EU Regulators Publish Positive Stress Test Peer Review

The following story originally appeared in NEI’s Nuclear Energy Overview.

A peer review by European nuclear regulators of the “stress tests” performed on 147 nuclear energy facilities in the European Union has found that most countries’ operators have identified and taken “significant steps” to improve plant safety in the wake of the Fukushima Daiichi accident of March 2011.

Within a month of the accident, the European Council requested a comprehensive safety and risk assessment of all EU nuclear plants, including “stress tests” to assess their ability to safely withstand the effects of severe natural hazards. The tests, whose scope was developed by the European Nuclear Safety Regulators Group (ENSREG) and the Western European Nuclear Regulators’ Association (WENRA), also gauged the effects of a loss of safety systems and reviewed operators’ severe accident management.

By the end of 2011, 15 EU countries with nuclear plants as well as Switzerland and Ukraine had submitted their national test results to the peer review board, which consisted of more than 70 experienced regulators, scientists and consultants from 24 countries.

The peer review results were published by ENSREG last week. Among the main findings were that despite some differences in national approach, there was overall consistency in the identification of lessons learned from Fukushima and measures to increase the safety of nuclear power plants. Among these are adding mobile equipment to prevent or mitigate severe accidents, installing hardened fixed equipment, and improving severe accident management.

The ENSREG peer review report noted that EU countries are already moving toward implementing some of these measures.

The report also recommends improvement in four main areas:

• Noting a lack of consistency among EU nations in assessing natural hazards, WENRA should solicit the “best available expertise” to develop consistent guidance to evaluate beyond-design-basis margins and “cliff-edge” effects.

• ENSREG should conduct periodic safety reviews to re-evaluate natural hazards and safety provisions to protect nuclear plants “at least every 10 years.”

• National regulators should urge prompt implementation of identified measures to protect reactor containment integrity in the event of a nuclear accident, including equipment, procedures and guidelines to depressurize the primary circuit and to prevent hydrogen explosions.

• Plant operators should take steps to prevent reactor accidents from beyond-design-basis natural hazards and to limit their consequences. Among the measures identified are the use of bunkered and mobile equipment, protected emergency response centers, and rapid-response rescue teams.

ENSREG noted that the peer review is expected to contribute to enhanced nuclear safety in Europe. However, it also said the effort was an “exceptional exercise” that required significant resources from participating countries.

The report is to be presented to the European Council heads of state in June. ENSREG and the European Council are developing an action plan to implement the report’s recommendations as well as those of the IAEA’s post-Fukushima action plan and the outcomes of an extraordinary meeting of the Convention on Nuclear Safety to be held in August.