Post irradiation examination of HANA claddings after research reactor test up to 34 GWD/MTU

The in-pile tested rods of HANA cladding in the Halden research reactor were subjected to a PIE, including LOM, hydrogen analysis, ring tensile test, and TEM observation in both the matrix and oxide. The accumulated burn-up and fluence of HANA claddings for PIE reached up to 34 GWD/MTU and 1.33 × 1025 n/m2 (E > 1 MeV), respectively. From the PIE tests, the oxide layer seems to be continuous for the circumference orientation in the HANA claddings, and no defects were seen in the oxide layer. The hydrogen content of HANA claddings ranged from 26 to 66 μg/g, and varied with alloy compositions. The yield strength and ultimate tensile strength were considerably increased by more than 20%, whereas the elongation was decreased by more than 17% when compared to the pre-irradiation test results. The increase of strength of HANA claddings was caused by the saturation of a-type dislocation loops.