The present invention relates to a nuclear reactor (1), in particular a pool -type nuclear reactor cooled with liquid metal (for example, a heavy metal such as lead or lead-bismuth eutectic) or with sodium or molten salts, having a core (4) formed by a bundle of fuel elements (12) and immersed in a primary fluid (F) circulating between the core and at least one heat exchanger (10); the fuel elements (12) extend along respective parallel longitudinal axes (A) and have respective bottom active parts (13) immersed in the primary fluid to constitute the core, and respective service parts (14) that extend at the top from the active parts and emerge from the primary fluid; the fuel elements (12) are mechanically supported via respective top end heads (32) anchored to supporting structures (120) and can be operated via handling machines.