The Department of Energy has announced that tank operations contractor Washington River Protection Solutions (WRPS) and subcontractor Atkins are making progress at the Hanford Site in Washington state in their preparations to provide replacement melters to treat radioactive and chemical tank waste for the site’s Direct-Feed Low-Activity Waste program.
Crews at Hanford successfully tested a gantry crane last month capable of lifting the 300-ton melters. The crane is a stationary steel structure with hydraulic legs that move a load up and down.
“Crews assembled the first two melters inside the Waste Treatment and Immobilization Plant [WTP], which is where we will vitrify, or immobilize in glass, radiological and chemical tank waste,” said Joe Renevitz, a DOE waste treatment operations engineer. “The melters are expected to last about five years, so we want to have replacement melters ready to install in order to minimize downtime.”
A single melter is composed of an assembly (melter base and walls), a gas barrier lid, a shield lid, a refractory brick interior, and other components that will feed, stir, and monitor a glass mixture for vitrification of waste materials. The melters are used to heat the waste and glass-forming materials to 2,100°F before the mixture is poured into stainless steel containers for permanent storage. The WTP uses a total of four melters: two in the Low-Activity Waste Vitrification facility and two in the High-Level Waste Vitrification facility.
The test: The crane test started with lifting a mock-up model weighted with concrete blocks to simulate the size and weight of a fully assembled melter. The crane lifted the mock-up a few inches off a flatbed trailer, leveled it out and moved it a distance, and then lowered it. Workers repeated the maneuvers several times to ensure a safe and successful transfer. Motion sensors collected data that engineers used to determine the acceleration forces that the mock-up had experienced. Acceleration forces are important to ensure that crane movements are slow enough for the heavy load.
“Assembled melters have never been transported and lifted as is planned on the Hanford Site,” said William Young, a WRPS engineer. “The weight of the melters when fully assembled is about 80 percent of the capacity of the gantry crane.”
Sensitive senors: The sensors will remain in place during practice runs to simulate transporting the melters within the Hanford Site more than 21 miles to the WTP. Engineers will use the sensor data to ensure that heating components inside the melters won’t shift during transport.
“We’re asking a lot of questions throughout the melter assembly process to identify potential challenges before encountering them,” said Young. “Testing various scenarios is an important part of making sure the system is ready.”