Heat Wave Shuts Down Alabama Reactor

mdsolar writes "In a first for the US, one of three nuclear reactors at the Browns Ferry nuclear plant in Alabama has been shut down because the Tennessee River is too hot to provide adequate cooling for the waste heat produced by the reactor. This is happening as the TVA faces its highest demand for power ever, reports the Houston Chronicle. This effect has been seen in Europe in the past, forcing reduced generation, but the US has until now been immune to the problem. The TVA will buy power elsewhere and impose higher rates, blaming reduced river flow as a result of drought."

Comments

What to do with all that waste heat...

[NeverVotedBush]

I hadn't heard of this before now but can see how it can really be a problem. It takes temperature differences to make heat energy flow and without that, or without enough of one, it doesn't. This will also affect regular power plants too.

Looks like future plants - nuclear or conventional (coal/natural gas) will need to be engineered to carry more of the work of cooling their water. It can be done. It's just less efficient as there are more parasitic loads on the system.

Just remember - there is no such thing as global warming. Hurricanes blasting up to category 5 in a few days, droughts, floods, etc. - all of it is just coincidence and would happen whether we pumped billions of tons of CO2 into the atmosphere or not.

;-)

Re:River too hot?

[Ash Vince]

Why not just let the thing overheat and blow up?

Who needs Alabama anyway?

Re:What "waste heat"?

[mi]

The "fundamental limit of thermodynamics" for a heat engine is not 1, but rather 1 - T_c/T_h, where T_c and T_h are the absolute temperatures of the cold and hot sinks, respectively.

The cold sink is river's water. Even if it is at the boiling point, T_c is under 300. T_h is the temperature of the nuclear reaction, which could be in the thousands. It is not there because of the engineering limits. The T_c/T_h ratio can thus be well under 10% allowing for over 90% efficiency.

None of the existing reactors are close, of course — because there remain many engineering problems to be solved. That's if look at the plant as a closed system, whose entropy can only grow.

any more efficient, and the second law of thermodynamics would be violated.

That formula (of the Carnot cycle's efficiency) applies to closed systems, which a power plant is not. Because the "supply of cold" is external and endless (a river), the limit does not apply. For example, the high-temperature steam/water ("waste heat") can be used as the heat source for another heat engine (of lesser efficiency)...