Solve the Gecko powerplant problem

The nuclear reactor in Gecko is the source of much friction between that community and Vault City. The reactor is damaged, and is putting out a considerable spill of radioactive coolant into the groundwater in the region. People in Vault City are becoming ill.

Both communities want the pollution stopped, but for different reasons. Lynette, First Citizen of Vault City, wants the pollution stopped because it's sickening her citizens. Harold, in Gecko, wants the pollution stopped because he knows, if it continues, it's only a matter of time before Vault City launches a military strike and kills off the ghoul population of Gecko.

Genocide
You can blow up the reactor either by shutting off the coolant yourself, or conning one of the reactor's tenders to do it for you. The Coolant Report in Harold's desk is enough to get them to shut down the coolant system for you. The reactor melts down, and the problem is solved. The downside is now you are vilified in Gecko, and you've essentially destroyed the lives of dozens of peaceful ghouls, and now the First Citizen will not let you into the Vault. She belives that the destruction of the plant will cause mass contamination and has the guards throw you out.

Repair
This approach takes a little more effort, but earns you both gratitude and more experience points than frying the reactor. A conversation with Harold uncovers the truth: the reactor has a broken part. The Hydroelectric Magnetosphere Regulator failed, and that's why the plant is pumping out radioactive coolant. The part needs to be replaced, but there's only one source: Vault City.

You may think that, with a solution in hand, Lynette would be happy to hand over the part and put the whole matter behind her. You would be wrong. Lynette will do absolutely nothing to help Gecko, even if it means helping her city in the process. Bringing up the idea can very easily get you banned from Vault City for good.

Instead, talk to Senior Councilmember McClure, in the large conference room nearby. He'll see the wisdom in repairing the plant, and send word to Randall, the Chief Amenities Officer in, as expected, the Amenities Office, to have the part ready. Fetch the part from Randall and return to Gecko.

Once inside the reactor control room, you have two options. You can make the run through the reactor pit room yourself, taking some damage and gaining some radiation, or you can reprogram the maintenance robot, an aging and cantankerous Mr. Handy, to do the job. The problem with the robot is that its logic circuits have long since gone to that big computer in the sky. You need to map out its path, using machines as waypoints, before you can get it to install the replacement part. With the installation of a functioning Hydroelectric Magnetosphere Regulator, the plant runs clean again, and the radiation threat is over.

Repairing the plant eases the tension between Gecko and Vault City, and unlocks another quest: to Optimize the powerplant.

Outcome
Whichever way you dealt with the problem, Gecko's reactor is no longer a threat.

If you blew up the reactor, you get 2,500 experience points (with a 550-point bonus if you braved the reactor pit and closed the coolant valve yourself, or if you convinced Hank to do it for you). However, talking to ghouls in Gecko will cause them to attack you, and the entire community will despise you.

However, if you repaired the reactor, you earn a handsome experience point reward. Doing the repair yourself earns you 4,000 experience points, having Festus do the job earns you 4,250 points, and using the robot to do the repair earns you 4,500 experience points.