2. Reactor types

Although the range of research reactors is very broad, there are essentially two main types:

• heavy water reactors, which extract large flows of thermal neutrons from the reactor in the form of beams, mainly used for fundamental research;

• ordinary water reactors, more suitable for materials testing, with two subgroups:

  • open-core pool reactors, cooled and moderated with ordinary water, generally versatile and very easy to access and use,

  • Pressurized water reactors (PWRs), which can operate at higher power levels than pool reactors, but whose experimental use is somewhat less straightforward due to the presence of the core vessel.