September 27, 1999
Nuclear Site Is Battling a Rising Tide of Waste
By MATTHEW L. WALD
ASHINGTON -- A giant radioactive souffle is rising toward the top of a million-gallon tank of nuclear waste buried in the desert near Richland, Wash.
Whipped up unexpectedly by a pump that was supposed to dissipate pockets of hydrogen gas, the waste has smothered one tube for vapor sampling, threatens other instruments and could eventually overflow, according to officials of the Department of Energy and the contractor in charge of the tank, Lockheed Martin Hanford Corp. They are rushing to pump some of the waste into another tank, possibly within a month.
In May, workers stopped the growth, at least temporarily, by lancing the crust with high-pressure water jets, but the hole they made is beginning to close.
"I don't make any claims about this tank," said Donald Oakley, a retired environmental expert from Los Alamos National Laboratory, hired by the Energy Department as an outside consultant. "I'm not convinced anyone understands the chemistry and physics involved in this crust."
At the Washington State Department of Ecology, Mike Wilson, manager of the nuclear waste program, said that before the crust was lanced, engineers were predicting the waste would reach the top of the tank this fall. "It was 'The Blob' kind of thing," he said.
The 20-year-old tank, called SY-101, is buried just under the surface at the Hanford nuclear reservation, 20 miles from Richland, a city of about 32,000 people. The tank produces unwanted hydrogen as radiation fields bombard organic chemicals that were added years ago in what officials now say was a mistaken strategy to reduce the waste's volume.
Until six years ago, the hydrogen was emitted in huge releases that official studies call burps, causing "waste-bergs," chunks of waste floating on the surface, to roll over.
With the tank belching thousands of cubic feet of gas at roughly 100-day intervals, Energy Department officials were afraid that at some point it would burp during a lightning storm and cause an explosion. "Under certain conditions, you could rupture the tank," said Leo Duffy Jr., who was the Energy Department's chief environmental official during the Bush administration. "You'd have a challenge on your hands in the state of Washington," he said.
An explosion would spread radioactive material into the environment, experts say.
In retrospect, the gassy eructations were the good old days.
To reduce the chance of fire or explosion, the Energy Department ordered installation of a huge pump in July 1993 to break the hydrogen into tiny bubbles, which engineers hoped would then rise to the surface like carbon dioxide fizzing out of a soft drink.
For a time that worked. But engineers theorize that the crust started to toughen because it no longer rolled over from time to time, and it prevented the hydrogen from coming to the surface. In December 1997, the crust began to rise, even though virtually nothing was being added to the tank.
The waste's surface climbed from about 403 inches above the bottom of the tank to 435 inches at its peak, before workers lanced it, with each inch representing almost 3,000 gallons. That level was 13 inches above the maximum specified for the tank's operation. By Friday, the waste had risen again to 432 inches. The tank is protected by a double shell, but the waste is within 2 feet of the level at which the outer shell ends.
"We were getting awfully close, closer than we wanted to be," said Dr. Carolyn Huntoon, assistant secretary of energy for environmental management.
The crust also grew downward, and could eventually threaten the intake nozzle of the mixer pump. Experts say that if it clogged the pump, the hydrogen would begin accumulating at the bottom again and burping to the surface, but the crust that would then roll over would be four times bigger than it was before the pump was installed. And the vapor space at the top of the tank would be far smaller, making it easier to reach a hydrogen concentration that would support a fire or explosion.
"The rollovers were spectacular, but now we've got another problem, caused by the solution to that problem," said Stephen Agnew, a chemist who worked at Hanford for years. "Unfortunately, there doesn't seem to be an end to it," he said.
Another expert, Robert Alvarez, a former senior adviser to the energy secretary on environment, safety and health, said of the managers at Hanford: "They were lulled into complacency and forgot the fact the pump was only meant to be a temporary measure to mitigate the problem. They completely ignored the fundamental problem of dispositioning these materials."
Hanford managers should have transferred some of the contents to a different tank and diluted the rest to break up the crust years ago, he and others say.
In fact, in June 1996, the Energy Department crossed hydrogen off its list of problems at SY-101; in October of that year it announced that "all safety issues with the tank are now understood."
Fran DeLozier, president of Lockheed Martin Hanford Corp., said in a telephone interview, "It really wasn't until the fall of 1998 that everyone was convinced the crust was growing, that we didn't know how to stop the growth and that the solution was to do a transfer."
Even then, some people thought the department was moving too slowly. In June Agnew sent an e-mail to Oakley that said, "It is amazing that the level has reached 435 inches and no one is freaked out yet."
Some experts say that they are not sure the pumping will work and that they will not trade a bad situation (one problem tank) for a worse one (two problem tanks). There is only one spare tank available, and some experts think the wastes may be incompatible with other wastes that are supposed to go into it, organic liquids from older, leaking tanks that the department wants pumped dry, and wastes from a defunct plutonium-processing plant nearby.
"The whole situation at Hanford is a reaction mode rather than a planning mode," Duffy said. "I gather they're baffled by what's going on."
Copyright 1999 The New York Times Company