Effects of hydride morphology on the embrittlement of Zircaloy-4 cladding

Kim, Ju-Seong; Kim, Tae-Hoon; Kook, Dong-Hak; Kim, Yong Soo

doi:10.1016/j.jnucmat.2014.09.025

Cited by 65 publications

(15 citation statements)

References 34 publications

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“…As mentioned above, circumferential hydrides can seriously damage the mechanical properties of the matrix only at high hydrogen concentrations or with localized precipitation [ 147 ]. In particular, the fractographs of Zircaloy materials containing circumferential hydrides and radial hydrides are quite different ( Figure 12 a,b) [ 154 , 155 , 156 , 157 , 158 , 159 , 160 ]. The fracture surface displayed in Figure 12 a has a quasi-cleavage fracture of micropores, cavities, and facets [ 155 ].…”

Section: Hydride-induced Embrittlementmentioning

confidence: 99%

Mechanisms of Hydride Nucleation, Growth, Reorientation, and Embrittlement in Zirconium: A Review

Jia

Han

2023

Materials

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Zirconium (Zr) hydrides threaten the reliability of fuel assembly and have repeatedly induced failures in cladding tubes and pressure vessels. Thus, they attract a broad range of research interests. For example, delayed hydride cracking induced a severe fracture and failure in a Zircaloy-2 pressure tube in 1983, causing the emergency shutdown of the Pickering nuclear reactor. Hydride has high hardness and very low toughness, and it tends to aggregate toward cooler or tensile regions, which initiates localized hydride precipitation and results in delayed hydride cracking. Notably, hydride reorientation under tensile stress substantially decreases the fracture toughness and increases the ductile-to-brittle transition temperature of Zr alloys, which reduces the safety of the long-term storage of spent nuclear fuel. Therefore, improving our knowledge of Zr hydrides is useful for effectively controlling hydride embrittlement in fuel assembly. The aim of this review is to reorganize the mechanisms of hydride nucleation and growth behaviors, hydride reorientation under external stress, and hydride-induced embrittlement. We revisit important examples of progress of research in this field and emphasize the key future aspects of research on Zr hydrides.

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Section: Hydride-induced Embrittlementmentioning

confidence: 99%

Mechanisms of Hydride Nucleation, Growth, Reorientation, and Embrittlement in Zirconium: A Review

Jia

Han

2023

Materials

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“…Selain karena friksi internal dislokasi karena larutnya hidrogen dalam matriks α-Zr [19], penurunan nilai regangan juga disebabkan oleh ukuran dan arah pembentukan presipitat hidrida [20]. Presipitat hidrida yang lebih panjang akan memiliki nilai regangan yang lebih rendah jika dibandingkan dengan hidrida yang lebih pendek.…”

Section: B) Uji Mekanikunclassified

Pengaruh Hidrogen Terhadap Kekuatan Tarik Kelongsong Bahan Bakar Nuklir Berbasis Paduan Zirkonium

Sigit

Afghani

Setiawan

et al. 2017

urania

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ABSTRAK PENGARUH HIDROGEN TERHADAP KEKUATAN TARIK KELONGSONG BAHAN BAKAR NUKLIR BERBASIS PADUAN ZIRKONIUM.Selama operasi reaktor nuklir, zircaloy-4 (Zr-4) sebagai kelongsong bahan bakar nuklir berada pada lingkungan yang berpotensi menimbulkan kegagalan mekanik, terutama akibat interaksinya dengan hidrogen. Hidrogen berdifusi ke dalam kelongsong dan pada saat melewati batas kelarutan akan terpresipitasi menjadi hidrida rapuh yang menyebabkan degradasi sifat mekanik. Teknik pengujian tarik ring digunakan dalam penelitian ini untuk mengetahui pengaruh keberadaan hidrida terhadap kekuatan tarik kelongsong Zr-4. Kelongsong Zr-4 dipanaskan pada temperatur 500 °C dan 600 °C dalam kondisi vakum selama satu jam yang diikuti dengan proses hidrogenasi bertahap hingga mencapai tekanan 1000 mbar dan ditahan selama tiga jam sebelum didinginkan secara normal di dalam tungku. Dengan menggunakan persamaan gas ideal diperoleh kandungan hidrogen yang terserap oleh kelongsong Zr-4 berturut-turut sebesar 674 ppm dan 1215 ppm pada temperatur hidrogenasi 500 °C dan 600 °C. Proses hidrogenasi pada temperatur 500 °C menyebabkan peningkatan kekerasan mikro hingga 36 % dan pada temperatur 600 °C dapat meningkatkan kekerasan mikro hingga 49 % jika dibandingkan dengan kelongsong Zr-4 tanpa perlakuan. Sementara itu, analisis mikrotruktur menunjukkan presipitat hidrida lebih banyak menempati batas butir. Presipitat hidrida lebih panjang dan tebal pada temperatur hidrogenasi yang lebih tinggi. Kenaikan jumlah hidrogen menghasilkan kenaikan nilai tegangan sebesar 4,4 %, penurunan nilai regangan sebesar 2,1 % dan kenaikan level kekerasan mikro Vickers sebesar 13 %. Hal ini menunjukkan bahwa keberadaan presipitat hidrida dalam kelongsong meningkatkan kekuatan tarik dan menurunkan daktilitasnya.. Kata kunci:Hidrogen, kekuatan tarik, kelongsong, uji tarik ring, daktilitas.

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“…However, the transition point from ductile to brittle is ambiguous. Kim et al [26] proposed the fracture energy per area of 90 kJ/m 2 where the starting point of large plastic deformation occurs and Billone et al [4] proposed the 2% offset strain which is roughly equivalent to 40 kJ/m 2 . In either case, 90H400C is in ductile regime at room temperature.…”

Section: Integrity Evaluation Of Cladding By Ring Compression Testmentioning

confidence: 99%

“…In general, ductility decreases with increasing hydrogen content; moreover, radial hydride has been recognized as an easier crack path. Recently, it was proposed that the DBTT of radial hydrided specimen (H content: 100-150 wppm, RHCF: 0.6-1.0) is around 200 • C [26] as shown in Figure 12. For comparison, RHCF of 90H470C is slightly low, but hydrogen content of 90H470C is higher than that of the reference and therefore has significant circumferential hydrides.…”

Section: Integrity Evaluation Of Cladding By Ring Compression Testmentioning

confidence: 99%

Stress and temperature-dependent hydride reorientation of Zircaloy-4 cladding and its effect on the ductility degradation

Kim

Kook

Kim

et al. 2014

Journal of Nuclear Science and Technology

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A hydride reorientation can deteriorate the mechanical ductility of spent fuel cladding and make it more susceptible to failure. Therefore, an evaluation of the reorientation under dry storage conditions and their effects on the cladding ductility are critical issues in terms of the regulation criteria. In this work, biaxial stress was applied to Zircaloy-4 cladding by pressurizing Ar gas. The study showed that the hydride reorientation can occur at around 60 and 80 MPa at 400 and 300 • C, respectively. The ring compression test at room temperature showed that the ductility decreases with an increase in radial hydride quantity: Fl(45) and radial hydride continuity factor. In addition, a significant hydride reorientation can occur at high temperature conditions even if the hoop stress is equal to or less than 90 MPa which can bring a significant ductility degradation.

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Effects of hydride morphology on the embrittlement of Zircaloy-4 cladding

Cited by 65 publications

References 34 publications

Mechanisms of Hydride Nucleation, Growth, Reorientation, and Embrittlement in Zirconium: A Review

Mechanisms of Hydride Nucleation, Growth, Reorientation, and Embrittlement in Zirconium: A Review

Pengaruh Hidrogen Terhadap Kekuatan Tarik Kelongsong Bahan Bakar Nuklir Berbasis Paduan Zirkonium

Stress and temperature-dependent hydride reorientation of Zircaloy-4 cladding and its effect on the ductility degradation

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