17
May
2016
|
06:40 PM
America/Los_Angeles

Vit Plant lifts out vessel that supports vitrification of nuclear waste after successful testing campaign

Summary

A 30-ton stainless steel vessel was removed to make way for a new vessel that will fulfill a critical role in verifying design and performance of the Pretreatment Facility.

“Out with the old and in with the new” is appropriate for removal of a 30-ton stainless steel vessel from the Full-Scale Vessel Test Facility, making way for a new vessel that will fulfill a critical role in verifying design and performance of the Pretreatment (PT) Facility at the Waste Treatment and Immobilization Plant, also known as the Vit Plant, which is a critical element in the vitrification of nuclear waste process.

The old vessel, standing 18 feet tall with a 13-foot diameter, allowed Vit Plant employees to demonstrate that pulse jet mixers (PJMs) planned for use in pretreatment would work as anticipated with a range of radioactive waste mixes. Testing of this vessel was completed last December.

For its removal, it was connected to a crane and then lifted up and out of the laboratory through a large skylight in the roof.

“Our recently completed tests demonstrated we can consistently and reliably control these mixers,” said Felice Presti, area project manager for the PT Facility. “We’re looking forward to conducting the full-scale testing. Our goal is to construct a safe, effective facility to help treat waste and, ultimately, protect the Columbia River and this community from Hanford waste.”

The Vit Plant will be the world’s largest radioactive nuclear waste vitrification facility and is being designed and constructed by Bechtel National, Inc. for the Department of Energy Office of River Protection. When complete, it will vitrify most of the 56 million gallons of the country’s most complex nuclear waste currently stored in tanks on the Hanford site.

Before removing the vessel, part of the test platform had to be decommissioned. Modifications are now under way to accommodate the new vessel.

The new vessel will be a full-size prototype. At 35 feet high with a 16-foot diameter, it will function as a final prototype for those to be installed in the PT facility. Greenberry Industrial is fabricating the prototype at its locations in Vancouver, Washington, and Corvallis, Oregon. Its delivery is scheduled for this summer.

In 2012, the testing protocol for the PJMs expanded to include studies with full-scale vessels. Previous plans relied upon computational models and testing in smaller vessels.

PJMs have been used in nuclear applications for mixing radioactive liquids, slurries and sludge for more than 40 years. The mixers, which contain no moving parts, mix waste by expelling it from the PJM using compressed air. The PJM is refilled with waste by applying a vacuum pressure to the PJM, allowing the PJM to repeat the mixing cycle.  The vessels will be located in an area sealed from access because of anticipated radioactivity levels. The control valves used to direct compressed air and vacuum to the PJMs will be in a separate area accessible for maintenance.

Testing with the smaller test vessel began in 2014. The first set of tests captured data on how the computer controls outside the vessel worked to operate mixers inside the vessel under a variety of tank levels using simulated waste with low amount of solids. A second set of tests, completed in late 2015, studied how the mixers performed under a variety of slurry and tank level conditions, from low to high amounts of solids, using simulants.

Vit Plant employees have begun developing a test plan for the full-scale vessel to support requirements verification. Test platform commissioning is expected to begin in late 2016.

The Pretreatment Facility’s Role In The Vitrification Of Nuclear Waste

The Pretreatment (PT) Facility is the largest of the four major nuclear facilities that make up the Hanford Vit Plant. It is 540 feet long and 215 feet wide, the size of nearly four football fields, and 120 feet tall, or 12 stories, high. When complete, its total area will be more than 490,000 square feet.
Waste will be pumped from the Hanford tanks via underground pipes to the PT Facility’s interior waste feed receipt vessels. There, during the first phase of pretreatment, the waste will be concentrated using an evaporation process. Solids will be filtered out, and the remaining soluble, highly radioactive isotopes will be removed using an ion-exchange process.

About the Full-Scale Vessel Test Facility

The Full-Scale Vessel Test Facility was built by EnergySolutions, donated to Washington State University Tri-Cities (WSU-TC) and then leased back for its work in support of the Hanford Vit Plant. The facility houses important testing programs in support of Hanford site projects, helping to ensure progress while reducing risk to workers and our environment. The test facility also provides a future operating laboratory environment in which WSU-TC students and faculty can learn and gain hands-on science, technology, engineering and mathematical experience. EnergySolutions is an international company headquartered in Salt Lake City that recently sold the division encompassing its Richland operations and Hanford support to Atkins Global.

The 18-foot tall vessel is loaded on to a truck after being lifted out of the Full-Scale Vessel Test Facility.