[Peace-discuss] 4pm today 3/15: Re: NPRE to Host Seminar on Japanese Nuclear Accident

[Morton K. Brussel]

A few comments on your text. Thanks for writing.
--mkb

On Mar 16, 2011, at 11:56 AM, Karen Medina wrote:

>>> "Evolving Issues Regarding Japan's Damaged Nuclear Plants"
>>> from the chair of UofI's Dept. of Nuclear, Plasma and Radiological
>>> Engineering
> 
>> Post an account if you go.  --CGE
> 
> The room was packed. The room probably sits 200 plus there were easily
> 50 people sitting in the aisles and standing.
> 
> There were physicists standing near me and Stuart, so we overheard
> some other comments as well as the information from the three
> professors who spoke. It started off a bit like a lecture, but then
> moved to question and answer. Then a bit more information on a few
> things, then back to question and answers. The audience ranged from
> nuclear physicists to undergraduates to humanities graduate students.
> There were a high number of people who probably had family and friends
> in Japan and China.
> 
> One particular diagram was very helpful. The distinction between a one
> (steam) and two (hot water, then steam) circuit was made early on.
> Both have a turbine turned by steam, but the one circuit system
> releases pressure by letting the steam out a one-way valve. The 6
> plants in Japan that are having troubles are all of the one circuit
> type. Which, they were saying, is a good thing.
> 
> The nuclear reactions were stopped when the earthquake hit but it
> takes a long time to cool the material down.

Rather, the byproducts of the fission process remain radioactive after the chain reaction ceases. This produces the heat. As the lifetime ("half-life") of these radioactive elements is finite, the heat produced by the decay radiation decreases with time. A curve displayed indicated after 10 days the chain reaction stops, the radiation decreases to a few tenths of 1%. O coure, if there is a lot of material radiating, that still can produce substantial heat, and it may require active cooling. But the hopeful aspect is that the heat will decrease with time.

> Water in the primary tank is vital while reacting and vital to cooling it down when the reaction
> is stopped. If the water in the primary tank (the first area outside
> of the nuclear chamber) drops below the level of the rods inside, then
> the nuclear material will go molten.

This is not necessarily true. It is, however, likely.

> The molten material is likely to crack just about any and all containers around it, including the
> stainless steel of the primary chamber and the thick concrete wall of
> the dry chamber and the 5 foot thick concrete wall in the outer outer
> chamber.

This is a possibility, but not necessarily likely. Most reactor experts do not expect the molten radioactive matter to penetrate the thick concrete, but it could conceivably happen. There is so far only speculation that the steel barrier containing the fuel rods may have been breached in one or more of the reactors. 
> 
> Electricity is needed to pump water into this primary chamber. As the
> pressure builds inside the chamber, it is harder to pump more water
> in. Hypothetically, the dry chamber can also be filled with water.
> 
> Nuclear explosion is unlikely.

Is impossible, given what we know well about the physics.
> 
> Hydrogen comes from several places, including from the water.

It comes from a chemical reaction with the Zirconium cladding of the fuel rods interacting with the steam given off by boiling water.
> 
> Radioactive Iodine is produced. In the body of humans and other
> animals, the radioactive iodine will bind tighter. So to protect the
> body, you basically saturate your system with regular iodine and make
> sure your levels stay high so you don't absorb the radioactive iodine.
> 
> These plants will not ever be usable again.
> 
> [There is loads more information, but I'll stop here so people can
> correct me - karen medina]

Very important is the amount of radioactivity dispersed outside the reactors. Adjacent, there have been "spikes" of activity which can be very harmful if one is exposed for any length of time, (hours, for example). This is a danger for those trying to control the damage. Most reports say that there is no dangerous health effects for those more remote, say kilometers away, although precautions have been taken to minimize danger to those within 30 km of the reactors.  Fortunately the winds are pushing the radioative elements seaward. Tokyo has higher than normal ambient radioactivity, but is not considered to have health hazards from it. Some say the stress on the population from fear will have more health effects than anything else (This was the case from the Chernobyl accident.) 

Time will tell just how bad the radioactive contamination will be. The information so far has been sketchy. 

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