Five Greenpeace activists last week entered the security zone of what will soon be the world's biggest nuclear power plant - the Kori nuclear power plant (NPP) near Busan in South Korea. Arriving via a black inflatable boat, they climbed out and scampered up a rocky slope unfurling a bright yellow banner in front of the fence of the Kori NPP. For 40 minutes they stood ground as guards looked on, sirens blazed, and warnings from the coast guard were broadcast over the loudspeaker.

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

When the next two planned reactors start operation by 2022, it will become the only nuclear power plant with 10 reactors. And what is most disturbing is that there are around 3.4 million people living within the 30km zone around the plant.

But what makes someone board a small boat - sometimes for the first time in their lives - on a cold morning and scamper up the slopes of nuclear power plant?

What keeps you standing strong as the coastguard and police descend on you?

Why take these personal risks?

Myungjin Choi explains why he took part in a non-violent action to expose the risks of the what will be the world's biggest nuclear power plant. 11 Oct, 2015 © Taekyong Jung / Greenpeace

Myungjin Choi decided to participate in the Greenpeace action because he believes that small actions leads to bigger change. At first, he worried  that the activity might be too risky or what would happen if he made a mistake. However, whenever he thought about the citizens living near Kori nuclear power plant, he became bolder.

Jeongmin Lee explains why she took part in a non-violent action to expose the risks of the what will be the world's biggest nuclear power plant. 11 Oct, 2015 © Taekyong Jung / Greenpeace 

Jeongmin Lee works as a fundraiser in a health and medical NGO. She is quiet and considers herself an introvert, but, she did not hesitate to take direct action to make the world a better place to live. She says  direct action empowers her to overcome an inherent fear inside of her.

Reiyoung Kim explains why he took part in a non-violent action to expose the risks of the what will be the world's biggest nuclear power plant. 11 Oct, 2015 © Taekyong Jung / Greenpeace

Activist Reiyoung Kim could not just sit still and watch the development of the nuclear power plants. He decided to act to let more people know about the dangers posed by the Kori nuclear plant.

Junho Lee explains why he took part in a non-violent action to expose the risks of the what will be the world's biggest nuclear power plant. 11 Oct, 2015 © Taekyong Jung / Greenpeace

Activist Junho Lee is a drummer in a rock band and a nature-lover who is actively engaged in environmental activities.

These five individuals are part of Greenpeace's tradition of non-violent direct action. They are part of a history of exposing environmental threats, putting their bodies on the line to bear witness and drive change.

Find out how you can get involved.

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