Timeline: 25 years of Hanford cleanup

1989 May: Hanford environmental cleanup formally begins with the signing of the Tri-Party Agreement. It set requirements and deadlines for cleanup of massive radioactive and hazardous chemicals left from producing nearly two-thirds of the nation’s weapons plutonium from World War II through 1988.

1990: Department of Energy and its regulators agreed enough information exists for an early start to cleanup of contaminated soil and groundwater along the Columbia River.

1990: Independent panel directing studies into past releases of radioactive materials from Hanford says thousands of Northwest residents may have been exposed to radioactive releases from Hanford from 1944 to 1971.

1991: First amendments to Tri-Party Agreement made over technical, safety and budget issues with planned vitrification plant.

1991: N Reactor, Hanford’s last operating plutonium-production reactor, ordered permanently shut down. It had been on standby since 1987.

1991: Wyden Watch List of 52 underground waste storage tanks initiated by Sen. Ron Wyden, D-Ore., over concerns that waste in tanks could explode or catch fire. The list would grow in future years.

1993 July: Hanford Advisory Board established.

1993 August: Hanford worker taped a rock to a rope and dropped it into a waste tank to see if a pipe was plugged.

1993: DOE admits to radiation testing on people during Cold War. Hanford-funded tests included injection of five people with phosphorus 32, irradiation of prison inmate sex organs and exposure of 15 people to tritium.

1995: New plan for vitrification of waste announced — a private company would be sought to treat the waste and would be paid for waste vitrification completed.

1996: Hanford budget reduced to allow DOE to close other nuclear sites early, with expectations that money would be restored as cleanup was completed elsewhere.

1998 December: DOE Office of River Protection established to focus only on Hanford waste tanks and treatment of their waste.

1998: 1100 Area in north Richland shifted from DOE to Port of Benton control.

1998: BNFL awarded contract to build a vitrification plant and vitrify waste. Estimated cost is $6.9 billion. Deadlines later are set for start of operation in 2009 and 10 percent of waste treated in 2018.

1999: Draft of Centers for Disease Control study released. Finds no evidence of increased thyroid disease as a result of Hanford releases from 1944 to 1957.

2000 June: Huge range fire burns across 45 percent of Hanford.

2000 July: First shipment of plutonium-contaminated debris leaves Hanford for disposal at the Waste Isolation Pilot Plant in New Mexico.

2010: Court-enforced consent decree resolves state of Washington lawsuit over missed or at risk Tri-Party Agreement milestones. It extends deadline to empty single-shell tanks from 2018 to 2040. It calls for vitrification plant to start treating waste in 2019 and be fully operating in 2022.

2012 September: Cleanup of two-square-miles area near F Reactor completed, including demolishing 112 facilities, digging up 88 waste sites and removing 1.5 million tons of contaminated material. It’s the first reactor cleaned up.

2012 October: One of Hanford’s 28 double-shell waste tanks, Tank AY-102, confirmed to have a leak between its walls.photo of tank being built

2012: Construction stops at areas of vitrification plant plagued by technical issues. DOE says cost of plant will increase, but it cannot say by how much until technical issues are resolved.

2013: At least one of Hanford’s single-shell tanks is leaking waste into the ground. Tanks were thought to be stabilized after pumpable liquid waste was removed.

2013: Eleventh single-shell waste tank emptied.

2014: Plutonium Recycle Test Reactor removed from the 300 Area just north of Richland. About 180 buildings have been torn down in the 300 Area, with only a few still standing.

2014 April: State of Washington triggers dispute resolution on the consent decree after DOE and the state cannot agree on how to amend deadlines to retrieve tank waste and treat it at the vitrification plant.