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euromodder -

I think the current generation designs take your questions into account.

BWR = Boiling water reactor - Wikipedia, the free encyclopedia = Fukushima
ABWR = Advanced boiling water reactor - Wikipedia, the free encyclopedia
ESBWR = Economic Simplified Boiling Water Reactor - Wikipedia, the free encyclopedia

The ESBWR uses natural circulation with no recirculation pumps or their associated piping, thereby greatly increasing design integrity and reducing overall costs.
The passively safe characteristics are mainly based on isolation condensers, which are heat exchangers that take steam from the vessel (isolation condensers, IC) or the containment (passive containment cooling system, PCCS), condense the steam, transfer the heat to a water pool, and introduce the water into the vessel again.
This is also based on the gravity driven cooling system (GDCS), which are pools above the vessel. When very low water level is detected in the reactor, the depressurization system opens several very large valves to reduce vessel pressure and finally to allow these GDCS pools to re-flood the vessel.
All of the safety systems operate without using pumps, thereby further increasing design safety reliability and reducing costs.

http://www.nuclear.gov/np2010/pdfs/esbwrOverview.pdf




CarloSW2