At dawn on Monday this week (local time), Greenpeace activists began blocking the construction of the European Pressurized Reactor (EPR) being built at Flamanville, France. Two trucks were anchored to the ground, blockading the entrance carrying activists. More activists scaled four cranes, attempting to impede further construction work at the site.

Why did we do this? The situation at Fukushima in Japan demands a reassessment of all reactor safety, and the first thing to do is stop construction of the new ones so that any modifications can be properly implemented. The EPR design in particular has a number of safety risks similar to Fukushima, as the French nuclear safety authority ASN pointed out a few weeks ago. The regulator must now act and enforce a moratorium on this site.

The EPR was designed after drawing lessons from Three Mile Island and Chernobyl. Now the lessons of the Fukushima accident need to be taken into account. Problems with the EPR include a vital dependence on a continuous power supply to cool the reactor, the risk of hydrogen explosions, the location of backup diesel generators close to the ground making them susceptible to flooding, pools with spent fuel located outside the protective containment building, and the close proximity of the control room to the reactor which could make it inaccessible in the event of a large radiation release.

The EPR is promoted as the flagship of new generation of reactors. It is the largest reactor in the world but none are currently in operation. Two projects are underway in Europe, one in Finland and one in France. They have both been struggling with thousands of technical and safety problems, delays and cost overruns.

Nuclear safety doesn’t exist, there are only inherent reactor risks. As we have seen most recently in Japan, the technology is too complex and vulnerable to a deadly mix of human error, technology failures and natural disaster. Thankfully, we have a choice. We need to move towards renewable energy and efficiency technologies which are mature enough to supply sufficient amount of affordable power to meet our needs even without dangerous reactors and fossils fuels.

Greenpeace demands the cancellation of the construction of all new reactors, and the phase-out of current nuclear power plants at the end of their design lifetime - at the latest.