“The Japanese elections seem like what people are pointing to,” Winer said in an interview. Buying by bears who borrowed the stock and sold it plays in “a little bit for sure, but I think this is just a frenzy,” he said.

The stock, which has about 4.7 million shares available for trading after a 1-for-25 reverse split this month, has gained or lost an average of 5.4 percent a day this year, compared with moves of 0.7 percent for the Russell 2000, according to data compiled by Bloomberg. Japan's Abe will likely seek to restart many of the country's nuclear reactors that were shut after the 2011 earthquake and tsunami, said Yousef Abbasi, market strategist at JonesTrading Institutional Services LLC, a Westlake, California-based broker. Paul Jacobson, spokesman for USEC, said the company would not comment on moves in the share price.

About 16 percent of USEC's shares available for trading were borrowed and sold short as of July 18, according to Markit, a London-based research firm. That compares with bearish wagers of 5 percent on average among stocks in the Russell 2000.

Eoin Treacy's view Few sectors are as depressed as uranium mining. Faced with a loss of market share in the utility sector and increased public antipathy following the Japanese tsunami, uranium shares have collapsed with a number going bust. Japan's restarting of its nuclear reactors can be viewed as a positive but considerably more will be required to reignite investor interest in the sector beyond current scope for short covering.

USEC is a uranium enrichment company rather than a mine. The share ranged mostly below $160 until 2011 and hit a low near $2 in July. It has rebounded to almost $13 over the last two weeks suggesting a medium-term low has been found but the most likely scenario from here is that a lengthy process of base formation unfolds which is likely to be volatile.