[en] Full text: Liquid waste is generated throughout the lifetime of any nuclear installations. To ensure minimal environmental impact, liquid waste management typically involves treatment steps where the volume of the radioactive waste is reduced, the physicochemical reactivity is stabilised, and the migration boundary is established. Initiatives of a new nuclear liquid waste treatment installation can originate from nuclear new build, from renewal of aged facilities, from new treatment needs (e.g., when shifting towards decommissioning stage), and from technical upgrade for a safer and more cost-efficient process. Fortum Power and Heat Oy (Fortum) is the license holder of Loviisa nuclear power plant (VVER-440, Finland), where the liquid waste treatment system renewal is currently underway. In addition to being an operator and license holder, Fortum is an active service provider that design and implements liquid waste treatment projects internationally. In this presentation, we share several key lessons learned from our recently completed and ongoing projects with a deep understanding across the system delivery boundary. A feasibility study based on strategy is an entry point for any design and implementation project. However, the focus of the feasibility study tends to be centred around finding a viable technical solution. Lesson learned 1 is that the emphases of the feasibility study shall be put on defining project lifecycles and boundary conditions, cost impact analysis which includes final disposal cost consequences, and technical feasibility with a wider range of solutions. When entering into the design and implementation phase, lesson learned 2 is that sufficient amount of resources are recommended to be reserved for piloting and design modifications. As the needs and boundary conditions are highly site-specific, optimising even a turn-key treatment solution might bring significant benefits. Open, customer-centric communications and project management is the 3 lessons learned, especially between the license holder organisation and the service provider organisation. Challenges are tackled together when the license holder’s needs are concretely understood, and overall waste routes taken into consideration in an early stage. The last lessons learned (4) is that owner organisations are recommended to implement a holistic fleet level approach and to consider the deployment of mobile systems used in multiple sites over a longer period of time.

[en] Full text: In Finland, the waste producer has the responsibility to manage the nuclear wastes produced, including the final disposal. The Finnish nuclear power companies dispose their own low and intermediate level wastes (LILW) in the repositories located at the nuclear power plant sites at Loviisa and Olkiluoto. Having the whole chain from waste production, handling, transportation, and disposal of the LILW within a single organisation has proven to be a straightforward and cost-effective way to manage and dispose of the nuclear waste produced. The disposal of spent nuclear fuel at Olkiluoto is managed by Posiva, a company which is jointly owned by the both power companies. An existing disposal solution promotes sustainable use of nuclear energy in near future, but also protects the environment after the repository closure. However, implementing and demonstrating a safe disposal consumes resources and therefore creates a challenge for sustainability. A balance between (long-term) safety goals and effective utilisation of resources has been established using a graded approach, where both the repository depth and engineered barriers are adjusted to the radioactivity content of wastes. The disposal plans are also periodically reviewed taking into account the results and uncertainties of the most recent long-term safety case. These are also considered in the on-going R&D-program to ensure safe and effective disposal.

[en] Decommissioning of a nuclear installation generates radioactive liquid wastes that are more complex compared to the liquid wastes being handled in the operational phase. Different types of wastewater involved in the dismantling processes and decontamination processes challenge the capability and performance of the existing liquid waste treatment facilities. The ultimate goal of any radioactive liquid waste management is essentially to immobilize the radionuclides contained in the liquid. Processes such as evaporation, drying, solidification, ion exchange, etc. are typically deployed. The case-by-case best strategy is always based on process(es) that prioritizes volume reduction, i.e. to minimize the amount of wastes that ends up in a final repository. A significant volume reduction helps mitigate the risks involved in the unknown final disposal costs in many countries. In our paper, we share Fortum's experience in managing radioactive liquid wastes in a recent nuclear decommissioning project. Mobile treatment system incorporating an ultra-selective ion-exchange process is the most suitable candidate for purifying a diversely-sourced liquid waste. The maximum volume reduction originates from the fact that only the radionuclides - not any salts or boric acid - are selectively captured and subsequently conditioned for disposal. We present a recent liquid waste treatment system delivered to a central European nuclear power plant with the aim of purifying 1300 m³ of high salt evaporator concentrate containing mostly Co-60, Cs-137, Cs-134 and Sb-125 radionuclides. Through a straightforward step-wise filtration process (as illustrated in Figure 1), the radionuclides are intercepted by the selective ion-exchange columns, enabling a free-releasable output liquid after the treatment. It is estimated, based on the real treatment outcome, that less than 20 units of the 12-litre filters are needed to finalize the treatment, thereby resulting in significant savings in the final disposal. (authors)