On March 30, 2012 I wrote a blog entry entitled “Review of Fukushima Daiichi Nuclear Disaster”. In this entry, I briefly discussed the necessity of providing adequate venting to prevent the escape of radioactive waste to the outside in the event of loss of power and a resulting explosion. Here is what I wrote:
“Venting channels to help relieve the high pressures resulting from any explosion inside the reactor are readily provided in a domed containment structure. These vents are typically filled with boron-based sand or aggregate, and activated carbon. This sand, aggregate and activated carbon remove radioactive material from explosive gasses as they pass through the venting channel, before they vent to the outside atmosphere.”
In response to this entry, some anonymous source posted the following remark on May 2, 2012:
“Containment is supposed to be virtually leak-tight under all Design Basis conditions. Venting Channels defeat this purpose.”
I replied on May 2, 2012:
“It is impossible to contain a supersonic explosion without venting, or else the containment structure becomes a "bomb". See this discussion by Arnie Gunderson of Fairewinds. Evidence seems to indicate "inadvertent criticality" as cause of explosion. In order to begin to control the effects of such an explosion venting is required. http://www.youtube.com/watch?v=vs53iOn2K2w
The same anonymous source then replied once more, also on May 2, 2012:
“An explosion is beyond Design Basis except for Steam Generator Faults and LOCAs. These are supposed to be complely contained within containment. Any explosion such as "inadvertent re-criticality" is not containable without loss of containment integrity.”
At this point, I realized that due to the language used, the defensive posturing, and the inability to admit a design flaw in an inherently flawed design; that I was most likely communicating with an engineer or Public Relations employee from General Electric (GE). The nuclear reactors involved in the Fukushima Daiich disaster are GE Mark I reactors. There are currently 31 reactors very similar to those at Fukushima Daiichi in the US.
In an effort to be clear, to emphasize a solution, and, furthermore, in an attempt not to antagonize or further alienate this anonymous commenter, I offered the following, final remark in our exchange (also on May 2, 2012):
“The containment structure is not adequate to contain an explosion without venting. (I think we are saying the same thing?) As proven by experience, explosions happen at nuclear reactors. The containment structure should be designed to withstand an explosion, this necessitates inclusion of proper venting. The existing structures at Fukushima were improperly designed and built. They need to be fixed, they need better containment (with venting) since explosions can and do happen.”
My hapless anonymous commenter did not respond.
Today, March 19, 2013, The US Nuclear Regulatory Commission (USNRC) posted an entry on their blog, entitled “NRC Commission Approves More Post-Fukushima Upgrades to Nuclear Plants.” In this blog entry, the NRC demands strengthened venting at the 31 nuclear reactors in the US which are similar to the GE reactors involved in the disaster at Fukushima Daiichi.
Quoting from today’s USNRC blog entry (3/18/13):
“The venting systems at Fukushima played a role in their nuclear crisis, and the NRC issued an Order to the 31 plants with similar designs to take action. The plants either had to install vents or improve their existing venting system. The goal was to make sure the vents can operate during the early phases of an accident, even if the plant lost all power for an extended time.
In their latest decision, the NRC Commission votes to further strengthen these vents. The NRC staff has 60 days to finalize an Order for these enhancements. Generally speaking, these additional requirements mean the vents could handle the pressures, temperatures and radiation levels from a damaged reactor, and that plant personnel could operate the vents under these conditions.
As part of the same decision, the Commissioners directed the staff to begin a formal rulemaking on filtering methods that would prevent radioactive material from escaping containment in an accident, either through new filter systems or a combination of existing systems. The staff will develop the technical analysis, a proposed rule and then a final rule. Throughout this process, the public and various stakeholders will have opportunities to submit comments and attend meetings to ask questions. And there will be many future posts about the progress!”
To my anonymous commenter: I told you so!
Luckily, there has not been a nuclear disaster in the US since the March 11, 2011 tsunami disaster in Japan. Hopefully there will not be a disaster before proper venting is provided to the 31 nuclear reactors in the US which are inherently flawed and pose a significant risk in the meantime. If any nuclear reactor operators are seeking an effective, affordable solution to this engineering challenge, I urge you to contact me. I was right when I posted on March 30, 2012; I am right now.