*Article* **Desorption of Implanted Deuterium in Heavy Ion-Irradiated Zry-2**

**Hideo Watanabe 1,\*, Yoshiki Saita <sup>2</sup> , Katsuhito Takahashi 2,3 and Kazufumi Yasunaga <sup>4</sup>**


**Abstract:** To understand the degradation behavior of light water reactor (LWR) fuel-cladding tubes under neutron irradiation, a detailed mechanism of hydrogen pickup related to the point defect formation (i.e., a-component and c-component dislocation loops) and to the dissolution of precipitates must be elucidated. In this study, 3.2 MeV Ni3+ ion irradiation was conducted on Zircaloy-2 samples at room temperature. Thermal desorption spectroscopy is used to evaluate the deuterium desorption with and without Ni3+ ion irradiation. A conventional transmission electron microscope and a spherical aberration-corrected high-resolution analytical electron microscope are used to observe the microstructure. The experimental results indicate that radiation-induced dislocation loops and hydrides form in Zircaloy-2 and act as major trapping sites at lower (400–600 ◦C) and higher (700–900 ◦C)-temperature regions, respectively. These results show that the detailed microstructural changes related to the hydrogen pickup at the defect sinks formed by irradiation are necessary for the degradation of LWR fuel-cladding tubes during operation.

**Keywords:** light water reactor; zirconium alloys; nuclear fuel cladding; thermal desorption spectroscopy; transmission electron microscopy
