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The Soviet Union was the first country to put a nuclear reactor on a polar icebreaker. And it was rad.

Their icebreakers helped clear a path through the Arctic, turning what had once been frequently unpassable into a reliable trade route into Siberia.

Russia remains the only country in the world with nuclear-powered icebreakers.

In this video, let's take a look at the Soviet Union's nuclear icebreakers, and the crushing impact they had in opening up the Arctic shipping routes.

Northern Sea Route

The Northern Sea Route - sometimes also called the Northeast Passage - runs alongside the Russian Arctic coast for some 4,375 miles across 11 time zones.

Through it, you can go from the European and Asiatic coasts, from the Barents and Karas seas in the west to the Bering Strait in the east.

It is an intimidating route. Its most dangerous segments are highlands where ice up to 2 meters thick can cluster and block routes for up to ten months of the year. Ships traveling the route run the risk of getting surrounded by ice.

In the second half of the 19th century, only about 60% of commercial trade ships made it through. But over time a semi-reliable trade route tentatively emerged transporting minerals and goods to and from Siberia.

When the Soviets took power after the October Revolution, the Soviets undertook large scale study of the Arctic ocean. They built a network of research stations and sent expeditions into the area.

Over time, a large deal of infrastructure has been built out to bring critical supplies to far-flung areas of the Soviet Union. The icebreakers have been key to making this whole system work smoothly.

Icebreakers

Purpose-built icebreakers first emerged at the end of the 19th century with Russia's Yermak cited as the pioneer.

They worked largely the same way back then as they do now - riding up onto the ice and breaking through it using their sheer weight.

An icebreaker's job is to lead merchant convoys through ice-infested waters. It might occasionally come to other ships' rescue, freeing them from the ice.

In order to do this job competently, an icebreaker needs to have a very particular set of skills.

First, icebreakers need a specialized, strengthened hull that is bigger and wider than traditional ships. The bow - or forward part of the ship - has to have a small angle between the surface ice and its very front.

Icebreakers may also have propellers at the bow, which makes it easier to back up and ram the ice again if they get stuck. Some of the Baltic icebreakers like the Urho had this.

These special shapes illustrate tradeoffs made between travel across the ice and the open sea. The angle reduces the ice's resistance but also makes it more vulnerable in the open ocean.

For this reason, Arctic and Antarctic icebreakers often have differently shaped hulls - because the latter has to survive the open oceans.

Engines

The second thing an icebreaker needs is an extremely powerful engine. One capable of maintaining constant propeller thrust and ship speeds in spite of large amounts of ice.

Pushing through the ice requires a system capable of handling great shocks. Sometimes it has to go from full speed ahead to full reverse in a very short period of time.

The first icebreakers had steam engines - capable of generating up to 10,000 shaft horsepower - before transitioning to diesel-electric. Many icebreakers still use such engines today, which can do up to 36,000 shaft horsepower.

At the end of World War II, most of the Soviet Union’s icebreaker fleet were still mostly steam-powered. It was clear that they needed to be updated.

Soviet scientists noticed the obvious value of using nuclear power to fuel their icebreakers. Using nuclear power allows the engine to output huge amounts of power without needing to refuel as often as its diesel and steam powered counterparts.

Such an icebreaker would be incredibly valuable in clearing ice-infested trade routes. Capable of turning the Arctic seas from some frozen wasteland into the Soviet Union's Panama Canal, as claimed in newspapers at the time.

Lenin

The Soviets' first nuclear icebreaker was the Lenin. 134 meters long, 27.6 meters high, and displacing over 16,000 tons, the Lenin was the biggest icebreaker ever made up until then.

Construction first began at the Admiralty shipyards of Leningrad in 1956. The effort brought together the latest technologies and methods to quickly put the ship together and launch it on December 1957.

Lenin is powered by a 3,100 ton nuclear plant, designed to handle 360 tons of steam each hour at a temperature of 300+ degrees Celsius.

Inside, the ship's three OK-150 pressured water reactors produce steam that goes on to generate consistent electricity for the ship's electric engines.

At full power, the Lenin was capable of outputting up to 44,000 shaft horsepower.

Each reactor contains 219 operating channels and stands 1.6 meters high. They are fueled with 80 kilograms of weapons-grade 90%-enriched Uranium 235, which is good for about 200 days of peak output before needing to refuel.

Later on in 1970, the Soviets replaced these three reactors with two more modern OK-900 plants. We will explain why later.

Doin' Work

After a few years of testing, the government certified the Lenin's seaworthiness in 1959 and the ship was dispatched to the Arctic.

An oil burning icebreaker burned up to 70 tons of fuel in a single day. The Lenin by comparison burns just 45 grams each day. In a single journey, it traveled 10,000 miles in 3 months, escorting 92 ships.

In 1960, Soviet leader Nikita Khrushchev lauded the ship as a successful demonstration of nuclear energy for peaceful uses.

Each year, the Lenin would break up ice passages in the Yenisei Gulf and clear trade channels through the ice in the Vilkitsky Strait. With this, a certain part of the northeast passage has been opened up essentially all year-round, saving weeks of travel time.

The Incident

Like the rest of its type, the Lenin never experienced a nuclear failure incident at sea that required it to return to port. There were a couple steam leaks and a cable fire, but nothing serious.

However, there was one incident during refueling that necessitated a reactor replacement.

In 1965 or 1966, the Lenin suffered a loss-of-coolant accident when an operator accidentally drained all the water from one of the three reactors. Probably because of a design flaw which put a coolant inlet at the bottom of the tank.

The reactor had already been shut down at the time, but residual heat left inside caused some of the fuel to melt and deform. Slightly less than half of the fuel could be removed from the damaged core. So technicians put it into a special stainless steel casket, sealed that with concrete, and finally dumped the whole thing off the coast of the Novaya Zemlya archipelago.

The archipelago is probably most well known in the West for being where they detonated the Tsar Bomba - the most powerful nuclear weapon ever tested.

Anyway, as a result of this incident, the ship was sent back to the shipyard in 1967. For the next three years, they cut the entire nuclear power plant out of the ship and replaced it with two OK-900 reactor units.

Lenin served the rest of its time without serious incident. In 1974, the Lenin received the Order of Lenin. The ship was decommissioned in 1989 and now exists as a museum ship.

America

The Soviet announcement in 1957 that they had finished the nuclear-powered Lenin took the USA by surprise. The Americans had known about the boat since at least 1956 but had not expected it to be done so fast.

A few years later, the United States would launch the NS Savannah, the world's first nuclear-powered cargo ship.

But coming right on the tail of the news about Sputnik, the media spun the Lenin news into another example of American scientific backwardness.

It also spurred the question. Should the Americans build their own nuclear-powered icebreakers?

Congressmen proposed several massive iterations - including a version that would be 182 meters long (589 feet). The budget-conscious Eisenhower however vetoed funding for its construction.

Furthermore, the US Coast Guard explained to Congress that the icebreaking needs of the Soviets were different from those of the Americans. The Northeast Passage is open ocean with dangerous icy choke points, making it more suitable for bigger boats.

The Canadian Arctic on the other hand is full of islands and narrow passes.

The debate went back and forth. But in the end, the Congressmen basically admitted that the only reason they wanted the US to build such a machine would be because the Soviets had one too.

The Americans opted to instead focus on nuclear submarines. The Soviets and the Russians who inherited them remain the only country to build, own and run nuclear icebreakers. Though there's one notable semi-exception that we will talk about later.

The Arctic

The Lenin had shown that nuclear-powered icebreakers were feasible. The Soviets decided that they could leverage their experience to build their next generation of icebreakers to be even bigger and more powerful.

And so began the "Arctic" - the second nuclear icebreaker ever made and the first of the Arctic-class icebreakers.

Arctic class nuclear icebreakers were the biggest such ships in the world until recently. First laid down in 1971 and completed in late 1972, the Arctic was 148 meters long and displaced 21,000 tons.

Its two OK-900 nuclear reactors produce steam to drive three electric motors capable of producing up to 75,000 shaft horsepower.

Many improvements learned from the Lenin were applied here. They fixed the design flaw that led to the Lenin's loss of coolant incident. They improved the corrosion resistance of the secondary loops, and so on.

The Arctic was deemed ready to sail in 1974. In 1977, the Soviets decided to send the icebreaker to the North Pole to celebrate the 60th anniversary of the October Revolution. It made the journey successfully, being the first to do so. Its sister ships have also since made similar journeys.

After traveling over a million nautical miles over 33 years with no significant incidents, the Arctic was decommissioned in 2008. She now sits in Murmansk, awaiting dismantlement.

There were 6 Arctic-class nuclear icebreakers built in total. Four of them have been decommissioned - sitting around at Murmansk - while two remain in service.

A New Generation

In its waning years, the Soviet Union struck a deal with a private Finnish shipyard to build the next class of nuclear icebreakers- the Taymyr class.

It was a unique opportunity and the only time a nuclear icebreaker has been built outside the Soviet Union.

The Fins built a significant portion of the Taymyr and its sister ship the Vaygach - despite the press calling them "floating Chernobyls" - and then delivered them to the Soviet Union in 1989.

The Soviets finished off the rest of the boat, installing its single KLT-40 nuclear power plant and the propellers.

The Taymyr and Vaygach were a sign of very warm Soviet-Finnish relations - the friendliest they had been in a long time. A third nuclear icebreaker had been expected, but the Soviet Union never made it that far.

Russia

The collapse of the Soviet Union forestalled development on new boats for a long time. At the start, Russia extended the operating life spans of their aging Arctic-class icebreakers. The original Arctic was extended from 100,000 operating hours to 175,000.

In recent years, the Russian Federation has taken extensive steps to revitalize old Soviet Arctic trade routes. Part of that included finishing the last ship of the old Arctic-series - the Fifty Years of Victory. Left unfinished in 1994 and completed in 2007.

With that done, Russia embarked on a revitalized class of mega-sized nuclear-powered icebreakers - named Project 22220. The biggest in the world, the first of these, also named the Arctic, was launched in 2016.

These new icebreakers represent Russia's renewed focus on the Northern Sea Route - and have triggered some nervousness amongst the other Arctic nations.

Conclusion

Global climate change is remaking the once-icy Northern Sea Route. It is believed that in the near-future the passage would find itself free of ice for up to half of the year.

The route is an attractive one that offers substantially shorter distances - up to 60% shorter or more - than existing alternatives. Furthermore, it opens up new, potentially lucrative fishing and natural resource locations.

The nuclear icebreakers will play a key role in maintaining control over this new resource. Despite being a largely civilian watercraft, they represent a powerful symbol of Arctic intentions.