Some remarks on how Fukushima is not Chenobyl
// March 14th, 2011 // Rambling
Disclaimer: I am not a nuclear scientist nor do I work in the nuclear field. I am, however, a staunch proponent of science and work with physicists and other scientists, but I have no qualifications beyond a fairly serviceable brain and a willingness to study, learn and listen.
First, this is a great post from William Tucker at WSJ. Two thumbs up. Also, if you’d like to follow the basic facts minus the hyperbole, please visit the NEI page on the current situation at Fukushima Daiichi.
Second, I thought I’d share some comments from one of the professors from my department. Prof. Richard Wilson (bio) has been active in humanitarian aide, outreach and education for many groups and has been especially vocal about arsenic poisoning and cancers from man-made problems (including radiation exposure). That said, he’s also a realist about nuclear energy, having worked in and around the field for decades. (FYI – He will be on NECN tonight at 6 and 9) In an email to all re: the Fukushima situation, he’s said:
The reactors all shut down at the earthquake automatically unlike Chernobyl. The problem then is to cool the core since the circulating water through the steam turbine has stopped.
Just after shut down the power level is 8% of full power (plus an extra 4% in neutrinos ). This drops in a well known way. (The Wigner Wey law of 1949) Roughly exponentially. After 10 hours it is about 1% and on to 0.1% after a year.
Note there the first thing we need to set straight: The plants shut down as expected and nothing was breached. It’s a cooling issue, full stop. Chernobyl had no containment and this more modern (but still not ‘modern’) plant does. If this were “a Chernobyl”, hundreds would be dying right now.
In Japan, there was no power from the grid to operate the pumps. Emergency DC power worked for a short while. Emergency diesels started up as planned but failed after 8 hours in one plant and longer in another due to flooding. In the absence of cooling the water cooling the core began to evaporate. At the power plant there is now basically no electricity. It took perhaps an hour or two for the top of the core to be uncovered and heat up (this time must be known but I do not know it). Then the core starts heating and the chemical reaction begins between the zirconium cladding for the fuel rods and water. This disassociates the water and Hydrogen is released.
You can see where this is going.
At TMI [note: TMI = Three Mile Island] cooling was interrupted by stupid manual action almost at once and 2 hours later hydrogen was produced which caused an explosion INSIDE THE CONTAINMENT at about noon (exact time in my files) 8 hours after the initial accident. In Japan the hydrogen and other gases were vented and the explosions were OUTSIDE (where they did no important damage) and much later
Cooling of the reactor is now maintained by sea water flooding the containment. (maybe also the reactor vessel but I do not know this) This can cool the reactor core by conduction through the pressure vessel. But the water is not circulating and stem is produced which is being vented. It is claimed that there is filtering for radioactivity but I do not know this for certain.
It seems to me that this can be continued indefinitely at least until electricity is available at the site.
No ‘Chernobyl’. Not even close. Not even in the same ballpark, much less the same type of incident or type of reactor.
Note that there are still TWO (2) barriers to release of radioactivity even if the core has completely melted which I believe is unlikely.
(1) the pressure vessel which seems intact
(2) the containment.
I believe that both these will continue to hold and the only problem will be in the controlled realease. Noble gases will be released but these do not interact much in the body (you breath them in and then breathe them out) Of these krypton is the longest lived.
Cesium is normally solid and even if the containment fails, the cesium may not evaporate . (Indeed at Chernobyl which was very hot very little of the strontium evaporated and did not contribute appreciably to the radiation dose.)
The highest recorded dose so far in the region of the plant is 150 mrem/hr (1.5 mSv per hour ). The natural back ground is about 300 mRem/yr Acceptable one time dose for accidents is 80 Rems for an astronaut and 20-40 Rems for a clean up worker.
And, finally, Dick’s prediction:
No one in the public will get acute radiation sickness and probably no one in the reactor staff either
No 0ne will have problems from iodine ingestion
There will be minimal cesium releases and not one fatal cancer will be CALCULATED (using the standard pessimistic formula) from the doses to the public.
This is to be compared to 1,000-10,000 direct, measurable and definite deaths from other earthquake problems
So, to all the Chicken Littles out there saying we have to stop and ‘review’ our nuclear programs (“ohmygawd ohmygawd!”) because of an incident that its so far outside the norm as to be unique, let me remind you of two things:
1) We’re CONSTANTLY reviewing our designs and programs. That’s how science works. And safety is THE primary review concern in nuclear energy production. Do you seriously think they’ve overlooked earthquakes??? That’s why we’ve gone on to design new and safer plants… so they’ll be as safe as possible. And they can be as safe as you’re willing to allow. Unless you also want to be stingy and would rather continue to dump pollutants into the atmosphere until we run out of oil.
2) “As possible” – Nothing can be made 100% safe. Everything is a weighing of risks against needs. That said, I didn’t see anyone calling for the halt and review of petroleum energy when BP polluted miles of ocean and coastal regions. No one’s called for a halt to automobile and coal pollution to review the deaths it causes each year.
I’ve heard several people toss out the “but what about a worst case scenario???” to which I want to shout “THIS IS THE WORST CASE SCENARIO!” And so far, it’s being contained despite the age of the technology and the crumbling of the infrastructure around the plants. This quake was unlike anything before it, and yet, despite the events leading to it being ‘worst case’, the crisis at the plants is not worst case.
What does your call for a ‘moratorium’ hope to do? Address the obvious? Ask the same questions that are asked every day in meetings and design reviews which seek to create safe, clean energy? No, it’s histrionics seasoned with a little bit of good ol’ political grandstanding. The incident at Fukushima is certainly worrisome, but it’s not an indictment of nuclear energy.
And it’s certainly no Chernobyl. Humans & Science 1, Histrionics & Emotion 0.