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?
And loss-of-coolant leads to INCREASED reaction.
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.
> 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.
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.
--
Rich Ulrich, [EMAIL PROTECTED]
http://www.pitt.edu/~wpilib/index.html
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