Provision for overpressure protection

All pressure retaining components of the RCSASs should be protected against overpressure conditions in compliance with applicable codes and standards. 

All pressure retaining components of the RCSASs should be designed with an appropriate safety margin to ensure that the pressure boundary will not be breached and that the fuel design limits will not be exceeded in operational states or in design basis accident conditions. 

The design of the RCS should include adequate features for overpressure protection that is, it should provide the capability to deal with vapours and liquids in the RCS. Safety and/or relief valves should be included in the design. 

The defence in depth concept should be applied to the overpressure protection. The diversity principle should be applied in the design of the overpressure protection of the RCS to reduce the likelihood of common cause failures. The design of overpressure protection devices should reflect their safety significance and it should be consistent with their expected performance in the most limiting PIEs. 

Overpressure protection of the reactor coolant pressure boundary can be achieved by means of the following provisions or actions  

---