Degradation of superconducting properties of ReBCO tapes due to transmutation of Gd and Eu by neutron irradiation in fission reactor

ReBCO tapes, GdBCO, EuBCO and YBCO tapes, were neutron irradiated in a fission reactor, JRR-3, and changes in superconductivity were evaluated. Also, isotopes of Gd, Eu and Y were investigated by a Ge detector and 153 Gd, 152 Eu and 155 Eu were detected along with isotopes of Ce and Ag which are present in layers of the tape other than the ReBCO layer. These isotopes are good evidence of the transmutation. Considering cross section of these elements, 155 Gd, 157 Gd, 151 Eu and 153 Eu are thought to capture thermal neutrons and become isotopes. The isotopes are transmuted by electron capture or electron release to different atoms. The electron state in the perovskite crystal would be disrupted by the electron exchange of the Re nuclei, resulting in a significant decrease in superconductivity.