Advanced Liquid Processing System

Advanced Liquid Processing System. It is a multi-nuclide removal system designed to decontaminate large volumes of radioactive wastewater generated at the Fukushima Daiichi Nuclear Power Plant following the 2011 Tōhoku earthquake and tsunami. The system was developed by Tokyo Electric Power Company Holdings with technical support from entities including Hitachi-GE Nuclear Energy and Toshiba Energy Systems & Solutions Corporation. Its primary function is to reduce the concentration of a wide array of radionuclides to levels that permit subsequent controlled discharge or management.

Overview

The necessity for the system arose directly from the ongoing need to cool the damaged reactor cores at the Fukushima Daiichi Nuclear Power Plant, a process that generates contaminated water daily. This water, stored in thousands of tanks on-site, contains a complex mixture of isotopes resulting from the meltdowns. Prior to the system's deployment, simpler systems like the SARRY (Simplified Active Water Retrieve and Recovery System) and KURION were used, but they had limitations in the range of isotopes they could remove effectively. The system was conceived as a more comprehensive solution to treat the accumulating wastewater, which also includes groundwater ingress, to a standard suitable for eventual release under regulatory oversight by bodies like the Nuclear Regulation Authority.

Design and technology

The system employs a series of chemical processes centered on co-precipitation and adsorption to isolate radioactive elements. The treatment chain begins with the removal of caesium and strontium using specific adsorbents, a step initially handled by preceding systems. The core technology then uses a combination of chemicals, including ferric chloride and carbonate salts, to precipitate out a broader suite of isotopes. A key reagent is a proprietary material developed to selectively capture tritium, though this isotope remains largely unaffected by the primary process. The treated water is subsequently passed through additional adsorbents, such as those containing titanium oxide, to further reduce concentrations of remaining nuclides like ruthenium and technetium. The entire process is housed within a dedicated facility on the Fukushima Daiichi Nuclear Power Plant site, designed with multiple treatment lines to ensure continuity and reliability.

Operational history

Construction of the first pilot system began in 2012, with full-scale operation commencing in 2013. Initial operations were marred by technical difficulties, including leaks from storage tanks and repeated failures of components like pumps and valves within the system's intricate piping network. These issues led to operational suspensions and significant public scrutiny, highlighting the challenges of managing such a novel and large-scale decontamination project in a post-accident environment. Despite these setbacks, Tokyo Electric Power Company Holdings implemented design improvements and enhanced monitoring, allowing the system to achieve more stable performance. By the late 2010s, it had processed a substantial portion of the stored contaminated water, though the accumulation of treated water awaiting final disposition continued to grow.

Performance and challenges

The system has demonstrated high removal efficiencies for over 60 radionuclides, including cobalt-60, strontium-90, and caesium-137, reducing their concentrations to levels far below regulatory standards set by the Ministry of Economy, Trade and Industry. However, its fundamental limitation is the inability to remove tritium, a radioactive isotope of hydrogen that is chemically inseparable from water. This has been the central point of scientific debate and public concern regarding the Japanese government's policy for the eventual discharge of treated water into the Pacific Ocean. Other challenges have included the management of secondary waste, specifically the highly radioactive sludge and spent adsorbents generated by the process, which require secure storage and future disposal. Independent reviews by the International Atomic Energy Agency have assessed the system's performance data while also examining broader safety plans.

Future developments

The long-term roadmap for the Fukushima Daiichi Nuclear Power Plant decommissioning, overseen by the Government of Japan and Tokyo Electric Power Company Holdings, envisions the system operating for decades to come. Current focus includes further optimization of the process to enhance reliability and reduce operational costs. Research continues into technologies for tritium separation, such as isotope separation techniques, though none are yet considered economically viable for the massive volumes at Fukushima. The planned gradual discharge of treated water, following dilution and verification, represents the next major phase dependent on the system's continued output. This strategy has been reviewed by the International Atomic Energy Agency and remains a subject of ongoing diplomatic engagement with neighboring countries and stakeholders.