The Andromeda Strain Part II: ILMO - my son

Dr. Mark Hall undertook the task of unarming the rigged satellite there in the secluded part of the lab. He is trapped in a section that, due to an oversight, has no substation. He must navigate Wildfire's obstacle course of automatic defenses to reach a working substation on an upper level. The perilous venture becomes notable when he is climbing a shaft ladder where a laser beam slices into his left hand. With that disability, he pushes onward even to the nuclear device getting ready to launch itself he hears nearby. He knows that he is close and barely disarms the bomb before all the air is evacuated from the deepest level of the Wildfire complex, which contains the remainder of the team and their assistants. Andromeda is suspected to have eventually mutated into a benign form and migrated to the upper atmosphere, where the oxygen content is lower, better suiting its growth. All the while with the events at Wildfire, a sad epilogue reveals that a crewed spacecraft named, Andros V, was incinerated during atmospheric re-entry. Recovery of the lifeless vessel and after their precautionary investigation, concluded that Andromeda had eaten its tungsten/plastic laminate heat shield and caused it to burn up. At the end of the movie when the lab triggers its failsafe nuclear explosion, Why does the lab start falling apart? (It makes sense that they would use a nuke to kill any common disease outbreak, but upon discovering andromeda eats radiation, why wouldn't they disable that function?) Any ways, they are in lockdown and have to climb to the next level to shut off the failsafe. They use the cooling tower for the nuclear power plant in the lowest level. As they are climbing the various things they are climbing on break because they aren't made to be climbed, but why is the rest of the cooling tower breaking? Things are falling from the ceiling. In fact the "odd man" who is the only one that can shut down the failsafe is hit in the head with the falling debris, which kills him. It makes absolutely no sense why a secure lab would start disintegrating when there is a 15 minute window to terminate the explosion. To halt the detonation, Hall must insert a special key he carries into an emergency substation, one of which should be accessible from any location in Wildfire. Unfortunately, he is trapped in a section that, due to an oversight, has no substation. He must navigate Wildfire's obstacle course of automatic defenses to reach a working substation on an upper level. He barely disarms the bomb before all the air is evacuated from the deepest level of the Wildfire complex, which contains the remainder of the team and their assistants. Andromeda is suspected to have eventually mutated into a benign form and migrated to the upper atmosphere, where the oxygen content is lower, better suiting its growth.