An aerial view of the Salt Waste Processing Facility at the Savannah River Site.
An aerial view of the Salt Waste Processing Facility at the Savannah River Site.

EM officials speaking at the 2021 RadWaste Summit last week detailed progress at the Savannah River, Idaho, and Hanford sites in the treatment of tank waste, the most significant challenge facing the environmental cleanup program.

The audience at the conference held in Las Vegas heard from Mike Budney, manager of the Savannah River Site (SRS) in South Carolina; Joel Case, assistant manager for facility and material disposition at the Idaho Cleanup Project; and Mat Irwin, deputy assistant manager of the Waste Treatment and Immobilization Plant (WTP) at Hanford in Washington state. The EM officials spoke via a virtual connection to the event.

At Savannah River, the Salt Waste Processing Facility began full radioactive operations at the beginning of the year and is proving to be the workhorse of the site’s liquid waste complex, where it is crucial for every facility to be synchronized and operational at the same time, Budney said. In fiscal 2021, Savannah River treated and disposed of more than 3 million gallons of decontaminate salt solution, a record amount.

Budney also extolled progress in the construction of mega-volume Saltstone Disposal Units (SDU). The approximately 33-million gallon capacity SDU 7 was completed in July and is receiving grout. SDUs 8 and 9 are being built, while construction will start soon on SDUs 10, 11, and 12.

“I’m pretty proud of our government contractor teams,” Budney said. “In terms of constant dollars, we’re really able to find efficiencies and reduce costs as we build each subsequent tank.”

Budney said the final piece to execute the SRS liquid waste mission was the recent award of the Integrated Mission Completion Contract. The contract will enable SRS to shift to an “end-state” approach that provides greater flexibility to define work scopes and assign tasks to the contractor. Budney said he expects nearly all the site’s salt waste inventory will be processed and its tank farm will be nearly empty by 2033.

Integrated Waste Treatment Unit (IWTU) operator Samantha Phillips operates a crane at the facility at DOE's Idaho National Laboratory Site while Trevor Clark, also an IWTU operator, observes.
Integrated Waste Treatment Unit (IWTU) operator Samantha Phillips operates a crane at the facility at DOE's Idaho National Laboratory Site while Trevor Clark, also an IWTU operator, observes.

At Idaho, the Integrated Waste Treatment Unit (IWTU) is nearing operations after years of confronting and overcoming technical challenges, Case said. IWTU will process about 850,000 gallons of sodium-bearing waste stored in three underground tanks. The liquid waste will be converted into grains similar in form to clothes detergent, and stored onsite pending final disposition.

The project was faced with redesigning a key IWTU component, the Denitration Mineralization Reformer. EM and its contractor Fluor Idaho brought in outside experts, collaborated with an industrial laboratory in Colorado where extensive testing occurred on a scaled model, and spent thousands of hours solving the problem.

“It was a very long and involved process,” Case said.

Workers also discovered that IWTU metal filters became clogged with fine particulates. They have since been replaced with ceramic filters better able to withstand heat and corrosive environments. On top of that, the IWTU workforce was impacted by the COVID-19 pandemic.

“We never had to shut down operations, but it did slow down efficiency,” Case said.

Now, Case said, the IWTU has initiated preparations for a final 50-day test during which waste simulant will be run through the system, one of the final steps before startup of radiological operations.

An engineer conducts tests on the turnstiles inside the pour caves of the Low-Activity Waste Facility at the Hanford Site. The turnstiles will hold three stainless steel containers into which vitrified waste will be poured during operations.
An engineer conducts tests on the turnstiles inside the pour caves of the Low-Activity Waste Facility at the Hanford Site. The turnstiles will hold three stainless steel containers into which vitrified waste will be poured during operations.

Irwin focused on startup of Hanford’s Direct-Feed Low-Activity Waste (DFLAW) system that will vitrify the low-activity fraction of Hanford tank waste. The Low-Activity Waste (LAW) Facility at WTP will mix liquid waste with glass-forming materials to produce a glassified product in stainless steel containers for long-term storage.

The LAW Facility over the past year has been testing individual system components like fans, pumps, power supplies, and the like. Irwin said systems have progressed from testing to being handed over to plant management for commissioning. The last of the systems was handed over just recently.

On Oct. 30, the plant had its first significant integrated commissioning test. Offsite power was cut off in a test of backup power systems and the ability of crews to restore full power.

“It tested the people-and-process part of the equation in making sure we could use our abnormal operating process and then recover the plant back to normal power,” Irwin said. “We’re working through the results but from my perspective I expected a lot more surprises. It was a very successful test to demonstrate the ground we still have to cover.”