The technology scaling has boosted the importance and gravity of radiation faults. Hardening techniques are required to ensure a high level of reliability, mainly to harsh critical applications. Hardware redundancy remains the most adopted option to deal with fault tolerance, mostly the TMR technique. However, the weakness of this technique is the voter circuit. This paper investigates the robustness of nineteen majority voter designs in the presence of a SET. The analysis explores critical diffusion areas and LET threshold. The results show designs with a 3X difference in the number of critical diffusion areas and 6X in the LET threshold.