Iron injection method and device to feedwater in BWR type power plant

Operation is controlled such that the amount of an amorphous iron in feedwater which forms composite oxides with Ni and Co in a reactor, is measured at a sampling point nearest to the reactor, and the amount of iron to be injected is previously calculated so as to keep the required amount of amorphous iron. As a result, concentration of radioactivity in reactor water can be stabilized easily. Further, partitioning plates forming a zigzag flow channel in a reaction vessel are disposed, and a line is additionally disposed for returning liquid from downstream of the injection pipeline system to a reaction vessel, to partially recycle injected iron. Separately, an adsorption vessel is disposed to the downstream of the reaction vessel, and an adsorption gas is blown to stabilize cruds, thereby enabling to supply amorphous ion to the reactor stably. As a result, concentration of radioactivity in the reactor can be kept more stable. Further, iron deposited to injection pipelines can be removed easily by adopting an iron injection facility to the injection pipelines, thereby enabling to facilitate injection operation. (N.H.)