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Activists' Claims Distort Facts about Advanced Reactor Design

Westinghouse AP1000 - China's Sanmen unitBelow is from our rapid response team.

Yesterday, regional anti-nuclear organizations asked federal nuclear energy regulators to launch an investigation into what it claims are “newly identified flaws” in Westinghouse’s advanced reactor design, the AP1000. During a teleconference releasing a report on the subject, participants urged the Nuclear Regulatory Commission to suspend license reviews of proposed AP1000 reactors.

In its news release, even the groups making these allegations provide conflicting information on its findings. In one instance, the groups cite “dozens of corrosion holes” at reactor vessels and in another says that eight holes have been documented. In all cases, there is another containment mechanism that would provide a barrier to radiation release.

Below, we examine why these claims are unwarranted and why the AP1000 design certification process should continue as designated by the NRC.


In the AP1000 reactor design, the gap between the shield building and reactor containment (which surrounds the reactor core to protect the public and the environment in the case of a radiation release) allows for “numerous locations where rust can develop on the steel containment.” This rust could create a hole large enough that, during an accident, the radiation dose to the public could be “ten times greater than the NRC allows.”

The Facts:

Compared to the example cited in the report, the AP1000 containment vessel is more accessible for inspection and makes use of thicker, corrosion-resistant steel. NRC requirements for inspection and maintenance, as well as operational testing, would preclude an undetected corrosion of steel used in the reactor containment structure.

The report alleges that the gap between the plant shield building and containment creates an area that is “extraordinarily difficult to detect until the rust creates a hole completely through the steel.” In reality, unlike the example cited by the report, the AP1000 containment vessel is accessible for inspection.

Furthermore, the AP1000 containment vessel is made of high-quality, 1.75” thick steel. Water corrosion as specified in the critics’ report would require rates that simply are not credible. Operational testing and inspection would reveal any flaw, especially those significant enough that could lead to a hole of the hypothetical size stated.

Finally, the containment vessel itself is built to American Society of Mechanical Engineers codes that have more than 100 years of proven safety margin protection to the public.

For a copy of Arnold Gundersen's statement and visuals used in the report, see

For more on the AP1000’s safety features, click here.

NEI Rapid Response Team

Picture of the AP1000’s containment vessel bottom head at China’s Sanmen nuclear station. Courtesy of the Shaw Group.

Update 6:20 PM:

After taking a closer look at the critics' report and materials, there are quite a few bits of data and claims that don't all jibe with each other. The NRC study Gunderson's report cites (pdf) says that there "have been at least 66 separate occurrences of degradation in operating containments." NIRS' press release claims 77 and Gunderson's press conference statement says more than 80 (p. 1). Talk about a counting mess. So what's the real number? Here's the NRC doc from above:

"Since 1986 [to 2000], there have been over 32 reported occurrences of corrosion of steel containments or liners of reinforced concrete containments" (p. 5).

The other 34 containment degradation occurrences were "related to the reinforced concrete or post-tensioning systems," (p. 6) which had nothing to do with corrosion. Thus, less than half of the examples the critics cite aren't directly related to the AP1000 issue they think they've discovered.

As well, while the anti's claim that there are 77 instances of degradation, according to the NRC pdf from above, just "one-fourth of all containments have experienced corrosion" (p. 5).

The critics claim that this is an AP1000 issue but corrosion is an issue that all designs have to address. One of the ways the AP1000 design addresses corrosion penetration is its 1.75 inch thick steel plate containment liner (as mentioned above). The existing nuclear plants have steel plates that are less than half of the thickness of the AP1000 and only a handful of those had corrosion problems that penetrated containment (all were promptly addressed once discovered, page 5 from NRC). As well, the Beaver Valley containment which Gunderson constantly references corroded 3/8" of a hole. Yet, his analysis gives little credit to the difference in steel thicknesses between designs. Well, we've noted above that the critics' numbers are all mixed up, guess it makes sense that this difference is mis-understood too.


Anonymous said…
Given that the NRC's review of the shield building has been stopped for over six months due to design flaws sounds like the AP1000 is in some deep trouble.
Michael Canney said…
This "rapid response" to legitimate concerns about the safety of AP1000 containment design does not address the main problems that were identified: the chimney effect, which is a fatal flaw unless you can guarantee there will be no corrosion. What about Dr. Hausler's analysis of the corrosion problem. Claiming that inspection will find and remedy any problem before it becomes a threat to safety is pure fantasy, given the historical record on existing reactors. Stop trying to defend the design flaw and DEAL WITH IT.
Meredith Angwin said…
Hi. Well, I was interested in the idea that somehow, activists were becoming corrosion engineers (without joining NACE or studying chemistry or...)

And then I see. Gundersen again. The man gets around, for sure. When he's in Vermont, the problem with Vermont Yankee is that it's old and not worth fixing. When he leaves Vermont, the problem is that the review of new plants is not good enough.

Nothing nuclear will ever satisfy Gundersen. Luckily for him, anti-nuke groups are well-funded and can employ him.

The problem is that the whole "review and challenge process" isn't adversarial ENOUGH. If Gundersen had to be sworn in, state his credentials (he's not a licensed Professional Engineer and I believe he never has been) and face cross-examination, he simply could not testify.
Brian Mays said…
"Claiming that inspection will find and remedy any problem before it becomes a threat to safety is pure fantasy,"

Heh ... go tell that to the FAA, Michael. They use repetitive inspections all the time to ensure airworthiness and safety of airliners (which suffer from the "fatal flaw" of gravity if the wrong component fails).

You don't refuse to fly, do you?
MIchael Canney said…
It cracks me up to see pro-nukers like Meredith Angwin comment about anti-nuke groups being "well-funded" and it is an insult to Arnie Gunderson to imply he is motivated by money when he could make 10 times what he's getting from these shoestring advocacy groups if he worked for the industry.

We all know there would be no nuclear industry if not for massive public subsidies. The worst thing is that we will keep paying for it IN PERPETUITY. I can't understand why the "lower taxes, smaller government" crowd are pro-nuclear, given that it inevitably leads to bigger government and higher taxes, forever.

Safety issues aside, we need a total moratorium on public funding for nuclear power, until all energy options are fully explored and until all the long term costs and risks are factored into the bogus argument that nuclear power is "cheap, clean energy."
Anonymous said…
Currently nuclear gets slightly more subsidies than fossil fuels per unit of generation, but an order of magnitude less than solar and wind. Wholesale cost of existing reactors is generally extremely low.

Fine, let's remove public support for Nuclear. But if we do that - we must do that with all forms of electricity. That means instant collapse of wind and solar. It also means internalizing the costs of coal - make the coal industry pay for the environmental, and health damages it causes.

Michael Canney, if we haven't explored 'all' energy options taking into account cost (etc) then how can you in the same sentence dismiss nuclear?
Anonymous said…
The man gets around, for sure.

And consulting engineers who work FOR the nuclear industry don't? This in and of itself proves nothing. That's how consulting works.
Luke said…
That's a picture of the AP1000’s reactor vessel bottom head?

It looks like a pretty large reactor vessel!

Perhaps I'm wrong, but isn't that actually the bottom head of the containment vessel, as distinct from the reactor vessel?
David Bradish said…
isn't that actually the bottom head of the containment vessel, as distinct from the reactor vessel?

Yep and I just corrected it on the caption, thank you much.
An actual expert said…
Gunderson's technical analysis is incomplete and quite flawed. As with most anti-nuclear reports, it would never survive technical peer review, either for presentation at a conference or in a journal, or NRC review as a licensing document.

The AP-1000 containment vessel is designed to meet ASME code requirements, and as with all reactor containments will be pressure tested to full design pressure prior to entering service and then every 10 years during operation.

The upper portion of the AP-1000 containment vessel is free standing and can be inspected on both sides. It will have corrosion resistant coatings and the regular in-service inspection would identify any damage to the coatings and incipient corrosion.

The bottom portion of the containment vessel is embedded into concrete to carry the gravity load down into the reactor building foundation. Here it is not possible to visually inspect the interface between the steel and the concrete, obviously, as is the case with all conventional steel-plate-lined concrete reactor containment structures.

In the embedded region, if corrosion did penetrate the AP-1000 containment in the embedded region, which is unlikely since the AP-1000 vessel is much thicker than a conventional steel liner for a concrete containment, then any leakage would have to also penetrate through the concrete structure.

Gunderson's argument is simply wrong, and upon modest inspection seems pretty stupid. In the upper portion of the AP-1000 containment where external ambient air flows on the outside, both sides can be easily inspected. In the embedded part below, if corrosion did occur leakage would be limited by the external concrete, just as Gunderson argues is the benefit of a conventional steel-lined concrete containment.

The sad part is that when the USNRC concludes that Gunderson's analysis is flawed and his concerns about the AP-1000 containment have no merit, anti-nuclear groups will cite this as being evidence that the USNRC is biased, not evidence that Gunderson is completely wrong.

In the end, though, the reason that the credibility of anti-nuclear groups continues to drop is because they have no capacity to screen and peer review their own information. Sad.
DocForesight said…
@Michael Canney -- The smear of pro-nukes being motivated by money (who besides an ascetic monk isn't?) or "well-funded" being turned around to apply to Mr. Gundersen would seem to be fair play. You guys can't have it both ways.

BTW, I assume you're riding your bicycle instead of using "dirty" combustion engines for transportation?
Sterling Archer said…
Thanks to the "actual expert" for a very interesting post!

Let me plug my new blog; in a strange coincidence, I made a post on materials science issues yesterday.
Anonymous said…
I believe that the AP1000 design is basically sound, and that the Gunderson report is basically BS, but I do get concerned when I see words like "preclude...undetected corrosion." The Davis Besse "hole in the head" was an unfortunate demonstration of the fact that nothing can be absolutely precluded, especially when both plant personnel and NRC inspectors fail to carry out their responsibilities.

The industry needs to ensure, in the future, that it does, indeed, carry out necessary inspections and take prompt remedial action when called for. Operating both the current reactor fleet and any new plants that are built with an absolute commitment--first and foremost--to safety is the only way to "preclude" future problems.
Meredith Angwin said…
Mr. Canney

As you may be aware, Gundersen is extremely proud of being "blackballed" by the nuclear industry. He was working as a schoolteacher until his recent consulting gigs. (There is no shame there, my mom was a schoolteacher. I'm just saying he didn't walk away from more-lucrative-industry-projects.)

In other words, he can't be employed by the nuclear industry. In his opinion, this is because he was a noble whistleblower. Other people have other opinions of why he is not particularly eligible for employment.
Brian Mays said…
"Other people have other opinions of why he is not particularly eligible for employment."

The opinion of "other people" doesn't really matter. I'd say that Mr. Gundersen's work speaks for itself.

Does anyone care to make a wager with me as to whether Mr. Gundersen's so-called "legitimate concerns" will be substantiated by the regulator? Anyone? Michael? Anyone?

Put your money where your mouth is.
Meredith Angwin said…
ouBrian Mays

I believe I have already put my money on Gundersen, or at least, given my money TO Gundersen. I am a tax-paying citizen of Vermont, and he is on a legislative oversight panel in this state. I do not know his contract, though I suppose it is a public document. I have heard that he is paid $300 an hour, and has already collected over $100K.

I think we are talking about my tax money, and he is not a licensed engineer. In some states, without a license, you can't serve on such panels.

But I don't have time to research this, and if you can find real information to contradict me, please share it. My own feeling is that Vermont should spend my tax money on a qualified engineer.

Gundersen may well give a break on his rates to the anti-VY groups he also consults for. But in general, if you were on any Google product during January and February, you KNOW the anti-s had enough money to flood the Internet with anti-VY banner ads, with pictures of the cooling tower collapse. These popped up on any search or gmail page or blog that included "nuclear." The antis also bought full page and half-page ads, in color, in most Vermont newspapers. At least once a week.

Let's put it this way. At the rate the anti-s buy ads (far more ads than Entergy bought) the anti-s also have the bucks to pay Gundersen.

You saw those ads unless you were deaf and blind, so don't tell me how sad and poor the anti-s are. They are well-funded, and I will repeat that. It is no crime to be well-funded.

I just don't like my TAX dollars paying so much for someone who doesn't meet the usual qualifications for professional engineering work.

As far as Gundersen being right...well, not really.

I agree with the Actual Expert:

"The sad part is that when the USNRC concludes that Gunderson's analysis is flawed and his concerns about the AP-1000 containment have no merit, anti-nuclear groups will cite this as being evidence that the USNRC is biased, not evidence that Gunderson is completely wrong."
Meredith Angwin said…
Brian Mays

I apologize most sincerely for the mistake (the typo "ou" thing) in your name in my last post. I am very sorry for the misspelling.

gmax137 said…
I don't know if Gundersen holds a PE or not. But I looked at the linked 'report' on the AP1000, includiing his Attachment 1 CV (it runs 12 pages). The only instances of 'professional' throughout the document are when he says, 'in my professional opinion..."

To be fair, though, I don't see where holding a PE license is pertinent in this case. He'd be just as wrong with or without the stamp.
Meredith Angwin said…
I don't think the certification is particularly pertinent to his opinions on a new reactor design. However, I don't like him being paid big bucks to advise the legislature in Vermont about an existing reactor, without the appropriate credentials to do so. It's like Vermont hired a lawyer who never took the bar exam, and paid this person as a high-level public prosecutor. Lawyers and engineers hired to work for the state should have the proper credentials.
Anonymous said…
Lawyers and engineers hired to work for the state should have the proper credentials.

Especially where taxpayer expenditures are concerned. But in this case, I think the state of Vermont simply hired someone who would tell them what they wanted to hear. Their "minds" were already made up. Hired guns who will validate a prejudiced opinion are a dime a dozen, PE cert or no.
Peter Joseph said…
From what I can see of the AP1000 it looks easier to inspect than previous designs. T

The main 'selling point' of Gundersen's report is the scary diagrams in the first few pages showing radiation symbols leaking out.

It's reeks of incredible bias to have a factually dodgy anti-nuclear report hosted on a site called Fairwinds. Also clearly stating that NIRS contracted for the report.
Brian Mays said…
Frankly, I found the little radiation symbols in the figures to be very tacky and unprofessional. It kind of foreshadowed the poor quality of the report itself.
Peter Joseph said…
That is exactly what I mean Brian. It appears to me as if the remainder of the report exists simply to prop up the "alarming" diagrams on the front page. As usual it's designed to take advantage of just how little 'Joe Public' knows about nuclear power.

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