This condition would result from a mechanical failure in the primary
loop pumps, piping, etc., or by accidentally stopping the pumps when the
reactor is at power, or by loss of power to the pumps. When a single
pump fails to operate for any reason, an alarm is sounded to warn the
operator. If all four pumps fail to operate for any reason, a signal is
sent to the reactor safety system to “scram” the reactor.