Run away heating in SEVEN nuclear reactors isn't significant?
I did not say that!
You have restated the comment in a manner that misrepresents both what I said and the actual situation.
I said the reactor situation was not
very significant
when compared to all the other things going on.
There is also not a run away heating situation!
You have to keep all this in context.
First there is no indication I have seen of
run away heating they are simply trying to cool the decay heat from fission products that were present at the time the reactor was scrammed. This decay heat rapidly goes away as the fission products cease to exist. Decay heat starts out at about 7% of the reactors power level at the time of shut down dropping to around 2% an hour or two after shut down, and then tapers off to about 1% of initial power after a day. It will drop very slowly after that as only the long half life fission products are left. This is not "run away heating" it is a predictable heat output that tapers of exponentially after shutdown. Highest heat loads for cooling are during the first few hours after shut down, then rapidly diminishing after that.
For those unfamiliar with the nuclear fission process, when a nuclear reactor is operational it is actively splitting atoms of uranium or plutonium or sometimes thorium to release energy. As those atoms break apart they form decay products of other atoms that are also radioactive but that decay away very rapidly (in most cases) releasing both radiation and heat energy. Each decay product either releases energy and becomes another radioactive decay product or it completes its final decay process and ceases to be radioactive. This is a step wise chain that once started
must go to completion. Unlike a fire you cannot put it out or stop it by any process known to man.
As a result you cannot just turn off a nuclear reactor like you turn off an engine. If you shut down the primary chain reaction it uses to produce power, the nuclear reactor must still let this secondary decay process run its course. This continues to release energy but is not a "run away" process.
A physical analogy would be a fire place. The primary nuclear chain reaction would be you constantly putting wood on the fire. Once you stop throwing wood on the fire, the then burning wood still has to burn out which continues to produce heat, but at an ever slowing rate until all the wood is consumed and turned to ashes.
The same thing happens in a nuclear reactor, the decay products of the initial fission of an atom are like a burning log, that must still finish burning out before it stops producing energy.
They are at this point trying to control this release of energy from decay heat and provide enough cooling so the fuel rods do not over heat and damage their protective coating that contains the radioactive material.
Based on the announcements that some small amounts of Cesium 137 and Iodine 131 had been detected, than a "few" fuel elements have likely gotten hot enough to damage their cladding, but the low radiation levels detected indicate that at this point there is no large scale breakdown in the fuel or large scale "uncontrolled" reaction. By flooding with sea water, and boric acid they are taking preventive measures to make sure it stays that way.
The information I have seen is that the plant that is most impacted was near the end of its design life anyway. It was going to be decommissioned anyhow and due to the present situation it would never operate again as a power reactor as they would never be able to recover the costs of repair, so the logical solution is to take the most cost effective means to ensure it goes cold as soon as possible.
Boron the element in boric acid, acts as a poison to nuclear fission. The boron atoms absorb neutrons that have the potential of triggering the fission another atom. By adding the boric acid they are ensuring that no large scale fission reaction can take place even if for some reason a large number of fuel elements were severely overheated and began to melt.
When compared to the direct impacts to life and property of the earthquake and the tidal wave, the nuclear reactors are orders of magnitude smaller in direct impact. --- ie not significant when compared to the other problems going on.
Mean while the explosion on the video simply blew the exterior sheet metal cladding off the building. These buildings are intentionally designed to blow out panels in case of a rapid internal pressure rise without damaging piping etc. All though it looked impressive on the video every indication I have seen is that the structural contents of the building were largely untouched, and only the cosmetic external panels were blown off.
Last of all --
1. There is absolutely nothing we can do about the situation in any case, it is all in the hands of the Japanese half a world away.
2. The radiation releases they are mentioning are gnat farts compared to the expanse of the pacific ocean basin and will have absolutely no impact on the U.S.
3. We are guessing based on 3rd hand info from 3rd hand sources processed for public release. The fact is we have no clue what is really going on, and based on historical nuclear accidents, the specialists on the scene don't fully understand what they are dealing with either and will not know for weeks-years what actually happened inside the reactor. They are making their best guess given loss of all instrumentation and power, and are winging it based on the evidence they have at hand.
There is no real time action you can take that will have any impact at all on you your friends or the resolution of the emergency so lets wait until we have some actual post accident analysis to deal with before we start discussing what shoulda coulda woulda happened.
Larry
