Very high swelling and embrittlement observed in a Fe-18Cr-10Ni-Ti hexagonal fuel wrapper irradiated in the BOR-60 fast reactor

Journal Article · Mon Sep 01 00:00:00 EDT 2008 · Journal of Nuclear Materials, 378(3):327-332

DOI:https://doi.org/10.1016/j.jnucmat.2008.06.036· OSTI ID:947043

Neustroev, V S; Garner, Francis A

The highest void swelling level ever observed in an operating fast reactor component has been found after irradiation in BOR-60 with swelling in Kh18H10T (Fe-18Cr-10Ni-Ti) austenitic steel exceeding 50%. At such high swelling levels the steel has reached a terminal swelling rate of ~1%/dpa after a transient that depends on both dpa rate and irradiation temperature. The transient duration at the higher irradiation temperatures is as small as 10-13 dpa depending on which face was examined. When irradiated in a fast reactor such as BOR-60 with a rather low inlet temperature, most of the swelling occurs above the core center-plane and produces a highly asymmetric swelling loop when plotted vs. dpa. Voids initially harden the alloy but as the swelling level becomes significant the elastic moduli of the alloy decreases strongly with swelling, leading to the consequence that the steel actually softens with increasing swelling. This softening occurs even as the elongation decreases as a result of void linkage during deformation. Finally, the elongation decreases to zero with further increases of swelling. This very brittle failure is known to arise from segregation of nickel to void surfaces which induces a martensitic instability leading to a zero tearing modulus and zero deformation.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 947043
• Report Number(s): PNNL-SA-58238; AT6020100
• Journal Information: Journal of Nuclear Materials, 378(3):327-332, Journal Name: Journal of Nuclear Materials, 378(3):327-332
• Country of Publication: United States
• Language: English