The stress tests in Belgium

After an undersea earthquake and the subsequent tsunami in 2011 with serious damage to the Fukushima nuclear power plant, Europe decided to subject all nuclear power plants to resistance tests or ‘stress tests’. These tests were intended to assess the safety margins of nuclear power plants in extreme circumstances.

What happened in Fukushima?

On 11 March 2011 the nuclear power plant of Fukushima – Daiichi was automatically shut down due to an earthquake. The tsunami which followed it destroyed the cooling system of the reactors 1, 2 and 3. Due to overheating, the fuel rods largely melted, and explosions occurred, which caused high levels of radioactivity to be released.

Can the Fukushima accident also occur in Belgium?

The seismic activity around the sites of Doel and Tihange is in nothing similar to that in Japan. The site in Japan is located on a fault line between large continental and oceanic plates. In addition, the investigation into the accident of Fukushima shows that it was not caused by the earthquake itself but by the subsequent tsunami. The risk of a tsunami in Doel and Tihange is very limited.

The Belgian nuclear power plants differ greatly from the Japanese power stations in Fukushima in terms of design. The Belgian power stations are PWR reactors (Pressurized Water Reactor). They are safer than BWR reactors (Boiling Water Reactor) such as Fukushima.

The uranium pellets are contained in sealed fuel rods which are placed in the reactor vessel. The steel reactor vessel has a thickness of 20 cm and is located in the reactor building. The reactor building is composed of 2 concrete walls, each of 1 metre thickness. The risk of a disaster due to an earthquake or flooding is almost negligible in Belgium. In addition, the Belgian nuclear power plants are resistant to extreme conditions, including floods.

What lessons were learned from these accidents?

After the disaster in Fukushima, all European sites with nuclear installations were subjected to tests by the European Union, the so-called ‘stress tests’ (resistance tests). These tests checked to what extent the installation is resistant to extreme natural phenomena. In Belgium, we also examined to what extent the power stations were resistant to human acts such as terrorism and cyber attacks. The tests showed that the Belgian power stations were among the most robust in Europe and were sufficiently protected from natural events and deliberate acts (terrorism).

What investments were carried out in our power stations after these Belgian Stress Tests (BEST)?

The total investments in relation to BEST are about 200 million euro. These investments contribute to the continuous improvement of the nuclear safety of the installations and make them resistant against the most extreme situations.

The most prominent action which was carried out in Tihange following the BEST project is the construction of the wall around the site. This structure protects the site of Tihange against floods in exceptionally high water conditions of the Maas. The complex structure is 2.3 meters high and 1.8 kilometres long and is equipped with locks, drain channels and pumps. The wall was taken into service in October 2015.

The fire-fighting trucks which were purchased by the sites are able to fight a fire up to a height of more than 65 meters, the height of the reactor building. The vehicle can also be used in the event of flooding on the site. It has submersible pumps which can pump away 10,000 litres per minute.

Both sites are equipped with specific emergency equipment. These are often mobile installations ( pumps, diesel generators …) which can be used if the electrical supply and/or all the possibilities to route away the heat from the core are unavailable.

In Doel a special seismic building (Building for Emergency Equipment) was set up to store mobile pumps, diesel generators, firefighting equipment and fire engines, in a safe location.

All nuclear power plants in Doel as well as Tihange are also equipped with a ‘Filtered Containment Vent’ system. This system is fitted with a special filter, which ensures that in extreme accident situations no radioactivity reaches the surrounding area.

And finally, on both sites a new emergency plan organisation was developed to control a major incident on all units at once.

The Federal Agency for Nuclear Control analysed the ‘Belgian Stress Tests’ reports for Doel and Tihange. Their conclusion? The nuclear power plants can withstand extreme conditions without risk, with a guarantee of the essential safety functions. The agency set up a plan with improvement actions and added the recommendations of the European Nuclear Safety Regulations Group (ENSREG). ENSREG has thoroughly examined the results of all stress tests. Based on its report, the European Commission decided that the Belgian nuclear power plants were among the most robust.

Additional info:


Infofolder weerstandstesten (NL) (pdf, 153.88 KB)

Infofolder weerstandstesten (FR) (pdf, 214.24 KB)

Actieplan BEST FANC december 2012 (EN) (pdf, 857.46 KB)

Weerstandstesten progress report augustus 2011 (EN) (pdf, 1.53 MB)

Resultaten weerstandstesten Doel november 2011 (NL) (pdf, 832.1 KB)

Persmededeling weerstandstesten november 2011 (NL) (pdf, 318.86 KB)

Eindrapport Doel oktober 2011 (NL) (pdf, 12.84 MB)

Eindrapport Tihange oktober 2011 (FR) (pdf, 13.4 MB)