PRESSURE TUBE REACTOR

PURPOSE:To improve the control performance of a reactor without enlarging a calandria tank, by arranging pressure tubes in the shape of an equilateral triangle lattice. CONSTITUTION:In a calandria tank 2, calandria tubes 1 in numbers necessary for obtaining a rated output of a reactor are arranged in the shape of an equilateral triangle lattice, and among the lattice points of these tubes, control rod guide tubes 4 and neutron counter tubes 5 in umbers necessary for control and measurement are disposed. The calandria tank 2 is hermetically sealed with an upper tube plate 6 and a lower tube plate 7 so that heavy water can be held therein. According to this arrangement in the shape of the equilateral triangle lattice of the calandria tubes 1, the volume of the heavy water can be reduced in comparison with a usual arrangement in the shape of a square lattice, neutron economy can be improved, and also the controllability of the reactor is improved.