Decommissioning strategy for liquid low-level radioactive waste surface storage water reservoir

The Techa Cascade of water reservoirs (TCR) is one of the most environmentally challenging facilities resulted from FSUE "PA "Mayak" operations. Its reservoirs hold over 360 mln m³ of liquid radioactive waste with a total activity of some 5 × 10¹⁵ Bq. A set of actions implemented under a special State program involving the development of a strategic plan aimed at complete elimination of TCR challenges (Strategic Master-Plan for the Techa Cascade of water reservoirs) resulted in considerable reduction of potential hazards associated with this facility. The paper summarizes the key elements of this master-plan: defining TCR final state, feasibility study of the main strategies aimed at its attainment, evaluation of relevant long-term decommissioning strategy, development of computational tools enabling the long-term forecast of TCR behavior depending on various engineering solutions and different weather conditions.