Disruptions in ITER present the risk of generating large Runaway Electron (RE) beams that may cause untolerable damage when impacting the wall. Assuming short Thermal Quenches (TQs) lasting around 1 ms, the hot tail mechanism, driven by the rapid temperature drop and the resulting non-Maxwellian electron population, may produce dangerous amounts of RE seeds [1]. This motivates modelling with 3D non-linear MHD codes in order to accurately take into account electron losses due to magnetic field stochasticity and other 3D aspects of the dynamics. We leverage the JOREK 3D non-linear MHD code in order to post-process MHD simulations with test electrons. A dedicated computational framework has been developed to simulate the behavior of a hot test electron population evolving in the pre-calculated MHD fields and undergoing collisions with the bulk electrons and ions. Before conducting comprehensive 2D and 3D hot tail seed estimations, we benchmark our results against the DREAM 1D-2P Fokker-Planck solver. Initial benchmarks involve a 2 dimensional (2P) velocity phase space within uniform fields, replicating a scenario from [2] where the temperature drops exponentially. Electron distribution functions from JOREK and DREAM show remarkable agreement. Using isotropic and pitch-dependent runaway criteria, we calculate the relative RE density and find that JOREK’s RE seed results align with both DREAM and results from [2], with a relative error of 5%. Further validation includes axisymmetric TQs in a DT H-mode ITER scenario. By varying the TQ duration from 0.36 ms to 7.2 ms, the generated RE population decreases from 4E18 RE/m3 to 5E11 RE/m3. Additionally, for a TQ duration of 0.36 ms, increasing the initial density (at constant thermal energy) from 8E19 /m3 to 4E20 /m3 reduces the RE seed from 4E18 RE/m3 to 0.4 RE/m3. Across these cases, JOREK’s RE estimates consistently match DREAM’s predictions, even for low-generation scenarios. Finally, experimental validation is performed. DIII-D pulse 178682, identified in [3] as producing a large hot tail RE seed, is currently being modeled with JOREK for this purpose. The next step of our work will consist in predicting hot tail RE generation in ITER disruptions to optimize the ITER disruption mitigation strategy. [1]: Smith, H. M., & Verwichte, E. (2008). Hot tail runaway electron generation in tokamak disruptions. Physics of plasmas, 15(7). [2]: Stahl, A., and al. (2016). Kinetic modelling of runaway electrons in dynamic scenarios. Nuclear Fusion, 56(11), 112009. [3]: Paz-Soldan, C., and al. (2020). Runaway electron seed formation at reactor-relevant temperature. Nuclear Fusion, 60(5), 056020.