The cooling towers at TVA's Sequoyah Nuclear Plant in Soddy-Daisy rise above the trees near a residential neighborhood / AP
By Anne Paine, The Tennessean
Sand baskets that the Tennessee Valley Authority installed at dams to
protect its nuclear plants from a worst-case flood could fail,
according to a federal nuclear oversight group.
Nuclear Regulatory Commission said the baskets are not capable of
standing up to the impact of debris barreling down the Tennessee River
in a massive flood.
is potential for this debris to damage the baskets or push the
individual baskets apart, causing a breach," an NRC letter dated
Wednesday to TVA says. "There would be no time to repair the baskets
because the flood would already be in progress."
Still, the baskets are considered adequate for the short term.
sand-filled, wire mesh baskets were placed around Cherokee, Fort
Loudon, Tellico and Watts Bar dams and earthen embankments to raise them
a few feet after it was determined.
Golden, a TVA spokesman, said the letter about the sand baskets, which
are considered a temporary measure, had just been received.
"We'll have to evaluate the NRC's response to us and determine what the next steps are," he said.
electric power producer had told the NRC in 2010 that a project to
resolve flooding concerns would extend into 2016 with dam modifications
handled by the U.S. Army Corps of Engineers. Lack of federal funds is
expected to cause more delay.
The NRC says the baskets will have to do for now.
"It's acceptable as a temporary fix," said NRC spokesman Joey Ledford.
Ferry, 100 miles south of Nashville, and Watts Bar, 60 miles southwest
of Knoxville, are considered to have enough safety margin.
Sequoyah that might have the most problems," he said, referring to the
nuclear plant about 20 miles northeast of Chattanooga.
talking basically historic floods. There's a lot of safety factors
already in play. I'm sure if there were any danger of flooding, plants
would be shut down and secured."
Sequoyah, diesel generators and spent fuel pool cooling pumps could be
affected, the letter said. Having backup power and keeping highly
radioactive waste cool at plants are critical and were the major reason
for a disaster that began last year after an earthquake and tsunami at
the Fukushima nuclear complex in Japan.
"We believe the plant is safe," Golden said. "If there is an opportunity to make it safer, we will pursue it."
the chances of the worst-case flood as envisioned is "extremely
remote," TVA wants to ensure against all possibilities, he said.
problem that the dams, as originally built, would not withstand what is
classified as a "probable maximum flood" came to light as TVA did
preliminary work toward completing Bellefonte Nuclear Plant about 110
miles southeast of Nashville.
cited the power producer with three violations in 2008 for shortcomings
that included an inability to provide the flood calculations done when
it first won approval to build its riverside nuclear plants.
officials found when redoing estimates using newer diagnostic tools
that the worst-case flood could be higher than anticipated, and decided
to use sand baskets for a quick, temporary patch.
The NRC letter requested TVA to provide a status update at least once a year on its work.