1. Slicing off the torpedo compartment
The bulkhead section of the submarine, containing the torpedo compartment, is fully destroyed. According to Russian officials, if an attempt is made to raise the submarine without cutting off the section, the forepart will just break off at some point of lifting.
The Kursk torpedo section contained, according to official returns, an overall amount of 10 tonnes TNT equivalent explosives.
The power of the explosion detected by the Norwegian seismological station Norsar on August 12th, the time of the accident, was ranging from one tonne to two tonnes TNT detonated underwater.
Oscar-II class submarines have four 533mm torpedo tubes and two 650mm torpedo tubes. The two 650mm torpedo tubes at the Kursk were reportedly loaded with 65-76-type torpedoes armed with conventional warheads. Two of the four 533mm torpedo tubes had USET-80 torpedoes with electric propulsion inside also armed with conventional warheads. The two remaining tubes were loaded with practice torpedoes. In addition, 18 torpedoes and tube-launched missiles with conventional warheads were in the torpedo room.
The torpedo, which to belief of many experts caused the explosion, was the 65-76-type (65cm / 11m) designed in 1976.
So the conclusion may be that there are still at least seven tonnes of TNT equivalent explosives scatted around the Kursk wreck.
According to the plan, the work of cutting off the section will start in mid July with washing the area around the slicing point, in attempt to remove the debris and avoid new detonations. The cutting off of the section will be performed by remotely controlled robotics. Should the slicing device meet a torpedo warhead, a new explosion can damage the submarine further. In the worst case scenario the explosion will inflict damage on the reactors.
2. Drilling holes and installing grappling devices
To install the grappling devices to lift the Kursk, the designers of the rescue operation plan to drill 26 holes in submarine’s hull. It is unclear, however, whether the grabbling devices will be set into the outer hull or the inner (stronger) hull of the submarine. The risk related to this operation is the further weakening of the construction and eventual breaking of the submarine apart when the lifting starts.
24 Granit class (SSN-19) cruise missiles are located between the inner and outer hulls of the submarine. Russian officials claim that the encapsulation of the missiles has the same impact resistance level as the inner hull. The actual damage inflicted on the missiles by the explosion is unknown. It is known, however, that the explosion was so powerful that the inner hull (the stronger hull) in the bow section was fully destroyed. So one cannot fully exclude the possibility of an emergency situation developing with the missiles involved during the lifting operation.
Furthermore, the submarine is partly deepened into the seabed and trimmed to one side. To get it tear off the seabed, there is a danger of jerking the submarine, what may destroy the grappling device and eventually damage further the hull.
3. Possible reactor meltdown
The submarine is lying at the depth of 108 meters. Its weight, even with the fore section sliced off, will still be 12,000 tonnes. The hoists installed on the barge have to work with high precision to ensure that each cable attached is having an equal or maximum load it can hold. Should something go wrong during the lifting, the submarine will go down, hit the seabed and may provoke the reactors start-up.
Russian officials claim that the reactors are intact and were shut down automatically. Bellona agrees with such supposition for 90%, as nobody could actually verify the condition of the reactors except for measuring close to zero radiation levels around the wreck.
The nuclear installation onboard the Kursk is equipped with an automatic blockage of the control grids once they have gone down to stop the reaction inside the reactors. Russian officials say that the blockage mechanism will not allow the grids to go up starting the chain reaction even if the submarine flips while going down. But such statements are purely theoretical as nobody was testing the reactors for such scenarios. A laid-up nuclear submarine has regularly the control grids welded in their extreme down positions to ensure they do not go up if the submarine sinks and capsizes.
Should the reactors start up, given the worst-case scenario, the shield around them can sustain the meltdown and not let the radiation leaking out theoretically. Even if the radiation leaks, there still will be no disaster, but a local contamination of the seabed, which will be quickly dissolved by the seawater to the levels hard to detect. The problem will be to decommission the submarine if it is ever lifted up again.
4. Missing Kursk during transportation
When the Kursk is lifted, it is fastened to the barge. The barge equipped with hoists, which will drag the cables up, is under reconstruction in Amsterdam with time pressing hard. There is still a possibility that the stormy sea or malfunction of the cables force the submarine go down. Russian officials claim they can do it in a controlled way. But as the director of the Rubin design bureau, Igor Spassky, put it: “Out at sea there will be no time for thinking.” (Strana.ru)
The depth on the way of the barge to its destination point shipyard no. 82 in Roslyakovo will vary from 50 meters to 200 meters. If the barge misses the submarine, the scenario described in 3. may occur.
5. Possible risks while placing Kursk into dry-dock
When the barge with the submarine arrives to the shipyard in Roslyakovo, it will enter the 80,000 tonne dry dock partly deepened into the water. Then with the help of pontoons, which are under construction in Severodvinsk, the submarine will be released from the barge and left in the dry-dock. Should anything go wrong here, the damages inflicted on both the dry-dock and the submarine will be difficult to recover, if possible at all. The shipyard in Roslyakovo is located between Murmansk and Severomorsk on the eastern side of the Kola Bay.
6. Taking Kursk to surface
When or if the submarine is safely placed in the dry-dock and the water is removed from it, the Kursk will be for the first time during the whole operation on the surface and the eventual radiation can be measured then. Earlier this month, Murmansk governor, Yury Yevdokimov, sent a letter to the Rubin bureau and the Russian officials in charge of the operation to get a clearer picture of the safety precautions to be taken. Roslyakovo is located just 10 km from the city of Murmansk, which has a population of 400,000.
7. Defuelling Kursk
Once in the dry-dock, the bodies of the sailors will be removed and the submarine itself will be investigated with scrutiny. After that the decision has to be made how and where submarine’s reactors will be defuelled and the cruise missiles onboard will be removed. Murmansk shipping company, which operates a fleet of nuclear powered icebreakers in Murmansk, has already proposed one of its service ships, Imandra, to defuel the submarine.
Defuelling of any submarine is the most potentially dangerous operation. The defuelling of the Kursk can be complicated due to the destruction after the accident. Since the submarine was recently in operation and the reactor cores are still hot, it is unlikely that the cooling water will be pumped out of the reactor before the control grid is lifted up to gain access to the fuel elements. The presence of water will increase the risk during the defuelling operation of a steam explosion inside the reactor. Such accident occurred in the Russian Far East in Chazhma Bay in 1985. The radioactive fallout could be detected in the radius of 30 km around the submarine.