For safety reasons, access through the heavy gauge secure door was operated from the outside, in the control room. As Sid, Sir and QTE-005 entered the cooling tunnel, the door sealed shut behind them. Immediately they could feel the rising temperature as the reactor struggled to vent away the excess heat.
They found themselves standing on a narrow gangway that curved along with the wall of the building. Below them were the coolant pipes, massive in diameter, that ringed the entire core. Walking along the ledge would enable them to reach a bridge across the pipes which would lead them to the containment vessel which housed the fuel elements and the cooling rods which had to be reinserted into them to bring down the temperature of the reaction. The vessel was already emitting an alarming glow of radiation Rot, it was questionable whether anyone could even handle it in order to insert the rods.
[ +- ] Cooling Tunnel Map
You entered through the door near 1, marked in yellow. Walking right along the narrow curved strip, and then turning left gets you to the bridge which leads to the vessel, also marked in yellow.
Something for visualisation!

That the situation was rapidly getting more and more dire was not in doubt. But something had slipped their notice, something uncharacteristic, which now posed the greatest risk to both of them ...
OOC:
I will need a Scan roll from one of you to figure out what's the danger, and a Datamine roll from the other, to tap into your knowledge related to Mechatron.