[at-l] Three Mile (On-List, Off-Topic)

[RoksnRoots@aol.com (RoksnRoots@aol.com)]

Bryan wrote:

What bunk, I've seen the engineering report on Three Mile Island and it was 
never near melt down. If you knew any nuclear engineering you would know that 
no US reactor could ever melt down because of the design. These are slow 
neutron reactors and without water you have no slow neutrons. Thus if you 
lose all the water from a reactor it just shuts itself down, period. You 
might get some damage to the internal structure of the core and so they 
certainly don't want that to happen but a disastrous release just won't 
happen.
 
    ~~~  We should respond on this topic off-list due to site traffic. 
However, my experience/information is based solely on a TV documentary. What 
I saw were the actual participants admitting that they did not tell the 
entire story to the public during the event. I don't know your particular 
experience with the Three Mile event, but the containment took an explosion 
shock from the core going critical and held, engineers said it was luck. 
     From the program, Three Mile was caused by a faulty valve in a drainage 
pipe similar to a garden spigot. The valve would not shut off, but was 
indicating that it had. Meanwhile the core was being drained exposing the 
rods. If they had done nothing the system was automated and would have 
refilled the core automatically. They took the low water indicator as being 
faulty and overrode the automatic failsafe. During this time, radioactive 
core water was drained directly into the Susquehanna.
     The program gave statements by involved-at-the-time nuclear engineers 
saying if it wasn't for a level-headed top-scientist realizing the correct 
scenario and ordering a last minute solution, the core would have gone 
terminal and exploded violently. These same engineers said there is no 
material capable of holding a molten nuclear core and it would have melted 
through the concrete containment underneath it. Upon contact with the 
watertable, this volatile ball of nuclear lava would destabilize in a major, 
violent  explosion that would blow away all above it including the 
containment dome. They said this would have contaminated a large area of the 
northeast. See: Chernobyl. Why was the Three Mile containment dome isolated 
and sealed if your type of reactor is so safe?

You should look at the Army SL1 reactor which suffered a catastrophic failure 
with instantaneous loss of all water from the unit. This unit had NO 
containment and was inside one of those sheet metal warehouse type buildings. 
There was zero escape of radioactive material despite a major steam 
explosion. There was NO meltdown. There were three fatalities, the three guys 
working on the unit were killed mainly by the steam explosion.
 
Russian reactors BTW do not have this inherent stability that US plants do. 
They copied a WWII design from Hanford Washington using graphite moderator 
that is basically unsafe. No plants using that design have been built in the 
US for 50 years.

   ~~~ It could be an issue of waste disposal, but the documentary said the 
government realized how close Three Mile came and came to the conclusion that 
nuclear plants could never be guaranteed safe due to the potential for human 
error. Three Mile is a few miles from the AT in beautiful Duncannon...


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