Canadian technology offers Fukushima tritium option

Friday, 27 September 2019

The Canadian company's Advanced Water Distillation (AWD) technology was initially developed for pressurised heavy water reactors. A test plant in Oakville, Ontario that has been in operation for a year has shown the detritiation of light water using AWD to be five times as efficient as that of heavy water, the company said. A multi-column demonstration plant is to be built in 2020.

Tritium is a heavy radioactive isotope of hydrogen that can replace ordinary hydrogen in light water or deuterium in heavy water, and occurs both naturally and in small amounts during the operation of nuclear power plants. Tritiated water molecules cannot be separated from light or heavy water by conventional filtration since all water molecules behave very similarly.

Water containing very low levels of tritium and other radioactive substances is normally released from nuclear power plants under tightly controlled and monitored conditions. Pressurised heavy water reactors - Candus - produce significantly more tritium than most other types of reactors owing to the use of heavy water (deuterium) in the moderator and heat transport system. Facilities to remove tritium from heavy water from Candu reactors currently operate at Darlington in Canada and Wolsong in South Korea.

Laker says its AWD technology exploits the latest advances in water distillation equipment design and configuration, and in testing has already achieved a five-fold equipment height reduction and 80% energy consumption reduction over conventional water distillation. The process operates under benign conditions of purified warm water under vacuum, which eliminates the possibility of chronic leakage and associated environmental emissions, it says.

Laker's prototype plant (Image: Laker)

Fukushima application

The AWD technology would be a suitable option, Laker says, for the detritiation of water stored at the Fukushima Daiichi site in Japan, where large volumes of water treated by a system known as ALPS (Advanced Liquid Processing System) remains in storage. ALPS removes most of the radioactive contamination from water which has come into contact with the damaged reactors and debris from the 2011 accident, with the exception of tritium.

Tokyo Electric Power Company has previously said storage capacity limits for the ALPS-treated water at Fukushima will be reached by 2022. Laker says its AWD technology can efficiently reduce the tritium concentrations to below naturally occurring rainwater levels, enabling safe release into the ocean. An AWD plant constructed at the Fukushima Daiichi site would also be capable of supplying the entire global demand of the stable medical radioisotope oxygen-18, which is produced as a by-product of the AWD process, the company says. Oxygen-18 is used as a precursor chemical for positron emission topography scans.

"We believe this is the only viable path to responsibly dispose of the tritiated water at the Fukushima Daiichi nuclear plant and we’re excited to deploy this technology on future projects such as ITER," said Laker Energy Products President and CEO Chris Hughes.

Laker TRF is an affiliate of Laker Energy Products.