From Colonial Marines Wiki
Good news, everyone! The SM engine is mostly set up already and ready to provide power the USS Sulaco. There are just a few additional steps you should undertake before flipping that Emitter on. But first, put on a handy pair of Optical Meson Scanners and put on a Radiation Suit and Radiation Hood. Remember, the SM (white) will ruin your eyes if you look at it without Mesons and you will receive radiation damage without the suit simply from being too close to an active supermatter core.
The SM Engine Area
1. Ensure cooling loop is functional
Check on the computer (blue) and refresh until it shows that the SM chamber is 'Injecting' coolant at a rate of 700 L/s. The output pressure should then be toggled to 'Open'. Make sure that the input is maximized and open because otherwise the coolant loop will not function properly.
2. Prep the radiation collectors
The radiation collectors (magenta) are what powers the Sulaco once the SM is active. First go to the phoron tanks (in orange) and fill them to the maximum 1013 kPa capacity using the phoron canister; (orange) To do this first grab a phoron tank in hand then click the phoron canister, (orange) the phoron tank should then be inserted into the canister (you will know if it is inside because a black mark will appear on the side of the canister if it is) after that set the kPa to 1013, then open the release valve, when the tank is full close the release valve and eject the phoron tank. Open the blast doors to the collector and put one full phoron tank into each collector. Make sure click on all eight of the collectors to activate them.
3. Turn on the Engine Room SMES
Turn both the input and output of the SMES (yellow) to maximum and set the input to Auto.
4. Fire the emitter
Open the blast door to the SM chamber using the handy toggle. Fire the emitter (red) 10 times. Emitters fire four shots before a longer pause so count carefully; the audio cue helps here. Turn the emitter off and close the blast door.
5. Maintain an eye on the SM
Use the engine chamber console (blue) to check that the temperature and pressure remain stable. A good safe goal to shoot for is a core temperature of under 500K. After you have done these steps the temperature and pressure should stabilize, which then tells you that you are all safe to walk away, do remember to check up on the SM every once in a while though to see if the temperature/pressure is dropping or rising.
On a side note this SM Engine setup will last you 6 hours and more. - [Tested And Proved]