the european stress test for nuclear power plants

WENRA Safety Objectives for New Nuclear Power Plants 

Compared to currently operating nuclear power plants, WENRA expects new nuclear power plants to be designed, sited, constructed, commissioned and operated with the objectives of: 

O1. Normal operation, abnormal events and prevention of accidents 

  • reducing the frequencies of abnormal events by enhancing plant capability to stay within normal operation. 
  • reducing the potential for escalation to accident situations by enhancing plant capability to control abnormal events. 

O2. Accidents without core melt 

  • ensuring that accidents without core melt induce90 no off-site radiological impact or only minor radiological impact (in particular, no necessity of iodine prophylaxis, sheltering nor evacuation91). 
  • educing, as far as reasonably achievable, 
    • the core damage frequency taking into account all types of credible hazards, failures, and credible combinations of events; 
    • the releases of radioactive material from all sources. 
    • providing due consideration to siting and design to reduce the impact of external hazards and malevolent acts. 

O3. Accidents with core melt 

  • reducing potential radioactive releases to the environment from accidents with core melt92, also in the long-term93, by following the qualitative criteria below: 
    • accidents with core melt which would lead to early94 or large95 releases have to be practically eliminated96
    • for accidents with core melt that have not been practically eliminated, design provisions have to be taken so that only limited protective measures in area and time are needed for the public (no permanent relocation, no need for emergency evacuation outside the immediate vicinity of the plant, limited sheltering, no long term restrictions in food consumption) and that sufficient time is available to implement these measures. 

O4. Independence between all levels of defence-in-depth 

  • enhancing the effectiveness of the independence between all levels of defence-in-depth, in particular through diversity provisions (in addition to the strengthening of each of these levels separately as addressed in the previous three objectives), to provide as far as reasonably achievable an overall reinforcement of defence-in-depth. 

O5. Safety and security interfaces 

  • ensuring that safety measures and security measures are designed and implemented in an integrated manner. Synergies between safety and security enhancements should be sought. 

O6. Radiation protection and waste management 

  • reducing as far as reasonably achievable by design provisions, for all operating states, decommissioning and dismantling activities: 
    • individual and collective doses for workers; 
    • radioactive discharges to the environment; 
    • quantity and activity of radioactive waste. 

O7. Leadership and management for safety 

  • ensuring effective management for safety from the design stage. This implies that the licensee: 
    • establishes effective leadership and management for safety over the entire new plant project and has sufficient in house technical and financial resources to fulfil its prime responsibility in safety; 
    • ensures that all other organizations involved in siting, design, construction, commissioning, operation and decommissioning of new plants demonstrate awareness among the staff of the nuclear safety issues associated with their work and their role in ensuring safety.

90 In a deterministic and conservative approach with respect to the evaluation of radiological consequences
91 However, restriction of food consumption could be needed in some scenarios.
92 For new plants, the scope of the safety demonstration has to cover all risks induced by the nuclear fuel, even when stored in the fuel pool. Hence, core melt accidents (severe accidents) have to be considered when the core is in the reactor, but also when the whole core or a large part of the core is unloaded and stored in the fuel pool. It has to be shown that such accident scenarios are either practically eliminated or prevented and mitigated.
93 Long term: considering the time over which the safety functions need to be maintained. It could be months or years, depending on the accident scenario.
94 Early releases: situations that would require off-site emergency measures but with insufficient time to implement them.
95 Large releases: situations that would require protective measures for the public that could not be limited in area or time.
96 In this context, the possibility of certain conditions occurring is considered to have been practically eliminated if it is physically impossible for the conditions to occur or if the conditions can be considered with a high degree of confidence to be extremely unlikely to arise (from IAEA NSG1.10).