NATURAL CIRCULATION TYPE BOILING WATER REACTOR
The natural circulation type boiling water reactor comprises a core in which a plurality of fuel assemblies are loaded, and a chimney which is disposed above the core and has a path partition which forms a plurality of vertical lattice paths. A uniform pressure space is formed between the core and the chimney and not disposed the path partition. The two-phase flow including the cooling water and the steam exhausted from the core through the uniform pressure space is supplied to the vertical lattice paths. The two-phase flow ascends in the vertical lattice paths. Thus, the flow distribution for each fuel assembly can be calculated using the pressure difference between the upper end and the lower end of the core can be calculated without the need for the void fraction of the lattice paths.
1 . A natural circulation type boiling water reactor which comprises:
a reactor pressure vessel;
a core for loading a plurality of fuel assemblies;
a chimney disposed above the core and having path partition forming a plurality of vertical lattice paths for introducing the coolant exhausted from the core;
and a space formed at the lower portion of the chimney and not having the path partitions.
2 . The natural circulation type boiling water reactor according to claim 1 , wherein given that the flow velocity of the steam ascending said space
is U; the inner diameter of said space is D; and the acoustic velocity of the steam in said space is v,
the lower limit Hmin of the height of said space in order for the pressure in the space to be uniform is obtained by a calculation formula Hmin=U×D/v.