By Dieter Bohrmann, communications manager, Nuclear Waste Program
On October 22, the U.S. Department of Energy (USDOE) announced that video inspections confirmed a leak from the inner shell of a double-shell tank at Hanford. This was the first confirmed leak from one of Hanford’s 28 double-shell tanks, and the discovery threatens to further complicate plans for treating 56 million gallons of high-level radioactive waste from leaking and failing single-shell tanks at the site.
Prior to this discovery, the assumption was that Hanford’s double-shell tanks were sound. They were built in the late 1960s through the ‘80s to store waste from the 149 aging and leak-prone single-shell tanks. That waste is destined for the Waste Treatment Plant (WTP), which is under construction but not scheduled to be operating until 2019 at the earliest. When operational, the WTP is designed to blend this waste with silica and turn it into glass, a process called vitrification. After the glass cools and solidifies, the waste is immobile and can no longer leak into soil and groundwater. This form allows for relatively safer long-term storage in specially designed facilities.
The double-shell tanks – which hold up to a million gallons each – remain critical to the retrieval and eventual treatment mission at Hanford. However, the determination of a leak will require USDOE and Ecology to take a harder look at the integrity of other double-shell tanks and weigh the options of what to do next. These options may include pumping waste from the leaking tank into other double-shell tanks or possibly recommending the construction of new double-shell tanks. Over the next few weeks, Ecology’s managers will be considering the practicability of possible actions as well as continuing discussions with USDOE before making recommendations on the path forward.
Fortunately, the leak is contained in the secondary shell and there is not an imminent threat of release of contamination to the environment. The leak consists of a slow ooze of sludge (think ketchup or peanut butter). However, this finding highlights the complexity and uncertainty of Hanford cleanup and is an important reminder that USDOE and its contractors must complete the Waste Treatment Plant and get it into service without further delays.
For more information and updates on the double-shell tank situation, please check out our new web page. There is also a link to this page under Spotlight on Ecology’s home page. Click on “Hanford tank leak.”