Posted on 04/18/2003 6:23:25 PM PDT by Paleo Conservative
What is the difference in the way they do it?
BTW I was nuke Machinist Mate, nuclear welder, that ended up on carriers anyway, instead of on tubes like the rest of the nuke welders.
OK. I was just wondering if the greater efficiency is in the design, or if perhaps it results simply from using the same design, be it an intrinsically "better" design or not.
You're probably right, since my hometown newspaper hasn't yet released a story about this. The Houston Chronicle has posted two stories already
First Story:
April 18, 2003, 4:00PM
A unit of nuclear plant is shut down
By MICHAEL DAVIS
Houston Chronicle
Unit 1 of the South Texas Project nuclear plant near Bay City is shut down indefinitely after some residue from reactor coolant fluid was found on tubes near the bottom of the reactor, plant officials said Friday.
Bay City is about 50 miles southwest of Houston.
Theradioactive boric acid residue -- described by the company as about the size of one-half of an aspirin -- was discovered a week ago when the unit was shut down for scheduled refueling and maintenance The water flowing through the reactor to cool it contains boric acid.
The powdery material was located on the outside of two instrument guide tubes where they enter the bottom of the reactor vessel. These contain instruments that measure reactor operations.
"We found two very minor indications of a slight seepage at the bottom of the reactor vessel and are in the process of determining the root cause and to fix it," said Ed Halpin, plant manager for STP. "Unit 1 will not be returned to service until the problem is solved."
Halpin could not say how long the repairs will take, but added that it will not have any effect on power consumers.
STP officials are working with the Nuclear Regulatory Commission, which will review any plan for corrective action before it is put into place.
"The unit is shut down and there is no danger to the public," said Victor Dricks, spokesman for the NRC in Fort Worth. "We have been impressed with the aggressive response of the licensee and are closely monitoring the situation."
While the seepage discovered was minor, gone unchecked it could have led to very serious problems, said Jim Riccio, nuclear policy analyst with Greenpeace in Washington, D.C.
"The real concern here is that if they had not found the leak, the crack could have grown large enough that they could not have made up the coolant loss," Riccio said. "You lose enough coolant, you melt the radioactive fuel rods in the core.
Early indications are that the seepage may have come from a weld where the tube enters the bottom of the reactor, Riccio said. He attended an NRC conference in Washington earlier this week at which initial information on the discovery of the seepage was disclosed.
"It stirred a few people up," Riccio said.
The NRC has been advising nuclear plants using Westinghouse reactors -- as STP does -- about so called "thimble tube thinning," for 15 years, according to an agency bulletin on the problem dated July 26, 1988. Thimble tubes run inside of the incore guide tubes where the residue was found.
"Wear of the thimble tubes results in degradation of the reactor coolant system's pressure boundary and can also create a potentially non-isolable leak of reactor coolant," according to the bulletin.
Unit 2 at the plant just south of Bay City is running normally. Each unit has the capacity to produce 1,250 megawatts of electricity. The reactor vessel is housed inside the concrete and steel-lined containment building.
In the meantime, the plant has a team of engineers who have re-examined all of the instrument guide tubes, and no additional residue was found, the company said.
In November of last year, Unit 1 had an unscheduled outage after operators noticed some problems with the secondary cooling system, Halpin said. The reactor was shut down manually.
The plant was plagued with problems a decade ago. It was shut down for most of 1993 by the NRC and a new management team was brought in by Houston Industries, the operator at the time.
Now, the plant is managed by the STP Nuclear Operating Co. It is owned by AEP Texas Central Co., Austin Energy, City Public Service of San Antonio and Texas Genco.
Second story:
Residue in Bay City nuclear plant focus of investigation
© 2003 The Associated Press
Engineers at a nuclear plant near Bay City are examining residue, about half the size of an aspirin, found a week ago while the one of the plant's reactors was shut for scheduled refueling and maintenance, officials at the South Texas Project Electric Generating Station said Friday.
The announcement came in the wake of a published report Friday in Ohio that the bottom of the South Texas Project reactor vessel may be leaking.
"Their preliminary thinking is they do have a small crack," Brian Sheron of the Nuclear Regulatory Commission told The Plain Dealer in Cleveland.
Plant manger Ed Halpin, describing the residue as minute, would not characterize it as the result of a crack.
"I think there are a lot of different ways to categorize the issue," he told The Associated Press Friday. "At this point we don't know the root cause. We do have some seepage."
Workers at the Davis-Besse nuclear plant west of Cleveland last summer found traces of possible leaks. The South Texas Project has a pressurized water reactor similar to the Ohio plant.
The Ohio plant's owner, FirstEnergy Corp., said it believed the residue washed down during attempts to clean the reactor's lid rather than leaking from the bottom, but tests are scheduled next month to be certain.
No reactor ever has been shown to have cracks or leaks in the instrument-carrying tubes that pierce the bottom of the heavy steel reactor vessel, the newspaper said, and any such disclosure, if confirmed, would be a serious development for the nation's nuclear plants. A large enough leak, undetected, could impede the ability of emergency pumps to keep hot, radioactive fuel cool.
However, Halpin said if the leak went undetected there would be "just a buildup of more seepage. This is not a rapidly moving problem." He said the guide tubes are not integral to the reactor's operation.
'They are instruments we use to monitor the activities of the plant," he said of the 58 tubes. "It is backup instrumentation essentially."
Sheron told The Plain Dealer it was possible a leak at the Texas plant about 125 miles southwest of Houston could be the result of a unique condition that does not exist at other plants.
In the statement released Friday by the South Texas Project, officials said the powdery material was found April 12 on the outside of two instrument guide tubes where the tubes enter the bottom of the reactor. The reactor is encased in a concrete and steel-lined containment building.
Test results indicate the residue came from reactor coolant fluid, plant officials said. Halpin said the residue was boric acid, which is part of the coolant system.
"Finding this minute amount of residue demonstrates our inspection process works," Halpin said in the statement.
Officials at the plant said they were working with the Nuclear Regulatory Commission to determine how to fix it. A team of engineers and chemists has reviewed all of the instrument guide tubes and found no additional residue.
The reactor will remain idle until the problem is fixed, Halpin said.
"There are a variety of options that really involve finding any flaws, if there are any, and repairing them via a welding process," he said.
The plant's other unit continues to operate at full power. The plant's two reactors combine to produce more than 2,500 megawatts of electricity.
The plant supplies power to customers from Houston to Austin and San Antonio to Corpus Christi.
Sabotage?
Another example of Botox abuse? ;-)
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