Hanford prepares to treat radioactive waste at the vitrification plant
The Department of Energy has rejected two of the five new requirements and related deadlines for Hanford cleanup recently set by the Washington state Department of Ecology, including a requirement that it design new waste storage tanks.
However, DOE remains open to negotiations on them, according to DOE’s response sent to the Department of Ecology on Thursday.
DOE rejected requirements that it design new waste storage tanks as the nuclear reservation’s 27 double-shell tanks near capacity and that it build five more barriers over the ground at single-shell tank farms.
Usually, requirements and deadlines in the Tri-Party Agreement are set through negotiations among DOE, the Washington state Department of Ecology and the Environmental Protection Agency.
But in late June the Department of Ecology exercised its prerogative to sign off on new deadlines related to the 56 million gallons of radioactive waste stored in underground tanks at Hanford after growing frustrated that DOE had not negotiated the deadlines as required by spring 2015.
In the arguably most controversial requirement, the Department of Ecology told DOE that it is requiring it to complete a design and permitting for new waste storage tanks by September 2023.
That would speed up the process of building new tanks, if needed.
DOE wants study before tank talks
DOE has previously resisted calls to build more waste storage tanks, saying its limited budget is better spent getting tank waste treated and permanently disposed.
DOE has 149 leak-prone single shell tanks, the oldest of which were built during World War II, to hold waste from chemically processing irradiated fuel to remove plutonium for the nation’s nuclear weapons program.
Waste in the single shell tanks is being emptied into 27 newer double shell tanks for storage until the waste can be treated for disposal. Much of the waste is expected to be treated at the vitrification plant starting in 2023.
The Department of Ecology is concerned that the 27 double shell tanks, most with a capacity of a little over 1 million gallons, are nearly full after some space is reserved for emergencies. There were 28 double shell tanks, but one tank was taken out of service after developing a leak from its inner shell, with radioactive waste accumulating in the space between its two shells.
DOE said in its letter to Ecology that it wants to discuss the design of new tanks, but not until it finishes an analysis underway now of how it plans to pretreat and treat high level radioactive waste.
The analysis could show a need for more multipurpose tanks.
Study looks at alternatives
The vitrification plant will initially treat low activity radioactive waste, after construction on parts of the plant that will handle high level radioactive waste have been on hold because of technical issues since 2012.
An audit done for DOE a year ago showed that the plant’s two facilities that will handle high level radioactive waste, the High Level Waste Facility and the Pretreatment Facility, have little chance of being completed by deadlines in 2030 and 2031 without a significant increase in spending.
DOE is studying alternatives, including for the Pretreatment Facility’s function of dividing waste into high level and low activity waste streams for separate treatment.
The solution it settles on could require tanks to be used for staging and characterizing waste for treatment at the High Level Waste Facility.
The results of the analysis will help DOE and Ecology better understand whether DOE should consider building additional tanks that could be used for multiple uses, such as storage and characterization, DOE said.
Any new tanks would be required to have double containment features, whether double shells or an alternate design such as a single-shell tank set in a leak-proof vault.
Negotiations could cover tank barriers
In DOE’s second objection to the new deadlines set by Ecology, it said negotiations have yet to cover additional new barriers over contaminated ground at the tank farms.
The requirements for new barriers could be addressed through routine annual negotiations.
Two barriers already have been built over groups of single shell waste tanks, with two more barriers planned to be completed by 2023. The ground barriers keep precipitation from driving radioactive and chemical contamination from leaks and spills deeper underground.
Ecology wants five more barriers built, with construction deadlines from 2025 to 2033.
The three requirements that DOE agreed with are:
▪ Coming up with a plan by June 2020 to remove more waste from the leak-prone single shell tanks.
DOE removed most of the easily pumpable liquids from the single shell tanks by summer 2004 to help stop or reduce leaks into the ground beneath the tanks.
However, at least 2.5 million gallons of liquid is estimated to remain in the enclosed, underground tanks, according to Ecology.
▪ Developing a plan to close the next group of Hanford single shell tanks to be emptied of waste, the A and AX Tank Farms. Deadlines have been set from 2021 to 2028.
DOE is likely to propose filling the tanks with concrete-like grout and leaving them in the ground.
▪ Setting deadlines for some work already planned to prepare for initial operation of the vitrification plant at the site north of Richland.
The deadlines deal with secondary waste created during vit plant operations, some plans to prepare a stream of low-activity radioactive waste for treatment and a planned performance assessment of a line landfill to dispose of some vitrified tank waste at Hanford.
The Department of Ecology continues to study and evaluate DOE’s response.
Talks between DOE and Ecology are continuing on a constant basis, including both formal negotiations at the management level and discussions at the staff level, said John Price, Ecology’s Tri-Party Agreement section manager.