and each said valve comprising fixed valve support means adjacent to its said associated coolant fluid opening, a substantially concave spherical-sector shaped valve seat surrounding said associated coolant fluid opening, a valve disc having a substantially convex spherical-sector shaped valve closure face for engaging said valve seat and closing said valve, and means mounting said valve disc on said fixed support means in a valve-open position wherein its said valve closure face is spaced away from, and aligned with the axis of said valve seat and its associated opening, said valve disc being linearly moveable to a valve-closed position wherein its said valve closure face so engages said valve seat, the periphery of said valve disc being exposed to permit accumulation of coolant fluid behind said valve disc during and after its movement to its said valve-closed position, said valve disc mounting means comprising a plurality of folded leaf springs disposed in annularly and equally spaced apart relation around said valve disc, each said leaf spring being folded in substantially overlapping relation providing a folded end facing towards the center of said valve disc and a pair of free ends adjacent to the periphery of said valve disc, one of said free ends of each of said leaf spring being attached to said fixed support means, and the other of said free ends of each said leaf spring being attached to said valve disc.