In a nuclear reactor(1)having a pressure vessel with a core barrel(9)having a bottom core support plate(11)disposed within the pressure vessel, with the core support plate being engaged about its periphery by a number of engagement means(17), of which each has a recess receiving a key(39)associated with said core barrel, the core support plate(11)has an aperture(31)extending therethrough above each recess of the engagement means(17)and the keys(39)are insertable into and mounted in the apertures(31), and have lower sections which extend into the recesses of said engagement means. |