Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: USEC (NYSE: USU) investors are getting slammed for the second day in a row as shares of the supplier of low-enriched uranium are lower by 10%.

So what: Today's move lower is a carryover from yesterday's concerns of a possible nuclear meltdown in Japan directly related to Friday's earthquake. Traders are questioning the long-term viability of nuclear power and the entire sector including Cameco (NYSE: CCJ), Uranium Resources (Nasdaq: URRE) and Denison Mines (AMEX: DNN) are trading off considerably.

Now what: I think it's a bit early to throw in the towel on nuclear energy in general, but it's also probably a bad idea to jump into a raging river. This sector is a mess right now. Uranium spot prices are falling rapidly, and USEC could potentially see demand disruptions directly related to this earthquake. In this case, I'd be more than willing to wait on the sidelines and let this situation play out until we have a clearer picture of where USEC might fall in the role of future nuclear generation.

Interested in more info on USEC? Add it to your watchlist by clicking here.

Fool contributor Sean Williams does not own shares in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong.

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