Jet Grouting with Molten Wax for In-Situ Encapsulation of Radioactive Beryllium Waste: Fid-Bau Portal

Jet Grouting with Molten Wax for In-Situ Encapsulation of Radioactive Beryllium Waste

Carter, Ernie / Webber, Frank

Jet grouting can be used to consolidate, treat, or waterproof deeply buried material with more precision than is possible with ordinary pressure grouting. However, in radioactive contaminated soil, bringing contaminated material back to the surface must be avoided. Industrial jet grouting is typically a very messy operation with large volumes of soil, water and grout returning to the surface. Over the last 9 years, special techniques were developed specifically for the Idaho National Laboratory (INL) to adapt this jet grouting technology to operate in radiologically contaminated environments. In a recent project at the INL an advanced jet grouting technique was performed using a molten thermoplastic wax grout in place of the traditional cement and water slurry. An old radioactive waste burial site at the INL contained large sections, or "blocks", of a nuclear reactor made from solid beryllium metal. After being in the reactor for many years, they were highly radioactive and INL scientists were concerned that corrosion chemistry could release radioactive carbon 14. Beryllium waste is of a special interest to the INL because it contains approximately 19% of the C-14 inventory at the burial site. Beryllium exposed to moisture corrodes rapidly, releasing C-14. The beryllium waste targeted for grouting represented approximately 90% of the C-14 that was releasable (mobile) in the environment. Past monitoring confirmed the C-14 release and it was considered good management practice to immobilize the C-14 and reduce the potential environmental threat to the vadose zone and groundwater. Jet grouting was selected as the means of isolating the blocks from the water environment. Jet grouted columns would be placed around the perimeter and throughout each disposal area. However, the scientists feared that cement based grouts could have undesirable chemical reactions with the Beryllium over time. A novel molten wax grout known as WAXFIX, previously demonstrated at the INL, was selected because it could better isolate the beryllium from water and thus prevent further chemical reaction.