A large, pressurized tank filled with a toxic chemical in Orange County is at risk of either exploding or leaking, and officials say their options are highly limited.<\/p>\n
By Friday night, fire crews were making progress lowering the temperature of the chemical tank, which is down to around 61 degrees, with 50 degrees being the goal, Craig Covey, an Orange County Fire Authority division chief, said. <\/p>\n
That could enable crews to implement some solutions that don\u2019t involve an explosion or destructive leak. But there is still a ways to go before the area is safe for people to return. <\/p>\n
Why is the chemical in this tank so dangerous right now?<\/p>\n
Inside the tank is an estimated 7,000 gallons of a chemical used to make plastics called methyl methacrylate, or MMA, stored in liquid form.<\/p>\n
\u201cIt\u2019s durable, lightweight, transparent, so it could even be used as a substitute for glass,\u201d Elias Picazo, assistant professor of chemistry at USC, said of the final plastic product. The polymer can also be used in household goods as well. <\/p>\n
The polymer itself isn\u2019t toxic, but its liquid MMA predecessor \u2014 a monomer, essentially a bunch of single molecules \u2014 is. If it gets into the air, it can harm people at high concentrations and through chronic or extended exposure. <\/p>\n
\u201cThe other hazard is the explosion itself. And it sounds like it\u2019s already the reaction has already initiated, and that\u2019s where the worry comes in for the explosion,\u201d Picazo said. <\/p>\n
In chemistry, there\u2019s a concept known as \u201cthermal runaway reactions. And those are really hard to control,\u201d Picazo said. <\/p>\n
If the temperature of the tank exceeds a certain threshold, Covey said, \u201cwe know the tank is going into thermal runaway, and we\u2019re going to pull everybody out of the area, make sure it\u2019s safe, and let the tank do what it\u2019s going to do.\u201d<\/p>\n
How did the crisis begin?<\/p>\n
The crisis began in Garden Grove on Thursday, when a tank with MMA started to experience an increase in temperature. At one point, the tank began bulging, and \u201cit got to a point where it does what we call a BLEVE, which is a \u2018boiling liquid expanding vapor explosion,\u2019\u201d Covey said Friday afternoon. <\/p>\n
It\u2019s not clear what problem caused the increase in temperature in the chemical tank. <\/p>\n
But it\u2019s something that should not have happened, experts say.<\/p>\n
What happens when you combine heat with this chemical in a large, pressurized tank?<\/p>\n
Some chemical reactions can be initiated with heat. With MMA, heat can cause a reaction, but then it causes more heat. <\/p>\n
\u201cYou can start to see the problem. You have a reaction that is initiated by heat, but it also releases heat as it goes on, that then leads to the runaway, where it\u2019s uncontrollable,\u201d Picazo said. \u201cAnd this is a very large scale reaction that produces a lot of heat very quickly.\u201d<\/p>\n
And this is all happening in a tank with high pressure. <\/p>\n
\u201cIf you build too much heat or pressure, then you get the explosion. And the material is also highly flammable, in addition to being toxic, and so you can have, fumes of toxins, flames like literal fireballs, and the explosion itself,\u201d Picazo said. <\/p>\n
The worst-case scenario is an uncontrolled explosion. \u201cIf you\u2019ve ever seen videos of tank cars on a railroad track blowing up, and that fireball it puts out, and it blows half the tank car a half a mile down the train track, that\u2019s the incident potential we are dealing with if this suffers a catastrophic failure,\u201d Covey said.<\/p>\n
Another scenario that could involve significant environmental damage to waterways and the ocean is a massive leak, although such a leak would make the chemicals no longer at risk of exploding. <\/p>\n
From there, teams in hazardous material suits can go in and \u201cneutralize and mitigate the vapors that will be coming off of that,\u201d Covey said. <\/p>\n
Can anything be done beyond waiting for an explosion or a massive leak that threatens streams, rivers and the ocean?<\/p>\n
The main strategy right now is doing everything possible to keep the tank cool. <\/p>\n
Crews on Thursday were able to cool the tank down with sprinklers leading officials to think the problem was being resolved. But conditions worsened Friday when they discovered they could not offload a neutralizing agent in the failing tank because the valves had broken and were gummed up.<\/p>\n
This would\u2019ve been a good solution had they been able to get the neutralizing agent in the tank. MMA is an electrophile \u2014 it likes taking electrons, and \u201cif you add another molecule that is a nucleophile that likes to give electrons, you can quench it, you can kill the reaction, you can stop the reactivity of whatever remains,\u201d Picazo said. <\/p>\n
Firefighters on Friday reissued evacuation orders and expanded the zone to include portions of the cities of Garden Grove, Anaheim, Buena Park, Cypress, Stanton and Westminster. They warned that they were told that at that point, the only two options ahead of them was either a massive leak or an explosion. <\/p>\n
But they are buying time now using cool sprinklers to try to keep the tank\u2019s temperature down. <\/p>\n
That\u2019s a viable solution, Picazo said, to \u201cjust wait it out by keeping the tanks cool. So by controlling the runaway, you can slow down the reaction and you can do your best to maintain the pressure.\u201d <\/p>\n
Covey said in an update on Friday night that efforts to cool the tank by spraying it with water have been successful so far.<\/p>\n
\u201cThose efforts are succeeding and it\u2019s giving us opportunity to reconsider engaging in close proximity to implement some of the concepts…to mitigate this thing,\u201d he said.<\/p>\n
Key questions for officials, Picazo said, will be determining how much MMA remains in the tank \u201cand how to quench whatever is remaining.\u201d <\/p>\n
One tank on Thursday did release vapor after the tank experienced an increase in temperature. By Friday afternoon, firefighters had cooled the tank enough that a valve on top of the tank was no longer purging any kind of chemical. <\/p>\n
If the temperature is equilibrating and the tank is no longer venting substances in the air, one possibility is that the reaction could be done. \u201cI wonder what would happen if they stopped trying to cool the tank, if it would start heating itself again,\u201d Picazo said. \u201cBasically, I\u2019m wondering if the reaction is over, or, or if upon stopping the cooling mechanism, if it would re-initiate itself.\u201d<\/p>\n
What could\u2019ve caused the valve in the tank to clog up, making it impossible to put a neutralizer in the tank that would resolve this crisis?<\/p>\n
One possibility is that the MMA chemical has already reacted in the valve and gone from a liquid to a solid state. <\/p>\n
\u201cMaybe the material has already polymerized in that outlet,\u201d Picazo said. \u201cAnd so you can\u2019t get anything in or out from it, because the monomer \u2014 which is a liquid \u2014 once it polymerizes, it becomes that plastic, glass-like material, and that\u2019s solid, so nothing\u2019s going to go in or out.\u201d<\/p>\n
Has anything like this happened before?<\/p>\n
Officials called this particular situation unprecedented Friday. But in a region dotted with chemical facilities, refineries and other heavy industries, accidents do happen.<\/p>\n
One recent incident <\/a>occurred in October at the Chevron oil refinery in El Segundo, triggered after a large fire broke out in a corner of the refinery where crude oil is turned to jet fuel, and resulted in a violent blast that rattled homes up to one mile away. Details on the cause and the extent of the environmental fallout haven\u2019t been released. <\/p>\n In 2015, an Exxon Mobile refinery in Torrance suffered an explosion; no one was seriously hurt. The U.S. Chemical Safety Board said<\/a> Exxon Mobile relied on outdated procedures and used equipment that was older than its safe operating life, adding that the explosion had the potential to be catastrophic because of the presence of a highly toxic chemical, hydrofluoric acid, on site, which can immediately penetrate the skin and destroy tissue. <\/p>\n