TVA stores spent fuel and fuel rods in pools at all three of its operating plants. Little has been transferred to dry cask storage. In March 2010 - the last time TVA would break down the stored amounts - the stored wastes included:
1,174 metric tons total*
- 812 in pool storage inside the plant in one common pool
- 282 in casks outside the plant
317 metric tons, all in one common pool storage inside the plant
1,771 metric tons
- 1,415 in three pools inside the plant
- 189 in casks outside the plant
Source: Tennessee Valley Authority
At TVA's three operating nuclear plants near Chattanooga, more than 2,544 metric tons of highly radioactive spent fuel are being held in cooling pools - far more than what is in the reactors themselves.
Looking at lessons learned from Japan's continuing nuclear crisis, the nuclear industry is taking fresh interest in spent fuel pools across the country that hold tons of radioactive materials.
"That quantity of fuel [from TVA's reactors] represents, very roughly, about 100 reactor-years worth of discharges," said Edwin Lyman, senior scientist for the Union of Concerned Scientists, a nonprofit group committed to safety issues.
"Keep in mind that Fukushima Dai-ichi Unit 4 had only about 240 tons of spent fuel [in the spent fuel pool], and it is believed to have caught fire," Lyman said Friday.
What's more, spent fuel pools here and across the U.S. are not housed within robust concrete containment structures designed to protect the public from the radioactivity.
Nor are they cooled by an array of highly reliable emergency systems that can be powered from the grid, diesel generators or batteries, said David Lochbaum. He is a nuclear engineer who once worked at TVA's Browns Ferry Nuclear Plant in Athens, Ala., and for the Nuclear Regulatory Commission.
"Instead, the pools are cooled by one regular system sometimes backed up by an alternate makeup system ... and instead the pools are often housed in buildings with sheet-metal siding like that in a Sears storage shed," Lochbaum said to members of the Senate Energy and Water Development Appropriations Subcommittee on March 30.
"I have nothing against the quality or utility of Sears storage sheds, but they are not suitable for nuclear waste storage," Lochbaum testified.
An end to pools
Both Lochbaum and Lyman have testified before congressional committees in recent weeks, urging better - and, especially, faster - regulation by the NRC.
He and Lyman told senators highly radioactive waste is languishing in pools across the country. At some sites, pools hold nearly 10 times as much spent fuel as the active fuel in the reactor cores.
Both men have been pressing for years to move spent fuel out of pools and into dry cask storage. Casks holding spent fuel rods are made of heavy steel, concrete or both and placed on concrete pads.
The warnings appeared to fall on deaf ears until the Japanese nuclear crisis began at four reactors and their spent fuel pools following a 9.0-magnitude earthquake and tsunami.
Ray Golden, spokesman for TVA's nuclear program, insists the five spent fuel pools at TVA's three nuclear plants are safe.
But he said the utility likely will move more aggressively to transfer spent fuel from pools to casks, though he couldn't say when that might happen.
And NRC spokesman Roger Hannah said Friday the regulatory agency has committed to Congress to make a 90-day "quick look" at potential problems, including spent fuel and seismic threats.
"We have not made any decision on spent fuel pools," he said. "We'll obviously look at that."
Evidence from Japan's Unit 4 spent fuel pool suggested fuel damage and the ejection of radioactive fuel particles - which some science observers said would explain the presence of plutonium in the air early in the crisis.
Spent fuel here
At Browns Ferry, a plant with the same design as Fukushima-Dai-ichi, more than 1,415 metric tons of spent fuel and rods lie in three pools on a massive concrete pad above the plant's three reactors.
All that encloses the pools is a heavy garagelike metal roof and walls.
"We may harden that," Golden said.
He said firehoses and other safety cooling back-ups were installed at the plant's pool level after the Sept. 11, 2001, terrorists attacks.
At Sequoyah and Watts Bar, about 812 and 315 metric tons of spent fuel, respectively, lie in pools next to the plants.
In the pools, cooling water and boron cover the radioactive fuel assemblies that have been removed from reactors. The cooling water is circulated by pumps run by electricity. If electricity and back-up power fails, as happened in Japan, the fuel heats the water to boiling and it can steam away.
Lyman and Lochbaum say nuclear scientists have known for more than two decades that losing water in a dense-packed pool would cause the waste fuel to heat up quickly and possibly catch fire.
"The long-term land-contamination consequences of such an event could be significantly worse than those from Chernobyl," states a Union of Concerned Scientists study that promotes moving spent fuel to dry casks.
Blaming Yucca Mountain
TVA, the nuclear industry and the NRC say there would be far less fuel in holding pools had Congress and the Department of Energy approved a long-term storage facility such as Yucca Mountain in Nevada.
"TVA paid in hundreds of millions of dollars" to the fund for the Yucca Mountain site, Golden said, adding the entire nuclear industry contributed $30 billion.
He said $13 billion was spent to study Yucca Mountain, which now appears to be off the table.
"There's about $17 billion that hasn't been allocated, but it's intended for the safe storage of high-level waste," Golden said.
Lyman said he thinks the build-up of spent fuel in pools is related to Yucca Mountain, but not in the way the nuclear industry relates it. He said keeping fuel in pools is an industry effort to "keep pressure on the government to take spent fuel off their sites."
"However, the reality is that utilities will be storing large quantities of spent fuel on their sites for decades to come no matter what happens with Yucca Mountain, so they need to takes steps to make on-site storage as safe and secure as possible."
Lochbaum told senators the same thing, but added a challenge.
"The irrefutable bottom line is that we have utterly failed to properly manage the risk from irradiated fuel stored at our nation's nuclear power plants. We can and must do better," he said in testimony.