Heat exchanger for reactor coolant cleanup system

A reactor coolant cleanup system of a BWR reactor comprises a regeneration heat exchangers, non-regenerative heat exchangers and a filtration desalter. Main pipelines connected to an inlet and an exit of each of the regenerative heat exchangers are connected with primary and secondary bypass lines bypassing each of the regenerative heat exchangers. Upon inspection of the regenerative heat exchangers, operation of one regenerative heat exchanger among a plurality of regenerative heat exchangers is stopped while the operation is continued using other regenerative heat exchangers. That is, opening/closing valves on the side of the inlet and the exit of one regeneration heat exchanger are closed and opening/closing valves of the bypass pipelines are opened. With such procedures, water from the reactor is not supplied to the inspected regenerative heat exchanger but supplied to other regeneration heat exchangers by way of the bypass lines. Accordingly, one regenerative heat exchanger can be inspected without stopping operation of all regenerative heat exchangers. (I.N.)