On 16/04/2011 02:14 PM, Warp wrote:

>    Improving public transportation to reduce the need for private cars is
> another efficient way to reduce pollution.

See, now, where I live, the government thinks that making private 
transport too expensive will make everybody use public transport.

This is absurd, of course. The way to make people use public transport 
is to make it ACTUALLY FRICKING WORK.

I still remember visiting my sister in Manchester one time. I was amazed 
when we just wandered up to the nearest bus stop, stood there for about 
2 minutes, and a bus arrived. If you did that in my town, you might 
stand there for *days* and never see a bus!

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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On Fri, 15 Apr 2011 14:04:56 -0400, Jim Henderson wrote:

> On Fri, 15 Apr 2011 18:48:14 +0100, Orchid XP v8 wrote:
> 
>>>>> Which tells you that it isn't *that* dangerous or there wouldn't be
>>>>> any life in the ground.
>>>>
>>>> It's also an extremely rare element. Not like a reactor core, which
>>>> is make out of pure Uranium...
>>>>
>>>>
>>> A reactor core is NEVER "pure uranium".
>> 
>> It's far nearer to being pure than anything in nature.
> 
> Would you like me to have a bona-fide nuclear physicist refute this?  I
> have a very close friend who has a doctorate in nuclear physics (and two
> others who hold advanced degrees, one doctorate and one masters), and
> after he stopped laughing, I'm sure he'd be more than happy to give you
> all the nitty-gritty details about what is wrong about that statement.

Here's what he had to say:

--- snip ---

It depends on the type of reactor and the fuel composition differs
between them. But generally they are not of "pure" Uranium but often
a mix but with a HIGH U content - most of the reason is that the
"unpureness" gives you a higher melting point and is a little
"safer."

Here is a good article about the different fuel types:

       http://en.wikipedia.org/wiki/Nuclear_fuel

--- snip ---

Jim

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On Sat, 16 Apr 2011 08:44:13 -0400, Warp wrote:

> Jim Henderson <nos### [at] nospamcom> wrote:
>> On Thu, 14 Apr 2011 15:04:11 -0400, Warp wrote:
> 
>> >> A solution to global warming? No.  A solution to running out of oil?
>> >> Quite possibly.  A solution to having a power generation technology
>> >> that a poor uneducated population can use without fear of actually
>> >> killing people on the other side of the world when they screw up?
>> >> Sure.
>> > 
>> >   Burning coal is only a temporary solution, and a bad one.
> 
>> I'd have to agree with Darren here, it may be a bad solution, but
>> unless there is another solution, the alternative is "well, it sucks to
>> be you since you won't have power - deal with it."
> 
>   The problem is that if poor countries started increasing their burning
> of fossil fuels significantly, *the entire world* would suffer from it,
> not just them.
> 
>   So if it sucks, then it sucks.

I don't disagree with you, Warp, but unfortunately there are those who 
have power who think what happens in other countries doesn't matter.  *I* 
am not one of those people, and I wish those who are would pull their 
heads out.

Jim

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On Sat, 16 Apr 2011 11:09:22 +0100, Orchid XP v8 wrote:

> I've often wondered about this. Why did people design a 33MHz CPU, and
> then a 66MHz one, and then 100MHz, and so forth? Why didn't they just go
> straight to 4GHz?

Because they didn't have the technology.

Jim

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On Sat, 16 Apr 2011 11:11:00 +0100, Orchid XP v8 wrote:

> Designing it so the car doesn't survive the crash but the people inside
> do would be even more miraculous...

You've never seen a car crash (or the results of one), have you?  Most of 
them are *designed* to crumple in order to protect the passengers.

My father-in-law and brother-in-law used to operate an auto body shop.

> It's news to me that anybody is producing electric cars yet. I'm aware
> that they've been producing proof-of-concept designs for decades. But I
> didn't think any of this stuff had reached the shops yet.

Most of them are hybrid petrol/electric vehicles, but there are a few 
production models.  You just need to look at the stuff on The Register 
(where I've read about a few as recently as *yesterday*).

Jim

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Le 2011/04/16 06:09, Orchid XP v8 a écrit :
> On 15/04/2011 07:24 PM, Darren New wrote:
>> On 4/15/2011 10:00, Orchid XP v8 wrote:
>>> If it's so simple and easy, why isn't everyone doing it?
>>
>> Hey, 3GHz 4-core processors only cost like $200. Why didn't we have
>> those back in the original PC?
>
> I've often wondered about this. Why did people design a 33MHz CPU, and
> then a 66MHz one, and then 100MHz, and so forth? Why didn't they just go
> straight to 4GHz?
>
>> The longer the half life, the less radiation is being emitted per pound
>> of material. That just falls out of the definition of half life.
>
> So the radiation is actually *caused by* the substance decaying?
>

Exactly.

When an uranium nucleus emits an alpha particle, it's no longer uranium 
as it just lost 2 protons and 2 neutrons to become thorium. That thorium 
will, in turn also deckay into radium, then radon, polonium and finaly 
into lead.
This is the alpha deckay of uranium. Plutonium can alpha deckay into 
uranium.

The beta radiation is usualy caused when an extra neutron mutate into a 
proton. The electron is emited to maintain the electrical balance.
The beta deckay of uranium 238 transforms the uranium into neptunium 238 
that further deckay into plutonium 238 in a second beta event.



Alain

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> On 4/15/2011 5:26 AM, Bill Pragnell wrote:
>> Invisible<voi### [at] devnull> wrote:
>>> Nuclear power works in theory. In practise, if you make even the tiniest
>>> mistake, just once, everything is ruined forever. (Or at least, for
>>> several centuries.) And there's nothing you can do to fix it.
>>
>> That's not really true. Chernobyl was caused by a very long chain of
>> mistakes,
>> all committed with a reactor design which was already itself a long
>> chain of
>> mistakes. It should be noted that most other countries have never built a
>> reactor that could fail as catastrophically as this, even through wilful
>> sabotage.
>>
>> TMI was also long chain of mistakes, which resulted in only the
>> reactor being
>> ruined, and they did fix it.
>>
>> I suppose you could say that Fukushima was really only one very big
>> mistake,
>> i.e. how big a tsunami was ever likely to be. However, they show every
>> sign of
>> being able to fix it eventually.
>>
> No, the "big" mistakes where:
>
> 1. Having no way to cool it, or certainty that the power systems would
> still work, to do so, if enough failures happened. And, no, battery
> backup doesn't work, if it lasts less than 24 hours.
>
> 2. Placing the old, spent, fuel in something that was ever *less*
> effectively cooled.
>
> And, I would add 3. Presuming that a *big* reactor, which produces
> massive amounts of power, but where it would be nearly impossible to
> either make it less hazardous, or run battery backup long enough, or
> otherwise create a system that *could* compensate for major problems,
> remains bloody stupid.
>

Some more gross mistakes at Fukushima:

a. Need *EXTERIOR* power source to run the cooling system when you 
produce that power localy.
The pumps failed when the power lines TO the reactor got damaged by the 
tsunami. That's a humongously huge mistake!

b. NO passive shutdown mechanism. Sanity *demands* that there are 
several controll rods suspended by electro magnets powered by the 
reactor itself over the core. If the cooling system fails, the turbines 
stop, they no longer produce current, shutting down the magnets whitch 
let the controll rods fall into the core, stoping the nuclear reaction 
and thus the heat generation. Those rods are usualy made of cadmium 
because that metal can absorbs huge amounts of neutrons.
Those rods must be set and designed so that gravity alone will make them 
fall completely into position.
There where obviously none! Totaly insane!

c. NO passive cooling mesures. A passive cooling mesure should be enough 
to evecuate the residual heat from the shut down reactor.

d. Severly skipping on maintenance for over 10 years.
The director of the station said so himself...



Alain

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On 4/15/2011 8:50 PM, Darren New wrote:
> On 4/15/2011 19:57, Patrick Elliott wrote:
>> The problem isn't nuclear explosions, its hydrogen generated by the
>> system,
>
> Are you talking about the alpha radiation or something? I can't imagine
> where hydrogen would come from unless they're cracking water or something.
>
As I understand it, with the reactors in question, the rods are stored 
in a "casing", which can resist the heat of a normal reactor, but.. and 
I may be incorrect with this, when they get hot enough to start 
corroding/failing, they either release hydrogen themselves. Right, 
confirmed from the a news link on it: "When the fuel rods are left 
uncovered by water, they'll get far too hot--we're talking thousands of 
degrees Celsius here--and begin to oxidize, or rust. That oxidation will 
react with the water that's left, producing highly explosive hydrogen gas."

So, the "steam" that breaches the containment on these isn't just steam, 
its hydrogen gas, which gets released at those excess temperatures. 
While some is produced during normal operation, its small, and easily 
dealt with. So.. Its not just a case of it getting real hot, and the 
water boiling off. You have *that* problem, then due to the construction 
of the rods/casings, you *also* produce a gas that is both a) expanding 
into the chamber, which can breach it, and b) extremely flammable, if 
air can mix into it at all, through say, a large enough crack, when 
combined with some ignition source.

All in all, a bad design, since any failure doesn't just create a known, 
and easy to deal with problem, i.e., getting it cool again, it escalates 
and produces even *more* problems, which turn a non-explosive system 
into one that emits flammable materials. Its sort of like building a car 
so that, if you hit something, the rear seat pops loose and hurls all 
the trunk contents into the passenger cab as well.

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On 4/16/2011 15:47, Patrick Elliott wrote:
> That oxidation will react with the water that's left,
> producing highly explosive hydrogen gas."

OK. That's what I guessed. Cracking the water to release hydrogen.

> All in all, a bad design,

Certainly not the best design, yeah. :-)

-- 
Darren New, San Diego CA, USA (PST)
   "Coding without comments is like
    driving without turn signals."

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On 4/16/2011 12:02 PM, Alain wrote:

>> On 4/15/2011 5:26 AM, Bill Pragnell wrote:
>>> Invisible<voi### [at] devnull> wrote:
>>>> Nuclear power works in theory. In practise, if you make even the
>>>> tiniest
>>>> mistake, just once, everything is ruined forever. (Or at least, for
>>>> several centuries.) And there's nothing you can do to fix it.
>>>
>>> That's not really true. Chernobyl was caused by a very long chain of
>>> mistakes,
>>> all committed with a reactor design which was already itself a long
>>> chain of
>>> mistakes. It should be noted that most other countries have never
>>> built a
>>> reactor that could fail as catastrophically as this, even through wilful
>>> sabotage.
>>>
>>> TMI was also long chain of mistakes, which resulted in only the
>>> reactor being
>>> ruined, and they did fix it.
>>>
>>> I suppose you could say that Fukushima was really only one very big
>>> mistake,
>>> i.e. how big a tsunami was ever likely to be. However, they show every
>>> sign of
>>> being able to fix it eventually.
>>>
>> No, the "big" mistakes where:
>>
>> 1. Having no way to cool it, or certainty that the power systems would
>> still work, to do so, if enough failures happened. And, no, battery
>> backup doesn't work, if it lasts less than 24 hours.
>>
>> 2. Placing the old, spent, fuel in something that was ever *less*
>> effectively cooled.
>>
>> And, I would add 3. Presuming that a *big* reactor, which produces
>> massive amounts of power, but where it would be nearly impossible to
>> either make it less hazardous, or run battery backup long enough, or
>> otherwise create a system that *could* compensate for major problems,
>> remains bloody stupid.
>>
>
> Some more gross mistakes at Fukushima:
>
> a. Need *EXTERIOR* power source to run the cooling system when you
> produce that power localy.
> The pumps failed when the power lines TO the reactor got damaged by the
> tsunami. That's a humongously huge mistake!
>
> b. NO passive shutdown mechanism. Sanity *demands* that there are
> several controll rods suspended by electro magnets powered by the
> reactor itself over the core. If the cooling system fails, the turbines
> stop, they no longer produce current, shutting down the magnets whitch
> let the controll rods fall into the core, stoping the nuclear reaction
> and thus the heat generation. Those rods are usualy made of cadmium
> because that metal can absorbs huge amounts of neutrons.
> Those rods must be set and designed so that gravity alone will make them
> fall completely into position.
> There where obviously none! Totaly insane!
>
> c. NO passive cooling mesures. A passive cooling mesure should be enough
> to evecuate the residual heat from the shut down reactor.
>
> d. Severly skipping on maintenance for over 10 years.
> The director of the station said so himself...
>
>
>
> Alain
Yeah. Those would have been a damn good idea too.

a) makes no damn sense to me at all (even if it was some minimal system, 
enough to just keep pumps going), unless the tsunami took out 
lines/systems in the actual turbine part of the system. I would have 
thought those would be internal to the reactor, but.. Then again, their 
systems reuse a lot of waste heat/energy, so its hard to say how complex 
the whole thing was, and thus "where" those systems where, and thus 
whether it was even feasible to have the turbines in the reactor 
buildings. Its a definite WTF for me, but may go towards the whole, "If 
you make the thing so damn big you can't do *basic* shit to keep it 
working, you may be building them too big." If I where to guess... They 
probably have "internal systems that funnel water to and from the 
reactor, then a "heat exchange" point, with and entirely separate 
system, which is external to the reactors themselves. This would then 
run out to their actual turbine systems, where the heated water produces 
the actual power, is cooled, then pumped back into the exchanger. You 
don't want to run radioactive water through the turbines, or use a 
system where water from one might get into the other. This means that, 
for practical purposes, power isn't generated "in" the reactor itself, 
at all. So...

b) not sure any of them have this. Its not enough to just drop in a few, 
in most cases, and.. well, if you can bend the damn things to shit in a 
system that runs them in slowly, you can imagine what sort of mess you 
end up with if some of them jam being "gravity dropped" into place. 
Again, the whole design seems a problem, and most of it due to scale, 
not just this one issue.

c) Hmm.. This is an interesting problem. How do you make a passive 
cooling system which doesn't move contaminated air, or water, or 
something else, and exchange it often/fast/effective enough to do that? 
We are talking about something heating to temperatures on massive 
scales, pretty damn fast, with a *major* exchange requirement. Again, 
size here matters. Think of it like trying to cool a high end CPU, using 
only a bit of foil taped to the top, because someone had to build the 
case so an actual radiator grill and electric fan wouldn't fit in there. 
You can get by with it if you are using low power, a lower end chip, 
etc., but... scale up to a PC, or, in the case of power plants, a full 
size nuclear reactor... and you "passive" systems are just not going to 
cut it in any practical sense.

So.. Again, seems to me, once you get past the basics of, "make sure the 
damn thing can run the active systems long enough to matter", everything 
else is, "scale, scale, scale", and the impracticality of doing jack to 
solve such problems at the scales being talked about. And, short of 
building the damn things in Antarctica, and somehow getting the power 
from there to every place else, I don't see "passive" being too viable...

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