Can Cement Be a Waste Solution?

An amendment added last month to the defense authorization bill will save taxpayers billions of dollars, take years off the time needed to clean up high-level radioactive tank waste at two U.S. nuclear weapons sites, and protect the environment, the Department of Energy and congressional supporters say.

Others, however, say the amendment will create permanent radioactive "sacrifice zones" at the two sites and will contaminate drinking water by leaving several million curies of radioactive waste to slowly leak from rusting underground storage tanks packed with concrete.

The amendment was drafted by the Department of Energy and cleared by a House-Senate conference committee last month. The bill is expected to be signed by the President.

Its impact is significant. DOE estimates that more than 100 million gal of liquid and semisolid high-level radioactive waste is held in some 300 underground tanks that were used to store and process mixed radioactive and chemical waste generated in decades of nuclear weapons production. Nearly all of the waste is at the Hanford Reservation in Washington state, the South Carolina Savannah River Site, and the Idaho National Engineering & Environmental Laboratory.

Most of the waste (60% by volume) is in Hanford's 177 tanks, followed by Savannah River with 51 tanks, and Idaho with 15 tanks, according to DOE. However, Savannah River has about two-thirds of the total radioactivity. All the waste is in steel tanks. Some tanks have already leaked, and the rest are sure to do so in the future.

The amendment modifies the Nuclear Waste Policy Act of 1982 by allowing high-level radioactive waste--once the radionuclides have been removed to the "maximum extent practical"--to be disposed of in a manner short of sending it to an underground repository. It allows the Secretary of Energy to determine the meaning of maximum extent practical but requires DOE to consult with the Nuclear Regulatory Commission and the states.

NRC's role is advisory, however, and the commission has no regulatory authority through the amendment. It is unclear what power the states have because they lack authority over nuclear material. But states must approve DOE's site-closure plans, and they regulate water quality and hazardous materials through state environmental laws.

The provision's purpose is to redefine small amounts of radioactive sludge left in the bottom of the huge underground tanks after most waste has been removed. Its approval by Congress was hard fought, and the amendment covers only DOE sites in Idaho and South Carolina.

IN DECADES PAST, DOE had planned to handle all the sludge--where most radioactivity resides--as "high-level" radioactive waste, the same way it addresses the rest of the tank waste. These plans meant removing waste from tanks, treating it, and sending it to an underground repository. In the late 1990s, DOE moved ahead on a plan at Savannah River to remove most of the volume of high-level radioactive tank waste from two tanks, vitrify it, and "grout" the rest by filling the 1.3 million-gal tanks with cement.

This low-tech solution to an immense problem had been discussed for years, but the use of cement or grout to hold the tank waste was not seen as a viable disposal solution for tank sludge until the last years of the Clinton Administration.

DOE officials are adamant that the department will remove at least 99% of the waste volume and radioactivity from the tanks before turning to grout. What will be left is the "stain left inside your coffee cup," says Charlie Anderson, deputy manager for cleanup at Savannah River. However, this is one big coffee cup.

Even if DOE can pull 99% of the waste out--and critics doubt it--a lot of radioactivity will remain. At Savannah River, for instance, 1% of the waste works out to 4.8 million curies and 340,000 gal left on-site out of the starting 480 million curies and 34 million gal in the tanks.

The grouting approach was challenged by the Natural Resources Defense Council (NRDC), joined by several Indian tribes and states, including South Carolina and Idaho. They said it violates the Nuclear Waste Policy Act. In 2003, they went to federal district court in Idaho and won. DOE's appeal of the decision was just heard by an appellate court. Meanwhile, the Bush Administration turned to Congress and changed the law for Idaho and South Carolina through the defense authorization amendment. DOE wanted to include Hanford, but Washington state's congressional delegation, especially its senators, strongly opposed the amendment and won an exemption in the provision.

The amendment makes ongoing litigation for Idaho and South Carolina moot, notes NRDC attorney Geoffrey Fettus, who argued the case. Fettus says the amendment sets "terrible policy," stressing that it establishes no regulatory standard and leaves that aspect up to DOE.

Fettus wants the waste removed from the tanks and treated as high-level radioactive waste. "But NRDC at no point objected to waste being reclassified as long as it was removed from the tanks and treated in such a way that it no longer presents a long-term danger," he adds.

THE AMENDMENT generated a contentious debate in Congress, with opponents charging that DOE held members hostage by withdrawing $350 million in tank cleanup funds for three sites in its 2005 budget request. On the other hand, Energy Secretary Spencer Abraham said in an Aug. 1, 2003, letter to Congress that confusion and uncertainty due to the litigation made it difficult for DOE to determine how to spend the cleanup money.

Abraham said the reclassification and grouting will save time and money as well as lead to less worker exposure. DOE estimates that for Savannah River, grouting would cost about $3.8 million to $4.6 million per tank versus more than $100 million per tank to clean, cut up, and remove the tanks. DOE also says in its environmental impact statement (EIS) that removing the tanks would lead to five cancer deaths of workers due to radiation exposure.

Congressional delegations were split. South Carolina's Sen. Lindsey Graham (R) led the fight for the amendment's approval, saying it would save DOE $16 billion and shave 23 years off the cleanup schedule. South Carolina's Rep. John M. Spratt Jr. (D) was opposed and urged that grouting be stopped until the National Academy of Sciences (NAS) could study its impact.

A congressional aide put it this way: "DOE tied up $350 million in high-level cleanup funding unless we accepted its resolution of the issue. South Carolina could have lost $188 million if it didn't acquiesce. This translates to a lot of jobs and a lot of money flowing into the state."

In the end, Spratt lost, and the grouting will continue. But NAS will do a study of the impact at Savannah River within six months, and within one year it will examine grouting at other sites.

Savannah River is furthest along in removing tank waste. It has emptied four tanks and filled two tanks with cement, Anderson says. Another eight tanks are being emptied, he adds, and the plan is to close all the tanks by 2020.

TANK SLUDGE constitutes 8.2% of the volume in the tanks at Savannah River but holds 66.7% of the radioactivity, some 320 million curies according to DOE reports.

DOE has used water jets, pumps, and other water-based technologies to break up as much sludge as possible in the tanks after all the liquid tank wastes are removed, Anderson says. He is sure DOE can get down to less than 99% of the waste and radioactivity before adding the grout.

But an EIS for the Savannah River tanks says that, to get below 97.98% of the radioactivity, DOE must use oxalic acid washing technologies. So far, DOE has not used these technologies, but it intends to, officials say.

The impact statement warns, however, that introducing oxalic acid or other chemical treatments for this waste runs the risk of a nuclear criticality accident and says tank-specific studies are needed before moving to oxalic acid as a cleaning agent.

For this cleanup--with 1% of waste holding 4.8 million curies--a percentage point matters.

"There isn't much of a cushion for error," says Brice Smith, a physicist with the Institute for Energy & Environmental Research, a Maryland-based nonprofit organization. For example, he points to strontium-90, a short-lived radionuclide with a large impact on children's development and health.

"DOE data show there is about 100 million curies of strontium-90 in the tanks," he says. "Assume you remove 99% of it, and the cement holds for 100 years, you'd have about 84,000 curies left. But let's assume that annually one-tenth of 1% of what remains starts leaking after 100 years. That amount of strontium would be enough to contaminate the nearby Savannah River to above drinking water standards."

The area is wet, and the EIS notes that several of the tanks are resting in the water table. Hence, much of the program's success will turn on the grout's durability, strength, and ability to bind and hold radioactive elements. Inside the tanks is a heterogeneous mix of chemicals and radioactive waste, and much of the radioactivity will be thermally hot for at least 100 years. Some isotopes are extremely long-lived, such as plutonium-239, with a half-life of 24,000 years, and technetium-99, with a half-life of 213,000 years.

Anderson says the grout will be poured in three levels and will be formulated as a reducing grout that will discourage acidity. It will also include absorbents to fix to radionuclides, he adds.

DOE studies show that much of the grout will not mix with the radioactive sludge. Indeed, first-pour studies show that the grout simply pinned the radioactive sludge against the tank's walls. The department now plans multiple pours into the tanks from several tank locations spread over several days. DOE also will drop dry grout into the tank to mix with water already there.

Anderson is confident, however. The constant sludge cleaning that DOE will do to kick loose the sludge will lower the residual radioactivity, he says, and the first four tanks are down to 104 to 50,000 curies each and volumes in the 7,000- to 17,000-gal range. He adds that DOE staff have become cement experts.

But Smith finds conflicting data and uncertainty reflected in different DOE reports. He observes that internal reports have called for more study on the concrete's durability over the time scales necessary to protect public health and the environment.

"The real world is much more complex than we think," he notes. "We need a public discussion about using this grout because once it is done, it is irreversible."