High thermal load heat removing plate

A rectangular flow channel in which subcooling water flows is formed on a surface of a heat receiving plate opposite to a heat receiving surface which undergoes high temperature neutron particles. The rectangular flow channel forms a turn-back flow channel which intersects the heat receiving plate by inner partitioning plates and outer partitioning plates. Then, subcooling water is introduced from a water supply port, and subcooling water heated by the heat receiving plate and having the temperature elevated is discharged from a water discharge port. Colliding and withdrawal of water streams are successively repeated on the opposite surface of the heat receiving plate by inner partitioning plates. Subcooling water containing bubbles is stirred by the outer partitioning plates to eliminate bubbles, and subcooling water not containing the bubbles is collided against the opposite surface of the receiving plate again. This can increase the greatest amount of heat to be removed by the heat receiving plate to improve a limit thermal fluxes. (I.N.)