The invention discloses a natural circulation
system based on in-
pipe condensation and an operation method, and the
system comprises a cooling water tank which is arranged outside a reactor containment and is filled with cooling water. And the
heat exchanger is arranged in the cooling water tank. The inlet end of the air inlet pipeline is connected inside the containment, and the outlet end is connected with the
heat exchanger. The inlet end of the drainage pipeline is connected with the
heat exchanger, and the outlet end extends into the in-shell water tank. The inlet end of the exhaust pipeline is communicated with the heat exchanger, and the outlet end extends into the suppression
pool. And the suppression
pool is internally filled with water, is arranged outside the containment, has a
pressure difference with the containment, and is communicated with the containment through a low-pressure-difference
communication device and a pipeline. And the in-shell water tank is arranged in the safety shell. The inlet end of the gravity injection pipeline is communicated with the in-shell water tank, and the outlet end is connected with the reactor. The problem that an existing
pipe external condensation type natural circulation
system is not suitable for the low level difference condition is solved, the operation stability of the natural circulation system under the condition is improved, and the starting time of the natural circulation system is shortened.