[PO-F1] Poster Session 1

[P1-33] UNDERSTANDING OF DELAYED HYDRIDE CRACKING FAILURE MECHANISM IN E110 ZIRCONIUM BASED FUEL CLADDINGS BY EBSD AND IN-SITU MECHANICAL TESTING

^○Hygreeva Kiran NAMBURI¹, Zbynek Spirit¹, Patricie Halodova¹, Ondrej Libera¹, Jakub krejci² (1.Research Centre REZ, Czech Republic, 2.UJP Praha, Czech Republic)

Zirconium based alloys are commonly used as material for fuel claddings in the light water reactors. Claddings act as first metallic barriers against loss of fission products during the nuclear power plant operation, intermittent storage or final dry storage. During the reactor operation, metallic claddings are prone to water side corrosion and subsequent hydrogen pick-up (in 10’s to 100’s of ppm) due to higher operating temperatures in reactor. Under specific favorable conditions (stress, temperature and hydrogen concentration level) claddings fail by a time dependent mechanism called Delayed Hydride Cracking (DHC). This results in critical issue for the safe performance of the power plants and storage used claddings.

In this work we present results from the DHC study on zirconium based E110 metallic fuel claddings. Test specimen is oxidized in an autoclave to have desired hydrogen content. DHC experiments are performed in scanning electron microscope chamber by using in-situ tensile testing device at high temperatures.

The paper emphases on microstructural studies, evaluation of threshold stress intensity, crack propagation rate, understanding fialure mechanism and role of crack tip hydrides fracture during the DHC failure in E110 fuel claddings.

Keywords: Zirconium alloys, nuclear fuel claddings, microstructure, crack tip hydride fracture, delayed hydride cracking failure.