Automated radio alarm is a radio station in the Commonwealth in Fallout 4. It can be picked up after extending the satellites at radio tower 3SM-U81. It is a monotonous, automated warning of a malfunctioning nuclear reactor.
To get to the sub-level, go into the mag locked cage. Take the fusion core out of the reactor and then turn around. Directly between the loading ramp and the push cart with two barrels on it there is a trap door that leads down into the sub-level. In the sub-level there is a lunchbox and a circuit breaker. The alarm stops once the circuit breaker is activated. The radio broadcast also stops. Many of the lights in the facility are also turned off. This can be disorienting because you will emerge from the sublevel into darkness and in the middle of several radioactive barrels.
Immediately to the left of the fusion core reactor is a caged storage location for radioactive drums. The gate can be opened, and a passage through the stacked drums followed. At the end of the access is a partially covered pit with radioactive waste, a steamer trunk containing ammunition, explosives and weapons, and a withered feral ghoul (possibly the fate of the inspector mentioned in supervisor terminal logs as disposed of).
Automated radio alarm broadcasts on frequency 87.300003 and with a transmitter range of 13,300 units.
The radio doesn't stop broadcasting when you deactivate the breaker.The issue occurs when you pass through the area prior to receiving the radio broadcast and prematurely remove the fusion core. [verified]