Hanford nuclear site in United States still poses threat despite cleanup efforts
15 February 2017
In late November, the US Department of Energy (DOE) published an update on the remediation work being carried out at the Hanford Nuclear Reservation in southeastern Washington State, heavily irradiated after five decades of nuclear weapons production and considered to be the most polluted nuclear site in the USA.
Hanford tank farms under construction - Image: Hanford / DOE
According to the DOE, Hanford made more than 20 million pieces of uranium metal fuel for nine nuclear reactors. Five huge plants in the centre of the Hanford Site processed 110,000 tons of fuel from the reactors, discharging an estimated 450 billion gallons of liquids to soil disposal sites and 56 million gallons of radioactive waste to 177 large underground tanks. Plutonium production ended in the late 1980s.
The site sits astride the Columbia River, upstream from Portland, the capital of Oregon, and with much of the population of the Pacific Northwest at risk if there were to be a major radioactive leak.
The Hanford cleanup started in 1989, when a landmark agreement was reached between DOE, the US Environmental Protection Agency, and Washington State. Known as the Tri-Party Agreement, the accord established hundreds of milestones for bringing the Hanford site into compliance with federal and state environmental regulations.
After more than 25 years of cleanup, the DOE says considerable progress has been made at Hanford, reducing the risk the site poses to the health and safety of workers, the public, and the environment.
The Hanford site cleanup so far
Before the cleanup programme began in 1989:
1. There was a 586-square-mile footprint of active cleanup
2. Some 2,300 tons of spent nuclear fuel were stored near the Columbia River
3. Some 20 tons of leftover plutonium were stored in the Plutonium Finishing Plant
4. 1,012 waste sites, 522 facilities and 9 plutonium production reactors were situated next to the Columbia River
5. More than 100 square miles of groundwater were contaminated
6. There were 56 million gallons of waste in 177 underground tanks, with up to 67 tanks presumed to have leaked
7. Only one tank waste retrieval technology was available
8. There was no treatment capability for underground tank waste
9. Some 15,000 cubic metres of plutonium-contaminated waste were buried or stored on site
By 2016, the following has been achieved:
1. Only an 82-square-mile footprint of active cleanup now remains
2. COMPLETED: All spent fuel moved to dry storage
3. COMPLETED: All plutonium stabilised and shipped off-site
4. 977 waste sites have been remediated, 428 facilities demolished, 18 million tons of soil/debris removed, 6 reactors cocooned (associated facilities demolished) and 1 preserved
5. 15.6 billion gallons have been treated and 306 tons of contamination removed
6. Pumpable liquids and 2 million gallons of solids have been transferred to newer, double-shell tanks, 16 tanks retrieved and 2 more underway
7. Now, 10 retrieval technologies are available
8. A Waste Treatment Plant is under construction and is 60% complete
9. A total of 12,417 cubic meters of waste have been retrieved and 649 shipments of waste have been made off-site
On September 30, 2016, the total of federal employees, employees of Hanford prime contractors and pre-selected subcontractors came to 9,175.
In 2014, the BBC said the Hanford cleanup had cost $40bn and high levels of expenditure were expected to continue for decades. The total cost of the project was likely to be $110 billion, according to a report in Newsweek, making it the most expensive environmental remediation project in the world.
In November 2016, work began on the demolition of the main plutonium-processing facility on the site, the Plutonium Finishing Plant (PFP), after 20 years of remediation and cleanup. The PFP was considered one of Hanford's most hazardous buildings.
The building, which had a footprint of over 220,000 square feet with sections up to six stories high, produced almost two-thirds of the nation’s weapons plutonium during the Cold War.
Most of the building debris will be sent to a lined landfill in central Hanford, but highly radioactive material will be packaged and held at Hanford until it can be shipped to the Waste Isolation Pilot Plant in New Mexico, which is currently closed after a fire in one of its underground waste disposal storage tunnels.
Despite the progress, there remain serious problems at Hanford. Safety managers, engineers and technicians at the site have gone public with their concerns over leaks of radioactive material, cover-ups and waste treatment programme delays.
The site's most complicated and potentially dangerous issue is the 56 million gallons of high-level radioactive waste sitting inside tanks at the centre of the site.
In February 2014, Oregon Senator Ron Wyden accused the DOE of a "never-ending pattern of failing to disclose what it actually knows about conditions at Hanford".
Wyden’s main concerns are those tanks, which hold by-products of plutonium production, buried just below the surface.
The original containers, single-shell tanks built in the 1940s and 1950s, had already leaked at least one million gallons of liquid waste into the ground. Hanford officials built double-shell tanks in the 1970s and 1980s and began transferring the radioactive waste into the newer vessels.
But in October 2012, the energy department announced one of the double-shell tanks was leaking into the space between the two shells. Waste in that tank has not entered the environment.
Wyden released an engineering review that said six other double-shells had similar construction flaws. He accused the agency of hiding what they knew, as the report had been made months after the initial leak announcement, but no other warnings from the DOE had followed.
Then, in late March 2014, two dozen workers fell ill because of chemical vapours near the tanks. Workers again noticed vapours around the tanks in May.
The double-shell tanks must do their job for several more decades until the waste treatment plant - currently under construction but much delayed - immobilises in glass all 56 million gallons of waste in the tanks.
Once the treatment plant goes into operation, parts of it must be run entirely by robotics because of the high radioactivity of the waste.
The treatment plant was scheduled to become operational by 2019, but construction has been slowed or entirely halted on key sections of the plant for additional testing.