I'm surprised: Japan's Earthquake/tsunami: No comments?

notbob wrote:

It's proof that Andy is the mature adult and Janet is the spoiled
child. I don't remember Andy ever telling people with whom to
associate/ignore. Decisions, decisions... if I associate with Andy
will Janet stop sexting me? LOL-LOL
 
In article ,
[email protected] says...

You gotta admire the Japanese--earthquake, tsunami, nuclear attack, they
take it all in stride and get right back to work, the ones who left work
to begin with. Compared to what they got in WWII this is actually
pretty small potatoes.
 
J. Clarke wrote:


Well, except that one problem with trying to cool a runaway reactor
with water is that water pools at the bottom of the building, then
when the melted-down core reaches it you get a gigantic steam explosion.
This could be as bad as the burning graphite. You're entering into
a devil's bargain once you start pumping in mass amounts of water.

Steve
 
Cindy Hamilton wrote:


I would say I disagree, at least in a general sense. Usually if
I help out a charitable cause, me doing so is part of a larger process
that involves (among other thing) discussing the situation in question in
some sort of social context.

RFC is a social newsgroup in which discussion of current events
is (IMO) on-topic, and to the extent that RFC or Usenet in
general form part of peoples' social groups, discussing such
matters here is ultimately part of the process of helping people
who are affected.

At least that's how I see it.


Steve
 
J. Clarke wrote:

It's something extremely few do understand. Unless some of the
moderator rods were bent enough that they could not get pushed into the
core the chain reactions have stopped.


Caveat - Water does electrolize into hydrogen and oxygen. Hydrogen and
oxygen can recombine again to burn in a chemical explosion. That's
probably what happened with the explosion being shown in the news.


At TMI no one died from radiation. That's close to the result we'll see
here. At TMI the reactor is still sitting there waiting for people who
allow a complete clean up. Again that's close to the result we'll see
here. I think Japan is probably more civilized than the US when it
comes to nuclear power - These plants will be cleaned up over time but
at least one of them might never come on line again.

No comparison to Chernobyl at all.
 
"J. Clarke" wrote:

-snip-

I think we humans still need to do some work on our ability to see the
future- so I'll say we don't know what it will be.

But I heard 2 physicists on different networks do some comparing. Who
knew there was a scale for Nuclear disast. . .er, event'?
http://en.wikipedia.org/wiki/International_Nuclear_Event_Scale

That places Chernobyl at 7, Three mile Island at 5.

One physicist this morning called Japan's problems a 6-- the other
said 5-6.

I feel for those folks-- but, barring even more major bad news, I have
faith that they will recover nicely. The eastern mindset is well
suited to facing such devastation.

Jim
 
In article , [email protected] says...


There are no "runaway reactors" in Japan at this time. Chernobyl was a
"runaway reactor".

Nearly all reactors are filled with water all the time. It is there for
cooling, for a necessary physical process in the nuclear chain reaction,
and for transferring heat to the loop that powers the turbines.

The only way there can be a pool of water under the reactor with no
water in the reactor is if someone has screwed up horribly or the
reactor is putting out such a vast amount of power that no amount of
cooling water can deal with it.

The job of the Japanese at this time is to simply keep water above the
top of the fuel rods for a couple or three days until all the high-level
secondary reaction products that are currently heating the reactor have
decayed.

Chernobyl was different. The reactor was not successfully shut down.
The device that shuts it down jammed with the reactor far above its
normal full power level, and with 30 gigawatts of heat energy being
produced, it was able to boil most of its cooling water and blow the lid
off. It continued to operate at this huge power level until enough
graphite burned off to poison the reaction (it _needs_ the graphite in
order to function). The steam explosion at Chernobyl happened _before_
anything melted. It was not the result of "the melted down core
reaching" "water pools at the bottom of the building".

The Japanese are not "trying to cool a runaway reactor", they are simply
keeping the rods covered.
 
"Mr. Bill" wrote:



Actually, after the past few days watching BBC World News each morning
and I've grown weary watching the same footage over and over. I wasn't
even watching my local morning news.

The cleanup will be a Herculean effort. Where do you dispose of so much
ruin?

Andy
 
In article , [email protected]
says...

_Control_ rods. Moderator serves a different function from control
rods, and is usually not in the form of rods.

Control rods absorb neutrons and stop the chain reaction or adjust the
reaction rate.

Moderator slows neutrons down--neutrons from the fission reaction
typically have an energy of around 2 MEV. Uranium 235 has a very low
neutron capture cross section at this energy, and a much higher one at
lower energies, so the moderator serves to reduce the energy of the
neutrons thus improving the efficiency of the reaction. Regular water
does absorb some neutrons as well--this is considered an inefficiency,
but an acceptable one all things considered, it's not a desirable
feature.

Most reactors, including the Japanese ones, use ordinary water for the
moderator. Chernobyl used graphite (same as the first reactor that
Fermi built). The other moderator in common use by the way is heavy
water.

Generally most of the space between the fuel rods will be filled with
moderator--there will be a quite large quantity of it in most reactors.


Yep. But it doesn't sit there burning for days like happened at
Chernobyl. There was plenty of water in Chernobyl to make a steam or
hydrogen explosion, which happened inside the pressure vessel, blowing
the lid off and scattering moderator and fuel elements outside the
reactor--at that point the reaction also pretty much stopped.

Note another issue--if the Japanese reactors do have a steam explosion,
they lose their moderator and even if the rods were out the reaction
would be reduced greatly in power level. At Chernobyl, losing the water
didn't lose the moderator so the reaction continued at very high power
until something else happened.


It's my understanding that they've decided to just wait until TMI-1
reaches its EOL and then do them both at once. They have completely
defueled the reactor including the damaged fuel elements.


What they'll do likely depends on cost. Land is expensive in Japan and
they have high energy needs, so they may rebuild all of the reactors.


Let alone Hiroshima and Nagasaki.
 
J. Clarke wrote:

Reactors with the chain reaction running are at well above boiling.
That's how the water boils to power the turbines.

The defueling procedure needs to be run with the water far below
boiling. There's a ton of latent heat in those reactors between turing
them off and them cooling down. Just how much is added by the short
half life products? I didn't think it would be that much. Mostly
running it down more than 100 degrees Celcuis where "it" is a huge
chamber filled with a lot of stuff.

It's not good that usually the electricity from the grid is used to
drive the pumps to do that cooling. The plants are off of the grid
because of quake damage.
 
In article , [email protected] says...



Andy certainly did, ( "what's wrong with you folks.. don't you care?");
and you responded, reposting and echoing his concern.

You also posted, elsewhere

"Is it somehow disrespectful to NOT give these things some attention? "


Janet.
 
"Jean B." wrote:

Completely different mindsets. The notion of working together needs to
be imprinted early on in children and reinforced subsequently for a
lifetime. If that's missing, then people do sit around and wait for
someone else to do something.
 
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