McNamara also wanted to use nuclear land mines. Cobalt rods are used to irradiated food by passing the food through a heavily shielded tunnel past them. Bacteria are thousands of times more resistant to radiation than humans. Those rods put out so many rads that a few short minutes in that tunnel are enough to sterilize the food down to an analytical level. Even with radiation falling off at the fourth power of distance a exposed rod would easily kill a human in seconds at 50 meters any closer and it’s instant incapacitating injury like a neutron weapon but it never shuts off for it’s half life time. Pretty much the nastiest stuff man ever came up with concentrated into a killing rod used for bacteria in its “peaceful” purpose. Of course to use such a weapon is against not only the Geneva conventions but also the prior laws of war. Again if you are building an evil lair and want to make sure no one can get close enough to your doors or air vents have these kinds of death rods exposed and cooking the surrounding areas retract them to come in and out into lead lined casks underground...easy peasy.
If that retracting mechanism breaks, the people inside are never going to come out again.