Molten fuel reactor thermal management configurations

A molten fuel nuclear reactor comprising:

• an upper neutron reflector defining a top of a reactor core;
• a lower neutron reflector defining a bottom of the reactor core;
• at least one inner neutron reflector defining sides of the reactor core;
• at least one heat exchanger that receives heated fuel salt at a heat exchanger fuel salt inlet below a reactor core heated fuel salt outlet, transfers heat from the fuel salt to a coolant, and discharges the cooled fuel salt at a heat exchanger fuel salt outlet fluidly connected to a reactor core cooled fuel salt inlet;
• the at least one heat exchanger including a welded component separated from the fuel salt by one of the upper neutron reflector, the lower neutron reflector, the at least one inner neutron reflector or a neutron moderator.

A radial loop molten salt reactor comprising:

• a reactor core containment vessel;
• one or more reflectors in the reactor core containment vessel the one or more reflectors defining a reactor core volume within the reactor core containment vessel;
• and
• a plurality of heat exchanger legs spaced apart outside of the reactor core containment vessel, each heat exchanger leg having a reactor outlet pipe configured to receive heated fuel salt from the reactor core volume, a heat exchanger that transfers heat from the heated fuel salt to a primary coolant thereby creating a cooled fuel salt, and a reactor inlet pipe configured to return the cooled fuel salt into the reactor core volume.