Patent Number: 040100707
Section: claims

1. A pebble-bed reactor comprising a reactor container, fuel pebbles having a characteristic cross-sectional size and forming a reactor pebble bed in said container, and at least one absorber element comprising a rod having an outside diameter substantially the same as said characteristic cross-sectional size of said fuel pebbles, said rod having the shape of a hollow helix-like spiral forming a single thread terminating with a leading tip, said element being substantially vertically positioned so that by applying torque to said element said rod is screwed into said pebble bed like being screwed into a thread with the rod's said tip having a direction of penetration into said pebble bed which deviates from a vertical direction. 2. The reactor of claim 1 in which the rod's said shape forms an interior and convolutions forming spaces, said interior and said spaces having cross-sectional sizes larger than said characteristic cross-sectional size of said pebbles and forming passages for the pebbles.