Compact fusion devices, which rely on high magnetic fields and are thus dependent on high-temperature superconductors will face major issues concerning the lifetime of their magnet systems. Based on the high expected neutron flux and the low radiation resistance of currently available coated conductors, recent reports predicted the lifetime of the magnet system of an ARC-like reactor to be as low as several months. If coated conductors don’t unexpectedly drop sharply in price, the magnets will be a major cost factor and exchanging them on a regular basis contradicts the goal of these concepts to be a cheap alternative to conventional approaches like DEMO. Both, improving the radiation resistance of coated conductors and development of possible mitigation strategies, requires a thorough understanding of the underlying degradation processes. In this study thermal and fast neutron irradiation experiments were conducted in the TRIGA Mark II reactor in Vienna on Rare-Earth-Barium-Copper-Oxide (REBCO) based commercial coated conductors. Irradiating samples containing gadolinium with thermalized neutrons leads to a strong degradation of the critical current density, Jc, and the critical temperature, Tc, due to a well-understood neutron capture reaction. The distinct energy and position of the primary knock on atom (PKA), allows us to use molecular dynamic simulations (MDS) to work out which defect structures are formed in the process. Results from MDS indicate the predominant formation of oxygen frenkel pairs, however, more complex defects as Gd-Cu antisites occur as well. Comparing the results of samples shielded from the low-energy peak of the TRIGA Mark II reactor spectrum with Cd foil as absorber of thermalized neutrons (Ekin < 0.55) and samples irradiated with the full neutron spectrum shows a comparable degradation behavior of the critical current as function of the critical temperature. Subsequent annealing experiments in pure O2 at atmospheric pressure showed the same recovery rates of Tc, independent of the irradiation technique and the very distinct pinning landscapes. These results are a strong indication that similar or even the same defects exist in both samples and are responsible for the degradation of Tc. Furthermore, the influence of the expected defects on the local density of states (DOS) was calculated using density functional theory (DFT), allowing to identify the defect structures that seem especially detrimental for the superfluid density and thus the Tc. One of the identified defects is predicted to exhibit a very low activation barrier of approximately 0.07 eV for recombination, indicating that defect annealing might start at temperatures of approximately 100 K, which is in agreement with data from cryogenic proton irradiation experiments.