As if there aren’t already enough compelling reasons to immediately retire BWR Mark 1 reactors like the ones at Fukushima and at Vermont Yankee, Arnie Gundersen of Fairewinds Associates has just identified a doozy of a containment flaw that had previously escaped detection!
Analyzing data from the first day of the Fukushima accident, after the tsunami but before the explosions; and comparing those numbers to data collected during a test forty years earlier at the Brunswick facility in North Carolina, Arnie noticed a striking similarity which suggests an entirely unanticpated explanation for how those explosions came to pass.
In the scenario proposed by Fairewinds, as cooling failed at Fukushima, there was an accompanying build-up of contaminated hydrogen gas in the containment vessel. After about eight hours, the pressure build-up in the vessel so far exceeded it’s designed capacity that it actually stretched retaining bolts on the vessel “lid,” creating a space through which volatile gas escaped into the reactor. A single spark was all it took to set off a blast, ripping through the reactor and rocketing contaminated debris and gases into the atmosphere.
When the possibility of a hydrogen explosion in the Mark 1 was finally recognized in the 1980’s, a design modification involving a vent was made to all containments for that generation of reactors. This modification has come to be widely accepted as a permanent fix for the problem.
It turns out that, even though the vent appears to have functioned properly at Fukushima, it never could have prevented the exact problem that precipitated the explosions that occurred there!
The potential for a similar chain of events linked to that single design flaw still exists in all Mark 1BWR reactors that remain online today.
The Nuclear Regulatory Commission has long maintained its official position that the original design flaw in this generation of reactors was resolved through the vent modification, and that the containment vessel could not be breached.
This new evidence suggests otherwise.
Have a look at the brief and very straightforward explanation that Arnie Gundersen provides for this phenomenon:
New Containment Flaw Identified in the BWR Mark 1 from Fairewinds Energy Education on Vimeo.
I just had a “click” moment. In Bill Irwin’s determination that Vermont fish are contaminated with “background” radiation from nuclear weapons testing (generations ago) and the massive release of radiation from the nuclear plant at Chernobyl in 1986 (more than a generation ago), he never once mentioned the possibility that we might be seeing contamination from Fukushima.
But, how likely is it that he would mention it? After all, Fukushima’s Mark 1 BWR is remarkably similar to Vernon’s VEntergy Mark 1 BWR, and he seems quite determined, despite any evidence to the contrary, to absolve VEntergy from any involvement in any activity that might put Vermonters’ environment and health at risk.
NanuqFC
More than two dozen reactors in the U.S. have aboveground [spent fuel] storage pools similar to those that have failed at Fukushima – the only difference is that the American pools contain far more waste than their Japanese counterparts. ~ Elizabeth Kolbert in the New Yorker
and the video animation is getting better also. Thank you.
The Japanese purposely let the primary containment get up to twice design pressure (~120 psig) before attempting to vent because that is what their emergency procedures said.
Here in the US, BWR Mark I’s installed a hardened vent which is used to maintain pressure below half of the pressure seen in Japan (~62 psig.) BWRs in the US would vent long before primary containment pressures reached the point where they would leak or fail due to excessive pressure.
The statement, “it never could have prevented the exact problem that precipitated the explosions that occurred there!” is patently false.
Ya know, I don’t know who you are, Tom–the only Tom Brady I got on Google was the quarterback–AND I don’t really know shit about the technicalities the Gundersons and Sue Prent are discussing. BUT, I do know THIS–I am suspect of anyone defending the nuke industry or trying to discredit the reporting here on Vt. Yankee and Japan. Are you Patrick Cashman with a new logo? Is your mission here to confuse the issues on nuke plants? Or, are you just an asshole, as you appear to be when you talk to Sue about knitting?
I think, if you were a serious and respectable expert, you’d flesh-out your background and credentials here. What do you know about that mysterious break-in/arson at the Vermont Yankee offices Last Year? (Just kidding, Tom–although you do sort of sound like a fireman; working for whom? I think you’d be taken more seriously if you hadn’t started out the discussion by saying: “Wrong again, Arnie.” A professional in the field would treat another professional in the field by saying: “I respectfully beg to disagree with your analysis, and here is why…”