Beyond our imagination: Fukushima and the problem of assessing risk

[kristopher]

Beyond our imagination: Fukushima and the problem of assessing risk
By M. V. Ramana | 19 April 2011
Article Highlights

-Severe accidents at nuclear reactors have occurred much more frequently than what risk-assessment models predicted.

-The probabilistic risk assessment method does a poor job of anticipating accidents in which a single event, such as a tsunami, causes failures in multiple safety systems.

-Catastrophic nuclear accidents are inevitable, because designers and risk modelers cannot envision all possible ways in which complex systems can fail.

<snip>

There are both empirical and theoretical reasons to doubt these numbers. A 2003 study on the future of nuclear power carried out by the Massachusetts Institute of Technology points out that "uncertainties in PRA methods and data bases make it prudent to keep actual historical risk experience in mind when making judgments about safety." What does history tell us? Globally, there have been close to 15,000 reactor-years of experience, with well-known severe accidents at five commercial power reactors -- three of them in Fukushima. However, as Thomas Cochran of the Natural Resources Defense Council explained in his recent testimony to the US Senate, depending on how core damage is defined, there are other accidents that should be included. The actuarial frequency of severe accidents may be as high as 1 in 1,400 reactor-years. At that rate, we can expect an accident involving core damage every 1.4 years if nuclear power expands from today's 440 commercial power reactors to the 1,000-reactor scenario laid out in the MIT study. In either case, though, our experience is too limited to make any reliable predictions.

http://thebulletin.org/web-edition/features/beyond-our-imagination-fukushima-and-the-problem-of-assessing-risk

I don't expect we'll hear too much from the Church of Uranus on this one.

[kristopher]

1. Told you they'd be frightened of this one...

[truedelphi]

2. Oneproblem is that we currently feel that the "scientific method"

Of dealing with policies, procedures, products etc, is to allow any and all policies, procedures, products to be used as much as anyone wants. Furthermore, we feel that being "scientific" means we have to prove without a shadow of a doubt that allowing the policies, procedures, products et al to flourish will cause harm.

But the fact is we have already seen a Space Shuttle crew that was incinerated in space due to the faulty O-rings not withstanding freezing temperatures. When the Challenger blew up, it showed how the "probability factor" of the Challenger facing a mere one in a billion possibility of blowing up must have been derived through some faulty reasoning process.

This blunder has come to be known as the Power Point blunder - as a presentation on all the many mishaps that might occur was done in Power Point, where the fonts on every item needing mention were all the same size. Nothing stuck out in anyone's minds, and the people who might have thought about the O-ring in more depth didn't bother to do so, since it was not given significant "font" highlighting.

Personally, I think when it comes to allowing civilization to undergo an immense change, such as using pesticides everywhere 24/7 for anything, even cosmetic reasons, or for using the laboratory genetic modification of seeds, or for using nuclear power, all those things need to be scrapped. As there is too much danger in those approaches.

I am firmly on the side of the Precautionary Principle: "if an action or policy might cause severe or irreversible harm to the public, in the absence of a scientific consensus that harm would not ensue, the burden of proof falls on those who would advocate taking the action."

[Throckmorton]

3. As I recall, the high end for shuttle failure was 1 in 500 flights

As solid rockets had, at that time anyway, a 0.1% chance of failure on launch, and the shuttle used two of them.

Complex things fail, and not withstanding what some of my cool-aid drinking associates would have you believe, nuclear power reactors are no exception.

All the bloviating about how I must love coal, because I refuse to embrace the widespread expansion of commercial power reactors and life extension of existing plants, which were never built to function beyond 40 years, will not alter that fact. I actually work in the industry, and I have seen both the good, and the bad personally. The bad is winning.

[truedelphi]

4. If coal didn't involve the strip mining of the

Entire topography of the land, with the waste pits for the sludge waters being placed above elementary schools, I would join you on the coal embrace.

Coal is now being produced that is much cleaner to burn. No longer would cities of people using coal for their needs be having to enforce smog alerts.

But until the industry resolves the ecological matters, such as land destruction, water being poisoned and citizens having to worry that should some levee break apart, their families will be washed away in the night, on a thunderous river of sludge, I can't accept coal.

[Throckmorton]

5. No, I'm anti-coal.

But, the charge that if you question the need, or safety, of nuclear, you want to burn more coal is a frequent charge here.

People like to deride renewables, as not ready for prime time, and maybe they are not today. But I believe they can fill a substantial role in the future. The humans of this world are energy hungry, and we may be on a truly unsustainable course.

New nuclear stations we be neither benign nor cheap to build. All the bluster about advanced designs to the contrary, they will still rely on humans, and their corporate masters to operate.

[txlibdem]

6. Uranium resources will only last another 55 years under the 1000 reactor MIT scenario

That is the best reason I can think of to replace the current Uranium-based nuclear power plants.

[truedelphi]

9. Funny how they never mention that talking point.

Thank you for bringing it to the table.

[kristopher]

12. Where do you find that statistic? nt

[SpoonFed]

8. +1 n/t

[kristopher]

13. Did you hear that strong opposition to nuclear has risen 24 points?

It is now 47% strongly opposed to 20% strongly in favor.

It is time to make our voices heard.

[txlibdem]

7. K&R -- excellent post. It proves that we should NOT build any old-style reactors: historical data

The thing with historical data is that it shows you problems with what *was* built and not what will be built. No nuclear power proponent I've ever heard of has stated that we need to build more 1960s design nuclear plants. No person in the West has ever said we should build any RBMK nuke plants like Chernobyl (ref: http://en.wikipedia.org/wiki/Chernobyl ) because it was a flawed design from its inception. Using historical data is an easy way to confuse the voting public and make your "study" end up with numbers that you want it to have.

The truth is that the nuclear designs that are now going through the approval process, even the Westinghouse AP1000 which utilities can start building now, are far safer than any reactors built to date. The AP1000 is a Gen III+ design which has a Passive Core Cooling System that does not need electricity from the grid or diesel backup generators, nor hydraulic or compressed air systems. Therefore a Fukushima-level event would not cause the same problems for the AP1000 as it did for the Fukushima Daiichi reactors that were designed in the 1960s. The Generation IV reactors are passively safe and, by the laws of physics, cannot have a core meltdown.

"We can expect an accident involving core damage every 1.4 years if nuclear power expands from today's 440 commercial power reactors to the 1,000-reactor scenario laid out in the MIT study."

But that projection denies the fact that none of those 1000 reactors will be of the older design so extrapolating from existing old-as-the-hills reactors forward to newer and safer designs is fraught with error.

So come on everybody! Let's all join hands with Kris and force our leaders NOT to approve building any more of the old-style reactors that we all know are not as safe as modern designs.

[bananas]

10. Gen II reactors are being built, and Gen III and IV reactors can melt down

For example Gen II reactors are being built in China:

http://www.world-nuclear-news.org/NP_Maintain_nuclear_perspective_China_told_1101112.html

However, ambitious targets to deploy AP1000s with reduced foreign input have proven difficult due to frequent quality control issues in the supply chain. As a result, more of the Generation-II CPR-1000 and CNP design units are under construction or on order. Only China is building Generation-II units in such large numbers, said the SCRO, counting 57 on the books.

That link is from here: http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=270383&mesg_id=270676

France has considered going back to Gen II designs after they lost the UAE deal,
their Gen III design is just too expensive.

Russia still has an RBMK under construction near Moscow: http://bellona.org/english_import_area/international/russia/npps/kursk/32692

You wrote: "The Generation IV reactors are passively safe and, by the laws of physics, cannot have a core meltdown."
That's incorrect, they can melt down, for example the IFR can melt down:

http://yarchive.net/nuke/ifr.html

>|> Tom, I have to take great exception to this kind of party line propaganda.
>|> There are a number of us nukes who have been active in this group
>|> for years who don't want to see our credibility destroyed by
>|> propagandizing. Specifically,
>|>
>|> * Neither oxide nor metal fuel is "meltdown-proof". "Meltdown" has
>|> become a loaded term and must be used carefully. Either type
>|> of fuel will melt from decay heat given loss of cooling for a
>|> reasonable interval after shutdown.

>You're reading way too much into my statements. The fuel was demonstrated
>meltdown proof in the conditions in which I described.

The PBMR and other Gen IV reactors can also melt down.

[kristopher]

11. That would be the fission industry's promotional myth #2

1. nuclear power is cheap;

2. learning and new standardized designs solve all past problems;

3. the waste problem is a non-problem, especially if we’d follow the lead of many other nations and “recycle” our spent fuel;

4. climate change makes a renaissance inevitable;

5. there are no other large low-carbon “baseload” alternatives;

6. there’s no particular reason to worry that a rapidly expanding global industry will put nuclear power and weapons technologies in highly unstable nations, often nations with ties to terrorist organizations.