All licensing and regulatory actions subject to this subpart require an environmental assessment except those identified in § 51.20(b) as requiring an environmental impact statement, those identified in § 51.22(c) as categorical exclusions, and those identified in § 51.22(d) as other actions not requiring environmental review. As provided in § 51.22(b) , the Commission may, in special circumstances, prepare an environmental assessment on an action covered by a categorical exclusion.
10 C.F.R. §51.21