Abstract: A semiconductor device with favorable electrical characteristics is provided. A semiconductor device with stable electrical characteristics is provided. The semiconductor device includes a semiconductor layer, a first insulating layer, and a first conductive layer. The first insulating layer is provided over the semiconductor layer. The first conductive layer is provided over the first insulating layer. The semiconductor layer includes a first region that overlaps with the first conductive layer and the first insulating layer, a second region that does not overlap with the first conductive layer and overlaps with the first insulating layer, and a third region that overlaps with neither the first conductive layer nor the first insulating layer. The semiconductor layer contains a metal oxide. The second region and the third region contain a first element. The first element is one or more elements selected from boron, phosphorus, aluminum, and magnesium.

Abstract: A power supply system for driving reactor coolant recirculation pumps within an advanced boiling water reactor is configured in such a manner that: at least one normal-operation busbar branches off from either a main on-site power line or from a power line for auxiliary power generation that branches off from the main on-site power line, with a house transformer therebetween; at least one MG set is connected to one of these normal-operation busbars; one static adjustable-frequency power supply device is connected to each MG set; and a plurality of recirculation pumps is connected to each static adjustable-frequency power supply device.