The scenario for this pseudo nuclear emergency was written much earlier, and most of the 700 people responding had no idea how it would play out.
It was all just a drill, but at the Tennessee Valley Authority building downtown officials were role playing as if the emergency was the real thing. On Wednesday, events began to unfold at 8:07 a.m. when a simulated earthquake rattled Watts Bar Nuclear Plant in Spring City.
One of two unit reactors shut down and more damage could come. One man, officials at the site reported, had been injured, trapped under equipment. "He's contaminated," someone announced.
In the test, those on site had 15 minutes to declare the emergency to the state, county and the Nuclear Regulatory Commission.
"All the players are playing," said Ray Golden, senior manager of nuclear communication at TVA.
Upstairs a group gathered in a key-locked room guarded by police. They looked at screens of maps and measurements covering a wall that helped them determine the next move. Radiation experts clustered to the left. Engineering experts clustered to the right.
Downstairs, in a joint information center, media contacts and public officials gathered to spread the word. They monitored Facebook, television and radio to see if the right information was getting out.
They didn't know if or when the emergency would escalate. Radioactive particles could seep into the water and escape the site as steam through the ventilation stack.
"At the fence line of the (nuclear plant) people will get more exposure than someone a mile away," Golden said.
TVA's nuclear headquarters in Chattanooga runs more than a dozen tests like this a year. The utility is evaluated every two years to ensure it meets federal standards. One of these evaluations is coming up in October, and an assessment will be open to the public a few days later, officials said.
During Wednesday's test, the Federal Emergency Management Agency, the Tennessee Emergency Management Agency, the Tennessee Department of Transportation, the American Red Cross and McMinn, Rhea, Meigs counties were involved.
As Wednesday's drill unfolded, the situation escalated through the four levels of seriousness -- unusual event, alert, site area emergency and, ultimately, general emergency -- the highest and most critical category.
In a simulation, everyone within 10 miles of the site, including those in Spring City, Evensville and Decatur, was asked to evacuate.
With police rushing traffic, the population of 30,000 residents could get out of the area in 7 to 8 hours, officials said. Evacuation is ordered when a leak occurs as a precaution because long-term exposure to radiation can cause cancer, according to the U.S. Environmental Protection Agency.
The injured chemistry technician was transported by a simulated helicopter. This time, Golden said, the worker wasn't required to travel to the hospital.
Other workers who stay on site, he said, are protected in a shielded room with ventilation. Scuba gear is on hand in case they need to breathe through an apparatus.
After the nuclear disaster in Fukashima, Japan, which was triggered by the devastating combination of an earthquake and a tsunami, nuclear plant operators have focused more on safety precautions, Golden said.
Since the event in March, TVA has purchased $500,000 worth of satellite communication equipment, emergency electric generators and on-site portable pumps to move water through nuclear reactors in the event electricity is lost.
"We won't let this opportunity go by," he said.
The drill wrapped at 2 p.m. At the end of the day, a person would have had to stand for 50 hours within two miles of the leak to get the radiation equivalent of a chest X-ray, Golden said. To decontaminate, those exposed would need to shower, get new clothes and be monitored.
"I think it went pretty well," he said.
But TVA officials did learn a few things. They might need to think harder about their approach to social media, and they forgot to mike reporters in the news conference.
"We always find little nuggets to improve," he said.