Regulators group responds to Fukushima

01 October 2014

New nuclear safety reference levels have been published by the Western European Nuclear Regulators Association (Wenra) as part of its response to the Fukushima Daiichi accident.

The new reference levels have been agreed by Wenra's 17 members, which are the independent nuclear regulators representing their respective countries. A principal aim of Wenra is to "develop a harmonized approach to nuclear safety" within its membership, which are now expected to converge their individual regimes around Wenra's levels.

Western European Nuclear Regulators Association (Wenra)
Wenra's members account for 136 nuclear power reactors in 17 countries: Belgium, Bulgaria, Czech Republic, Finland, France, Germany, Hungary, Italy, Lithuania, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, the Netherlands and the UK. It also counts nuclear power users Armenia, Russia and Ukraine among its official observers.

Wenra's reference levels were initially drafted in 2006, and updated in 2007 and 2008. With this 2014 revision they have been "further updated to take into account the lessons learned, including the insight from the EU stress tests" that followed the Fukushima Daiichi accident, said Wenra.

Additions include a new passage on natural hazards, wordings on the need to be able to remove heat from used fuel pools, and to ensure basic information is available on the status of the reactor core and used fuel pool during accident conditions. If the main control room is not available, plant operators should have sufficient information and control capability from a separate location.

The principle of 'continuous improvement' that underlies human and plant performance should also be applied to the design basis of nuclear power plants, said Wenra. It introduced the concept of 'design extension conditions' beyond a plant's design basis. Even under these extraordinary circumstances, said Wenra, a nuclear power plant and its staff should be more robust against challenging events or conditions, avoid radioactive releases and have sufficient margins to avoid 'cliff edge effects' beyond which a severe accident would become unavoidable. This kind of analysis, as well as resulting technical and operation improvements, would be applied to the reactor system as well as the used fuel pool.

"By issuing the revised reference levels, Wenra aims at further convergence of national requirements and safety improvements at nuclear power plants in Wenra member countries, as necessary," said the body.

Researched and written
by World Nuclear News