ACCIDENT OPERATING CONDITIONS .
Emergency core cooling.
Spray of the reactor containment.

During a loss of coolant accident, heat and radioactive materials are released inside the reactor containment .

Among other functions, the containment spray aims to reduce the ambient temperature and pressure. If the emergency cooling does not fail, it can last months; the operating conditions would be certainly both unusual and very adverse; there is no guaranty that every safety related equipment will perform the expected functions.

Large amounts of highly contaminated coolant must be processed outside the reactor containment (pumping, heat exchanger...); the risk of radiation leak has to be taken into account .