Richland — One of the final buildings that will be demolished in the Hanford 300 Area is coming down.
An industrial city once stood just north of Richland to support the production of plutonium for the nations nuclear weapons program. Since 2005, Washington Closure Hanford has reduced about 150 buildings there to rubble, and more were knocked down before Washington Closure won the contract to clean up the Hanford nuclear reservation near the Columbia River.
Thursday, two excavators equipped with shears were tearing down the 326 Building. It was known as the Pile Technology building when it was constructed in 1953 and later was called the Material Sciences Laboratory.
The 63,107-square-foot building is the second-to-last major laboratory expected to be torn down in the 300 Area as part of cleanup of Hanford land near the Columbia River. Its also the second-to-last building standing in the 300 Area where workers are expecting to encounter significant hazardous contamination.
Work has been postponed for additional planning for the removal of the other remaining laboratory, the 324 Building after a major spill of high level radioactive waste was discovered beneath it.
The Department of Energy is legally required by the Tri-Party Agreement to have all excess 300 Area buildings, except the 324 Building, removed by September 2015. A few buildings will remain because they continue to be used by Pacific Northwest National Laboratory.
Because underground utilities must continue to serve those buildings, the 326 Building is being torn down to only about three feet below ground to avoid disturbing any services, said Chris Strand, the environmental protection lead for Washington Closure. Then the buildings basement will be cleaned out and filled with dirt.
When buildings used by PNNL eventually come down, the 326 Buildings basement also could be excavated.
Work to tear down the building started about four weeks ago and the aboveground structure should be gone by the end of October, said Ruben Trevino, 300 Area closure manager for Washington Closure. Below-grade work should be completed a few weeks later and debris removed by the end of the year.
The building was used to experiment with the graphite piles that made up reactor cores to find new lattice configurations for loading uranium fuel that would be irradiated. It also was used to examine reactor components and fuel elements.
It made plutonium production more efficient, said Mark French, DOE project director for Hanford along the river.
The L-shaped building had offices along the outside and laboratories along the inside on two floors aboveground. The basement contained large laboratories, large reactor mock-ups and graphite piles like those that made up the core of Hanford reactors. Uranium fuel was loaded into reactor cores to be irradiated. Work with radioactive materials at the lab was done in lead-brick enclosures.
The earliest and most intense radioactive work in the buildings was the operation of the piles in the early 1950s, according to Washington Closure. The work potentially was hazardous to workers, but produced minimal environmental contamination.
During the 70s and 80s, several of the buildings labs were converted for chemical work involving low-level radioactive material.
Work has been under way to prepare the building for demolition since workers moved out in 2011.
Among the work done was characterization of 12 tritium storage tubes, each 12 feet long. The lead brick enclosures and a glovebox had to be stabilized and an irradiated fuel fragment removed from one of them.
A network of trenches was filled with grout, and a furnace booth contaminated with cadmium was prepared for demolition. Materials containing asbestos also were removed, including piping insulation, floor tiles, paneling and fire-proof file cabinets, doors and safes. Next on Washington Closures schedule is removing a large office building used to issue badges to Hanford visitors.
Although most of the hazardous above-ground work is completed, the contractor also is continuing work on removing two below-ground structures, a reactor and a vault, each weighing an estimated 1,100 tons. Both projects have been challenging but could be completed by the end of the calendar year.
Plans are being prepared to demolish the last remaining major laboratory that will come down, the 324 Building, and remove cesium and strontium beneath it. Possible bidders for the work have been allowed to walk through the building, but a schedule for its demolition has not been set. w Annette Cary: 582-1533; email@example.com; Twitter: @HanfordNews