My wife and I have been watching the new HBO miniseries on the 1986 Chernobyl nuclear disaster. During the second episode, she asked me the question that is probably on everyone’s minds as they watch the drama unfold: “Could a Chernobyl-type event happen today?”
I told her “No, I don’t believe that’s possible.” However, it’s important to note that we never dreamed such an accident was possible in the first place. So, let’s explore the question in a little more depth.
The Recipe for Disaster
An accident is the result of an initiating event or series of events and an inadequate response. Accidents are mitigated by lowering the probability of the event(s) and ensuring a response that prevents the consequences from escalating.
In the event that the potential worst case scenario is catastrophic, there needs to be substantial reduction in the probability of the event, as well as a response that reliably mitigates the consequence. A catastrophic consequence could be one that involved multiple human fatalities, huge environmental contamination, major property damage, or major financial losses.
But a catastrophic consequence would also include major disruptions to the population, like having to evacuate 50,000 people from their homes. In the case of Chernobyl, the evacuations happened on short notice, and they were permanent. I think if you have to permanently leave your home on short notice, that’s a catastrophic outcome.
Further, in the second episode of the HBO series, they presented a narrowly-averted scenario in which millions of people could have died. I can’t say whether those events actually unfolded — or whether this is a dramatization to make for more exciting TV — but viewers will certainly have the impression that Chernobyl nearly killed millions of people.
Thus, the public must have absolute confidence that another Chernobyl (or Fukushima) can’t possibly happen again.
Reducing the Risks
There are still 11 operating RBMK reactors of the type involved in the Chernobyl accident. All of them are in Russia. Since Chernobyl, there have been significant design modifications that were recommended by the International Atomic Energy Agency (IAEA).
In 2006, IAEA deputy director Tomihiro Taniguchi told The Associated Press “Very significant changes have been made in the technology. The IAEA is firmly committed that such an accident not happen again.”
There’s no doubt that the potential for a Chernobyl-type event has been greatly reduced as a result of design changes and additional training, but has it been reduced to zero? Hold that thought for a moment.
While there are no RBMK reactors in the U.S., around 30% of U.S. nuclear power plants use General Electric-designed boiling water reactors (BWR). This was the type involved in the core meltdowns in Fukushima following the 2011 tsunami off the coast of Japan.
Again, training and design changes have reduced the risks of a repeat, but has the risk been reduced to zero? Again, let’s hold that thought for a moment.
The Unknown Unknowns
I do believe that the probability of having a similar set of events lead to a similar outcome has been reduced to zero for both Chernobyl and Fukushima-type events. The causes were identified and addressed in other plants with those designs.
But, bear in mind that nobody had any idea that such huge disasters were possible for either of these locations. Indeed, it took years to fully understand what had precisely caused the accident at Chernobyl.