Inhibition of deposition of radioactive substances on nuclear power plant components
AssigneeHitachi, Ltd.
InventorsTakashi Honda, Yasumasa Furutani, Kenya Ohashi, Eiji Kashimura, Akira Minato, Katsumi Ohsumi, Hisao Itou
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Abstract
A nuclear power plant wherein surfaces of components contacting with nuclear reactor cooling water containing radioactive substances are coated with an oxide film, preferably being charged positively and/or containing chromium in an amount of 12% by weight or more, is prevented effectively from the deposition of radioactive substances thereon.
Claims36
A process for inhibiting deposition of radioactive substances on nuclear power plant components which comprises forming a positively charged oxide film on surface of components contacting with nuclear reactor cooling water containing radioactive substances by treating the surface of components with a solution containing anions and polyvalent metal cations, the anions having a lower valence number than the cations at a time of forming an oxide film or after the formation of the oxide film, wherein the polyvalent metal cations are at least one member selected from the group consisting of Al.sup.3+, Fe.sup.3+, Ba.sup.2+, Ca.sup.2+, Co.sup.2+, Mg.sup.2+, Ni.sup.2+, Pb.sup.2+, Zn.sup.2+ and Cu.sup.2+, and the anions are at least one member selected from the group consisting of HCO.sub.3.sup.-, H.sub.2 PO.sub.4.sup.-, MnO.sub.4.sup.-, NO.sub.2.sup.-, NO.sub.3.sup.-, OH.sup.-, HCOO.sup.-, CH.sub.3 COO.sup.-, MnO.sub.4.sup.2-, HPO.sub.4.sup.2-, SO.sub.4.sup.2- and WO.sub.4.sup.2-.
A process for inhibiting deposition of radioactive substances on nuclear power plant components which comprises forming a positively charged iron oxide film containing metallic elements giving polyvalent metal cations and chromium on surfaces of components contacting with nuclear reactor cooling water containing radioactive substances, the positively charged iron oxide film being formed by contacting said surfaces of components with a solution containing said polyvalent metal cations and anions having a lower valence number than the cations, wherein the polyvalent metal cations are at least one member selected from the group consisting of Al.sup.3+, Fe.sup.3+, Ba.sup.2+, Ca.sup.2+, Co.sup.2+, Mg.sup.2+, Ni.sup.2+, Pb.sup.2+, Zn.sup.2+ and Cu.sup.2+, and the anions are at least one member selected from the group consisting of HCO.sub.3.sup.-, H.sub.2 PO.sub.4.sup.-, MnO.sub.4.sup.-, NO.sub.2.sup.-, NO.sub.3.sup.-, OH.sup.-, HCOO.sup.-, CH.sub.3 COO.sup.-, MnO.sub.4.sup.2-, HPO.sub.4.sup.2- , SO.sub.4.sup.2- and WO.sub.4.sup.2-.
A process for inhibiting deposition of radioactive substances on nuclear power plant components made of an iron series material and contacting with reactor cooling water containing radioactive substances, which comprises treating surfaces of components made of a chromium-containing iron series material with heated water or heated steam to form an oxide film containing chromium in an amount of 12% by weight or more. formed thereon, prior to operation of the plant to provide nuclear heating, the oxide film having a chromium content of at least 12% by weight, wherein said oxide film is a positively charged oxide film, formed by contacting said surfaces with a solution containing polyvalent metal cations and anions having a lower valence number than the cations.
In a nuclear power plant comprising a reactor, a turbine, a condenser, a condensed water demineralizer, a supplying water heater, a demineralizer for a reactor cleaning system, and a reactor re-circulation piping system, the improvement wherein a positively charged iron oxide film is formed on surfaces which contact with nuclear reactor cooling water in said plant, the positively charged iron oxide film being formed by contacting said surfaces with a solution containing polyvalent metal cations and anions having a lower valence number than the cations.
In a nuclear power plant comprising a reactor, a turbine, a condenser, a condensed water demineralizer, a supplying water heater, a demineralizer for a reactor cleaning system, and a reactor re-circulation piping system, the improvement wherein a positively charged iron oxide film is formed on surfaces which contact with nuclear reactor cooling water in said plant, the positively charged iron oxide film being formed by contacting said surfaces with a solution containing polyvalent metal cations and anions having a lower valence number than the cations, after the construction of said plant and prior to the operation thereof to provide nuclear heating.
In a nuclear power plant comprising a reactor, a turbine, a condenser, a condensed water demineralizer, a supplying water heater, a demineralizer for a reactor cleaning system, and a reactor re-circulation piping system, the improvement wherein a positively charged iron oxide film is formed on surfaces which contact with nuclear reactor cooling water contaminated with radioactive substances after the operation of said plant, the positively charged iron oxide film being formed by contacting said surfaces with a solution containing polyvalent metal cations and anions having a lower valence number than the cations.
In a nuclear power plant comprising a reactor, a turbine, a condenser, a condensed water demineralizer, a supplying water heater, a demineralizer for a reactor cleaning system, and a reactor re-circulation piping system, the improvement wherein surfaces of the plant which contact with nuclear reactor cooling water have an oxide film formed thereon, prior to operation of the plant to provide nuclear heating, the oxide film having a chromium content of at least 12% by weight, wherein said oxide film is a positively charged oxide film, formed by contacting said surfaces with a solution containing polyvalent metal cations and anions having a lower valence number than the cations.
Dependencies are inferred from the claim text.