Assessment of the Recoverability of Dumped Spent Fuel in the Kara Sea

Sixteen reactor units, six of which plus a special container retain spent fuel, have been dumped by the Russian Federation in the Kara Sea off the island of Novaya Zemlya. The total radioactive inventory is of ∼4.2 × 10¹⁵ Bq. There has been widespread concern over their safety and current and future impacts on the local environment. This paper assesses the options for the recovery and permanent management of the spent nuclear fuel (SNF). The study was undertaken as part of the European Commission’s TACIS Programme to improve the safety of radioactive waste management in the north-west region of Russia [1]. It involved reviewing existing studies into the radiological situation in Arctic waters; identifying the key factors affecting potential recovery; determining and assessing potential options and recommending the preferred strategy. Two basic choices exist for the dumped reactors and fuel: 1. Leave dumped in the sea; 2. Salvage to land and treat/dispose. In total 11 options were identified and evaluated. Three were variants of 1), i.e. leave unchanged, improve the containment, and partially raise and redump in deeper waters. The remainder involved combinations of salvage of reactor compartments or only the reactor pressure vessels, followed by direct disposal on land of the reactor with or without the spent fuel and reprocessing or direct burial of any extracted fuel. The first stage of the assessment included preparation for each option of engineering cost and net present value (NPV) estimates; a cost benefit analysis based on the cost-of-dose saving using the ALARP principle; a Strengths, Weaknesses, Opportunities and Risks (SWOR) analysis and the generation of a detailed Environmental Aspect register, including a semi-quantitative Environmental Risk Assessment. The risk assessment methodology was based on a risk matrix, which compared environmental consequence with likely frequency to determine the significance of the impacts. The risk matrix was developed from established systems used for safety risk assessment of industrial, nuclear and chemical hazards. A scoring system was developed to cover factors that could affect decision-making. It included: i) Radiological impact to man. ii) Environmental impact assessment. iii) Ease of disposal. iv) Regulatory pressure. v) Technical feasibility. vi) Integrity of containment. vii) Up-front capital cost. viii) Discounted total cost. ix) Cost Benefit with ALARP. x) International will. xi) Risk from terrorist intrusion. xii) Public acceptability. The scoring system was subject to weighting to put priority on the most important issues. A sensitivity assessment was used to ensure the selection system was robust. Finally, the Best Practicable Environmental Option (BPEO) for the dumped SNF was determined. The study concludes that it is technically feasible to recover the reactors and spent fuel. However, the cost will be a minimum of £50M. The radiological consequences of leaving the reactors and fuel in their present location are very small. Thus the benefits of recovery are not justifiable. The overall conclusion is that a continuation of the current strategy is the preferred management option.