IRSN reports some severe accident phenomena still not understood

摘要

Significant uncertainties remain in international understanding of some severe accident phenomena, the Institute of Radiological Protection and Nuclear Safety concluded in a report made public last week. The report cites "strong uncertainties" about the efficiency of maintaining cooling of a molten core within the reactor vessel, notably by external cooling. Studies conducted by French researchers, it says, "have demonstrated that it is difficult to maintain ... integrity of the vessel by this measure." Other studies showed that if corium escaped the vessel and interacted with the reactor basemat, it is possible to slow concrete erosion by cooling the corium mass with water. But it wasn't possible to quantify the efficiency of the measure in preventing basemat erosion, IRSN said.