Zirconium alloy composition for nuclear fuel cladding tube forming protective oxide film, zirconium alloy nuclear fuel cladding tube manufactured using the composition, and method of manufacturing the zirconium alloy nuclear fuel cladding tube

Abstract

Disclosed herein is a zirconium alloy composition for nuclear fuel cladding tubes, comprising: 1.6˜2.0 wt % of Nb; 0.05˜0.14 wt % of Sn; 0.02˜0.2 wt % of one or more elements selected from the group consisting of Fe, Cr and Cu; 0.09˜0.15 wt % of O; 0.008˜0.012 wt % of Si; and a balance of Zr, a nuclear fuel cladding tube comprising the zirconium alloy composition, and a method of manufacturing the nuclear fuel cladding tube. Since the nuclear fuel cladding tube made of the zirconium alloy composition can maintain excellent corrosion resistance by forming a protective oxide film thereon under the conditions of high-temperature and high-pressure cooling water and water vapor, it can be usefully used as a nuclear fuel cladding tube for light water reactors or heavy water reactors, thus improving the economical efficiency and safety of the use of nuclear fuel.

1 . A zirconium alloy composition for nuclear fuel cladding tubes, comprising: 1.6˜2.0 wt % of Nb; 0.05˜0.14 wt % of Sn; 0.02˜0.2 wt % of one or two elements selected from the group consisting of Fe, Cr and Cu; 0.09˜0.15 wt % of O; 0.008˜0.012 wt % of Si; and a balance of Zr. 
   
   
       2 . The zirconium alloy composition according to  claim 1 , wherein the composition comprises: 1.8 wt % of Nb; 0.1 wt % of Sn; 0.05 wt % of one element selected from the group consisting of Fe, Cr and Cu; 0.12 wt % of O; 0.01 wt % of Si; and a balance of Zr. 
   
   
       3 . The zirconium alloy composition according to  claim 1 , wherein the composition comprises: 1.6˜2.0 wt % of Nb; 0.05˜0.14 wt % of Sn; 0.02˜0.2 wt % of Fe; 0.02˜0.2 wt % of Cr or Cu; 0.09˜0.15 wt % of O; 0.008˜0.012 wt % of Si; and a balance of Zr. 
   
   
       4 . The zirconium alloy composition according to  claim 3 , wherein the composition comprises: 1.8 wt % of Nb; 0.1 wt % of Sn; 0.05 wt % of Fe; 0.05 wt % of Cr or Cu; 0.12 wt % of O; 0.01 wt % of Si; and a balance of Zr. 
   
   
       5 . The zirconium alloy composition according to  claim 3 , wherein the composition comprises: 1.8 wt % of Nb; 0.1 wt % of Sn; 0.1 wt % of Fe; 0.1 wt % of Cr or Cu; 0.12 wt % of O; 0.01 wt % of Si; and a balance of Zr. 
   
   
       6 . The zirconium alloy composition according to  claim 3 , wherein the composition comprises: 1.8 wt % of Nb; 0.1 wt % of Sn; 0.2 wt % of Fe; 0.1 wt % of Cr or Cu; 0.12 wt % of O; 0.01 wt % of Si; and a balance of Zr. 
   
   
       7 . A nuclear fuel cladding tube comprising the zirconium alloy composition of  claim 1 . 
   
   
       8 . A method of manufacturing a zirconium alloy nuclear fuel cladding tube, comprising:
 1) vacuum-arc-remelting and cooling a mixture of the elements constituting the zirconium alloy composition of  claim 1  to form an ingot;   2) forging the ingot at a temperature of 1000˜1200° C.;   3) solution-heat-treating the forged ingot at a temperature of 1000˜1200° C. for 10˜40 minutes and then cooling the solution-heat-treated ingot to a temperature of 300˜400° C. at a cooling rate of 300˜400° C./s;   4) extruding the cooled ingot at a temperature of 600˜640° C. to form an extruded shell;   5) primarily heat-treating the extruded shell at a temperature of 570˜610 for 2˜4 hours;   6) cold-working the primarily heat-treated extruded shell 2 times and intermediately heat-treating it 1˜4 times between the cold working processes at a temperature of 570˜610° C. for 3˜10 hours to prepare a zirconium alloy nuclear fuel cladding tube; and   7) finally heat-treating the prepared zirconium alloy nuclear fuel cladding tube at a temperature of 470˜580° C. for 1˜100 hours to manufacture a zirconium alloy nuclear fuel cladding tube.   
   
   
       9 . The method of manufacturing a zirconium alloy nuclear fuel cladding tube according to  claim 8 , wherein, in step 1, the mixture is repetitively vacuum-arc-remelted 3˜6 times to form an ingot. 
   
   
       10 . The method of manufacturing a zirconium alloy nuclear fuel cladding tube according to  claim 9 , wherein the mixture is vacuum-arc-remelted and then cooled while injecting an inert gas to form an ingot. 
   
   
       11 . The method of manufacturing a zirconium alloy nuclear fuel cladding tube according to  claim 8 , wherein, in step 7, the final heat treatment is performed in a vacuum. 
   
   
       12 . The method of manufacturing a zirconium alloy nuclear fuel cladding tube according to  claim 8 , wherein, in step 7, the final heat treatment is performed such that an average particle size of β-niobium precipitates is controlled to be 70 nm or less.