Boiling water reactor with staggered chimney

A reactor system comprising:

• conversion means for converting kinetic energy of vapor flow into another form of energy;
• and
• a natural-convection boiling-water reactor employing free-surface steam separation, said reactor including:
• a reactor vessel having a vapor exit for outputting vapor generated within said vessel, said vessel having a liquid input for inputting liquid into said vessel, said vessel having a nominal liquid level;
• transfer means for transferring heated fluid from said vessel to said conversion means, said transfer means being in fluid communication with said vapor exit;
• replenishment means for supplying a liquid to replace fluid transferred from said vessel to said conversion means so as to maintain a relatively constant liquid level at said nominal liquid level within said vessel, said replenishment means being in fluid communication with said vessel through said liquid input;
• a reactor core for generating heat, said core being disposed within said vessel below said nominal liquid level, said core being adapted for converting liquid flowing therethrough to vapor;
• and
• a chimney disposed within said vessel, said chimney extending from said core to a level below said nominal liquid level, said chimney having structural section means defining vertically extending sections, each of said sections extending vertically from said core to a level below said nominal liquid level, each of said sections radially confining fluid flowing therethrough, said sections defining a radially extending array, said array including at least first and second groups of said sections, said first group including at least one of said sections, said structural section means dividing said second group into plural substantially equal sections arranged annularly about said first group so that each of said sections in said second group is in contact with two other sections of said second group, the sections of said first group having a first average height, the sections of said second group having a second average height which is less than said first average height.