Abstract: A method of manufacturing a zirconium alloy for a nuclear fuel cladding tube includes melting a mixture of 0.5 wt % of Nb, 0.4 wt % of Mo, 0.1 to 0.15 wt % of Cu, 0.15 to 0.2 wt % of Fe, and a balance of zirconium to prepare a melted ingot; heat treating the melted ingot at 1,000 to 1,050° C. for 30 to 40 min. followed by quenching in water to prepare a heat-treated ingot; preheating the heat-treated ingot at 630 to 650° C. for 20 to 30 min. to prepare a preheated ingot followed by hot rolling the preheated ingot at a reduction ratio of 60 to 65% to provide a hot-rolled material; thrice performing vacuum annealing followed by cold-rolling; and vacuum annealing a third cold-rolled material in a final vacuum annealing at 510 to 520° C. for 7 to 9 hrs. to provide the zirconium alloy as a cold-rolled material.

Abstract: Provided is a nuclear fuel pellet having excellent impact resistance, the pellet being prepared with UO2 powder and having a cylindrical shape with a height of 9 to 13 mm and a horizontal cross-section diameter of 8 to 8.5 mm, and including: at each of a top surface and a bottom surface thereof, a dish configured as a spherical groove shape having a predetermined curvature and a groove diameter of 4.8 to 5.2 mm on a center; a shoulder configured as an annular plane along a rim of the dish; and a chamfer configured as a shape in which a corner is chamfered along a rim of the shoulder, wherein a width of the shoulder is 0.20 mm to 0.80 mm, and an angle between the chamfer and a horizontal plane is a 14-degree angle to 18-degree angle.

Abstract: Provided is a nuclear fuel pellet having excellent compression resistance and a reduced missing pellet surface, the pellet being a cylindrical shape and including, on each of a top surface and a bottom surface thereof: a dish configured as a spherical groove shape having a predetermined curved surface at a center; a land configured as a horizontal annular shape along a rim of the dish; and a chamfer configured as a shape in which a corner is chamfered at a predetermined angle along a rim of the land, wherein the chamfer includes: a primary chamfer adjacent to the rim of the land; and a secondary chamfer configured as a shape additionally chamfered along a rim of the primary chamfer.

Abstract: A device for maintaining the internal temperature of a pressure vessel. The device includes a pressure vessel equipped with a main heater for heating test water to a predetermined test temperature and for maintaining the predetermined test temperature, a preheater for primarily heating the test water to the predetermined test temperature before the main heater heats the test water, and a heat exchanger including an feed pipe for feeding the test water heated by the preheater to the pressure vessel and a discharge pipe for transporting the test water discharged from the pressure vessel, in which the feed pipe is disposed inside the discharge pipe.

Abstract: The present invention relates to a recrystallization rate measurement method of zirconium alloy cladding of a nuclear fuel rod, the method including: step 1 of irradiating SEM electron beams at a given scanning interval onto a first specimen to a third specimen which were electrolytically polished and obtaining electron backscattered signals therefrom by an EBSD camera; step 2 of converting electron backscattered signals obtained in step 1 into pattern quality values, respectively, and generating the pattern quality values as frequencies by a specified interval; step 3 of obtaining pattern quality frequencies (B+D) which are a portion of a whole frequency distribution of the second specimen, and pattern quality frequencies (D+E) which are a portion of a whole frequency distribution of the first specimen; and step 4 of obtaining the recrystallization rate of the second specimen with an equation of X ? = ( B + D ) ( D + E ) × 100 , % .

Abstract: A zirconium alloy is manufactured through melting; solution heat treatment at 1,000 to 1,050° C. (?) for 30 to 40 min and ?-quenching using water; preheating at 630 to 650° C. for 20 to 30 min and hot rolling at a reduction ratio of 60 to 65%; primary intermediate vacuum annealing at 570 to 590° C. for 3 to 4 hr and primarily cold-rolled at a reduction ratio of 30 to 40%; secondary intermediate vacuum annealing at 560 to 580° C. for 2 to 3 hr and secondarily cold-rolled at a reduction ratio of 50 to 60%; tertiary intermediate vacuum annealing at 560 to 580° C. for 2 to 3 hr and tertiarily cold-rolled at a reduction ratio of 30 to 40%; and final vacuum annealing at 460 to 590° C. for 7 to 9 hr.

Abstract: A device for maintaining the internal temperature of a pressure vessel. The device includes a pressure vessel equipped with a main heater for heating test water to a predetermined test temperature and for maintaining the predetermined test temperature, a preheater for primarily heating the test water to the predetermined test temperature before the main heater heats the test water, and a heat exchanger including an feed pipe for feeding the test water heated by the preheater to the pressure vessel and a discharge pipe for transporting the test water discharged from the pressure vessel, in which the feed pipe is disposed inside the discharge pipe.

Abstract: The present invention relates to a recrystallization rate measurement method of zirconium alloy cladding of a nuclear fuel rod, the method including: step 1 of irradiating SEM electron beams at a given scanning interval onto a first specimen to a third specimen which were electrolytically polished and obtaining electron backscattered signals therefrom by an EBSD camera; step 2 of converting electron backscattered signals obtained in step 1 into pattern quality values, respectively, and generating the pattern quality values as frequencies by a specified interval; step 3 of obtaining pattern quality frequencies (B+D) which are a portion of a whole frequency distribution of the second specimen, and pattern quality frequencies (D+E) which are a portion of a whole frequency distribution of the first specimen; and step 4 of obtaining the recrystallization rate of the second specimen with an equation of X ? = ( B + D ) ( D + E ) × 100 , % .

Abstract: Disclosed is a method of manufacturing a zirconium alloy plate, wherein fine precipitates having an average size of 35 nm or less are uniformly distributed in a matrix through multi-pass hot rolling, thus increasing corrosion resistance and fatigue failure resistance, the method including forming a zirconium alloy ingot (step 1); subjecting the ingot of step 1 to beta annealing and rapid cooling (step 2); preheating the ingot of step 2 (step 3); forming a multi-pass hot-rolled plate through primary hot rolling and then air cooling during which secondary hot rolling is subsequently conducted (step 4); subjecting the multi-pass hot-rolled plate of step 4 to primary intermediate annealing and primary cold rolling (step 5); subjecting the rolled plate of step 5 to secondary intermediate annealing and secondary cold rolling (step 6); subjecting the rolled plate of step 6 to tertiary intermediate annealing and tertiary cold rolling (step 7); and finally annealing the rolled plate of step 7 (step 8).

Abstract: This invention relates to a composition and method for manufacturing a large-grained uranium oxide nuclear fuel pellet containing an additive. The nuclear fuel pellet is configured such that a uranium oxide powder and an additive powder composed of an Mg compound and a Si compound or Ca compound and a Al compound are mixed together, thus increasing a grain size to thus suppress the release of fission products, thereby increasing the stability of nuclear fuel, preventing cladding tubes from breaking, and contributing to the stable operation of nuclear power plants, ultimately increasing the overall stability of nuclear power plants including nuclear fuel.

Abstract: Disclosed herein are zirconium alloy compositions having a low hydrogen pick-up rate and high hydrogen embrittlement resistance. This zirconium alloy composition can be usefully used as a nuclear fuel components in a nuclear power plant because it has a very low hydrogen pick-up rate and high hydrogen embrittlement resistance under operation environments of nuclear power plant.

Abstract: A zirconium alloy is manufactured through melting; solution heat treatment at 1,000 to 1,050° C. for 30 to 40 min and ?-quenching using water; preheating at 630 to 650° C. for 20 to 30 min and hot rolling at a reduction ratio of 60 to 65%; primary intermediate vacuum annealing at 570 to 590° C. for 3 to 4 hr and primarily cold-rolled at a reduction ratio of 30 to 40%; secondary intermediate vacuum annealing at 560 to 580° C. for 2 to 3 hr and secondarily cold-rolled at a reduction ratio of 50 to 60%; tertiary intermediate vacuum annealing at 560 to 580° C. for 2 to 3 hr and tertiarily cold-rolled at a reduction ratio of 30 to 40%; and final vacuum annealing at 440 to 650° C. for 7 to 9 hr.

Abstract: A zirconium alloy is manufactured through melting; solution heat treatment at 1,000 to 1,050° C. (?) for 30 to 40 min and ?-quenching using water; preheating at 630 to 650° C. for 20 to 30 min and hot rolling at a reduction ratio of 60 to 65%; primary intermediate vacuum annealing at 570 to 590° C. for 3 to 4 hr and primarily cold-rolled at a reduction ratio of 30 to 40%; secondary intermediate vacuum annealing at 560 to 580° C. for 2 to 3 hr and secondarily cold-rolled at a reduction ratio of 50 to 60%; tertiary intermediate vacuum annealing at 560 to 580° C. for 2 to 3 hr and tertiarily cold-rolled at a reduction ratio of 30 to 40%; and final vacuum annealing at 460 to 590° C. for 7 to 9 hr.

Abstract: Disclosed herein is a free drop tester wherein an angle of a test piece can be freely adjusted, a weight can fall on the exact spot, and an impulse of the weight can be controlled, and provides a free drop tester comprising a vertical guide disposed perpendicularly to the ground, a support body for supporting the vertical guide against the floor, a weight of which falling path is guided by the vertical guide, a test piece holder disposed under the bottom surface of the vertical guide, a horizontal rotation shaft of which one end is connected to a test piece holder, a power transmission unit connected to the other end of the horizontal rotation shaft, a test piece angle adjuster including a driving unit for supplying power to the power transmission unit, and a means for adjusting the height of the weight.

Abstract: Disclosed herein are zirconium alloy compositions having a low hydrogen pick-up rate and high hydrogen embrittlement resistance. This zirconium alloy composition can be usefully used as a nuclear fuel components in a nuclear power plant because it has a very low hydrogen pick-up rate and high hydrogen embrittlement resistance under operation environments of nuclear power plant.