DEC safety evaluations and challenges in Belgium.

• DEC safety evaluations. • Challenging issues for DEC assessements. Safety Criteria for DEC Analyses. Experiments for Computational tools validation. After the Fukushima-Daiichi accident, the need to consider safety analyses under design extension conditions of the nuclear power installations has largely increased. The objective is to reassess and investigate the possibilities of the current nuclear installations to withstand accidental conditions that were not originally covered by the design basis accident. In Belgium, new regulation introduces the Design Extension Conditions (DEC) in the requirements for the design and operation of nuclear power plants. The purpose is to assess the safety of the current operating nuclear power installations and to identify design improvements, procedural measures and additional practicable provisions or mitigation means that could be used to prevent severe accidents. This paper provides a brief overview of the issues and challenges related to DEC safety evaluations in Belgium for the Licensee and also for the Safety Authority. [ABSTRACT FROM AUTHOR]