Patent Number: 
Section: claims

1. A nuclear island comprising:a nuclear reactor including a nuclear reactor core comprising fissile material disposed in a reactor pressure vessel having a lower vessel head disposed below the nuclear reactor core;a lateral seismic restraint including:a vertically oriented pin attached to one of the bottom of the lower vessel head and a floor underneath the nuclear reactor, and a mating pin socket attached to the other of the bottom of the lower vessel head and the floor underneath the nuclear reactor, the pin being received within the pin socket; anda reactor core retention cooling system comprising one or more baffles disposed alongside the exterior surface of a lower portion of the reactor pressure vessel including at least the lower vessel head,wherein the one or more baffles define a lower inlet surrounding the lateral seismic restraint that is in fluid communication with both the exterior surface of the lower portion of the reactor pressure vessel and the floor underneath the nuclear reactor. 2. The nuclear island of claim 1 further comprising:a support base secured to the floor underneath the nuclear reactor, wherein the vertically oriented pin or mating pin socket is attached to the floor via the support base. 3. The nuclear island of claim 1 wherein the one or more baffles comprise:a cylindrical jacket surrounding the lower portion of the pressure vessel including the lower vessel head, the cylindrical jacket having a narrowed lower end defining a central plenum inlet containing the lateral seismic restraint. 4. The nuclear island of claim 3 wherein the reactor core retention cooling system further comprises:radial ducts configured to admit water into the central plenum inlet. 5. The nuclear island of claim 1 wherein the one or more baffles include thermally insulating material.