A molten fuel salt nuclear reactor comprising: at least one reflector surrounding a reactor core, the reactor core for containing nuclear fuel salt and having an upper region and a lower region; a heat exchanger circuit separated from the reactor core by a reflector, the heat exchanger circuit having a first connection to the upper region and a second connection to the lower region and the heat exchanger circuit including: a direct reactor auxiliary cooling system, DRACS, heat exchanger configured to remove heat from the nuclear fuel salt and transfer the heat to a DRACS coolant, wherein a DRACS is an auxiliary cooling system configured to remove decay heat from the nuclear fuel salt during a loss of forced flow event or other events; a primary heat exchanger that is a shell and tube heat exchanger in which a shell-side primary coolant removes heat from vertical tubes containing nuclear fuel salt; the DRACS heat exchanger located above and fluidicly connected to the primary heat exchanger and the DRACS heat exchanger fluidicly connected to the upper region of the reactor core via the first connection; the vertical tubes of the primary heat exchanger fluidicly connected to the lower region of the reactor core via the second connection; an impeller configured to drive circulation of the nuclear fuel salt in a direction opposite of that driven by natural circulation of the nuclear fuel salt. at least one reflector surrounding a reactor core, the reactor core for containing nuclear fuel salt and having an upper region and a lower region; a heat exchanger circuit separated from the reactor core by a reflector, the heat exchanger circuit having a first connection to the upper region and a second connection to the lower region and the heat exchanger circuit including: a direct reactor auxiliary cooling system, DRACS, heat exchanger configured to remove heat from the nuclear fuel salt and transfer the heat to a DRACS coolant, wherein a DRACS is an auxiliary cooling system configured to remove decay heat from the nuclear fuel salt during a loss of forced flow event or other events; a primary heat exchanger that is a shell and tube heat exchanger in which a shell-side primary coolant removes heat from vertical tubes containing nuclear fuel salt; the DRACS heat exchanger located above and fluidicly connected to the primary heat exchanger and the DRACS heat exchanger fluidicly connected to the upper region of the reactor core via the first connection; the vertical tubes of the primary heat exchanger fluidicly connected to the lower region of the reactor core via the second connection; a direct reactor auxiliary cooling system, DRACS, heat exchanger configured to remove heat from the nuclear fuel salt and transfer the heat to a DRACS coolant, wherein a DRACS is an auxiliary cooling system configured to remove decay heat from the nuclear fuel salt during a loss of forced flow event or other events; a primary heat exchanger that is a shell and tube heat exchanger in which a shell-side primary coolant removes heat from vertical tubes containing nuclear fuel salt; the DRACS heat exchanger located above and fluidicly connected to the primary heat exchanger and the DRACS heat exchanger fluidicly connected to the upper region of the reactor core via the first connection; the vertical tubes of the primary heat exchanger fluidicly connected to the lower region of the reactor core via the second connection; an impeller configured to drive circulation of the nuclear fuel salt in a direction opposite of that driven by natural circulation of the nuclear fuel salt.