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Name: Kate P.
Status: Student
Age: 14
Location: N/A
Country: N/A
Date: November 2002


Question:
What is the efficiency of nuclear energy?



Replies:
This is not an easy question, because it depends upon how you define "efficiency". From a fundamental perspective, efficiency can be defined as: Efficiency = 100x [Th -Tc] / Th where:

Th and Tc are the temperature of the reactor core and Tc is the temperature at which the heat is expelled from the generator (all temperatures in kelvins). So, let's say Th = 1000 K and Tc = 300 K, then: Efficiency is: 100x [1000 - 300] / 1000 or 70%. This is an ideal maximum. It does not take into account heat exchanger efficiency, heat losses in pipes, the energy used to pump fluids around, and all the other "machinery" necessary to produce energy in an operating power plant. All of those losses could cut this "efficiency" in half. Some models for efficiency go into more detail by incorporating "down time". For example, if a power plant has to be put on hold for 36.5 days per year for maintenance, then its efficiency would be decreased by another 10%.

Other efficiency "models" incorporate the "cost" of operation in terms energy output. Such costs involve dollars required for monitoring, cost of waste disposal, and so on.

So the answer to your question has a lot to do who and why the calculation is being done.

Vince Calder



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