The summary on Wikipedia says: &quot;The SCRAM was started when the EPS-5 button (also known as the AZ-5 button) of the reactor emergency protection system was pressed: this engaged the drive mechanism on all control rods to fully insert them, including the manual control rods that had been incautiously withdrawn earlier.&quot;<p>I don&#x27;t know if that&#x27;s true or not, but it seems like it ought to be true from a fail-safe perspective.