Shouldn't we disable Nuclear Reactors in California?

[clancy688]

But while the Japanese response to terrorism is discussed in my post #80, US plants have taken significant and expensive steps to prepare for possible attacks.

I'm relieved to hear that at least one nation did something like this. Here in Germany, we did it the typical german way.
We realized that NPPs may be danger, we discussed it, we did studies, we got proof that NPPs are in danger and meanwhile ten years went past without any improvements to the plants.
At least they are turning them off now.Regarding the Hiroshima Cs levels:

I have found two studies, but I can't access them... http://www.ncbi.nlm.nih.gov/pubmed/1762121 http://www.ncbi.nlm.nih.gov/pubmed/8698576

And I found a US military report about contamination in Hiroshima and Nagasaki:

http://www.dtra.mil/documents/ntpr/relatedpub/DNATR805512F.pdf

On page 58 they calculate surface contamination rates for several isotopes at a location one mile east of and 45 days after the blast. The location was shielded, so there's no neutron activation, only surface deposition.
They get 0.37 uCi/m², or ~14.000 Bq/m² Cs-137. In Fukushima, large areas are contaminated with 1.000.000 to 30.000.000 Bq/m2...

 

[NUCENG]

Well I am not a terrorist, but a 46 yrs old electronic engineer, masters degree, automatic controls as degree thesys, MBA a couple of years later.
I am interested in the topic only since I have 2 children that I 'd like to see grow up, in the safest possible world.

I am very happy to read about your expert confidence about those added security gizmos that would eventually kill all would be suicidal attackers, before thay can put NPPs (and the world by the way, not just the US) in danger.

Only I hope you will allow me, as an engineer with some 23 yrs + experience, to keep a rather skeptical attitude towards any unproved and undiscussed claim.

In any case if the gizmos that must be in place are in fact so effective, we need not to bother checking resistance of concrete to airplane impact that would not matter and hence it proves my point that the Phantom video is in fact irrelevant.

What is more appropriate it would be hopeful for the US government to share such measures with (not me of course that may be suspected of being a dangerous extremist) but with allied european governments.
You will have probabably noticed that AREVA is marketing increased impact resistance of EPR 3G+ reactors has an important safety feature.
Since they carry a quite significant price tag for it, some european country could save a couple of millions euros, to begin with.

I, in the meantime, will adopt a somewhat more radical stance toward nuclear security.
For what is worth, in my home country, having watched the attitude toward nuclear security in Europe, with episodes like France and UK opposing anti-terrorist response to be thoroughly included in "nuclear stress test", I am just going to go today (better yet, immediately after finishing writing this) to cast my ballot to BAN nuclear energy from Italy.

Thanks for having reinforced my opinion on the specific matter.

Regards

Surprise, surprise, I doubt that you were really on the fence about your vote anyway. You want your children to be safe and because you get mad at me you'll vote to ban a baseline generation source that doesn't emit greenhouse gases. Hope you don't live in Venice. Believe me or don't. I won't miss any sleep if Italy goes either way.

I didn't need your bio, I have no reason to believe you are a terrorist or Mafia, I aplologize if you think otherwise. But, did you ever consider that you can't know everything? People probably trust you to not design unsafe electronics and if you work in a private company you aren't allowed to put all your proprietary information on a web blog. The same limitation applies about security to those of us working in the US nuclear industry. My claim has to remain unproven and undiscussed. Even if I was involved in international discussions and information sharing on intelligence or security, I wouldn't be able to discuss it here.

 

[NUCENG]

I'm relieved to hear that at least one nation did something like this. Here in Germany, we did it the typical german way.
We realized that NPPs may be danger, we discussed it, we did studies, we got proof that NPPs are in danger and meanwhile ten years went past without any improvements to the plants.
At least they are turning them off now.


Regarding the Hiroshima Cs levels:

I have found two studies, but I can't access them... http://www.ncbi.nlm.nih.gov/pubmed/1762121 http://www.ncbi.nlm.nih.gov/pubmed/8698576

And I found a US military report about contamination in Hiroshima and Nagasaki:

http://www.dtra.mil/documents/ntpr/relatedpub/DNATR805512F.pdf

On page 58 they calculate surface contamination rates for several isotopes at a location one mile east of and 45 days after the blast. The location was shielded, so there's no neutron activation, only surface deposition.
They get 0.37 uCi/m², or ~14.000 Bq/m² Cs-137. In Fukushima, large areas are contaminated with 1.000.000 to 30.000.000 Bq/m2...

Germany announced they would shut all plants down in the next few years. Does that get voted on like Italy or does the Chancelor have that authority?

 

[clancy688]

Germany announced they would shut all plants down in the next few years. Does that get voted on like Italy or does the Chancelor have that authority?

Historically, there are four big partys in Germany: CDU (conservative), FDP (liberal), SPD (socialists) and the Greens. You need at least 50% of all seats in the Bundestag to have a stable government, and no party achieves this alone. So they build coalitions.
It's nearly always a CDU-FDP or SPD-Greens coalition. While CDU-FDP was pro-nuclear (until March 13th...), SPD-Greens was always contra-nuclear.
In 2000, the SPD-Greens introduced a "nuclear consens" which basically declared the shutdown of every nuclear power plant after a certain amount of power generated.
This consens was abolished in 2010 by the now governing CDU-FDP coalition. Most germans were against this new lifetime extension.

Now, nearly everybody here is against nuclear power. Every ruling and non-ruling party. There will be no vote. The chancelor will propose a law to abolish nuclear power by 2021 and that's how it's done.
There was no vote to decide on the lifetime extension (of course not, the population would have voted against it for sure) and there'll be no vote for the shut down either.
Plebiscites in Germany are very rare. It's a consequence of World War II. It was feared that plebiscites are a tool for populism.

 

[Luca Bevil]

Surprise, surprise, I doubt that you were really on the fence about your vote anyway. You want your children to be safe and because you get mad at me you'll vote to ban a baseline generation source that doesn't emit greenhouse gases. Hope you don't live in Venice. Believe me or don't. I won't miss any sleep if Italy goes either way.

I didn't need your bio, I have no reason to believe you are a terrorist or Mafia, I aplologize if you think otherwise. But, did you ever consider that you can't know everything? People probably trust you to not design unsafe electronics and if you work in a private company you aren't allowed to put all your proprietary information on a web blog. The same limitation applies about security to those of us working in the US nuclear industry. My claim has to remain unproven and undiscussed. Even if I was involved in international discussions and information sharing on intelligence or security, I wouldn't be able to discuss it here.

Well I can assure that I was actually quite convinced already.
Altough I do not have your specific experience so I do enjoy all of you technical post, in the technical 3d, however I do have more than enough technical proficiency to grasp all the basics, to become convinced that at Fukushima there would have bee total meltdowns at the very first clear news about the accident.
In short I think i recognize each and every aspect of the nuclear risk.

Whereas I understand that there may be safety measures that is better not to disclose in a public forum, I am sure you realize that this add to the conclusion that the sector is highly militarised, that the measures are of an "active" nature and might be compromised if enough is known about them, that nations using nuclear power (the US in this case) are basically asking other other nations people to trust such measures on an unchallenged and undisputed basys.

I am sure you are a patriot and a giant morale stature but some other people that like you has had some exposure to such measures might not be.
Some of them may get depressed, may get swamped by terrorist propaganda, may fall in love with an islamist goddess that makes them think they and not us are in fact right and being oppressed, may get kidnapped and tortured.

The tought that such measures are to be kept secret to be effective and relied upon on a blind basys is not reassuring.
In any case all this exchange of ideas was especially referred to the stress resilience of concrete to impacts.

In more general political terms while I may decide to thrust the US on the effectiveness of such measures, and in any case more than discussing the issue with Us citizens cannot, I do think that Italy in particular does have issues of its own in dealing with nuclear safety.

Suffice it to say that the renewed nuclear pronge began in Italy with vast amount of technical disinformation.
You may or may not have noticed that Silvio Berlusconi has endorsed the nuclear energy choiche on bases that are completely false such as that:
1) 1987 Italy referendum was an error that deprived Italy from a world leading nuclear sector (you certainly know that Italy had installed 4 reactors, of which just 1 Mark III BWR reactor was rated at any significant power output + 2 other MARK III were being finished), had no reactor design worth of commercial selling of any kind, the most significant contribution having given to the nuclear sector being the CP1 Fermi's work
2) that AREVA EPR are so strong as to withstand "nuclear" terrorist attack (this unbelievable stupidity was announced to our people while having Sarkozy at his side the French president stood imbarassed by the enormity but he did rather keep quiet that further embarasse Berlusconi)

3) the "to be" equivalent to NRC was "set up" and given as a responsability to an oncologist (Veronesi9 that understands absolutely nothing about any tecnhical issue related to nuclear safety, the guy given the vast majority of antinuclear sentiment prevalent in Italy bagan immediately to act as a sponsor rather than a a controller

Apparently the claim about NPP security will have in fact to remain undisclosed and undisputed and in a democratic nation that need will be enough to highlight the critical nature of the nuclear option in that aspect.

best regards again

 

[Morbius]

Indeed. I don't deny that at all. It's just that you replied to "NPPs were tied to nuclear weapons programs" with "that's ********" and I corrected you. No need to get emotional.

Clancy,

I'm NOT emotional - I'm just for scientific ACCURACY.

You did NOT "correct" me - because you are WRONG

It's an oft quoted MYTH among anti-nukes that nuclear power programs beget nuclear weapons programs; but the history is to the contrary.

The USA, Soviet Union, Great Britain, France, China, Israel, and North Korea, ALL had nuclear weapons in their possession before they built their first nuclear power plant, for those in the list that have power plants. India and Pakistan had nuclear weapons programs in existence before they build their first nuclear power plant, but those programs did not yield a working weapon until after the power plant was in operation.

So it is illogical to say that there is a causal link between nuclear power and nuclear weapons. Nations build nuclear weapons for various reasons, but NONE of those reasons is because they have nuclear power plants.

You didn't "correct" me; because it is you that is 100'% WRONG, WRONG, WRONG

Dr. Gregory Greenman

 

[clancy688]

Clancy,
You didn't "correct" me; because it is you that is 100'% WRONG, WRONG, WRONG

Where did the plutonium for the first nuclear bombs come from? Nuclear reactors, of course. Hanford, Windscale... those were nuclear reactors. No civil reactors. But still nuclear ones.

I'm lazy, so I'll quote wikipedia:

Eventually, the first artificial nuclear reactor, Chicago Pile-1, was constructed at the University of Chicago, by a team led by Enrico Fermi, in late 1942. By this time, the program had been pressured for a year by U.S. entry into the war. The Chicago Pile achieved criticality on December 2, 1942[8] at 3:25 PM. The reactor support structure was made of wood, which supported a pile (hence the name) of graphite blocks, embedded in which was natural uranium-oxide 'pseudospheres' or 'briquettes'.
Soon after the Chicago Pile, the U.S. military developed a number of nuclear reactors for the Manhattan Project starting in 1943. The primary purpose for the largest reactors (located at the Hanford Site in Washington state), was the mass production of plutonium for nuclear weapons. Fermi and Szilard applied for a patent on reactors on 19 December 1944. Its issuance was delayed for 10 years because of wartime secrecy.[9]

[...]

The first nuclear power plant built for civil purposes was the AM-1 Obninsk Nuclear Power Plant, launched on June 27, 1954 in the Soviet Union. It produced around 5 MW (electrical).

http://en.wikipedia.org/wiki/Nuclear_reactor#Early_reactorsAs for your scientific accuracy, do you mind replying on the other topics of our previous discussion?
Such as evacuations out of mountain villages because of tsunami damages and Fukushima prefecture C137 contaminations (magnitude: 10^7) which are not as high as the ones in Nagasaki (magnitude: 10^4)...?

But it would probably be better to outsource that in the right thread: https://www.physicsforums.com/showthread.php?t=501637

 

[Argentum Vulpes]

Weight of a F4 Phantom: ~13 tons

Weight of a commercial passenger plane: ~130+ tons

Would you rather have a 1 lbs rock dropped on you or 100 lbs of foam? Any military plane (F4 included) is incredibly dense, any civilian plane is just a hollow tube. If the wall can survive a military plane it can survive a commercial plane.

 

[clancy688]

If the wall can survive a military plane it can survive a commercial plane.

German scientists obviously think otherwise. Some of the nuclear engineers in this forum referred to our plants as "one of the safest in the world", so I don't think they are worse than anything in the US (which are also way older than our german plants).
And as I already stated, the reinforced concrete and hardened elevator shafts at WTC and Pentagon could, apparently, not.
Moreover, mass is mass. I remember an often quoted joke way back in kindergarten. "What's more mass? Ten kg iron or ten kg feathers?"

 

[daveb]

I am very happy to read about your expert confidence about those added security gizmos that would eventually kill all would be suicidal attackers, before thay can put NPPs (and the world by the way, not just the US) in danger.

The security measures in place in NPPs are very stringent. I don't work at an NPP, but if I did, I couldn't tell you about them anyway, since it would be a crminal act to discuss specifics of security measures. However, other licensees that possesses large activities of radionuclides (called quantities of concern) are required to have stringent security measures. Since NPPs pose an even greater security concern, I imagine their measures are even tighter than those used by hospitals and irradiator facilities.

Here are the details of increased controls requirements. http://www.nrc.gov/security/byproduct/orders.html"

 

[Luca Bevil]

The security measures in place in NPPs are very stringent. I don't work at an NPP, but if I did, I couldn't tell you about them anyway, since it would be a crminal act to discuss specifics of security measures. However, other licensees that possesses large activities of radionuclides (called quantities of concern) are required to have stringent security measures. Since NPPs pose an even greater security concern, I imagine their measures are even tighter than those used by hospitals and irradiator facilities.

Here are the details of increased controls requirements. http://www.nrc.gov/security/byproduct/orders.html"

I am happy to learn that.

I am even happier to announce you that at this very moment the Italian people is reaching the required quorum to ban nuclear energy from Italy.

It is a great signal that security must be put before anything else and the italian people are not satisfied with the perceived level of nuclear safety, and even more with the completely incompetent attitude of the italian Berlusconi government in front of the issue.

iI'll keep you up to date as soon as the result is final

 

[daveb]

And as I already stated, the reinforced concrete and hardened elevator shafts at WTC and Pentagon could, apparently, not.

The design of the WTC and Pentagon and the design of a containment structure are two completely different things. You can't really compare them.

Moreover, mass is mass. I remember an often quoted joke way back in kindergarten. "What's more mass? Ten kg iron or ten kg feathers?

Yes, mass is mass, but it also depends on the structure of what's hitting it. I'd rather be hit by 1000 pounds of feathers falling on me than 100 pounds of lead.

 

[clancy688]

Yes, mass is mass, but it also depends on the structure of what's hitting it. I'd rather be hit by 1000 pounds of feathers falling on me than 100 pounds of lead.

The 100 pounds of lead probably kill you by squashing your head and nothing else. The 1000 pounds of feathers will kill you by squashing everything. Not only your head...

Let's take the Columbia disaster for example. The thermal shield got a hole punched in through a part of foam hitting it at high speed.


Either way, I've said it often enough. German scientists researched commercial plane crashes on NPPs and came to the conclusion that the impact would penetrate the walls.

 

[Danuta]

I'm mentioning the jet fuel again -- an airliner has a larger capacity for fuel.

No one really knows what would happen if a large airline passenger plane hit a reactor building. In the U.S. the NRC and IAEA have said that U.S. reactors were not designed to withstand the impact of a large airline passenger plane loaded with jet fuel because when the reactors were built there was no anticipation of such an event(before 9/11).

 

[daveb]

Either way, I've said it often enough. German scientists researched commercial plane crashes on NPPs and came to the conclusion that the impact would penetrate the walls.

Can you provide a source for that one? I spent a while doing a google search, and the worst I found was this:

One year after 9/11, the International Committee on Nuclear Technology (ILK), an investigative body set up by the German states of Bavaria, Hesse and Baden-Württemberg, reached a devastating conclusion. According to the classified ILK study, "severe to catastrophic releases of radioactive materials could be expected in the event of a crash against the reactor building" in all but three nuclear power plants.

- http://www.spiegel.de/international/germany/0,1518,753158-2,00.html" . I found the report they referred to (I think) but it's written in German. I'm wondering what the article means by "severe to catastrophic releases of radioactive materials could be expected in the event of a crash against the reactor building".

 

[clancy688]

Can you provide a source for that one? I spent a while doing a google search, and the worst I found was this:

- http://www.spiegel.de/international/germany/0,1518,753158-2,00.html" . I found the report they referred to (I think) but it's written in German. I'm wondering what the article means by "severe to catastrophic releases of radioactive materials could be expected in the event of a crash against the reactor building".

Here you are:

http://www.oeko.de/oekodoc/623/2007-163-de.pdf

But it's in german... and I don't think that I'll be able to find any english sources. Perhaps you can try translating it via google.
On page 30ff you can see several plume scenarios for "major releases". The maps are displaying the areas which would need to be evacuated.

 

[clancy688]

Addendum: Arg, I should've known better, I shouldn't trust anything the german mass media write about technical issues.

They read about an accident probability and then kept rumbling about the nightmare scenario. And me idiot assumed the same without checking the facts. I'm very sorry.

So, a quick summary of the studies conclusion:

Bei neueren deutschen Anlagen besteht aufgrund der vorhandenen Auslegung ge*
gen den Absturz einer schnellfliegenden Militärmaschine ein hoher Schutz auch
gegenüber dem Aufprall eines zivilen Großflugzeugs. Dabei kann jedoch auch bei
diesen Anlagen nicht für alle Flugzeugklassen und Aufprallgeschwindigkeiten eine
Beherrschung des Ereignisses nachgewiesen werden. Insbesondere bzgl. der mög*
lichen Folgeschäden aufgrund von induzierten Erschütterungen I am Inneren der An*
lage bestehen hier Ungewissheiten, die eine sichere Aussage zur Beherrschbarkeit
eines solchen Ereignisses verhindern.

Newer NPP designs which are designed to withstand a 20t 800 km/h fast F-4 have a very high protection even against large and fast flying civil airplanes. Penetration is ruled out (in the main part, it's not mentioned here) but there are uncertainties regarding shock induced damages inside the reactor.

Bei den ältesten, nicht explizit gegen Flugzeugabsturz ausgelegten Kernkraftwer*
ken, zu denen die Anlage Biblis-A zählt, ist bei realistisch möglichen Absturzszena*
rien eine großflächige Zerstörung des Reaktorgebäudes nicht sicher ausgeschlos*
sen. Durch Trümmer und Wrackteile sowie Treibstoffbränden kommt es zu weiteren
Folgeschäden an der Anlage. Diese können dazu führen, dass sich ein durch die
verbleibenden Sicherheitssysteme nicht mehr beherrschbarer Unfallablauf ergibt. In
der Folge kann es zu einer Kernschmelze kommen. Aufgrund der Zerstörung des Reaktorgebäudes und des Sicherheitsbehälters bereits durch den Flugzeugein*
schlag kommt es dann zu einer frühzeitigen Freisetzung großer Mengen Radioakti*
vität in die Umgebung der Anlage.

Older NPPs which are not designed to withstand plane crashes (http://en.wikipedia.org/wiki/Biblis_Nuclear_Power_Plant" for example) may suffer large reactor building and containment damages, debris and burning fuel may further damage emergency systems. The exact phrasing of the german version is "it can't be safely ruled out". The widespread damages to building and containment may then give birth to widespread contamination.

 

[daveb]

Addendum: Arg, I should've known better, I shouldn't trust anything the german mass media write about technical issues.

They read about an accident probability and then kept rumbling about the nightmare scenario. And me idiot assumed the same without checking the facts. I'm very sorry.

So, a quick summary of the studies conclusion:



Newer NPP designs which are designed to withstand a 20t 800 km/h fast F-4 have a very high protection even against large and fast flying civil airplanes. Penetration is ruled out (in the main part, it's not mentioned here) but there are uncertainties regarding shock induced damages inside the reactor.



Older NPPs which are not designed to withstand plane crashes (http://en.wikipedia.org/wiki/Biblis_Nuclear_Power_Plant" for example) may suffer large reactor building and containment damages, debris and burning fuel may further damage emergency systems. The exact phrasing of the german version is "it can't be safely ruled out". The widespread damages to building and containment may then give birth to widespread contamination.

Danke! (The only German word I know, which is shameful since I'm of mostly German descent)

 

[clancy688]

Danke! (The only German word I know, which is shameful since I'm of mostly German descent)

Mark Twain once said: "My philological studies have satisfied me that a gifted person ought to learn English (barring spelling and pronouncing) in thirty hours, French in thirty days, and German in thirty years. It seems manifest, then, that the latter tongue ought to be trimmed down and repaired. If it is to remain as it is, it ought to be gently and reverently set aside among the dead languages, for only the dead have time to learn it." ;)

 

[mheslep]

I'm mentioning the jet fuel again -- an airliner has a larger capacity for fuel.

No one really knows what would happen if a large airline passenger plane hit a reactor building. In the U.S. the NRC and IAEA have said that U.S. reactors were not designed to withstand the impact of a large airline passenger plane loaded with jet fuel because when the reactors were built there was no anticipation of such an event(before 9/11).

No, apparently you don't know what would happen. The matter has been studied in depth by others.

According to former NRC Chairman Nils Diaz, NRC studies, which have not been released, “confirm that the likelihood of both damaging the reactor core and releasing radioactivity that could affect public health and safety is low.”

http://www.fas.org/sgp/crs/homesec/RL34331.pdf

 

[clancy688]

According to former NRC Chairman Nils Diaz, NRC studies, which have not been released, “confirm that the likelihood of both damaging the reactor core and releasing radioactivity that could affect public health and safety is low.”

Very interesting. That's the same information as in the german study regarding plane crashes. The germans called it "can't be safely ruled out" and the americans called it "likelihood is low". It's exactly the same thing. Fascinating what you can do with words...

Personally I think the "likelihood is low" thinking is exactly what brought us to TMI and Fukushima.

 

[daveb]

Fukushima, yes, they may have underestimated certain events in the PRA. (I haven't seen it and probably could only understand portions of it if I did anyway). On the other hand, even if the liklihood of an event of this nature is accurately assessed at below 10^-6, the fact that it happened now, albeit very unlikely, doesn't necessarily negate the process of PRA. It's similar to a person calling heads 5 times in a row for 5 coin tosses, getting five heads, and stating with 100% certainty that there are either 2 heads, or the coin is unfair. It was highly unikely, but it could still have happened.

As for TMI, most of the fault with that was due to operators not believing their instruments.

 

[clancy688]

Hm...

There is one thing I'd like to know. It seems that most US citizens are in favor of nuclear power. But then why is the newest plant in the US from ~1980?

Why did you decide to stop building NPPs...? And why didn't you start again in the nineties and the 21st century when more and more energy was needed?

Don't misunderstand me, please. I'm just curious.

 

[NUCENG]

Very interesting. That's the same information as in the german study regarding plane crashes. The germans called it "can't be safely ruled out" and the americans called it "likelihood is low". It's exactly the same thing. Fascinating what you can do with words...

Personally I think the "likelihood is low" thinking is exactly what brought us to TMI and Fukushima.

Remember, the important thing is that even though the probability was low, the NRC has regulated significant increases in plant security that has resulted in millions of dollars of added costs and modifications at every plant. We didn't use a low risk to justify ignoring the problem. Would utilities have done that voluntarily? Probably not, but that is why an independent regulatory body could have made a significant difference in Japan. I posted Japan's response to questions from the Convention on Nuclear Safety. TMI emphasized that lesson 32 years ago. Hopefully Japan will learn that lesson now.

 

[NUCENG]

Hm...

There is one thing I'd like to know. It seems that most US citizens are in favor of nuclear power. But then why is the newest plant in the US from ~1980?

Why did you decide to stop building NPPs...? And why didn't you start again in the nineties and the 21st century when more and more energy was needed?

Don't misunderstand me, please. I'm just curious.

Political reality is that immediately after TMI, there was little or no support for nuclear power in the US. Planned plants were cancelled, some in the middle of construction. But rather tha throwing the baby out with the bathwater and shutting down the remaining nuclear plants it was decided to operate them as safely as possible to end on life.

NUREG-0737 was kind of a summary of all the post-TMI requirements. There are too many to even list here, but that might make another useful thread.

Funny thing about us Americans, we tend to reward performance. All those investments, modifications, increased training, and analysis made the remaining plants more reliable. Nuclear generation grew even though no new plants were built. Political reality changed. Go to www.nrc.gov[/URL] and check out the applications for combined construction/operation licenses. Also look at descriptions of the new plant designs in terms of passive (Power-independent) safety design. Will the Fukushima accident put a dent in that? It already has.

Will the US follow Germany in phasing out nuclear? Maybe, when we have designed a distribution system that can service a country as large as the US, supporting wind or solar energy and still remaining stable. Maybe, when something better comes along. But probably not this week.

 

[NUCENG]

Fukushima, yes, they may have underestimated certain events in the PRA. (I haven't seen it and probably could only understand portions of it if I did anyway). On the other hand, even if the liklihood of an event of this nature is accurately assessed at below 10^-6, the fact that it happened now, albeit very unlikely, doesn't necessarily negate the process of PRA. It's similar to a person calling heads 5 times in a row for 5 coin tosses, getting five heads, and stating with 100% certainty that there are either 2 heads, or the coin is unfair. It was highly unikely, but it could still have happened.

As for TMI, most of the fault with that was due to operators not believing their instruments.

Fukushima risk for tsunami was evaluated using a method developed by the Japan Society of Civil Engineers, but only considered historical events since the late 19th century. From information I have seen on this forum. NISA had "suggested" plants revaluate seismic risk a couple of years ago. TEPCO was in the process of re-analyzing the plant to withstand a ground acceleration of 600 gal for an offshore earthquake but hadn't completed it. TEPCO had reportedly ignored appeals to reexamine tsunami risk during that process but those appeals were denied. IAEA safety standards guidance for reevaluating seismic and tsunami risks is also fairly recent. TEPCO may have completed an IPE PRA analysis (determines probability of core damage events for design basis events and equipment failures), but may not heve even started a IPEEE analysis for frequency of external events (seismic, flooding, tsunami, typhoon, etc.) In short, my interpretation is that TEPCO had never adequately performed any analysis to justify the magnitude or frequency of tsunami hazards at Fukushima or any of their other plants.


At TMI they believed some instruments that were misleading them while disbelieving other instruments that were accurate. Their training had not covered the exact scenario, even though another plant had had the same event (stuck-open PORV) shortly before the accident. Specifically they focused in on the rising pressurizer level indication that told them there was a danger of the pressurized going solid making pressure control problematic. The pressuriozer level was rising because the plant was being depressurized and they ignored indications that there was an ongoing loss of coolant accident that led to boiling in the core.
Many of the vulnerabilities that led to TMI no longer exist. Others still depend on reducing potential for human error and continuously reassessing design bases.

 

[clancy688]

NUREG-0737 was kind of a summary of all the post-TMI requirements. There are too many to even list here, but that might make another useful thread.

So in 1979 the US suddenly burned its hands with nuclear power and shuddered back? And when they recovered from that shock, safety requirements had made new reactors to expensive?

Or is there a change now, and new reactors are suddenly economical despite those expensive safety requirements? The NRC website you referred to lists over two dozen new reactors.
But as far as I know, no new reactor is being built right now.

 

[Danuta]

No, apparently you don't know what would happen. The matter has been studied in depth by others.http://www.fas.org/sgp/crs/homesec/RL34331.pdf

Obviously *I* don't know what would happen. How could I? The whole point being if we can trust what has been studied "in depth" by these others. And this "in depth" study of theirs, is it like the "in depth" study of earthquake and tsunami risk assessment done at Fukushima? Meh.

 

[NUCENG]

So in 1979 the US suddenly burned its hands with nuclear power and shuddered back? And when they recovered from that shock, safety requirements had made new reactors to expensive?

Or is there a change now, and new reactors are suddenly economical despite those expensive safety requirements? The NRC website you referred to lists over two dozen new reactors.
But as far as I know, no new reactor is being built right now.

Apparently there are over two dozen reasons to think they aren't too expensive, but we'll see.

 

[clancy688]

Apparently there are over two dozen reasons to think they aren't too expensive, but we'll see.

Well, I just wanted an explanation for over 30 years without building a new NPP. I can't believe that TMI alone was responsible for that... maybe for the first 10 years, but what's with the period after that?

Maybe they are not expensive anymore, so there are over two dozen new plants being planned. Maybe it's something else. I just want to know the reason. Don't worry, I won't give you any anti-nuclear opinions etc. I just want to know the reason for that gap.