Merged nuclear power safe?

[ceptimus]

Indeed. But what would you have done ? Build the diesels higher ? What if the wave had reached them ? Would you still critisize that decision ?

I think that if a reactor design requires back up power for a certain length of time, then there should be a backup battery that can provide that power for the full period. If no such battery is available, then the reactor should not be built.

Diesel generators are not reliable enough - they require a plentiful supply of normal air, and sufficient uncontaminated fuel to keep them going - either of these may be absent - the same hazard that caused the reactor to shut down - fire, floods,... is likely to affect the diesels too.

Newer reactor designs are much less reliant on back-up power to keep them safe, so the question is perhaps moot for new installations anyway.

In the case of war or terrorism, a reactor still poses a great hazard even though it may not require backup power.

I think current fission reactors are just too dirty - when the costs (environmental and fiscal) of decommissioning and managing the waste are considered, I don't think they make sense. We need something cleaner - like fusion (which has always been '20 years away' for the last 50 years or so) or maybe Thorium-based fission, or something else.

If no such cleaner power is available, I think humans should learn to live with less power, and many fewer humans. But I don't believe that will happen voluntarily - I think it's going to take war, famine or some other disaster to cull our population back to something more sustainable.

 

[MarkCorrigan]

You are severly misinformed,

http://en.wikipedia.org/wiki/Fission_products_(by_element)

Fixed link.

 

[BenBurch]

How are the short lived nobel gas isotopes separated from all the other fission products?

They are a gas and do not react chemically, so they escape when not much else will, so they are the predominant gas after core damage during a reactor failure.

¹³⁷Cs is not a gas, and needs to have some event to mechanically aerosolize it. A fire will do that, or spallation due to thermal stress or quenching of molten core elements. The particles will tend to settle out and won't escape from even a breached containment very efficiently. I do not expect this to be significant. It's boiling point is fairly high, so large amounts of vapor are unlikely.

¹³¹I however has a fairly low boiling point, and it is water-soluble, biologically active, and is one of the primary products of Uranium fission. It has a half-life around a week, so if it is emitted, it will tend to degrade fairly quickly. Primary risk is Thyroid cancer. After Chernobyl there were around 4000 cases of Thyroid cancer attributable to that event, and 99% were curable.

 

[marplots]

I need help filling in a part of the picture that has been under-reported. When the catastrophe narrative is told, it usually ends with something like: meltdown... wide spread radiation.

So my question is how does the one lead to the other? What is the mechanism that has a melted pool of radioactive material getting spread out over a large area (rather than somewhere in the footprint of the plant)?

Side note on Al, which I do know something about -- at a high enough temperature and a small enough particle size, Aluminum burns quite well in air. In pyrotechnic formulations, this is commonly relied on for spark production along with other metals that don't burn in traditional contexts, like, for example the iron you see burning in a "sparkler." This is completely different than burning ships however. Ref: http://cameochemicals.noaa.gov/unna/1383

 

[Hindmost]

I think that if a reactor design requires back up power for a certain length of time, then there should be a backup battery that can provide that power for the full period. If no such battery is available, then the reactor should not be built.

Diesel generators are not reliable enough - they require a plentiful supply of normal air, and sufficient uncontaminated fuel to keep them going - either of these may be absent - the same hazard that caused the reactor to shut down - fire, floods,... is likely to affect the diesels too.

Newer reactor designs are much less reliant on back-up power to keep them safe, so the question is perhaps moot for new installations anyway.

In the case of war or terrorism, a reactor still poses a great hazard even though it may not require backup power.

I think current fission reactors are just too dirty - when the costs (environmental and fiscal) of decommissioning and managing the waste are considered, I don't think they make sense. We need something cleaner - like fusion (which has always been '20 years away' for the last 50 years or so) or maybe Thorium-based fission, or something else.

If no such cleaner power is available, I think humans should learn to live with less power, and many fewer humans. But I don't believe that will happen voluntarily - I think it's going to take war, famine or some other disaster to cull our population back to something more sustainable.

You are doing a bit of a post hoc analysis here. Diesels happen to be very realiable...that is why they are used. There are very stringent requirements for maintenance and operation...if they have a problem, the plant has to shut down until they are fixed. Batteries can't run pumps needed to cool the plant as the pumps are typically 4KV or 7KV. Generation III plants can survive for a longer periods of time under severe accidents, however, after about 72 hours, power will be needed to cool the plant and spent fuel pools. Thorium based fission would not have changed what happened here. There still will be the same amount of decay heat in the fuel.

You can postulate just about any hypothetical situation that will cripple a nuke or anything. But then we would never leave home...

glenn

 

[Kestrel]

You are severly misinformed,

http://en.wikipedia.org/wiki/Fission_products_(by_element)

Radioisotopes with short half lives give off a lot of radiation, but only for a short time. Some of the noble gas isotopes produced in reactors have very short half lives. They will be released when steam is vented from a reactor, even if fuel rod integrity has not been compromised. When the venting is stopped, the radioactivity from these isotopes will drop off rapidly. They are not a long term contamination problem.

 

[ceptimus]

You are doing a bit of a post hoc analysis here.

I've not changed my position since the Three Mile Island incident, or Chernobyl or other accidents - the pollution of the Irish Sea and nuclear particles on beaches in northern Scotland from Dounreay, etc. Each time I've been criticised for being 'wise after the event' and I suppose the same will happen after the next "couldn't possibly have been predicted" nuclear accident, when it occurs.

 

[bobdroege7]

Fixed link.

Thanks

 

[Kestrel]

I've not changed my position since the Three Mile Island incident, or Chernobyl or other accidents - the pollution of the Irish Sea and nuclear particles on beaches in northern Scotland from Dounreay, etc. Each time I've been criticised for being 'wise after the event' and I suppose the same will happen after the next "couldn't possibly have been predicted" nuclear accident, when it occurs.

So in the worst case accident, nuclear power kills thousands of innocent humans. But from your earlier post, it seems you are willing to let most of the human population die to avoid that worst case incident.

 

[ceptimus]

No.

I'd like to see the population reduced, but that doesn't mean we have to die early - just that less babies are born than people dying natural deaths.

And I also said we could learn to live with less power. If we use less power then we don't need dirty nuclear reactors to provide that power.

And I also said that I don't believe that will happen - I don't have enough faith in human society to believe that it can do what's in its own best long-term interest.

 

[MattusMaximus]

They have been saying things all along like, "it's only a level four", well it's not, it's now being called a level 6, "It's not Chernobyl", that's not really saying much, "It's been managed well", it's been managed poorly, "it's only a hydrogen explosion, and it's only superficial", it's an explosion at a nuclear plant right on top of the containment vessel, and it's possibly compromised the integrity of one of the vessels, as well as compromised the integrity of the support infrastructure needed to cool the systems when AC power becomes available again. ...

I have been hearing this "it is at a rating of 6 on the INES" line for the last day or so, and every single time I challenge someone to backup this claim with a solid, confirming source, it doesn't happen. In fact, let me share with you what I wrote specifically on my blog about this particular issue (it is specifically referenced under point #1)...

I have seen some references around the Internet, and on the comments to this entry, that the INES rating for Fukushima has been upgraded to a 6 (or even to a 7). A 6 or 7 on the INES? That seems really high in light of the most recent events, the only source I can find for that is the Wikipedia page on the Fukushima plant, which references this German article.

And when I went to that article, the only thing it said in reference to the INES is this...

ATOMIC ACCIDENT (INES SCALE): An international scale, in order to evaluate the weight of nuclear accidents. It is enough from zero (event without or with small meaning in terms of safety) to seven (catastrophic accident). Starting from stage two one speaks of incident, starting from stage four of accident. The explosion of the nuclear reactor in Tschernobyl before scarcely 25 years was so far the only event of the stage seven. The partial core melt-through in the reactor Three Mile Island in the USA 1979 was arranged on stage five. With the misfortune in Japan stage six is to be expected at least after today's conditions, if there is and in its entirety disaster control measures is introduced a substantial release of radioactive material. Of Japan atomic energy authority in the nuclear power plant Fukushima classifies the incident so far however less badly than the incidents in the US nuclear power station Three Mile Island 1979 and in Tschernobyl 1986. The classification of an event takes over the operator of the power station, it however by the national atomic supervision and the international atomic energy authority in Vienna is examined and possibly corrected. (emphasis mine)

And that page doesn't reference anyone for where they got those estimates. So this is yet another example of sloppy reporting, because it basically says "if the absolute worst case scenario happens, it will be a 6 on the INES, but right now it ranks as a 4 according to the nuclear experts on site."

Now, if there is solid evidence to the contrary, I'd like to see it. But claiming, again and again, on this message board that it's now a 6 on the INES, especially when no nuclear authority involved has come out and said so, just seems like hand-waving.

 

[MattusMaximus]

I have been trained in the methods for the detection of discrete highly radioactive particles one would encounter when dealing with suspected fuel element defects.

Radiation levels aren't normal in Tokyo.
And you?

But do you agree now that I have posted evidence that the evacuation is required?

What exactly are the radiation levels in Tokyo? Do you have a number? Saying "they're not normal" doesn't really provide any significant context, you know.

ETA: For example, here is some real context with real numbers (from a post earlier today)...

If you want to get more regular, reliable updates, I suggest using the World Nuclear News website - http://www.world-nuclear-news.org – Here’s more from that site in the latest update…

**************

… peaking at 400 millisieverts per hour (40,000 mrem/hour) on the inland side of unit 3, and 100 millisieverts per hour (10,000 mrem/hour) on the inland side of unit 4. At the highest exposure rate, a nuclear worker or soldier could remain in the area for less than 40 minutes before leaving the site, unable to return. …

… Despite high levels of radiation close to the units, levels detected at the edge of the power plant site have been steadily decreasing.

17 March, 4.00pm à 0.64 millisieverts per hour (64 mrem/hour)

17 March, 9.00am à 1.47 millisieverts per hour (147 mrem/hour)

16 March, 7.00pm à 1.93 millisieverts per hour (193 mrem/hour)

16 March, 12.30pm à 3.39 millisieverts per hour (339 mrem/hour)

****************

It should also be noted that if the radiation levels are that low at the edge of the power plant site, then they are most likely well within acceptable levels by the time you get to the edge of the evacuation zone, 30+ km away. And there’s certainly no danger to people here in the United States.

In addition, a good reference on the levels of radiation exposure (and related health effects) can be found here - http://www.epa.gov/radiation/understand/health_effects.html#anyamount – note that those values are in rems, whereas most of the exposure we’ve been referencing in the handout I gave on Tuesday and in these reports is in milli-rems (mrems). Bottom line: the people who are going to be affected the most are the workers right there on site, and I wouldn’t be surprised if some of them are getting a potentially lethal dose; as for everyone else, I think the danger is pretty minimal.

 

[Hindmost]

I've not changed my position since the Three Mile Island incident, or Chernobyl or other accidents - the pollution of the Irish Sea and nuclear particles on beaches in northern Scotland from Dounreay, etc. Each time I've been criticised for being 'wise after the event' and I suppose the same will happen after the next "couldn't possibly have been predicted" nuclear accident, when it occurs.

Criticizing Chernobyl is legitimate as there were fundamental problems with the design coupled with a failure to follow safety procedures. TMI--no one even got hurt and no one received any radiation exposure that was excessvive...and has provided information to prevent future problems--something for the industry to be proud of.

This plant survived a really big quake even though it was 40 years old...it operated as designed until a tsunami came along...but the people in the plant were certainly safe during that event. One person has died. Based on reports, so far, no one has received a severe overdose of radiation. This event certainly wasn't typical and sometimes there are unforseeable thing do occur on this planet. Compare the results with any industry and nuclear alway comes up looking fairly good. It's just the connotations associated with nuclear seem to scare people. For information: People that work in nuke plants tend to live longer, have less incident of cancer and less on the job accidents.

No one expects the inquisition...which was much worse.

glenn

 

[bobdroege7]

They are a gas and do not react chemically, so they escape when not much else will, so they are the predominant gas after core damage during a reactor failure.

¹³⁷Cs is not a gas, and needs to have some event to mechanically aerosolize it. A fire will do that, or spallation due to thermal stress or quenching of molten core elements. The particles will tend to settle out and won't escape from even a breached containment very efficiently. I do not expect this to be significant. It's boiling point is fairly high, so large amounts of vapor are unlikely.

¹³¹I however has a fairly low boiling point, and it is water-soluble, biologically active, and is one of the primary products of Uranium fission. It has a half-life around a week, so if it is emitted, it will tend to degrade fairly quickly. Primary risk is Thyroid cancer. After Chernobyl there were around 4000 cases of Thyroid cancer attributable to that event, and 99% were curable.

It was a rhetorical question Ben.

There has been some misinformation I have seen from what should be considered reliable sources of information.

This is one

http://mitnse.com/2011/03/13/modified-version-of-original-post/

So basically in a nutshell the nuclear engineering department of MIT is wrong and I am right.
(sarc on) So that puts me in good company on this site (sarc off)

The folks at MIT are saying the hydrogen explosions only released a small amount of radioactivity and I am saying otherwise.

The spent fuel pool fires being another story.

It seemed to me that some posters were arguing that the hydrogen explosions only released a small amount of radioactive noble gases, and I was asking how they separated from the other fission products that would be expected to accompany the Krypton and Xenon.

The TEPCO seem to be on the verge of restoring electrical power to at least one reactor, things will get interesting.

 

[MattusMaximus]

Speaking of updates, here is the latest from the World Nuclear News, including some information on radiation levels and the necessary context...

http://www.world-nuclear-news.org/RS_Progress_by_on-site_workers_1703111.html

... Normally nuclear workers are allowed to receive a dose of 20 millisieverts per year, although in practice they often receive very much less. If that limit is exceeded in any year, the worker cannot undertake nuclear duties for the remainder.

In emergency circumstances safety regulators allow workers to receive up to 100 millisieverts with the same conditions applying, that they must leave the site should that limit be reached. The 100 millisievert level is roughly the point at which health effects from radiation become more likely. Below this it is statistically difficult to connect radiation dose to cancer rates, but above this the relationship starts to become apparent.

Under a special allowance from the Nuclear and Industrial Safety Agency, workers at Fukushima were permitted doses of up to 250 millisieverts. Managers must be careful to make the best use of those experienced workers with the most detailed knowledge and experience of the plant. ...

 

[simper]

No.

I'd like to see the population reduced, but that doesn't mean we have to die early - just that less babies are born than people dying natural deaths.

And I also said we could learn to live with less power. If we use less power then we don't need dirty nuclear reactors to provide that power.

And I also said that I don't believe that will happen - I don't have enough faith in human society to believe that it can do what's in its own best long-term interest.

Human society does not exist in the form you imagine. With the possible exception of the richest of the rich West human beings act in their own short term interests. The population of the world will increase, the power requirements will increase and global warming will get worse. Adopting nuclear power will lessen the effects of global warming.

 

[bobdroege7]

What exactly are the radiation levels in Tokyo? Do you have a number? Saying "they're not normal" doesn't really provide any significant context, you know.

ETA: For example, here is some real context with real numbers (from a post earlier today)...

No source, just heard on CNN I believe that levels in Tokyo were twice normal background.

My point was that levels at the site boundary are 2500 times high enough to require evacuation using a radiation level one half of the lowest one you just posted.

And levels in Tokyo were twice background, so the limit for the required evacuation is reached somewhere between the gates of the facility and Tokyo.

So a required evacuation would put it at a 5.

Study the cite I posted about the legal limits that I posted.

And no, they are not Japanese limits, but they typically are higher limits in the US than Europe, and I don't know what the limits are in Japan, but it is fair to assume they are similar or more restrictive.


Peace and out guys, I am done for a while.

 

[MarkCorrigan]

No source, just heard on CNN I believe that levels in Tokyo were twice normal background.

I may be entirely wrong, but haven't CNN been one of the single worst news sources so far on this?

 

[Christian Klippel]

I have been hearing this "it is at a rating of 6 on the INES" line for the last day or so, and every single time I challenge someone to backup this claim with a solid, confirming source, it doesn't happen. In fact, let me share with you what I wrote specifically on my blog about this particular issue (it is specifically referenced under point #1)...

Now, if there is solid evidence to the contrary, I'd like to see it. But claiming, again and again, on this message board that it's now a 6 on the INES, especially when no nuclear authority involved has come out and said so, just seems like hand-waving.

What's especially noteworthy is that the article on Sueddeutsche does not talk about any INES levels at all, let alone that Fukushima has been elevated to INES 6.

However, several media outlets have reported that according to the French Nuclear Safety Agency (ASN), it should be rated at INES 6 or 7.

Try a Google search for "asn japan ines 6". Since i'm in Germany, i get only results on German pages, due to the sheer flood of reports about that in our media.

So, blame the French not us, for once

Greetings,

Chris

 

[Belz...]

I think that if a reactor design requires back up power for a certain length of time, then there should be a backup battery that can provide that power for the full period. If no such battery is available, then the reactor should not be built.

I thought you said there was those things. You still haven't adressed the main critisim against your stance: that there is no way to be 100% safe.

I think current fission reactors are just too dirty - when the costs (environmental and fiscal) of decommissioning and managing the waste are considered, I don't think they make sense. We need something cleaner - like fusion (which has always been '20 years away' for the last 50 years or so) or maybe Thorium-based fission, or something else.

Imagining non-existent techs is fun, but pointless. Let's work with what we have until, if, they devellop new ones.

If no such cleaner power is available, I think humans should learn to live with less power, and many fewer humans.

Again, let's work with reality, not idealistic dreams.