The EPA’s role, as stated in the Energy Policy Act of 1992 (Public Law 102-486), Section 801(a), is to set public health and safety radiation protection standards for protection of the public from releases from radioactive materials stored or disposed of in the repository. The Nuclear Regulatory Commission must determine whether the performance of the Yucca Mountain facility complies with the standards set by the EPA, in order to grant the operator of the facility a license (the Department of Energy). However, the Department of Energy is not currently pursuing a license.
For more information about the standards set by the EPA, 40 CFR Part 197.