ADSWORTH, Tex., April 30 Reactor experts around the
country hope that there is something unique about Reactor No. 1 at
the South Texas Project here. If not, the little crust of white
powder that technicians found at the bottom of the reactor vessel, a
discovery that has brought operations here to a halt for the
indefinite future, could be the beginning of a broad problem for the
nuclear power industry.
The powder, which managers here repeatedly compare in volume to
about half an aspirin tablet, is boric acid, which is used in
reactor cooling water to soak up excess neutrons, and its presence
under the vessel presumably means there is a leak.
Highly corrosive when damp, boric acid has been found in the last
few years on the lids of reactor vessels around the world. A plant
near Toledo, Ohio, accumulated 900 pounds, some of which ate away a
football-size chunk of steel in the vessel lid, leaving only a thin
stainless-steel liner and bringing the plant uncomfortably close to
But until the discovery here, on April 12, nobody had ever seen a
leak on the bottom. A leak in that location is far harder to repair,
and would be harder to control if a significant hole developed in
the vessel, although the chances of accident seem far smaller than
they did in Ohio.
"It is something different," said Gary Parkey, vice president of
the South Texas Project Nuclear Operating Company, which runs the
two reactors here.
Measuring the problem and then resolving it will take new
applications of technology, he said, adding with no evident
pleasure, "We are at the cutting edge of this issue."
Until the discovery, in an inspection during a routine shutdown
for maintenance, the Nuclear Regulatory Commission believed that it
understood the mechanism for leaks in reactor vessels. It assumed
that such leaks were caused by an occurrence called stress corrosion
cracking, which, after long periods of operation, develops in hard
metals that are under strain and high temperature.
Not long ago, the commission developed a formula combining
temperature and years of operation, and used it to tell reactor
operators around the country whether they needed to shut down
promptly for inspection or could do the job at a more convenient
But the South Texas Project, here amid beef cattle and
wildflowers 90 miles southwest of Houston, is only 15 years old, and
its reactors operate at a relatively low temperature. That raises
the possibility that there may be a problem even with plants that
scored well in the regulatory commission's formula, and have not
"If this turns out to be stress corrosion cracking, and there's
nothing unique about it, then it raises questions about the validity
of that equation," said Brian W. Sheron, the commission's associate
director for project licensing and technical analysis.
That would be bad news for the nation's 102 other commercial
power reactors, which despite vast electricity deregulation have
prospered in the last few years, by achieving new levels of
The South Texas Project boasted last year that its Reactor No. 1
generated more electricity than any other in the nation in 2001, and
ranked eighth among the 433 power reactors worldwide. A majority of
the plant is owned by two commercial companies: Reliant Energy and an American Electric Power
subsidiary, AEP Central Power
and Light; an additional 44 percent is owned by the municipal
utilities of Austin and San Antonio.
The plant's operators underscore that they caught the problem
"There was no puddle, no buildup of boric acid on the bottom,"
said the general manager, Ed Halpin.
David Lochbaum, a nuclear safety engineer at the Union of
Concerned Scientists, a group often sharply critical of nuclear
operators, also pointed out that the leak had been discovered early,
but in an inspection, he said, that was more thorough than the
regulatory commission requires.
"It does show the prudence of looking periodically in places you
don't expect to have problems," he said, "rather than blindly
assuming you're not going to have problems except where you're
One difficulty at the Ohio plant, Davis-Besse, was that
management delayed taking the time to remove thermal insulation
around the vessel lid to check for leaks. As a result, corrosion
continued unnoticed for years. That corrosion has been a nightmare
for the Davis-Besse owners, keeping the plant shut for 14 months so
far and probably some months to come.