The Nuclear Hazards of the Recovery of the Nuclear Powered Submarine Kursk

It is clear from the sonar records of the very much larger second explosion that this was from five to seven individual events occupying, in all, just over one-fifth of a second. This multi-explosion, equivalent to 2 to 3 tonnes of TNT, is believed to have derived from the detonation of up to 7 fully armed torpedo rounds in the forward port magazine rack. This massive explosion, inside the pressure hull, dealt a catastrophic blow to the Kursk, ripping out a very large section of the forward pressure hull (10 × 8m area) and outer casing and, at the same time, sending a reverberating hammer blow through the compartments towards the stern. Structural and flood bulkheads № 2 and 3 were ripped through, with № 4 buckling and subsequently collapsing under the hydrostatic flood loading. № 5, the forward reactor compartment bulkhead, and the remaining bulkheads through to the ninth compartment remained intact.

^{The bow damage showing failure of both flood and pressure hulls — internally the damage extended into the boat, collapsing lateral bulkheads into through to № 5 compartment — the red cylinders are gas bottles}

The second seabed debris field (at 69°36,99N, 37°34,50E) provides clues to the remaining split seconds of the Kursk and for all those crew present in the forward five compartments. The Kursk came to rest relatively upright lying on the seabed, with the stem buffered against a sediment bank at an angle of 2° bow down and with the hull pitched to the port side by 1.5°. The major part of the second debris field lay 20 to 30m starboard of the wreck, whereas the pressure hull damage indicates that the major blast direction was upwards and to the port side.

A most telling clue to the dying moments of the Kursk was the final position of a 4 by 2m section of forward section casing (the outer flood hull) on the seabed to starboard of the stern, having traveled the 154m length of the hull to its final resting place. This casing plate must have ‘swum’ from the point of the second explosion through the water down to the seabed; thereafter she drifted down and settled on the seabed at a depth of 110m. Analysis of this gives the Kursk at 30–35m above the seabed at the instance of the plate detachment.

When operating submerged, twenty-three crewmembers of the Kursk would be positioned aft of the reactor compartment. These crewmembers attended to the steam raising and electricity generating plant generally dispersed about compartments № 7, 8 and 9. At all times whilst the reactors are operational there are two crew members present in the reactor control room which is located at the higher deck level immediately aft of the reactor compartment. All of these individuals survived the two explosions and sought refuge in the stern most № 9 compartment surviving for, it is believed, two to three hours in very cramped conditions on existing oxygen supplies and oxygen breathing apparatus canisters. Whether they perished by hypothermia, nitrogen narcosis or simply lack of oxygen is not known.

What is known is that a number of the crew members subsequently recovered from the № 9 compartment had sustained quite severe body burns and the water-filled compartment was strewn with dust and ash — the surviving crew had closed the compartment hatch thereby isolating themselves in this final refuge. The source of the fire has not been established, although a survivor trying to recharge an oxygen regenerator plate in the compartment could have sparked it.

CONDITION OF THE KURSK

Two expeditions to the Kursk site were undertaken jointly between the Russian Federation Navy and the Norwegian Radiation Protection Authority. The first of these expeditions was in August, immediately following the sinking, and the second in October 2000 during which twelve of the twenty-three casualties in the stern compartment were recovered.

These two expeditions, particularly the latter, established the radiological regime in and around the Kursk. Air, sediment and seawater samples were taken and analyzed, and water samples within the submarine, from compartments № 3, 4 and 7, were collected and sealed in cans for subsequent gamma spectrometry. Similarly, the remote operated vehicles (ROV) and the diving personnel were rigged to monitor dose rates at various locations about the casing of the submarine (Amundsen Ingar, 2001).

The preliminary results from these two expeditions did not indicate the presence of radionuclides that may have been released from the submarine reactors or, potentially, from any nuclear weapons carried on board.