Methods for airflow control in reactor passive decay heat removal using a damper

A method of passively cooling a nuclear power plant, the method comprising:

• placing a moveable damper in a coolant flowpath about a nuclear power reactor, wherein the flowpath is configured to carry a coolant flow to remove heat from the reactor;
• attaching the damper to an attachment configured to hold the moveable damper in a closed position when powered so as to restrict coolant flow in the flowpath and allow the moveable damper to move to an open position when unpowered so as to allow full coolant flow in the flowpath, wherein the flowpath is a divided flow channel surrounding a perimeter of a containment structure surrounding a reactor vessel, wherein the divided flow channel includes a coolant downcomer opening at a coolant source inlet, and a coolant riser between the coolant downcomer and the containment structure, wherein the coolant downcomer and coolant riser are in fluid communication at a bottom of the divided flow channel;
• placing a temperature-dependent switch in the coolant flowpath;
• and
• connecting a power source to the temperature-dependent switch and the attachment such that the power source powers the attachment when the temperature-dependent switch is closed and the power source is unpowered when the temperature-dependent switch is opened.