A system for attenuating seismic forces includes a reactor pressure vessel containing nuclear fuel and a containment vessel that houses the reactor pressure vessel. Both the reactor pressure vessel and the containment vessel may include a bottom head. Additionally, the system may include a base support that is configured to contact a support surface on which the containment vessel is positioned in a substantially vertical orientation. An attenuation device may be located between the bottom head of the reactor pressure vessel and the bottom head of the containment vessel. Seismic forces that travel from the base support to the reactor pressure vessel via the containment vessel may be attenuated by the attenuation device in a direction that is substantially lateral to the vertical orientation of the containment vessel.