Showing posts with label corrosion. Show all posts
Showing posts with label corrosion. Show all posts

Tuesday, November 9, 2010

Transformer Fires? Erosion-Corrosion? Recent Events at Indian Point and Vermont Yankee

Two days ago was not the best day for Entergy. Indian Point Reactors Unit 2 was taken off-line by a transformer fire, while Vermont Yankee was shut to repair a 60-drop-a-minute leak of radioactive water within the plant. In my opinion, the best description of these incidents is in the Wall Street Journal.

Quick on the trigger, David Lochbaum of Union of Concerned Scientists was on the job about the transformer fire, while Ray Shadis of New England Coalition hopped aboard to discuss the leak. You can read their remarks in the Brattleboro Reformer.

In this case, they have made statements without knowledge. On the other hand, knowledge isn't their job. They are paid for anti-nuclear activism, not for scientific or technical credibility. Unlike science, which actually looks for causes, Lochbaum and Shadis's remarks always fit this theme: "The plant is aging and can't run anymore."

Okay. Let's look at the facts, instead.

The Transformer Fire at Indian Point

Quoting Mr. Lochbaum:

David Lochbaum,
director of the nuclear safety program for the Union of Concerned Scientists, said both problems were probably due to their age. As plants get older, they face more and more such challenges, said Lochbaum......Transformer explosions happen, on average, about a half dozen times a year at U.S. nuclear power plants, Lochbaum said.

Really? It happened because the transformer was old? The Wall Street Journal is pretty famous for digging deep, and they asked Entergy about that transformer. Here's the answer:

The transformer that failed was made by Siemens AG (SIE.XE) and installed in 2006, Nappi said.

The question then arises: Why would a new transformer fail?

Well, because it is new.

They Don't Build Them Like They Used To

Transformer fires are nothing new, but more transformer fires are happening. There's a company whose business is transformer fire prevention. (There are several companies in this market, but this is the biggest one I found by Googling.) Transformer Protection Corp.

Transformer Protection Corporation says on its website that they expect transformer fires to increase in the future because: .....This (regulatory) weakness, in addition to the globalization market, has opened the door to a disturbing drop in the quality of new transformers...Many experts anticipate that the number of failures will increase significantly in the near future, from 1% in 2001 to 2% in 2008 ..... In addition, the shorter lifetime of new transformers will sharply increase above this rate after 2008

The website also notes that there were around 800 transformer fires in the U.S. in one year. I have no idea if Lochbaum's "a half-dozen fires at nuclear plants" is correct. If it is correct, I can rephrase his statement as below.
  • Less than 1 % of the transformer fires in the U.S. were in nuclear plants last year.
  • Nuclear plants should be careful to not replace transformers unless they absolutely need to do so. The old (aging) transformers usually have better life expectancy than their replacements.
Erosion Corrosion

For years I was a member of NACE and a working corrosion engineer. Mr. Shadis's description of erosion-corrosion is accurate. It is a terrible, sometimes catastrophic form of corrosion. It breaks pipes.

In other words, erosion-corrosion rarely seeps. It busts things. It causes pipe failure. I would say "Erosion-corrosion never seeps" but I have been a corrosion engineer too long to be throwing around the word "never." Things happen, you know. Not everything goes according to form. Erosion-corrosion could make one through-wall pit, under some complex circumstances, a single pit that leaks. It would be unlikely to leak at a drop-per-minute rate, however. Also, erosion-corrosion is rarely seen in straight flows of steel pipes. It is far more common in copper, or at places where the flow in a pipe becomes turbulent.

Let's say that erosion corrosion would NOT be the first thing I would consider in a case of seepage in a straight run of pipe. Indeed, Vermont Yankee had seepage around a weld, the most common thing on earth, corrosion-wise. Mr. Shadis decided that to say that the seepage was erosion-corrosion because that was the worst thing he could think of. It was not a likely cause for the leak.

As I said, Shadis is paid to attack the plant, and that is what he does. Most of the time, frankly, he does it better than he did in this case.