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Zirconium alloy compositions having excellent corrosion resistance by the control of various metal-oxide and precipitate and preparation method thereof

a technology of zinc alloy and control of various metal-oxides, applied in the field of zinc alloy compositions, can solve the problems of deterioration of mechanical properties, serious corrosion phenomenon of nuclear fuel, and deterioration of corrosion resistance of metal-oxides, and achieve excellent corrosion resistance and excellent corrosion resistan

Inactive Publication Date: 2012-06-14
KOREA ATOMIC ENERGY RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0018]Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a zirconium alloy composition, which can be used as a raw material for nuclear fuel cladding tubes, spacer girds, nuclear reactor internals and the like used during a high burn-up and long period of operation, and which can exhibit excellent corrosion resistance by the control of various metal oxides and precipitates of the composition.
[0020]In order to accomplish the above object, the present invention provides a zirconium alloy composition, which exhibits excellent corrosion resistance by the control of various metal oxides and precipitates of the composition, comprising 1.05˜1.45 wt % of Nb; at least one of 0.1˜0.7 wt % of Fe and 0.05˜0.6 wt % of Cr; 0.12 wt % of Sn; and residual Zr, and a method of preparing the same.
[0021]Since the zirconium alloy composition according to the present invention exhibits excellent corrosion resistance by controlling the kinds and amounts of the elements included in the zirconium alloy composition and the heat-treatment temperature and thus varying the kinds of metal oxides formed during an oxidation process and controlling the size of precipitates of the zirconium alloy, it can be usefully used as a raw material of nuclear fuel cladding tubes, spacer grids, nuclear reactor internals and the like of a light-water reactor or a heavy-water reactor in a nuclear power plant.

Problems solved by technology

Nuclear fuel cladding tubes, spacer grids and nuclear reactor internals, which are used in a nuclear fuel assembly of a nuclear power plant, are easily embrittled and corroded due to the nuclear irradiation and the corrosive environment of high temperature and high pressure, and thus their mechanical properties are deteriorated.
Therefore, when the conventional Zircaloy-2 or Zircaloy-4 is used as a raw material for a nuclear fuel cladding tube, there is a problem in that the corrosion phenomenon of the nuclear fuel becomes serious.
That is, since carbon atoms interposed between iron atoms serve to prevent the movement of iron atoms, as the amount of carbon included in iron is increased, the hardness of iron increases, whereas as the hardness of iron increases, iron is easily broken.

Method used

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  • Zirconium alloy compositions having excellent corrosion resistance by the control of various metal-oxide and precipitate and preparation method thereof

Examples

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example 1

Preparation of a Zirconium Alloy Composition

[0059](1) Ingot Formation

[0060]1.2 wt % of niobium, 0.2 wt % of iron and residual zirconium were formed into an ingot through a vacuum arc remelting (VAR) process. Reactor-grade sponge zirconium defined clearly in the ASTM B349 was used as the zirconium, and other alloy elements had a purity of 99.99%. In order to prevent the segregation of impurities and the nonuniform distribution of a zirconium alloy composition, the vacuum arc remelting process was repeatedly conducted four times. Subsequently, the zirconium alloy composition was formed into the ingot in a water-cooled copper crucible having a cooling water pressure of 1 kgf / cm2 and a diameter of 60 mm by applying an electric current of 500 Å thereto in a state in which the vacuum in a chamber was maintained at a pressure of 1×10−5 torr and then high-purity argon gas (99.99%) was charged in the chamber in order to prevent the oxidization of the zirconium alloy composition.

[0061](2) β-F...

examples 2 to 18

[0073]The zirconium alloy compositions having excellent corrosion resistance of Examples 2 to 18 were prepared using the same method as in Example 1, except that chemical compositions constituting the zirconium alloy compositions and stepwise heat treatment conditions were changed. The chemical compositions constituting the zirconium alloy compositions and stepwise heat treatment conditions are shown in Table 1.

experimental example 1

Manufacturability of a Zirconium Alloy Composition

[0075]The manufacturability of the zirconium alloy composition according to the present invention was evaluated by the zirconium alloy composition preparation processes of Examples 1 to 18 and Comparative Examples 1 to 6.

[0076]In Examples 1 to 18 and Comparative Examples 3 to 6, the zirconium alloy compositions were smoothly prepared without damage, but, in Comparative Examples 1 and 2, the zirconium alloy compositions were seriously damaged during their preparation processes. From this phenomenon, it can be seen that, when 0.85 wt % or more of Fe or 0.75 wt % or more of Cr is added to a zirconium alloy composition including 1.2 wt % of Nb, it is difficult to impart excellent manufacturability to the zirconium alloy composition, and thus it is not preferred that the amount of iron or chromium be excessively increased.

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Abstract

Disclosed herein are a zirconium alloy composition, which exhibits excellent corrosion resistance by varying the kinds of metal oxides and controlling the size of precipitates of the composition, including: 1.05˜1.45 wt % of Nb; one or more selected from the group consisting of 0.1˜0.7 wt % of Fe and 0.05˜0.6 wt % of Cr; and residual Zr, and a method of preparing the same. The zirconium alloy composition exhibits excellent corrosion resistance by controlling the kinds and amounts of the elements included in the zirconium alloy composition and the heat-treatment temperature and thus varying the kinds of metal oxides formed during an oxidation process and controlling the size of precipitates of the zirconium alloy, so that it can be usefully used as a raw material for nuclear fuel cladding tubes, spacer grids, nuclear reactor internals and the like of a light-water reactor or a heavy-water reactor in a nuclear power plant.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a zirconium alloy composition having excellent corrosion resistance by the control of various metal oxides and precipitates of the composition, and a method of preparing the same.[0003]2. Description of the Related Art[0004]Nuclear fuel cladding tubes, spacer grids and nuclear reactor internals, which are used in a nuclear fuel assembly of a nuclear power plant, are easily embrittled and corroded due to the nuclear irradiation and the corrosive environment of high temperature and high pressure, and thus their mechanical properties are deteriorated. For this reason, it is important to control their alloy compositions. Therefore, zirconium alloys having small neutron absorption cross sections, high mechanical strength and excellent corrosion resistance have been widely used in a pressurized water reactor (PWR) and a boiling water reactor (BWR). Among conventional zirconium alloys including...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22F1/18C22C16/00
CPCC22C16/00
Inventor KIM, HYUN GILJEONG, YONG HWANCHOI, BYOUNG KWONPARK, SANG YOONLEE, MYUNG HOPARK, JEONG YONGKIM, JUN HWAN
Owner KOREA ATOMIC ENERGY RES INST
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