Abstract: A calculation method of nuclear reactor core on neutronic characteristics and thermal hydraulic characteristics is provided, which is capable of getting an equivalent calculation precision to a heterogeneous core calculation by a coarse mesh core calculation thereby achieving curtailment and reduction of calculation time and memory capacity.

Abstract: A bandgap reference voltage circuit includes a constant-current circuit, a reference voltage output circuit that generates a reference voltage according to the constant current, a power supply voltage detection circuit, and a start-up output circuit. The start-up output circuit supplies a starting potential to a node in the constant-current circuit until the power supply voltage detection circuit detects that the power supply has reached a voltage sufficient for the constant-current circuit to maintain operation. The power supply voltage detection circuit has circuit elements analogous to the circuit elements in the constant-current circuit that determine this voltage, enabling the start-up operation to be carried out and ended reliably. The start-up output circuit preferably includes a low-impedance path from the power supply to a node controlling supply of the starting potential, so that power-supply noise does not trigger unwanted output of the starting potential after the start-up operation has ended.