The EBR-II Fuel Facility 

leerman22 EBR-II operated completely safely for 30 years using sodium coolant. Other sodium-cooled test and demonstration reactors (Fast Flux Test Facility, Phénix, Superphénix, BN-350, and BN-600) also operated safely for many years; BN-600 is still in operation. Plus, one of the US submarine fleet had a reactor that used a liquid metal coolant, without incident. And there is significant US industrial process experience using metallic sodium as an alloying metal, as an anti-scaling agent, and as a reducing agent, all quite safely. So the experience base for handling metallic sodium safely is substantial and has been leveraged to allow safe use of sodium coolant in advanced reactor designs.

Nuclear Engineering at Argonne I would prefer lead coolant for a fast spectrum reactor than something than "can" burst into flames or explode in water.

leerman22 Lead is being evaluated as an alternative fast reactor coolant. Both lead and sodium have their relative strengths; the idea is to evaluate these to determine which is better from the standpoints of efficiency, corrosion, and safety.

leerman22 If isolated correctly the risk should be relatively small.

Zypofaeser It just gives greenies ammunition. They don't care about engineering.