US stocks fell yesterday in the aftermath of Japan s devastating earthquake, but other than specific industries such as nuclear power, the broad impact on equities was expected to be short-lived.  Trading volume was unusually low when compared to other sell-offs, coming in at 7.54 billion shares traded on the New York Stock Exchange, the american Stock Exchange and Nasdaq, lower than last year s daily average of 8.47 billion. The recent pullback in stocks had been accompanied by high volume.  I m encouraged that we re seeing lighter volume on a down day since that could suggest less enthusiasm for selling,  said Hank Herrmann, chief executive of Waddell & Reed Financial in Overland Park, Kansas, which manages $90 billion in assets.  Nuclear power stocks fell after explosions at a Japanese plant. The Market Vectors uranium and nuclear energy exchange traded fund slumped 12%, while the Global X Uranium ETF sank 17%. But the Market Vectors Solar Energy ETF of alternative energy shares climbed 7.2%.  General Electric, which has combined nuclear ventures with Hitachi, dropped 2.2%.  The Dow Jones industrials  fell 51.24 points, or 0.43%, at 11,993.16. The S&P 500 lost 7.89 points, or 0.60%, at 1296.39. The Nasdaq Composite dropped 14.64 points, or 0.54%, at 2700.97.