An evolution of molten core cooling strategies

Evaluation of Samg Effectiveness in View of Group Decision

“…We analyzed the operator's actions to determine if they are realistic and effective, and if the guidelines really enhance the plant's capability to handle severe accidents in terms of mitigating the negative impacts of each action in the accident progression. In the following, we summarize the evaluation results of our previous studies [3][4][5], and we believe the conclusions are still valid for the SAMGs of many other operating plants.…”

“…In conclusion, the current SAMG is very weak in handling the debris coolability issue. [4] In Mitigation-05 (control fission product release), the major action is to find the leak path and to isolate it, which is a rather mechanical guideline without deep physics. The other actions recommended are 1) to lower containment pressure using spray or fan coolers in order to reduce the driving force of fission product release, 2) to dump the steam generator into the condenser, and 3) to dump the fission product to aux-building.…”

“…[4] Mitigation-4 is a strategy to inject water into the reactor cavity and the current SAMG mentions only implementing the strategy with the evaluation of the negative and positive impacts of the strategy as in Table 2. However, the simulation by the authors for an operating plant shows that the operator should flood the cavity within 10 hours after the SBO accident initiates.…”

Safety features in nuclear power plants to eliminate the need of emergency planning in public domain

“…• In-vessel retention (IVR)-IVR by pre-flooding of the reactor cavity is a strategy to cool the molten core from outside the reactor vessel. This concept was adopted for Loviisa, AP600 and AP1000 (Song and Suh 2009). The heat from the molten corium in the reactor vessel is transferred via the vessel wall to the coolant outside the vessel.…”

“…Water flow channel is provided along the surface of the reactor pit to cool the mixture of corium and sacrificial material. In addition, water is flooded over the mixture (Song and Suh 2009).…”