Effect of molybdenum on properties of zirconium components of nuclear reactor core

Nikulina, A. V.; Kon'kov, V.F.; Peregud, M. M.; Vorob’ev, E. E.

doi:10.1016/j.nme.2018.01.001

Cited by 15 publications

(3 citation statements)

References 9 publications

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“…Zirconium alloy has become the preferred material for positioning grids in nuclear reactors because of its good nuclear properties, low thermal neutron absorption crosssection, high tensile strength, good corrosion resistance and comprehensive mechanical properties [1][2][3][4][5][6]. A positioning grid is a key clamping structure for fixing the transverse and axial positions of fuel assemblies in nuclear reactors [7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Study on Formability Improvement of Zr-4 Sheets Based on Texture Optimization

Liu,

Song,

Deng

et al. 2024

Metals

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A positioning grid is a key clamping structure for fixing the transverse and axial positions of fuel assemblies in nuclear reactors, and it is generally prepared by the transverse stamping of a Zr-4 sheet. However, the texture formed in the processing process of Zr-4 sheets can affect formability, resulting in cracking in the stamping process. Therefore, the relationship between the formability of Zr-4 sheets and the normal Kearns factor (Fn) of basal texture was studied in this paper. The results showed that the Zr-4 sheet with an Fn equaling 0.720, prepared by an isobaric reduction rolling process, would crack in the stamping process. To avoid the cracking during stamping, the formability improvement of Zr-4 sheets based on texture optimization was discussed. By using the finite element model (FEM) and a visco plastic self-consistent (VPSC) model coupled simulation, the relationship between the initial textures and formabilities of Zr-4 sheet is established. It is found that the hardening exponents (n) decreased with increasing Fns in VPSC simulations. Meanwhile, as the Fn increases, cracks are prone to occur at the bottom corner of the stamped sheet in finite element simulation. Given the results from FEM and VPSC simulations, it is proposed that the Fn should be controlled to be less than 0.7 for preventing cracks in the sheet during stamping. Additionally, a new rolling process named non-isobaric reduction rolling was designed in which the Fn of the Zr-4 sheet is successfully reduced to 0.690. The stamping results indicate that the sheet is free of cracks under an Fn of 0.690. Therefore, texture optimization with the proposed rolling process can improve the formability of Zr-4 sheets, which effectively solves the cracking problem of Zr-4 sheets.

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Section: Introductionmentioning

confidence: 99%

Study on Formability Improvement of Zr-4 Sheets Based on Texture Optimization

Liu,

Song,

Deng

et al. 2024

Metals

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“…Zirconium alloy is widely used to produce nuclear fuel claddings and core structural parts [1][2][3]. However, when the temperature exceeds 1200 • C, zirconium can react with water vapor to produce large amounts of hydrogen, easily causing explosions, and release large amounts of heat, further accelerating the melting of a reactor core [4,5]. Molybdenum (Mo) has advantages, such as high melting point (2610 • C), small cross-section area of neutron absorption, small linear expansion coefficient, good high-temperature strength, high thermal conductivity, and excellent corrosion resistance.…”

Section: Introductionmentioning

confidence: 99%

Rotary Friction Welding of Molybdenum without Upset Forging

Xie

Shang

et al. 2020

Materials

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A large instantaneous axial forging load is required to be applied for the final stage of rotary friction welding (RFW), which is usually conducive to obtaining clean, compact, and high-quality joints. However, for slender fuel claddings made of molybdenum (Mo) with low stiffness, the instantaneous axial forging load cannot be applied at the final stage of welding. This study carried out RFW tests without upset forging on Mo in the atmospheric environment and investigated the effects of welding time on joint morphology, axial shortening, microstructures, microhardness, tensile strength, and tensile fracture morphology. It found that the excessive and abrupt burning and a lot of smoke were generated around the weld zone during welding and spiral flashes were observed after welding. Under welding pressure of 80 MPa and spindle speed of 2000 r/min, the minimum average grain size and maximum tensile strength can be obtained in 4 s when the welding time is between 2–5 s. Scanning electron microscope (SEM) results show that there were morphologies of a large number of intergranular fractures and a small number of transgranular fractures in the fracture. The above results demonstrated that it is feasible to use RFW without upset forging to seal the last weld spot on upper end plugs of fuel claddings made of Mo in high-pressure inert gas, which would not only obtain reliable welding quality but also seal high-pressure inert gas in cladding tubes. The research results have a practical guiding significance of manufacturing accident-tolerant Mo nuclear fuel cladding.

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“…Pure copper has good resistance to corrosion. On the other hand, molybdenum has been used as reinforcement, for example, in stainless steels to inhibit chloride pitting, Zn coatings electrodeposited on steel [6], and Zr nucleus of nuclear reactors [7]. Some authors have conducted studies about copper matrix compounds and their behavior against corrosion [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Effects of Mo Concentration on the Structural and Corrosion Properties of Cu–Alloy

Hernández

Aguilar

Medína

2019

Metals

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Mechanical Alloying (MA) has the ability to extend the solubility limits of immiscible alloys in a solid state. In this work, a Cu-10 wt% Mo alloy was synthesized by mechanical alloying, using a high-energy mill type SPEX. The X-ray diffraction and Rietveld results show a crystallite size of 24 and 22 nm of Cu and Mo, respectively, with an occupation value of Mo inside the Cu structure of 27%, which was identificated by Energy Dispersive X-ray Spectroscopy and High-Resolution Transmission Electron Microscopy analysis. After that, the alloy was sinterized in an oven, heating the alloy to 1000 °C—close to the melting point of Cu (1085 °C). Electrochemical tests were carried out under a saline environment of synthetic seawater. The results show that the polarization curve of the alloy showed a pitting corrosion at about 134.83 mV, as well as a repasivation phenomenon (Erp = 241.47 mV) in the cathodic branch. Finally, three time constants were observed in the Nyquist diagrams: formation of a corrosion product film, load transfer, and diffusion, indicating that the corrosion properties in this alloy were improved compared with other Cu–alloys.

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Effect of molybdenum on properties of zirconium components of nuclear reactor core

Cited by 15 publications

References 9 publications

Study on Formability Improvement of Zr-4 Sheets Based on Texture Optimization

Study on Formability Improvement of Zr-4 Sheets Based on Texture Optimization

Rotary Friction Welding of Molybdenum without Upset Forging

Effects of Mo Concentration on the Structural and Corrosion Properties of Cu–Alloy

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