Over 3 million people live within 30 km of what is set to become the largest nuclear power plant in South Korea and the world. So why is the government expanding nuclear and locking out safe, clean renewables?

Greenpeace activists holds a non-violent direct action at the Kori Nuclear Power Plant Complex.

Two inflatables with ten courageous and committed activists from around the world departed this morning to protest the expansion of the Kori Nuclear Power Plant, near Busan. They are taking action to highlight the risk of nuclear power and the urgent need to transition to clean, safe renewables.

The situation at Kori is insane, and it's only getting worse. Here's why the need for action is so urgent.

1. When the next unit is expected to go online next month, it will become the world's largest nuclear power plant in terms of installed capacity (6860MW) with 7 reactors in operation.

Greenpeace activists holds a non-violent direct action at the Kori Nuclear Power Plant Complex.

2. What is most disturbing is that there are around 3.4 million people living within the 30km zone around the plant. This compares to 160,000 in the case of Fukushima.

Greenpeace ship the Rainbow Warrior near the Kori Nuclear Power Plant in South Korea

3. When the two planned reactors start operation by 2020, it will become the only nuclear power plant with 10 reactors and more than 10,000 MW in the world.

Greenpeace activists holds a non-violent direct action at the Kori Nuclear Power Plant Complex. In Ulsan, South Korea.

4. More reactors = more risk. One of the critical lessons from the disastrous Fukushima disaster is that multiple reactors means increased risk.

 Greenpeace activists holds a non-violent direct action at the Kori Nuclear Power Plant Complex. In Ulsan, South Korea

5. Since beginning operation in 1978, the plant has continuously encountered problems including malfunctions, lack of safety regulations and poor maintenance. In February 2012 a complete station blackout was deliberately concealed by the high level decision makers at the Kori plant, only to be reported to the Nuclear Safety and Security Commission (NSCC), South Korea's regulatory body, a month later.

Greenpeace activists holds a non-violent direct action at the Kori Nuclear Power Plant Complex. In Ulsan, South Korea

We aim to expose the intolerable risk of adding two more reactors to the world's largest nuclear power plant and the threat it poses to the general public and the citizens of Busan. The future is renewables. We've already helped convince one big company in South Korea to switch to 100% renewable energy – so what is the South Korean government waiting for? Out with the old, and in with the new!

It's time to switch on renewables and abandon costly, dangerous nuclear.

Daul Jang is the Project Leader for the Climate and Energy Campaign at Greenpeace East Asia in Seoul.