natural uranium
enriched uranium
pure uranium
any type of uranium
boiling water
gas cooled
pressurised water
all of the above
plates
pallets
pins
any one of the above
does not absorb neutrons
absorbs neutrons
accelerates neutrons
eats up neutrons
slowing down fast neutrons so that Uranium fission continues by slow motion neutrons
accelerating fast neutrons
absorbing all neutrons
using moderator