Complex sentence: Thick biological shielding (consisting of thick steel water filled tanks and lead blocks) combined with the full undergrounding of the nuclear island, provides protection for operating personnel as well as resistance to aircraft crash, storm-produced missiles and other external threats.
Split into simpler sentences: Thick biological shielding, consisting of thick steel tanks filled with water and lead blocks, combined with the full undergrounding of the nuclear island, provides protection for operating personnel. It also provides resistance to aircraft crash, storm-produced missiles and other external threats.