Wanted to make a quick recommendation that you take a look at a post over at gCaptain. It reports that a contract has been issued for Azipods to equip a new Russian icebreaker, but it also has a good video advertisement that explains the systems and shows them in operation including the relatively new method of icebreaking by going astern and its maneuvering advantages on a very large cruise ship. If you are not already familiar with these systems, I think you’ll find it interesting.
The arrangement being used on the icebreaker is interesting, there are two 7.5 MW thrusters and a 10 MW shafted centerline unit. Total output is 25MW or 33,500 HP.
Chuck Hill's CG Blog 
The new Mackinaw uses Pods effectively.
This article on planned improvements to Russian shipbuilding states that Russia will need 26 icebreakers by 2020, including one 110MW (approx 150,000HP) nuclear powered icebreaker and five 60MW (80,000HP) icebreakers. http://navaltoday.com/2012/10/17/russia-drafted-shipbuilding-development-program-2030/?utm_source=Naval+Today.com&utm_campaign=e8f6de5af7-RSS_EMAIL_CAMPAIGN&utm_medium=email
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Not so great news about the 25-megawatt icebreaker under construction in St. Petersburg. First, it was about 2,500 tons overweight and now the sanctions are starting to bite:
http://thebarentsobserver.com/arctic/2016/02/more-delays-worlds-biggest-conventional-icebreaker
“The world’s biggest diesel-electric icebreaker is unlikely to clear Arctic waters in 2017 as previously announced by the Russian shipbuilders.
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The keel of the ship was officially laid at the Baltic Yard in St. Petersburg in 2012, and construction was originally to be completed in 2015. That schedule was later moved to 2017.”