Boiling water nuclear plant and steam dryer

In the boiling water nuclear plant of the present invention, a steam dryer is disposed in a reactor pressure vessel. Materials that have capability of capturing nitrogen compounds containing N-16 are supported on porous member. The porous members are placed in a region where steam goes through in the steam dryer. For example, both or either of perforated plates installed in the steam dryer is constituted of the porous member on which N-16 capture material is supported. When steam containing N-16 goes through the perforated plates, the N-16 is captured by the porous member, whereby the N-16 transfer amount into the turbine system is reduced.