On July 6, CERAD researches Hans-Christian Teien and PhD student Shane Sheibener are going on a research cruise with colleagues from the Institute of Marine Research (HI), the Norwegian Radiation and Nuclear Safety Authority (DSA) and from Russia to investigate the sunken nuclear submarine "Komsomolets".
"Komsomolets" has been lying on the bottom of the sea for 30 years and there is risk of leakage from the old wreck, making this expedition an important societal mission. TV2 will participate and will cover the expedition with daily updates.
- Our job will be to find out where the plutonium in the samples we take comes from, says Teien.
- Are we finding residues from past nuclear bomb fallout, or is it a result of a leak from the submarine?
Fire in the boardroom
On April 7, 1989, fire broke out in the submarine "Komsomolets" while it was in the submerged condition. The fire spread quickly along the cable passages on board, and by triggering the ballast tank, the boat came up to the surface and was able to send emergency signals. The crew did everything to put down the fire but the boat sank. Although both aircraft and vessels came to the rescue, many remained in the cold water for too long. Out of the 69 crew members, 42 people died.
Today, the submarine is located at a depth of 1680 meters in the Norwegian Sea (see map).
Contains reactor and nuclear warheads
"Komsomolets" was equipped with a 190 MW pressurized water reactor and 2 nuclear warhead torpedoes. When the fire broke out, the reactor was shut down. Based on Russian estimates, the reactor contained a total activity of about 29 PBq at the time of the accident, while the warheads contain plutonium with total activity of about 16 TBq. (Becquerel - Bq, is unit for activity of a radioactive substance, ed. rem.)
There have been several expeditions to the Norwegian Sea to investigate whether radioactive pollution leaks from the submarine, both Russian expeditions in the period 1989 and 2007, as well as annual Norwegian surveys conducted by the Institute of Marine Research and the Norwegian Radiation and Nuclear Safety Authority in connection with monitoring of the marine environment. The investigations are difficult as the wreck is at a great depth.
Filming and collecting samples
This year's research cruise is the first cruise since 2007 with the goal of taking samples from the submarine itself. This voyage includes the use of a highly advanced ROV (remotely operated underwater vehicle) that allows the wreck to be filmed and samples collected at selected locations in and around the wreck. The samples should be checked for radioactivity before they can be taken on board.
Where does plutonium come from?
Water samples will be filtered and processed chemically on board to identify possible contents of radionuclides in the water or in association with particles. Collected sediment cores will be cut prior to analysis to identify possible contents of radionuclides both in the upper and deep layers of the sediments. Simple analyzes will be carried out on board, while far more advanced analyzes of radionuclides will later be carried out at HI, DSA and CERAD/NMBU. CERAD will in particular be responsible for the determination of various plutonium isotopes in samples taken close to the submarine for source identification – is plutonium from the nuclear bomb fallout of the 1950-1960s, or due to leakage from the submarine.