Posted on 04/18/2003 6:23:25 PM PDT by Paleo Conservative
WASHINGTON, April 18 — A nuclear reactor in Texas is leaking cooling water from the bottom of its giant reactor vessel, a development that experts view with concern because they have never seen it before, the Nuclear Regulatory Commission said today.
Technicians at the South Texas Nuclear Project, about 90 miles southwest of Houston, have found residues indicating that cooling water leaked from the vessel through two penetrations where instruments are inserted into the core, according to the company that operates the plant. Operators at all 103 commercial nuclear reactors have been giving closer attention to their reactor vessels since the discovery last year of extensive leaks in the vessel head at another plant, Davis-Besse, near Toledo, Ohio.
The Texas plant, South Texas 1, shows much smaller signs of leakage than the Ohio plant. In both cases, technicians found deposits of boron, a chemical added to the water to control the nuclear reaction, which remains after the water evaporates. At Davis-Besse, technicians cleaned out boron with shovels; in Texas, technicians found an amount about half the volume of an aspirin tablet, according to Ed Halpin, the plant general manager.
No corrosion is visible but no one is sure what is underneath. At Davis-Besse, the steel of the vessel was so corroded that a metal part on the head flopped over like a mailbox that was no longer stuck properly into the front lawn. At that plant, workers have replaced the vessel head, a part that was intended to last for the lifetime of the reactor. Davis-Besse has remained closed since the leak was discovered, 13 months ago.
The South Texas leak is unexpected and, so far, unexplained. "This is the first time it's been seen, either here or abroad," said Victor Dricks, a spokesman for the Nuclear Regulatory Commission. Representatives of two national nuclear industry groups are at the plant to study the problem, and plant managers have promised to keep the reactor shut until they find the cause and fix it to the commission's satisfaction, he said. The plant is currently shut for re-fueling.
The vessel is 14.4 feet wide and 46 feet high, made of steel about six inches thick. Its bottom has 58 penetrations, where instruments can be inserted to measure the flow of neutrons, the subatomic particles that sustain the chain reaction. There are leaks at two of the penetrations, although the volume of water was apparently small, Mr. Dricks said.
At plants around the country, cracks of some metal parts have been traced to stresses created in construction. Others have been caused by a phenomenon called intergranular stress corrosion cracking, which occurs in some metals when they are under stress at high temperature. But Mr. Halpin said he would not speculate about the cause of the South Texas leak.
Water inside the vessel is at a temperature of more than 500 degrees and a pressure of more than 2,000 pounds per square inch, so even a small hole could release large volumes of radioactive water into the containment building. Mr. Dricks said, however, that the pumps in the plant's emergency core cooling system could inject water faster than it could leak through a hole the size of the penetration, so that the nuclear core would stay covered. The design is for contamination in such cases to stay within the containment dome.
A problem for repair is that the radiation field under the reactor is about 500 millirem per hour, Mr. Halpin said. At that rate, a worker would absorb in four hours the radiation dose that most reactor operators set as a limit for a full year. Repair work in such high fields is usually carried out by large teams of workers, each spending only a short period at work.
South Texas 1 is one of the youngest plants in the country. It went on line in August 1988. South Texas 2, which is adjacent, followed in June 1989. It shows no sign of leakage. The two reactors are owned by the cities of Austin and San Antonio, a subsidiary of American Electric Power, and Texas Genco LP, a generating company.
This would not have been noticed in most countries that use nuclear power. It was caught, will be fixed and you didn't offer a " 0 " on your scale. I put the danger level at zero.
Thanks, I do appreciate that.
I have been down in the reactor sump at a Westinghouse PWR (before activation). It's been a while, but I seem to recall that the NIS piping which comes out the bottom of the vessel then curves back up [20' radius?] to a table outside the reactor shield. This table is where the NIS probes are routed to the proper area of the core that they want to look at. I had it in my head that this table was the primary pressure boundry, but maybe not...
Hence, your tag line.
Got that right! Someone told me once that you only stop learning when you die.
ROFLMAO.......
Actually this is a self-sustaining operation in that it saves electricity.
I no longer have to burn the night light.
I just pee in the commode and don't flush; the glow lights up most of the house.
OK - have a great Easter, or just a great day if you don't celebrate Easter.
Now you tell me that in Texas, not flushing saves electricity! Who knew.......?
Happy Easter my friend
Actually this is not true. The French put all their eggs in ONE basket. They build PWR's (Pressurized Water Reactor), and the PWR design is the design that is under scrutiny at this time (not manufacturer specific, but type specific with all PWR's subject to the same problems).
The US allowed many different designs by different manufacturers, with the predominant design built being the PWR followed by the BWR (boiling Water Reactor), and then some others that never caught on for one reason or another. Since our eggs are spread out in several different baskets, I personally think we are in better shape than the French.
And in reality, the problems surfacing now are problems of age, creep, and stress corrosion cracking, which are issues of design, materials, and welding that are related to when the reactors were designed and built and not who designed or built them (US or French).
If the USA were to design and build a new reactor today, be it PWR or BWR, the stress analysis and design, metallurgy, and welding technology would be much better. But this is a function of the technology we have TODAY, not WHO.
The French have their problems too, and they most likely have these same problems in their reactors of the same age. The big difference is, they do not have to deal with the NRC as we do. Plus, since the French reactor builders and operators are socialist insititutions, I have no doubt that any problems they have are kept hush-hush as much as possible, unlike over here where any problem is blown WAY out of proportion. You don't expect the French to be honest and trustworthy do you? After their recent display of honesty and integrity, I should think that speaks volumes on this subject (hi hi)
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