What a week for the stock market! We saw just how fast we can go from greed to fear when the ground trembles and a wall of water flows over an economic power a half world away. The 10% Promise Team has been trying to decipher what all of these moves mean, but no matter how you dice it, this week was all about Japan.

A meltdown isn't good for anyone, or is it?
It was no surprise when we saw nuclear stocks tumble early this week as news about Japan's nuclear plants affected by the earthquake and tsunami got worse by the day. USEC (NYSE: USU) led the way, plunging twice this week, and engineering and construction firm Shaw (NYSE: SHAW) followed a similar path as investors questioned the future of its projects.

But investors are betting that EnergySolutions (NYSE: ES) and Landauer (NYSE: LDR) will pick up business in Japan when the nuclear cleanup begins. There are always opportunities in investing no matter how bad a situation looks, and these two companies have a chance to turn a terrible situation into dollar signs for investors.

Tsunamis + nuclear meltdown = rising solar stocks?
What intrigued me most was the speculation outside of the nuclear sector that ensued throughout the week. Solar stocks were the biggest beneficiaries in the energy industry. JinkoSolar (NYSE: JKS), SunPower (Nasdaq: SPWRA), and Trina Solar (NYSE: TSL) all jumped this week on speculation that new pressure on the nuclear industry would be good for solar manufacturers.

We may be taking a bigger leap than even a solar booster would be comfortable with by assuming Japan's disaster is good for solar. Yes, in the long term this may change the political discussion, but we're making a lot of assumptions pushing solar stocks 10% higher in the short term. Japan is a supplier to the market, and if any economic slowdown ensues as a result of this disaster, it would likely hurt solar. I think this is more of a wash for the sector in the short term, but that's just one Fool's opinion.

Do I know more today than I did a week ago?
My biggest lesson this week is I know even less about the future of nuclear energy than I did seven days ago. I can't find a positive way to spin Japan's nuclear disaster for nuclear stocks, but the big question is if it will change how we look at nuclear in the U.S., Europe, and emerging economies like Russia. Once we answer that we may be able to speculate what it means for other energy sources like coal, natural gas, and solar. But until then I don't know if nuclear is dead in the water or still moving forward.

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