It will be her, Azula, and Yulan taking on the creature. This will take place before Chocolat goes down to fix the reactor so she doesn't have the radiation suit yet, but she is at least aware of the radiation. What will probably happen is that they will instead probably break down the door and distract the creature out into the hall. Chocolat will tie some stripped electrical wire she has along the door frame to to trip up the creature as it charges out, only to use the batons she traded with Sandy as well as whatever martial experience/tools both Azula and Yulan have in order to try and kill it.

Chocolat wont go into the room itself though until after she finishes the reactor quest with Saya, she will then wear the suit she found to enter the room and explore whatever may be inside.

Here is the thread between Chocolat, Yulan, and Azula to take down the creature.