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,
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
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