I have been watching all the major news shows this morning reporting on the nuclear disaster at Fukushima plant and decided to stop and Tivo CNN. Every once-in-a- while CNN gives a pair of two-minute segments on what is going that has at least a degree of depth and coherency. Otherwise, the news shows mostly have casually knowledgeable anchors talking between themselves in completely lay terms, or interviewing reporters (who the anchors always congratulate as doing a “great job of explaining things”) or rushing experts through complex ideas into vague conclusions so they can get to their next segment. The anchors discuss gibberish amongst themselves debating questions like “Would you evacuate your family from Tokyo?” and cut off experts in mid-sentence to ask vague, innocuous questions like “Are the Japanese doing enough?”, or “Bottom-line, are things getting better or worse?”
Both the news media and the Obama administration seem absolutely unwilling to give a worst-case scenario. Below is my assessment of the situation only as a layman who has some background on how these plants work and who has have learned from reports on television and the web of the current situation.
What is clear is that the industry never planned for handling a multiple-reactor unit plant failure while protecting the workers needed to limit damage in the worst case scenario. And that scenario is far worse than Chernobyl.
Anyone with expertise that can straighten me out, please help me to understand what's going on.
The Fukushima I plant has four reactor units. Units 1, 2 and 3 face similar problems. Unit 4 was shut down for maintenance before the earthquake/tsunami and has a unique problem which is the current one that is causing the greater release of radioactivity Fukushima Radioactivity Increases.
Each of Units 1, 2 and 3 have exposed radioactive rods which can now only be cooled down by pumping seawater over them. Whether this process will work or not is not is uncertain, but they are having some problems with it because the seawater vaporizes. If the rods are not cooled down gradually, which will take days or weeks to accomplish, the rods will melt, partially or completely, to the bottom of their containment structure (CS). Each CS is designed to contain a complete meltdown, but each appears to be vulnerable to explosions.
Unit 1 was hit by the first explosion but the explosion only harmed the outer building. Reports are that the CS is intact.
Unit 2 was recently hit by an explosion (reported as the third explosion) which caused a short-term spike in radioactivity. Reports are that the CS was damaged and is cracked or punctured in some way, although there is no significant release going on now.
Unit 3 was hit by an explosion (reported as the second explosion) which apparently, like Unit 1 only damaged the outer building and not the CS.
It is not clear if Unit 4 has a problem of exposed fuel rods in the CS. Unit 4 however, was hit by a fire yesterday and radiation temporarily spiked. Spent fuel rods that were sitting in a pool outside the containment vessel are in danger. The water pool is boiling and threatening to expose these rods in which case radioactivity would be emitted since they are not in the CS.
The unanswered questions are:
1) Can the rods be cooled successfully with seawater? 2) If not, and a meltdown occurs, will it be partial or complete? 3) If a meltdown occurs, will the residual radioactive material be contained by the unit’s CS?
The current process of cooling the rods by seawater has shown problems already and a partially meltdown has apparently begun at least one unit. A partially meltdown will occur if it continues for a while but the rod cools sufficiently before complete meltdown. A full meltdown will occur if the meltdown goes unchecked. The containment vessels will hold if they do what they are designed to do and are not damaged by exterior explosions (as Unit 2 has apparently been damaged).
If the all CS structures withstand a meltdown, we will have a “Three Mile island” incident. There, the one affected CS held a relatively small partial meltdown (1/3 of one rod) and released relatively low levels of radiation and no proven deaths resulted. If a meltdown occurs and the CS fails, we will have a “Chernobyl” incident.
What is concerning is that due to increased dangers, 750 of the 800 workers that were at the plant yesterday, have been evacuated. This leaves only 50 people to deal with the problems at all four units. All four units need people at the site to makes assessments, to open and close valves, and do the other manual work to keep the recovery efforts going.
Simple questions experts have not been able to answer are: 1) Do units 1, 2 and 3 also have spent fuel rods outside their CS which are subject to the same problem as Unit 4?; and 2) Does Unit 4 also have the problem of needing seawater to cool exposed fuel rods?
The chilling reality as pointed out by one expert, is that the nuclear industry does not have a plan for what to do when only one problem causes a deadly rise of radioactivity at the plant (perhaps the Tepco executives should be required to help out on-site now). How can you deal with trying to limit the damage posed by other problems with people working at the site when those workers would be exposing themselves to deadly levels of radiation?
Thus, if a meltdown occurs at any one unit and the CS does not hold, or any pool containing spent fuel rods evaporates and the result is deadly radiation, can the rest of the units still be worked on? Any continuing recovery efforts would have to be undertaken by those willing to be exposed to deadly radiation. Since it requires continued maintenance to keep the seawater cooling going, and perhaps the spent fuel rods to cool in the water they are in, abandonment by workers of all units would lead to complete meltdown at each unit and perhaps the exposure of all the spent fuel rods. Each CS would either hold or not based on its own ability to maintain structural integrity in response to a complete meltdown (which they are designed to do) and any explosions (perhaps not designed to do since reports are that the Japanese believe that the CS at Unit 2 is already damaged by an explosion).
The Chernobyl plant had no CS, so once a meltdown started and could not be stopped, massive radiation leakage was inevitable. Chernobyl exploded. I have not been able to determine if there were any spent fuel rods at Chernobyl. But Chernobyl only had one unit affected as opposed to four. And of course Chernobyl was located in an area not nearly as densely populated as the eastern coast of Japan. Accordingly, this disaster would seem to have at least the potential of being greater than Chernobyl, with the release of radiation from any breached CS or spent fuel rod pool going into the ground, water and/or atmosphere.