Nuclear reactor support and seismic restraint with in-vessel core retention cooling features

1. A nuclear island comprising:

a nuclear reactor including a nuclear reactor core comprising fissile material disposed in a reactor pressure vessel;

a vertically oriented pin attached to the bottom of a lower vessel head of the reactor pressure vessel;

a pin socket disposed on a floor underneath the nuclear reactor and receiving the vertically oriented pin so that lateral motion of the lower vessel head is restrained;

a support base including the pin socket and one or more peripheral surfaces, the support base being disposed on the floor underneath the nuclear reactor;

one or more abutment elements secured to the floor underneath the nuclear reactor, wherein one or more of the peripheral surfaces of the support base engage the one or more abutment elements secured to the floor underneath the nuclear reactor to laterally restrain the support base; and

thermal insulation jacketing the lower portion of the reactor pressure vessel including the lower vessel head.

2. The nuclear island of claim 1 wherein the vertically oriented pin defines a vertical axis that intersects the center of gravity of the nuclear reactor.

3. The nuclear island of claim 2 wherein the vertically oriented pin comprises a circular cylindrical pin.

4. The nuclear island of claim 1 wherein the abutment elements comprise walls of a reactor cavity that contains a lower portion of the nuclear reactor including at least the nuclear reactor core and the lower vessel head.

5. The nuclear island of claim 1 wherein the support base includes radial beams extending radially outward from the pin socket and the one or more peripheral surfaces of the support base that engage the one or more abutment elements secured to the floor underneath the nuclear reactor comprise outboard ends of the radial beams.

6. The nuclear island of claim 1 wherein the support base includes a socket plate on which the pin socket is attached, and the one or more peripheral surfaces of the support base that engage the one or more abutment elements secured to the floor underneath the nuclear reactor comprises an outer perimeter of the socket plate.

7. The nuclear island of claim 6 wherein the one or more abutment elements secured to the floor underneath the nuclear reactor comprises a retaining ring plate secured to the floor underneath the nuclear reactor and having an inside perimeter that comports with the outer perimeter of the socket plate.

8. The nuclear island of claim 1 wherein the thermal insulation jacketing the lower portion of the reactor pressure vessel including the lower vessel head comprises:

a cylindrical jacket comprising thermal insulation that surrounds the lower portion of the pressure vessel including the lower vessel head, wherein the cylindrical jacket narrows toward the vertically oriented pin attached to the bottom of the lower vessel head of the reactor pressure vessel.

9. The nuclear island of claim 8 wherein a cylindrical plenum is defined between the outside surface of the reactor pressure vessel and the inside surface of the cylindrical jacket, the cylindrical plenum having a lower inlet defined by the narrowing of the cylindrical jacket toward the vertically oriented pin attached to the bottom of the lower vessel head of the reactor pressure vessel.

10. The nuclear island of claim 9 further comprising ducts configured to admit water into the lower inlet of the cylindrical plenum.

11. The nuclear island of claim 1 wherein the thermal insulation comprises a thermally reflective metal multi-foil.