The Orsan plan is the emergency plan in France to face a sudden increase of activity in a hospital, such as a massive arrival of casualties due to an accident or a disaster (who may come by their own means to the emergency department or are evacuated by an Orsec-Novi plan), an epidemic or a lasting climatic event that becomes deadly for fragile people such as a heatwave.
It was created in 2014. "Orsan" stands for French: organisation de la réponse du système de santé en situations sanitaires exceptionnelles, i.e. "organisation of the healthcare response system in exceptional public health situations".
It is a nationwide emergency plan that is the frame for the white plans (French: plans blancs, French pronunciation: [plɑ̃ blɑ̃]) that are locally developed for hospitals.