I'm no nuclear expert but couldn't they dig a pit around the plant and then dig a deep canal to the ocean (first make a big burm with floating cement boats and then dirt and cement or whatever debri is available) then destroy the burm or levee and flood the whole area cooling the rods.
Not sure if this would work just throwing it out there. Dig a trench and flood the area with sea water. From the images I can see at the Guardian the ocean is very close to the overheated rods and ponds.
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