• The temperature inside the failing tank has increased to 90 degrees, which was 77 degrees a day earlier. The boiling point of the poisonous chemical is 101 degrees Celsius.
• The main hope of avoiding an explosion is to keep the tank sprayed with water to keep the temperature cool.
• It is possible that an explosion can be avoided if the chemical reaction inside the tank is slowed down.
The fight to keep a highly toxic chemical from exploding took a step backward on Saturday.
The temperature in a tank filled with highly toxic chemicals in Orange County and at risk of explosion is rising, not falling, officials said.
By Saturday morning, the temperature in a pressurized tank at an aerospace firm in Garden Grove was 90 degrees, up from 77 degrees the day before. Temperatures are rising about a degree per hour, Orange County Fire Authority Division Chief Craig Covey said Saturday morning.
But as the chemical crisis approaches its third day, new details are providing more insight into how it might be resolved, though no one is sure when.
Experts say the question is whether authorities can somehow deal with the dangerous chemicals in a way that doesn’t end in the type of explosion or leak that causes environmental degradation.
Chemical leak at GKN Aerospace
There is an elementary school and residential neighborhood near the Garden Grove facility.
An attempt is being made to cool the damaged tank.
The risk of explosion increases with increase in temperature.
The boiling point of the chemical methyl methacrylate inside the tank is 101 degrees Celsius. The temperature gauge on the tank only detects temperatures up to 100 degrees. Officials have not disclosed at what specific temperature they would feel an eruption is imminent.
It’s not necessarily true that the tank will explode at 101 degrees, said Elias Picazo, an assistant professor of chemistry at USC.
“It depends on the integrity of the tank, and the structure of the tank, and the pressure capacity of the tank,” Picazo said. “But, yes, above 100, the pressure starts to increase dramatically, as the liquid phase becomes the gas phase, and the gas takes up any available space. It will take up more volume and become extremely pressurized.”
What does it mean that the temperature is rising?
The fact that the temperature in the tank is that high indicates that the liquid MMA molecules – monomers, essentially a group of single molecules – are reacting with each other to form polymers, forming a solid, according to Picasso. “The reaction is releasing heat. This will cause more reactions to occur, so it may collapse even faster.”
The bigger fear is causing what are known as “thermal runaway reactions.”
Covey has said that if the temperature in the tank exceeds a certain threshold, “we know the tank is going into thermal runaway, and we’re going to get everyone out of the area, make sure it’s safe, and let the tank do what it’s going to do.”
The fact that some of the liquid in the tank is reacting to become solid is probably what has happened to the glue going into the valve going into the tank. The primary solution to resolve this crisis would be to pump a neutralizing agent into the problem tank, extinguishing it and making it no longer explosive.
But that valve is closed, and so there is no way to get the neutralizing agent inside the tank. Nor is there any way to slowly empty the tank of MMA toxic chemicals.
Keeping the tank as cool as possible can be a practical way to prevent explosions.
How are the officials playing with the scenarios?
There remains a possibility that the tank would still burst or rupture causing a massive leak, which could spill the chemical into waterways and the sea. Officials have marked a massive evacuation zone — about 1 to 3 miles from the tank — affecting an estimated 40,000 residents covering parts of the cities of Garden Grove, Anaheim, Buena Park, Cypress, Stanton and Westminster.
It is clear that spraying water on the tank is helping.
Picazo said that even though the temperature inside the tank is rising, not pouring cold water on it at all can cause the internal temperature of the tank to rise more quickly.
So the main solution for now is for workers to do their best to keep the tank as cool as possible – and save time.
How to prevent an explosion by keeping the tank cool
Continuing to pour cold water over the tank can slow the liquid chemistry inside to cure — turning into a solid at a slower rate — and reduce the pressure build-up inside the tank, Covey said.
“Like a snowflake that freezes from the outside in — this stuff heals, it heats up and heals from the outside in. While it’s doing that process, it’s building up that pressure,” Covey said.
The tank has the ability to withstand some pressure. MMA is the empty space between the level of the surface of the chemical and the roof of the tank.
“We’re hoping that space can absorb the slower cure rate and not overpressurize and explode,” Covey said.
In other words, continuing to cool the tank allows the chemical reaction inside to slow down in a way that avoids an explosion.
Picasso agreed.
“One of the best-case scenarios is to let the (MMA) monomers react, but you do it in a controlled way,” he said.
“Maybe if it’s slow enough, you can create solids within the tank and cause the monomers, the reacting monomers, to stay separated from each other.
“If they don’t come into contact, they can’t react,” Picazo said. “You need contact for reactivity, and you can’t have contact if you have a solid state.
At that point, “you can then start thinking about other solutions for how to quench unused starting material.”
Can a worse situation be prevented?
Firefighters said they hoped they could stop the blaze.
“We’re optimistic,” Covey said. “We’re bringing in people from all over the country, talking to people from all over, trying to bring in additional options.
“Letting this thing fail and blow up is unacceptable to us.”
Why did workers mistakenly think the temperature inside the tank was getting cooler?
Officials on Friday thought the spraying of water was actually cooling the problematic tank — and not just slowing the speed at which temperatures were rising.
On Friday evening, Picazo said the drone thermometer indicated the tank was at 61 degrees, and the goal was to get the tank down to 50 degrees, which would be its “happy place.”
But as it turns out, the drone thermometers were only measuring the temperature outside the problem tank, not inside it.
Officials discovered the error of their assumptions when a crew of workers returned overnight to the problem tank, which contained an estimated 7,000 gallons of MMA. Next to the problematic tank is a second tank, which holds 15,000 gallons of chemicals, but is not in immediate danger of spoiling.
However, officials wanted to add a neutralizing agent to that second tank, so that if the primary failed tank exploded, it would not ignite the second tank and cause an even larger explosion. So an overnight operation of chemists and first responders was sent in to try to accomplish this, which was attempted, even though it “damaged them,” Covey said.
When they arrived, they were able to manually read the defective tank’s internal temperature gauge again. (That gauge is not visible unless someone is there to read it; it is covered in cold spray of water and cannot be seen from a distance, nor by placing a drone camera near it, Covey said.)
And then the crew realized that the internal temperature of the tank was at 90 degrees, and relying on drones to estimate the temperature remotely only showed the temperature outside the tank, not the inside.
Staff writers Hailey Branson-Potts, Hannah Fry and Eric Likas contributed to this report.
