Game Play

Reactor Fuel

Active Fuel Rod

Shut Down Fuel Rod

Reactor Cores are made up of one or more fuel rods. As long as these fuel rods are covered with coolant, they maintain a steady temperature. If an Absorber or a Poison make contact with the fuel rod, the temperature and neutron production of the fuel rod is reduced. When the temperature and neutron production are low enough, the rod shuts down. Shutting down all of the fuel rods in a reactor core renders that reactor safe. If any part of a fuel rod is not covered with coolant, the temperature and neutron production of the fuel rod increases. In the absence of any coolant in the reactor vessel, the fuel rod temperature rises so quickly that a steam explosion will occur.


The Absorber is reflected by all surfaces inside a reactor vessel. When it makes contact with a fuel rod, it absorbs some of that rod's heat and reduces its neutron production. If that rod is already sufficiently cooled, this will cause the rod to shut down.  When the Absorber reflects off of the inside of the reactor vessel itself, it cracks the vessel resulting in reactor coolant leaking out of the vessel. If enough coolant leaks out, the fuel rods may no longer be covered and they will begin to heat up. To prevent this damage to the reactor vessel, maneuver the Reflector to place it between the Absorber and the reactor vessel.



The Reflector is maneuvered around the internal surfaces of the reactor vessel in order to prevent damage from the Absorber. Moving is easiest when you hold your device with the screen parallel to the ground facing the sky. Gently roll your device left/right and away/toward yourself in order to move the Reflector. Think about moving a marble around the inside of a bowl of water while trying not to spill the water. Keep in mind that you are moving the Reflector's center of gravity, this will help you when transitioning the Reflector from on surface of the reactor vessel to another.

Equipment Rack

There are 18 pieces of Equipment which can be used to help render a reactor safe. This Equipment is displayed to the left and right of the reactor vessel during game play. Swiping up or down over the Equipment causes the displayed items to scroll, revealing those pieces of equipment which are not currently visible on screen. Tapping on a piece of equipment selects it and readies it for immediate deployment, accomplished by tapping it again.

Large Reflector Unavailable

The various pieces of Equipment available to you can generally hold three different states.  The first is that a piece of Equipment might just be Unavailable. This is the case before it has been unlocked, if you no longer have any remaining, or (for a few pieces of Equipment) if no additional instances of that particular piece can be activated on the current attempt to render a reactor safe.  This state is indicated by a dark background.

Large Reflector

The second state a piece of Equipment can hold is Available. This means that piece of Equipment can be deployed during your current attempt to render a reactor safe. This state is indicated by the light grey background.

Large Reflector Selected

The final state a piece of Equipment can hold is Selected.  This state is achieved when you tap on an Available piece of Equipment.  Once Selected, the background changes to green, indicating that a second tap will cause that piece of Equipment to be deployed immediately.

Full Reactor Vessel

Reactor vessels normally operate completely filled with coolant. When the reactor vessel is damaged, coolant begins to leak out of the reactor vessel, forced through even small cracks due to the high temperature and pressure inside the reactor vessel. Damage may exist prior to your attempt to render the reactor safe, more commonly though, this damage is caused when the Absorber makes contact with the reactor vessel. Additionally, over-filling a reactor vessel causes it to "go solid" which over pressurizes and damages the reactor vessel.

Partially Full Reactor Vessel

Once coolant begins to leak from the reactor vessel, the coolant level in the vessel slowly drops. If the coolant level gets low enough, the fuel can be uncovered and begin to overheat.

Vessel Low Level Warning

If the coolant level drops below 30% of the full capacity of the reactor vessel, amber warning lights are lit, indicating a very dangerous lack of coolant condition. At this point the core is very likely uncovered and rapidly overheating.

Vessel Low Level Alarm


If the coolant level drops below 20% of the full capacity of the reactor vessel, the amber warning lights are extinguished and a flashing red alarm light is lit.

If the coolant level drops below 10% of the full capacity of the reactor vessel, the red alarm light is lit solid. At this point, the core is uncovered, and the reactor is in extreme danger of experiencing a steam explosion.

If the reactor vessel is ever completely empty of coolant, the uncovered core enters an uncontrolled chain reaction that results in a steam explosion.

Back to The Story Equipment