The shipbuilder will deliver the 60-megawatt (MW) Project 22220 ships to Russian nuclear energy agency Rosatom in 2019 and 2020.
The yard is already building the first in the series, the most powerful icebreaker in the world, due in 2017.
The vessels will be able to sail in ice up to three metres thick.
The latest deal is said to be worth RUB 84.4bn ($2.34bn).
