TEPCO announced the completion of the installation of an 80 meter wide underground zeolite wall at Fukushima Daiichi. This wall’s purpose is to block strontium 90 that leaked into the soil from migrating to the sea. A leak of highly contaminated water from the H4 tank farm caused the problem.
We submitted a plan to IRID in their first round of public requests for ideas towards dealing with the challenges at Fukushima Daiichi. One of our submissions included using this technology to contain underground strontium 90 leaks at the plant. The original concept was based on a similar underground wall at the West Valley nuclear site. Details about our plan design can be found here.
TEPCO mentions a combination of zeolite and apatite, a mineral similar in composition to teeth and bone as being used to fill the underground wall. Work on the full wall began in June of this year and has just been completed. A process of drilling holes, packing them with zeolite then concreting over the top was done to complete the wall. TEPCO will monitor the zeolite to check for exhaustion of the material. If it becomes too saturated with strontium 90, it can be removed and replaced.
More details and diagrams can be found in the English machine translation below: