**Implementation of Hot-Tail and Avalanche Runaway Electron Generation Models for the 3D nonlinear MHD code M3D-C1** G Hu(1,2), R Datta(1), C Clauser(1), RA Tinguely(1) (1)MIT Plasma Science and Fusion Center, Cambridge, MA, USA 02139 (2)Wellesley College, Wellesley, MA 02481 Runaway electrons (REs) produced during tokamak disruptions represent a critical risk to plasma-facing components in high-current devices. Predictive modeling of RE dynamics requires accurate treatment of both primary and secondary generation mechanisms. In this work, we implemented two RE source models: the Hesslow avalanching model (Hesslow et al. 2018\) and a hot-tail generation model (Smith et al. 2008). These models were initially developed and verified against analytic expectations and benchmark cases, and incorporated into reduced 0D/1D disruption models to quantify their effect in SPARC-like and ARC-like conditions. This work provides a framework for incorporating advanced RE‑generation physics into extended magnetohydrodynamic simulations, with both the Hesslow and hot-tail models now implemented in the 3D nonlinear MHD code M3D‑C1 (Jardin et al. 2012\) for self‑consistent modeling of RE generation and transport. Application to SPARC‑like and ARC‑like scenarios provides initial tests of the models’ performance under reactor‑relevant disruption conditions. Thank you to the MIT UROP office for their support. ***References*** Hesslow, L., Embréus, O., Wilkie, G. J., Papp, G., & Fülöp, T. (2018). Effect of partially ionized impurities and radiation on the effective critical electric field for runaway generation \- IOPscience. *Plasma Physics and Controlled Fusion*, *60*(7). [https://doi.org/10.1088/1361-6587/aac33e](https://doi.org/10.1088/1361-6587/aac33e) Jardin, S. C., Ferraro, N., Breslau, J., & Chen, J. (2012). Multiple timescale calculations of sawteeth and other global macroscopic dynamics of tokamak plasmas \- IOPscience. *Computational Science & Discovery*, *5*(1). [https://doi.org/10.1088/1749-4699/5/1/014002](https://doi.org/10.1088/1749-4699/5/1/014002) Smith, H. M., & Verwichte, E. (2008). Hot tail runaway electron generation in tokamak disruptions. *Physics of Plasmas*, *15*(7). [https://doi.org/10.1063/1.2949692](https://doi.org/10.1063/1.2949692)