South Korea's nuclear regulator may decide as soon as today whether to extend the operating license for the Wolsong No. 1 nuclear reactor, the first to come up for renewal since the 2011 Fukushima disaster in neighboring Japan.

The 679-megawatt reactor, South Korea's second-oldest, has been offline since its original 30-year license expired in 2012. Operator Korea Hydro & Nuclear Power Co. has already spent 560 billion won ($520 million) to refit the reactor as it seeks approval to extend its operating life to 2022.

While approval was essentially a foregone conclusion when regulators last faced this issue in 2007, since then the triple meltdown at Fukushima, a domestic scandal over forged safety documents and a hacking attack on Korea Hydro's computer network have galvanized the country's anti-nuclear movement. Even if money already spent tips the Wolsong decision in its favor this time, mounting public opposition means the state-run operator can no longer be guaranteed to get its own way.