Submarine K-27 - the Soviet Union's 'undersea Chernobyl disaster'

The K-27 submarine was sunk by the Soviet Union with its reactor not dismantled, which could pose a risk of radioactive leakage no less than the Chernobyl disaster.

The wreck of the submarine K-27 in the Kara Sea

At the height of the Cold War in 1968, 144 Soviet sailors on the submarine K-27 set off for the Arctic on a mission to gather information about NATO bases. They had no idea that they were about to face a radioactive disaster under the sea, according to the BBC.

The K-27 was the only Project 645 attack submarine, developed from Project 627 (NATO designation: November). Like the United States, the Soviet Union often experimented with advanced technologies that were ahead of their time. The K-27 was equipped with two VT-1 liquid-metal-cooled nuclear reactors. This design had never appeared on a Soviet submarine, making the K-27 more of a science project than an attack submarine.

When launched on June 15, 1958, the K-27 was the first Soviet submarine to have a lead-bismuth-cooled nuclear reactor. This reactor was smaller and more powerful than the traditional water-cooled design. It allowed the submarine to remain hidden for weeks at a time without needing to surface or refuel. The K-27 set an impressive record in the Soviet Navy, becoming the first nuclear attack submarine to remain submerged for 50 consecutive days.

Despite its impressive technology and specifications, the K-27 had a short operational life due to a nuclear reactor failure. On May 24, 1968, during an Arctic reconnaissance mission, one of the two VT-1 reactors malfunctioned, causing the ship’s power supply to drop abruptly from 87% to 7%. At the same time, gamma radiation spiked in the reactor compartment. Toxic gases and steam also leaked from the reactor into other compartments.

K-27 during an exercise near NATO forces. Photo: The Lean Submariner.

"After 5 days of travel, everything was normal. I was chattingtalk to other people"We were in compartment 5, next to compartment 4, which contained two nuclear reactors, when suddenly we heard someone running. We had radiation detectors, but they were not turned on, and no one paid attention to the parameters until the technician turned on the radiation meter. His face was shocked and full of worry," submarine officer Vyacheslav Mazurenko recalled.

The crew did not understand the severity of the problem until it was too late, as radioactive gas has no taste or smell. Two hours after the initial alarm, those in compartment 4 had to be carried out on stretchers due to severe radiation exposure. The crew managed to refloat the ship, then spent five hours returning it to base on the Kola Peninsula.

"When the ship surfaced, the superiors ordered to turn off the engine and wait for special instructions. However, Captain Pavel Leonov decided to continue the journey. If he stopped for a few more hours, no one would survive to bring the K-27 back to base," Mazurenko said.

All 144 crew members on board were exposed to radiation, nine of whom died. However, the Soviet Union continued to let the K-27 sail a month later and conducted numerous experiments until 1973.

By February 1979, the Soviet military decided to decommission the K-27, but had to find a way to dispose of the nuclear reactor on board. They finally decided to sink the K-27 in 30-meter-deep water in the Kara Sea on September 6, 1982.

The K-27's hull is filled with concrete and asphalt to enclose the two reactors and 90 kg of uranium-235 fuel inside, but this protection is expected to last only 50 years. By mid-year, the concrete and asphalt hull on the ship will have only about 15 years left to serve. That makes the K-27 an underwater Chernobyl waiting to happen.

The K-27 during the process of being sunk. Photo: Barents Observer.

"Sooner or later, a radioactive leak will occur if the K-27 is left there. The ship has been lying on the seabed for more than 30 years, rusting. The challenge now is to find a way to raise it without shaking the reactors too much. If that happens, an uncontrolled chain reaction could be triggered, causing a large leak of radioactive material into the Arctic marine environment. This type of pollution cannot be removed from the seabed," said Thomas Nilsen, editor-in-chief of the Barents Observer.

Despite the problems on the K-27, the liquid metal-cooled reactor was completed and equipped on the Project 705 "Lira" (NATO designation: Alfa) submarines. They had unprecedented speed and incredible diving ability. However, all seven Lira submarines were decommissioned early due to high maintenance costs.

The US also equipped the USS Seawolf (SSN-575) with liquid-metal-cooled nuclear reactors in the 1950s, but the country quickly abandoned them in favor of high-pressure water reactors.

According to VNE