Rich Ulrich wrote:
> On Thu, 07 Sep 2000 02:20:27 GMT, Thomas Gatliffe
> <[EMAIL PROTECTED]> wrote:
>
> > Rich Ulrich wrote:
> >
> > > An example in English: I think this underlies the delicacy needed in
> > > the control of a nuclear power plant (in the most common U.S. design).
>
> > Actually, once a power reactor has been brought slowly but correctly into the
> > normal operating condition, it doesn't really require all that much delicacy. It
> > becomes pretty much self-controlling. The temperature of the primary coolant
> > determines its effectiveness as a neutron moderator and how well neutrons are
> > able to remain within the reactor to initiate another fission or be lost to other
> > possibilities such as absorption in a control rod or other non-fissionable
> > material before reaching the apropriate thermal energy level. The temperature of
> > the primary coolant is a function of the balance between power produced in the
> > core and power extracted for energy applications. If more power is extracted,
> > the primary coolant cools and becomes a more effective neutron moderator
> > increasing the flux of thermal neutrons and causing the fission rate to increase,
>
> - so the temperature of the pressurized water has soooo much effect
> on its neutron-absorbancy, that it can be used as an effective
> feedback control on the reaction.
>
> I don't know about your standards, but that sounds a little-bit
> delicate, to me, since it implies 100% control over all outside
> sources of variation in the temperature. Doesn't it?
>
No, it doesn't. The engineering design includes temperature variations, but because
you are unfamiliar with core design I am not supprised that you seem to think that
"outside sources" have a significant influence or are even detectable in normal
operation. It is true that certain accident scenarios include significant temperature
excursions based at least partially in external conditions, but I was talking about
normal power production conditions. If you want to concentrate on potential accident
scenarios, also consider the likelihood of such events and look at the considerable
mitigating effects of the several levels of redundancy built into the safety systems.
(We don't build to Russian standards.)
>
> And loss-of-coolant leads to INCREASED reaction.
>
No, a "loss-of-coolant" leads to automatic shutdown and, thus, DECREASED reaction. (If
you want to shout for emphasis, you give me permission to do so, too, but it doesn't
really lend any more validity to either point of view.)
>
> During the TMI incident, they worried that there was a hydrogen bubble
> imitating loss-of-coolant. I don't remember if it really was, or not.
>
Who were "they"? The anti-nuke crowd? This is a pretty far-fetched possibility but
when you experience an unplanned event all possible scenarios do need to be evaluated
and appropriate countermeasures prepared. But don't confuse "possibility" with
"probability".
>
> > generating more power in the form of heat which can be extracted in the form of
> > thermal energy or which will make the coolant warmer and thus a less effective
> > neutron moderator, slowing the fission rate and power production. Under normal
> > opearting conditions, very little control rod movement ever is required (old
> > "Voyage to the Bottom of the Sea" episodes not withstanding. "Kawalski, don't go
> > into that compartment! Everybody knows this week's monster is going to smack you
> > over the head and get you!")
> >
> > The most common U.S. design is a pressurized water reactor and is pretty damned
> > safe in spite of the Greens' hysteria.
> >
> > Tom Gatliffe
>
> I was anti-nuke before 1980, and I never felt 'hysterical' by
> standards I have ever employed.
> History since then has only seemed to confirm my early convictions.
>
I define "hysteria" as spreading fears based in ignorance and I stand by my
assessment. People fear that which they do not understand and nuclear power production
is not as easily understood or as familiar as burning fossil fuels to the averge
person. The anti-nuke activists were shrewd enough to use this to their advantage.
>
> Actually, it was the interest rates in the late 1970s-1980s that
> killed off nuclear investments, before the US Greens ever acted out
> any hysteria on this subject.
>
> I always had far more faith in the engineers to make robust designs.
> than my faith in MBAs to keep the plants running. And profitable.
> And running safely, even when not-quite-profitable....
>
> And I had little faith that Congressmen or energy-industry VPs would
> see that the wastes would be disposed of. And that doubt has been
> justified.
>
Really? Right now the Department of Energy is spending hundreds of millions of dollars
to properly dispose of nuclear waste, in spite of the activists' protestations that the
stuff is too dangerous to move and we should leave it in place. Fear, fear, fear,
mindless fear based once again in ignorance.
>
> --
> Rich Ulrich, [EMAIL PROTECTED]
> http://www.pitt.edu/~wpilib/index.html
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