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

From about January 2001, the Russian Federation Navy and the Kursk designers, RUBIN, jointly asked a consortium of companies from the West to tender for the entire recovery of the wreck (with the exception of the totally devastated forward compartment) and, specifically to complete the salvage within the year. This was in order

to comply with the promise of President Putin to the relatives of the crew. The first consortium formed, Smit-Heerema-Halliburton, withdrew because Halliburton believed the end of the year recovery deadline could not be safely achieved. In mid May 2001, the Russian Federation and RUBIN, jointly contracted Mammoet-Smit (M-S) to recover the Kursk within the year deadline. Although the salvage plan was to be produced by M-S the Russian Federation Navy was to provide a floating dock where the submarine was to be finally berthed.

The M-S strategy was to effect the recovery in three phases, these being:

Phase 1: Preparatory activities, including surveying, radiation monitoring of the submarine, removal of silt around the area of the intended hull cutting operation, and cutting of the hull just forward of the № 1 bulkhead to sever the most damaged part of the submarine. Then, to give a stable and predictable lift and to mount the rigs, to cut 26 holes through the casing and pressure hull either side of the vertical centerline of the main hull for the subsequent insertion and clamping of the lifting fittings. The positions of these holes were selected by the RF to minimize hull bending during the lift and none were positioned in the reactor compartment. This also included the modification of the Giant 4 barge by preparing 26 tubes through the barge hull so that the strand jack system, used to lift the submarine, could be fitted.

Phase 2: Installation of the 26 lifting fittings, the lowering through the pre-inserted tubes in the barge hull and connecting of 26 sets of lifting cables, each comprising 54 strands of seven twisted wires each 6mm diameter and the raising of the Kursk using Mammoet’s strand jack system. The cables would then hold the Kursk against a pre-fitted inverted cradle under the barge during transit to a floating dock near Murmansk.

Phase 3: The fitting of two large pontoons, one under each side of the barge, to lift it entirely out of the water to give sufficient clearance of the underslung Kursk over the cradles when entering the floating dock, the lowering of the Kursk onto the cradles, followed by demobilization and withdrawal of all M-S equipment and personnel.

Severing the remains of № 1 compartment deployed a heavy cable carrying thick-walled tubular sections coated with a very coarse (~25mm) abrasive. Reciprocating motion was to be provided by two 30 tonne hydraulic rams attached by suction anchors to the seabed.

^{The cable cutting rig trials on Giant 4 suction anchors (top) acting against an opposite set actual underwater cutting (inset)}

The strand jack system relies on two collets on each strand, the upper collets being hydraulically lifted/lowered as a cable group. Additional hydraulics activate the collets under computer control, the timing of the collet activation determining whether the strands are raised or lowered. Each cable lifting system was to be supported by four pneumatic cylinders with 4m strokes and with a large nitrogen gas reservoir, the pressure being matched to the cable load so that large movements due to swell (within the cylinder stroke limits) would have minimal effect on the cable loads.

^{The strand jack (inset) mounted within the cable reel platform with the swell compensator rams underneath}

NUCLEAR & RADIOLOGICAL SAFETY

In early June, Large & Associates were engaged by M-S to complete a preliminary assessment of the nuclear hazard and held a number of meetings with RUBIN to discuss and determine the information and data likely to be made available from the RF authorities with respect to radiation and nuclear safety issues. On the basis of this information, Large & Associates was instructed to form and head up the Nuclear Coordinating Group (NCG).