Design Safety Improvements at Swiss BWRs after Fukushima

Post-Fukushima Safety Targets: • Assure robustness to withstand and cope with any severe Swiss natural hazard (10000 yearly extreme weather, flooding, earthquake events or combinations). • Assure control of T-LOOP during minimum 72 h without loosing safe shutdown condition. • Assure additional SAM-hardware and necessary auxiliary material as well as SAM staff preparedness (availability, level of training, procedures) so that: - a BDB event (with T-SBO) can be controlled during minimum 72 h without challenging safe shutdown condition; - a BDB event - if safe shutdown is not possible - will be limited to the lowest consequential level: - avoid major core damage; - avoid RPV-damage; - avoid H₂-explosion; - avoid major radiological releases to the environment. • Assure safety of long-term fuel pool cooling.