Energy Secretary Chris Wright is expected to announce the loan at Vistra's nuclear plant on Lake Erie in Ohio, according to a source cited by CNBC.
Nikol Pashinyan said approved investment programs have pushed Armenia from an electricity surplus into a deficit.
Russian state nuclear firm Rosatom says a Ukrainian drone incident caused minor damage at the plant but did not affect its operations, which continue at full capacity.
Russian state news agency TASS reports that work has started on preparing the automated process control system (APCS) of Unit 1 at Turkey's Akkuyu Nuclear Power Plant for pre-commissioning.