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Cleaning up the Hanford underground radwaste tanks

Nuclear Monitor Issue: 
WISE Amsterdam

Given the high cost to empty and treat Hanford's radioactive tank wastes, the government should consider leaving more waste in the underground tanks, according to a new Government Accountability Office report: Nuclear Waste: Uncertainties and Questions about Costs and Risks Persist with DOE's Tank Waste Cleanup Strategy at Hanford. The estimated price tag to empty the underground tanks of radioactive waste and treat it are rapidly escalating and could be more than US$ 100 billion (Euro 67 billion) -- rather than the US$ 77 billion that Department of Energy estimates, according to the report.

The Department of Energy (DOE) is responsible for one of the world’s largest environmental cleanup programs: the treatment and disposal of nuclear waste created as a by-product of producing nuclear weapons. Decades of nuclear weapons production have left a legacy of radioactive and hazardous wastes to be cleaned up at DOE sites across the country. One of DOE’s most contaminated locations is its Hanford Site, which lies along the Columbia River in southeastern Washington State.

From 1944 through 1988, about 525 million gallons of radioactive tank waste was generated by Hanford’s plutonium-processing plants. The federal government initially managed this waste by intentionally discharging it into the ground; reducing its volume through various waste concentration methods, such as evaporating off the liquids; and building underground tanks to store the waste until it could be treated and permanently disposed of.

From the 1940s through the mid-1960s, 149 underground “single-shell” storage tanks were built at Hanford. Originally expected to last 10 to 20 years until a permanent disposal solution could be found, each of these tanks consisted of an outer concrete wall lined with one layer of carbon steel. Together, the single-shell tanks contain almost 30 million gallons of waste; about 27 million gallons are in solid or semisolid form, and about 3 million gallons are liquid. By the mid-1990s, 67 of the single-shell tanks had leaked or were presumed to have leaked about 1 million gallons of waste into the surrounding soil. To address concerns with the design of the single-shell tanks, a new tank design with two carbon-steel shells was adopted in the late 1960s. From 1968 through 1986, 28 of these double-shell tanks, were built and sited in 6 more tank farms. Together, these double-shell tanks contain about 26 million gallons of waste.

In 1989, DOE’s original strategy called for treating waste only from the double-shell tanks, but in 1991, DOE decided to treat waste from all 177 tanks. To help minimize further leaking, DOE had, by 2005, transferred most of the liquid in the single-shell tanks to the double-shell tanks, a process called interim stabilization. DOE is currently retrieving the remaining waste from single-shell tanks and moving it to the double-shell tanks in preparation for treatment.

Since plutonium production ended at Hanford in the late 1980s, DOE has spent more than US$ 12 billion (in current dollars) to manage the tank waste and explore ways to treat and dispose of it. After beginning and discontinuing several different tank waste cleanup strategies, DOE has now embarked on a strategy that involves building a complex of treatment facilities, collectively called the Hanford  Waste Treatment and Immobilization Plant. Currently under construction and estimated to cost US$ 12.3 billion to design, build, and commission, this waste treatment plant consists of a laboratory for analyzing the waste’s composition; a pretreatment plant to separate the waste into two streams (a highly radioactive fraction called high-level waste and a lower-radioactivity fraction called low-activity waste); two waste treatment facilities, one for high-level waste and one for low-activity waste; and more than 20 support facilities. DOE estimates that it will cost tens of billions of dollars and take until 2047 to complete tank waste cleanup and permanently close the underground storage tanks.

The Government Accountability Office (GAO) was asked by the House Appropriations Subcommittee on Energy and Water Development, to assess (1) DOE's current tank waste cleanup strategy and key technical, legal, and other uncertainties; (2) the extent to which DOE has analyzed whether this strategy is commensurate with risks from the wastes; and (3) opportunities to reduce tank waste cleanup costs.

DOE's tank waste cleanup strategy consists of five key phases--waste characterization, retrieval, pretreatment, treatment, and permanent disposal--but critical uncertainties call into question whether the strategy can succeed as planned. Technical uncertainties include whether DOE can retrieve waste from tanks at the rate needed to support continuous operation of the waste treatment complex now under construction and whether key treatment technologies will work. Legal uncertainties include whether DOE can treat and dispose of some tank waste as other than high-level (highly radioactive) waste and how much residual waste can be left in the tanks when they are eventually closed. Such uncertainties could lead to significant cost increases and further delays in completing Hanford's tank waste cleanup activities. DOE has not systematically evaluated whether its tank waste cleanup strategy is commensurate with risks posed by the wastes. DOE lacks credible or complete estimates of how much the strategy will cost or how long it will take. The total project cost of constructing the waste treatment plant alone grew from US$ 4.3 billion in 2000 to US$ 12.3 billion in 2006. In addition, DOE did not include, or has been unable to quantify, a number of significant costs in its current estimate of the overall cost of its cleanup strategy. For example, DOE has not included some actual expenditures to date or storage costs for high-level waste canisters. Hanford workers have emptied tanks at the rate of about one a year since 2003, finding the work to be more difficult than expected. The GAO report says Hanford will need to retrieve waste at the rate of five to seven tanks a year when the vitrification plant starts turning the waste into a stable glass form. If not, the plant will not be able to operate continuously and costs will rise.

Further, DOE's schedule targets have slipped, with end of treatment extending from 2028 to 2047, which increases overall operations costs. Overall the total estimated cost could significantly exceed DOE's current estimate of US$ 77 billion, with estimates ranging from about US$ 86 billion to over US$ 100 billion, depending upon the date cleanup is completed. DOE has also fallen short in terms of risk-informed decision making. While DOE has analyzed risks in environmental impact statements required for its tank waste treatment activities at Hanford, it has not followed a systematic risk assessment framework, like one outlined in a 1983 report, updated in 2008, by the National Academy of Sciences. As a result, DOE cannot be assured that its present strategy is proportional to the reduction in risk that cleanup is to achieve. Some opportunities may still exist to reduce the costs of DOE's tank waste cleanup strategy, but the likelihood of success is unknown. For example, DOE is trying to increase the concentration of high-level waste in each disposal canister, thereby reducing the number of canisters and possibly shortening treatment time frames. DOE could also work with regulators to demonstrate, on a tank-farm basis, the feasibility of leaving varying amounts of residual waste in tanks at closing without threatening human or ecological health. In removing waste from tanks, DOE has found that the last portion can be disproportionately difficult and costly to remove. Specifically, the cost of removing the last 15 percent of waste can equal or exceed the cost of removing the first 85 percent.

Cost escalation is the result of a range of issues, including the difficulties Hanford workers have had in emptying the leak-prone tanks of millions of gallons of waste, questions about how well vitrification plant technology will work and a decision not to send treated wastes to Yucca Mountain, Nev., for disposal, the report says.

DOE disagreed with the increased cost estimate. It pointed out that GAO's predictions of cost and schedule problems at the Rocky Flats, Colo., nuclear site had not materialized. It also argued DOE has shown it could successfully treat radioactive waste at several of its other nuclear sites. But the report countered that DOE had not yet faced a tank waste challenge of the magnitude at Hanford, both in the volume of waste and the complex variety of chemical and radioactive elements that are mixed in the tanks.

DOE is legally required to empty 99 percent of the waste in the tanks or to empty each tank to the limits of technology before the tanks can be closed. But the report says, "More than half the experts we spoke with said that the 99 percent figure has no scientific basis, and several recommended that DOE conduct a comprehensive risk assessment of residual tank waste." As workers try to get the last waste out of each tank, the cost rises. "DOE has estimated that the cost of retrieving the last 15 percent of the waste can equal or exceed the cost of removing the first 85 percent," the report says.

The retrieved waste is planned to be treated at the Hanford Waste Treatment and Immobilization Plant for disposal. But DOE faces technical uncertainties, whether key treatment technologies at the vitrification plant will work, the report says. "Unless DOE successfully resolves these uncertainties, it could face problems, such as facility shutdowns, facility modifications and retrofitting, or significant cost increases and delays in completing Hanford's tank waste cleanup activities," according to the report.

DOE is researching ways to make sure the vitrification plant will operate as planned, including by operating large test facilities with materials that simulate radioactive waste. If DOE can solve technical issues to allow more high-level waste and less glass-forming materials to be used to produce the glassified logs at the vitrification plant, the number of waste canisters and costs would be reduced.

However, there still remains the question of what to do with the glassified waste now that the Obama administration has ruled out sending it to Yucca Mountain. That means Hanford will need capacity for at least temporary storage of the treated waste.

Meanwhile, a helicopter equipped with radiation detecting equipment has been used to scan almost 4000 hectares of the Hanford reservation in search of radioactive rabbit droppings. The helicopter was able to map each of the slightly radioactive stools with GPS coordinates. Rabbits developed an appetite for the radioactive caesium and strontium salts, leaking from the underground tanks. This resulted in slightly radioactive droppings. Use of the helicopter means that the droppings can be located and removed in a matter of days rather than the months that would have been needed for people to search for it on the ground. The droppings will be put into landfill at the Hanford site.

The September 30, report "Nuclear Waste: Uncertainties and Questions about Costs and Risks Persist with DOE's Tank Waste Cleanup Strategy at Hanford" can be found at:

Sources: GAO Report Nuclear Waste: Uncertainties and Questions about Costs and Risks Persist with DOE's Tank Waste Cleanup Strategy at Hanford, 30 September 2009 / Tri-City Herald, 2 October 2009 / World Nuclear news, 9 October 2009
Contact: Hanford Challenge, 219 First Avenue S, Suite 220, Seattle, WA 98104, USA.
Tel: +1 206-292-2850

High Level Waste storage tanks at Sellafield (U.K.)

The first vital step in combating and reducing the highest hazard area at Sellafield – the High Level Waste (HLW) storage tanks – has been put out to tender by Sellafield Ltd., early October.  Invitations to tender for the work contract, relates to ‘the design and build of a highly active liquid effluent plant’. Sellafield Ltd has confirmed that the contract relates to the provision of a number of new HLW storage tanks as well as additional ‘evaporative capacity’ - a reference to downstream plant that condense the liquid HLW prior to its conversion to solid glass form. In a number of phases stretching over the next 8 or 9 years, the contract is believed to be worth up to BP 1.5 billion (Euro 1.6 bn , US$ 2.4 bn).

Sellafield has 21 HLW storage tanks. Whilst the older tanks, numbered 1-8 and commissioned between 1955 and 1968, are no longer in service, the condition of some of the newer tanks 9-21 (1970-1990) has been the subject of significant concern by the Health & Safety Executive’s Nuclear Installations Inspectorate (NII) in recent years.

Sellafield’s existing HLW storage tanks (9-21) are each designed to hold up to 150 cubic meters of liquid HLW. Each is fitted with 7 internal cooling coils as well as external cooling jackets. Whilst the jackets on tanks 9-11 cover the tank base and extend 1 meter up the side, the jackets on tanks 12-21 cover not only the tank base but also extend the full height of the tanks to a point above the maximum liquor level.

Whilst the failure of some of the cooling coils, which cannot be replaced, has led to repeated concerns in recent years, new warnings have been issued by the NII on other high risk facilities at Sellafield. Included in the high risk category is an old fuel storage pond B30 known to the workforce as ‘Dirty Thirty’. Built in 1959 to prepare and store Magnox reactor fuel prior to reprocessing, B30 was closed in the early 1970’s. Now under decommissioning, its inventory includes large quantities of sludge from corroded fuel and a variety of old operational equipment. At a local liaison meeting on the October 1, NII warned that the risks of something serious happening in Sellafield’s old plants are far too high.

CORE Briefing 05/09, 9 October 2009