The Department of Energy has determined that its current operating plans for the Waste Treatment Plant at the Hanford Site do not require a supplement to a comprehensive 2012 supplemental environmental impact statement (EIS) on radioactive tank waste at the Washington state cleanup complex.
The agency concluded in a new analysis that altered plans for the plant, under which different operations would be phased in over several years, will not produce significant changes to its environmental impacts.
The 2012 EIS addressed all functions of the altered plans, other than building a storage pad for used ion exchange columns containing cesium that will be needed because the vitrification plant will initially not treat high-level radioactive waste, according to an analysis completed in January. However, the storage pad does not present a significant new environmental concern, the analysis found.
Anne White, DOE assistant secretary for environmental management, on Jan. 17 signed an amended record of decision saying the EIS will be amended only to include information about construction and operation of the storage pad. The Energy Department published the record of decision Monday.
Bechtel is building the $17 billion Waste Treatment Plant, which will convert a large portion of 56 million gallons of radioactive waste stored at Hanford into a glass form safe for disposal. The material is the byproduct of decades of plutonium production at the 586-square-mile complex.
Due to technical issues that have since 2012 slowed construction on parts of the vitrification plant that will process high-level waste, DOE now plans to separate out a waste stream of low-activity waste from storage tanks before sending it to the plant to be treated first. When the comprehensive Hanford Final Tank Closure and Waste Management EIS was completed in 2012, the plan was to separate the material into high-level and low-activity radioactive waste streams at the plant’s Pretreatment Facility and treat the waste streams separately but simultaneously.
Under federal court order, DOE must start treating low-activity waste at the vitrification plant no later than 2023, but the department has until 2036 to have the plant’s Pretreatment Facility and High-Level Waste Facility fully operational. Initial operations would use the Low-Activity Waste Facility, the Analytical Laboratory, and support facilities.
The analysis of the EIS evaluated possible environmental impacts of the change to the new Direct Feed Low-Activity Waste approach for the vitrification plant. It concluded the new approach does not represent substantial changes to the tank waste proposal evaluated in the 2012 EIS or significant new circumstances or information relevant to environmental concerns.
The analysis looked at how the direct-feed approach would manage effluents, waste transfers between facilities, and the removal of solids and cesium from tank waste to create a low-activity waste stream. The work will be done in central Hanford, which is already a contaminated industrial area, and any environmental impacts would be negligible to those considered in the 2012 tank waste EIS, according to the analysis.
However, DOE did take a closer look at the proposed outdoor storage pad for ion exchange columns that will be used to remove cesium from tanks because they were not in the tank waste EIS.
The vitrification plant’s Pretreatment Facility will not be available for separating tank waste into separate streams when low-activity waste treatment starts at the plant. Instead, a system employing ion-exchange columns with similar technology to what is planned for the Pretreatment Facility, will be used to remove cesium, which is considered high-level waste. The spent columns will need to be stored until the vitrification plant is ready to treat high level waste.
The DLAW approach calls for at least initially using a Tank-Side Cesium Removal (TSCR) system being developed as a demonstration project by AVANTech Inc. of Columbia, S.C. The spent ion exchange columns containing cesium would be stored on a steel-reinforced concrete pad as large as 190 by 180 feet. The pad would be large enough for both the first phase of the cesium removal, using a single TSCR, and a second phase, which could include an additional TSCR unit or a permanent facility to prepare low-activity waste in the tank farms for treatment at the vitrification plant.
The TSCR ion-exchange columns are expected to be about 10-feet tall with a 34-inch diameter, and each TSCR unit is expected to generate two fully loaded columns each month. The columns for a possible permanent facility to prepare waste for treatment as low-activity waste would be larger, at about 12-feet tall with a 38-inch diameter. Two of the columns could be generated each month.
The pad would be sloped to remove precipitation and include anchor points for the spent ion exchange columns. The columns would be self-shielded, not requiring any additional shielding when they are stored at the pad to protect workers from radiation. Preliminary calculations show expected dose rates of 1 millirem per hour to workers a foot away. The spent columns would be stored on the pad until the vitrification plant High Level Waste Facility is operating and could accept the cesium for treatment.
