California climate groups on Tuesday filed a motion to intervene in the relicensing process for the Diablo Canyon Nuclear Power Plant, citing concerns over safety and environmental hazards at the plant that they say could risk disaster.

The motion, filed by Friends of the Earth, Mothers for Peace, and the Environmental Working Group, comes less than a year after the Nuclear Regulatory Commission approved the Pacific Gas and Electric Company’s request to extend the lifespan of Diablo Canyon beyond its originally planned 2025 closure date.