Biological Shield

The thick shielding that protects people from neutron and gamma radiation.

A biological shield — typically thick concrete and steel — surrounds the machine to attenuate neutrons and gammas to safe levels outside. Its design follows directly from the neutron source strength.

A thick concrete-and-steel biological shield attenuates neutrons and gammas to safe levels outside the machine, and its design follows directly from the neutron source strength — heavy for the breeder, far lighter for the low-neutron burner. It is conventional radiation-protection engineering scaled to the source.