Maria is a pool type reactor with a power of 30 MW (thermal). Despite it being a pool reactor, it contains channels (aluminum tubes) individually connected to the primary coolant. The water pool provides cooling for elements (e.g., fuel elements) that are not otherwise cooled, and also acts as radiation shielding. Maria uses enriched uranium as fuel (80% enrichment in 235U till year 1999; 36% since). The fuel elements and channels are vertical but arranged conically. Water and beryllium blocks serve as the moderator (70% and 30% of the moderation, respectively). Elements of boron carbide sheathed in aluminum are utilized for control, compensation, and safety. The use of beryllium blocks results in a comparatively large fuel lattice pitch, and consequently large volume for payload targets. There is also a graphite reflector (aluminum sheathed). Maria supplies a neutron flux of 4x1014 n/cm2s (thermal neutrons) and 2x1014 n/cm2s (fast neutrons). There are six horizontal channels for controlled use of neutron beams. There is also a window of lead-containing glass through which the core can be viewed. The reactor is housed in a sealed containment.