Fukushima operator TEPCO's shares soared almost 33 percent Monday, leading an energy firm rally after a conservative election win likely to mean any short-term plans to ditch atomic power will be shelved.
Tokyo Electric Power (TEPCO) rocketed 32.89 percent to 202 yen by the break, Chubu Electric Power jumped 7.56 percent to 1,166 yen and Kansai Electric was up 13.68 percent at 889 yen.
The huge surge on the Tokyo Stock Exchange came after voters on Sunday dumped Prime Minister Yoshihiko Noda and his Democratic Party of Japan (DPJ), giving the pro-business Liberal Democratic Party a landslide victory.
Anti-nuclear sentiment has run high in Japan after last year's Fukushima atomic crisis, with opinion polls showing a majority of voters wanted to phase out nuclear power.
However, that failed to translate into wider support for the DPJ, which had pledged to work toward a zero-nuclear country, or a group of small anti-nuclear parties which had little impact at the polling booth.
Premier-in-waiting Shinzo Abe, the LDP's hawkish head, derided the zero-nuclear goal as unrealistic and "irresponsible" -- and hinted at keeping atomic power.
The LDP has said it would decide on reactor restarts in three years and the nation's "best energy mix" within a decade.
Major business lobby Keidanren said in a statement Monday that it "welcomes the LDP's landslide victory".
Japan's private sector had bemoaned the nation's energy bills as already too high with less nuclear meaning more challenges for Japan Inc. which was wrestling with a strong yen and weakening overseas demand.
All but two of Japan's 50 reactors remain switched off in the wake of last year's atomic accident, the worst in a generation.
To plug the energy gap, Japan turned to pricey fossil fuel alternatives -- nuclear once supplied about one-third of the resource-poor nation's power mix.
"We think an LDP victory would reduce the long-term risk of even relatively new nuclear power plants being forcibly decommissioned," Nomura Securities said in a client note.
The Abe administration was unlikely to rush on reactor restarts until experts from the Nuclear Regulation Authority decide which plants are safe to go back online, the brokerage said.
"Japanese electric power companies will still look to LNG (liquefied natural gas) as an alternative to nuclear power even if the LDP returns to government," it added.
"However, the move away from nuclear power would probably be slower than under the DPJ, meaning a corresponding slower shift to LNG."
Abe's opponents say the LDP's cosy attitude to regulation was a big factor in the lax supervision that worsened the disaster at Fukushima, which saw a quake-sparked tsunami slam into the plant, swamping its cooling systems and sending reactors into meltdown.