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Topic Title: Japan Earthquake
Topic Summary: Nuclear Power Criticality Analysis and Maximum Credibility Analysis
Created On: 13 March 2011 07:25 PM
Status: Read Only
Related E&T article: Fukushima - the facts
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 13 March 2011 07:25 PM
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dvaidr

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So, we have the possibility of three reactors going up. Hardly surprising, really given the full force of the tsunami.

But, the risk of a major earthquake was always there. I just wonder how much longer we are going to ignore maximum credible accident analysis and criticality analysis. Moreover, was any maximum credible accident analysis ever carried out?

I don't suppose for minute that we'll learn anything from this, which is perhaps the most disappointing aspect of it.

Rather than spend billions of nuclear power, (for which we evidently can't mitigate risk), why don't we use the billions to develop other alternatives? Or is this too simple a thought?
 13 March 2011 07:51 PM
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poo

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We are told we must have new nuclear in order to keep the lights on. Tell that to the Japanese.
 14 March 2011 08:11 AM
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dvaidr

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The sad part about it all, is that if a dummy in the Houses of Parliament regards 'nuclear' as being the sexy source of energy, then regardless of what has gone before or whatever the experts say, it will be built.

Gross Prescott comes to mind with his building plan of several billion houses in the South East. He was told that the majority of the land would flood significantly. He wasn't convinced. And all this from the man who ate all the pies and candy floss at the church fete he was opening.

Sly Fox with his wind farms - he forgot it that it takes wind for the principle to work.

Even more desperate than this though are the British people, that allow all this to go without as much as a squeak.
 15 March 2011 09:13 AM
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rogerbryant

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I find it very concerning the way that the anti nuclear activists have taken over the catastrophe in Japan for their own political agenda.

If you glance at the news reports most of what you see is the problems at the nuclear power plants. The tragic deaths of thousands, or maybe tens of thousands, of people and the loss of almost everything for hundreds of thousands doesn't really seem to feature. The destruction of most of the local infrastructure is hardly mentioned (almost all of the thermal power stations in the area and several substations were also shutdown by the earthquake and tsunami).

The presenters seem to be trying to mention Chernobyl and meltdown as many times as possible, they find as many doomsayer 'experts' as they can. There is very little information from people who actually have knowledge of the reactors involved and the various layers of protection that exist. Thousands of real deaths seem to be overshadowed by 22 people receiving an unspecified dose of radiation.

Is this real reporting or is it blatant political manipulation?

Best regards

Roger
 15 March 2011 12:34 PM
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dvaidr

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I quite agree, Roger. News coverage, including BBC News are just electronic tabolids. If they get any opportunity to scare the public, destroy reputations or exaggerate, inordinately, they'll do it. Channel 4 news is marginally better and they hate politicans, so I tend to wathc this only.

On the flipside, we have senior Japanese people telling the world that it's merely a sniff of a leak, when those of us, with a bit of engineering knowledge are cringing. They must have been able to see that this was a catastrophic event.

I remeber 7/7 when a newsflash came on to the car radio reporting a loud blast at an underground station.........."Engineers have stated that it is probably an aged fuse failing". WHAT?! How stupid do these people think we are?
 15 March 2011 02:54 PM
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rogerbryant

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What are you cringing for?

The worst affected reactors appear to be of a 40 year old design which already incorporated multiple levels of redundancy to cope with varying degrees of accidents. Several levels of protection still remain before significant amounts of radioactive materials could be dispersed and the reactors are still inside their design based accident conditions even after a very severe natural catastrophe.
Newer designs of reactors have even more robust systems (natural convection cooling and much greater volume of water in the reactor vessel) and would probably survived this event without core damage.

Best regards

Roger
 15 March 2011 04:43 PM
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dvaidr

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Perhaps I'm overly sensitive.

I do think that building five reactors 150 miles from the main fault line, which has continuous background activity, is a no-brainer as they say......I would have thought.
 15 March 2011 09:55 PM
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poo

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The nuclear industry in Japan have a history of being economical with the truth. This is why the Japanese public are confused and frightened about the situation they are in now. No insurance company will touch Nuclear Power. The risk is too high for them.
The only people that can do it are governments. (taxpayers)
 16 March 2011 08:49 AM
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rogerbryant

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The reactor systems were designed to withstand a certain magnitude of earthquake ( it appears in fact to be a little more advanced in that the maximum accelerations that will be transmitted to the structure are considered) which they withstood, apparently without significant damage.

What caused the problem in this case was the subsequent tsunami which destroyed a lot of the local infrastructure, including the back up generators.

In the adjacent, but apparently more recent facility, the back up generators remained functional and the reactors are being cooled normally to allow inspection and restart (when there is something to connect to).

The open question remains as to what is the maximum incident level the system should be designed to withstand and remain operational, and at what point do you leave the passive 'last resort' measure to take over. The engineers and management will always try to minimise damage to aid the subsequent clean up. It should be noted that this reactor complex was due to be decommisioned in the near future.

Another point to consider is what sort of natural incident should 'renewables' be designed to withstand. If this generator complex had already been replaced by 10 000 (?) offshore wind turbines what would be left? Probably a large tangled mess of metal that would be difficult (impossible?) to navigate through and would have to be slowly cleaned up from the edges and would take 10's of years to replace. Who would be paying for the clean up? What environmental impact would it have?

Best regards

Roger
 16 March 2011 06:36 PM
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poo

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Call me old fashioned if you like but I would rather have a large tangled mass of metal than several reactors damaged/burning and venting radioactivity into the atmosphere. The clean up (decommissioning) of our old Nuclear Power Stations will be paid for by us (taxpayers). The last figure I heard was about £70 billion. No one really knows.
 16 March 2011 07:52 PM
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dvaidr

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But, tonight we hearing reports that "Engineers are racing to avert a catastrophe", the nuclear watchdog is very concerned and that the reporting of the accident by Japanese authorities has been heavily criticised.

I don't really know what you're trying to say, Roger. Regardless of what caused the catastrophe, then fact remains that these built 150 miles from a major fault line with almost continuous background activity. It should have been establish in the max credible accident analysis that should there be significant tectonic activity, the likelihood of significant tsunami would be very high.

<<The engineers and management will always try to minimise damage to aid the subsequent clean up>> More like the management will see the life cycle cost, slash it by 30-40% and hope for the best. The Engineers will say, "Uh, right. OK"
 17 March 2011 11:46 AM
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rogerbryant

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As I said in my first post the reporting, as ever, has been taken over by sensationalism and anti nuclear hype. The reactors in Japan have been damaged, and are requiring some care to reduce further damage, but are a long way from releasing most of their radioactivity. There have been some localised very high radiation levels that have caused problems for the workers, but the offsite radiation levels and the spread of radioactive material off site is very low. Figures are hard to find, but it is likely that more natural radioactive material has been released by the earthquake itself (Radon etc) than has so far been released from the nuclear power plants.

As far as I can find looking at the GE designs for these reactors they are designed for a 'worst case' accident of complete melting of the core and pressure vessel with the molten remains ending up in a large concrete bowl at the base of the concrete shielding. Cleaning this up is obviously more difficult and costly than if the pressure vessel and most of the core remains intact, hence the effort put into keeping up the cooling rather than leaving it to melt.

If you don't want to site a suitably designed nuclear power plant near a fault line what about all the other hazardous things? There is an oil refinery also on the coast that has been burning out of control for six days spewing out vast amounts of known carcinogens. Is this headlined in the media? How big is the evacuation zone? Are other countries shutting down their oil refineries as a precaution? There are a lot of semiconductor manufactures in the area that use a lot of very nasty chemicals. Have these been released? What precautions have been taken? Should we move everyone out of Japan and California as a precaution?

Poo,

You imply that you would rather replace nuclear power with wind or similar. Have you actually looked at the surface areas required and the amount of wind turbines, PV systems, etc required? I would recommend that you read 'Sustainable Energy - without the hot air' by David JC MacKay. It's available as a PDF online. Who actually pays for this? Us via taxes and FITs.

You also comment on the uncertainty of the cost of the decommissioning of nuclear power plants. A significant part of the cost depends on the levels of radioactivity that are accepted. These have been driven down to unjustifiable levels by anti nuclear hype based on the LNT (linear no threshold) theory, which is just that, a theory. The current regulatory levels mean that the granite worktop in your kitchen would be classed as radioactive material if it was installed in a nuclear facility. Is that sensible?
£70billion sounds a lot when it is used as a headline number. How does it compare to the decommissioning of other power generation facilities on a £ per GW year of generation basis?

There is far too much, hype, emotion and rhetoric surrounding radiation and nuclear power. Real information is available if people are prepared to look and not just believe the headlines.

The E&T news I received yesterday gives a good overview of the true level of problems facing Japan of which the nuclear power plants is a very small part.

http://eandt.theiet.org/news/2...mar/japan-rebuild.cfm

Best regards

Roger
 17 March 2011 12:27 PM
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dvaidr

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Originally posted by: g3xoi

Having an excellend demonstration of the power of the sea, IF we wanted to rely on "Alternative Technology", then not the fickle wind but the more regular, and powerful, tide.



As for geological problems, where, on Sicily, could you build anthing over 150 miles from a volcano!


There's a hell of difference between a volcano and a significant seismic shift, in terms of parametric analysis and 'real life'. You usually have a bit if a warning with volcanoes and the destruction is limited to the local area. This is radiation! Soemwhat different.

If one carried out MCA analysis on the same island for say a volcano and an eathquake and used empirical data, I guess the earthquake would 'come out tops', by a signiifcant margin!
I've said before now and I'll say it again. We're just not ready for nuclear sources..
 18 March 2011 10:22 AM
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rogerbryant

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'This is radiation! Soemwhat different.'

'Nuclear energy is invisible. People don't understand. It's potentially long lasting and invariable lethal to those who are significantly affected by it.'

You appear to follow the view that radiation is something that is different from every other sort of hazard, yet in another thread you say that you had trained as a Radiation Protection Supervisor and so should have a reasonable understanding of dose, dose rates, natural background radiation and half lives.

Radiation at any significant dose rate is very easy to detect and measure, much easier than most toxic or carcinogenic chemicals. It is probably too easy to detect at trivial levels. We read 'the back ground radiation level has doubled'. Given that the background radiation level is trivial, doubling it is still trivial.

It is generally agreed that 10 Sv delivered over a short time is lethal and 1 Sv produces a measurable short term change in blood count. At doses below these the science is not so clear. Current regulations are based on the Linear No Threshold theory, which implies that all levels of radiation pose a risk. For high dose levels, around 1 Sv, the increase in the risk of cancer is around 5%. If the LNT theory is correct this means that at the regulatory dose limit for the general public of 1 mSv per year the increased risk of cancer is 0.005% per year. However as the natural background radiation (cosmic rays, radon, gamma rays from granite, etc) varies between 2 and 5 mSv per year (some areas are considerably higher) it is not possible to determine if this is valid or not. There is other evidence that suggests that the LNT theory is not valid and even that low levels of radiation are beneficial.

One interesting example is a group of apartment blocks in Taiwan that were built using reinforcing bars contaminated with Cobalt 60. They were built around 1983 and the high radiation levels were first detected in some buildings in 1992. There were several hundred apartments built with these rebars and several thousand people received long term radiation exposure in excess of 5 mSv year with around a thousand receiving more than 15 mSv year.
When this group of people were studied 20 years later in 2003 there was a less than expected incidence of cancers relative to the comparable general population. This was reported in the 'Journal of American Physicians and Surgeons' Volume 9 Number 1 Spring 2004.

http://www.jpands.org/vol9no1/chen.pdf

There has been other animal research that suggests that low to moderate (less than 1 sV per year) doses of radiation protect against cancer and that radiation is an essential 'trace element'.

As I always say, don't just believe the hype and rhetoric, look into the source documents, trace a few references, look into the affiliations of the authors. Why is radiation any more dangerous than many other of the chemicals we are subjected to? Radioactivity decays away to nothing arsenic is forever.

Best regards

Roger
 18 March 2011 11:57 AM
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rogerbryant

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The post by dvaidr I took my second quote from seems to have disapeared?

Best regards

Roger
 18 March 2011 01:46 PM
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dvaidr

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Roger,

I don't know where my post has gone. I don't remember deleting it!

You are right, I was an RPS in times gone by. What I'm saying is that the media and general Joe Blog public is far more wary, (terrified?), of radiation than other invisible hazards such as electricity - they know not to get too close to it as it can kill.

Taking into account that authorities lie, (a good deal of the time), information provided by the Japanese should be challenged. Surely? As an armchair ex-RPS I took a grim view rather than saying, all will be well and there's nothing to cringe about. Good policy under the circumstances.

Taking into account that the Japanese didn't really have any really effective plan of mitigation, (it has included from choppers dropping lots water onto the affected area to importing sea water.....and I'm sure other 'controlled actions' too), it's hardly surprising that most of the world's population in their armchairs took a grim of the situation. Now, if you think that is a satisfactory response in terms of mitigating damage, then that's a problem you need to address.

Moreover, considering that even the IAEA took a grim view of the situation too, says something.............and it doesn't really matter whether it was a knee jerk reaction or an analysis of what appeared to be an abysmal response by management.

I can assure everyone reading these forums that I had no reason to withdraw my last post. That remains a mystery.
 18 March 2011 03:10 PM
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rogerbryant

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I think there was a thread on here a while ago about missing posts. I'll try and search it out.

I agree entirely that the situation in Japan is grim, but I disagree with the focus that is being put on the nuclear/radioactivity side of the problem. The Japanese did not have an effective mitigation plan for total power loss to the facility, but I doubt if they had effective plans for many other grim situations. There is an oil refinery that is still burning, there are all sorts of chemical plants in the disaster area. Is one of these the next Bhopal?

As you say Joe public is terrified by the media portrayal of radiation (sensationalism sells newspapers). I try to educate as many as possible that high levels of radiation are lethal, but for lower levels we are not certain. There is sufficient evidence to suggest that lower levels are neutral or may be beneficial. If these these lower levels of radiation were as hazardous as some people would like us to believe we would expect to see significant cancer clusters in areas of high natural radiation such as Cornwall which has around 8 mSv per year in contrast to around 2 mSv per year in London. 4 times the dose four times as many cancers!

I also think that criticism of the Japanese response to this disaster should wait until we have a rather better picture. A lot of areas have no infrastructure or comunication left. You can find little snippets of information such as the use of bulldozers to clear a path to bring in the offsite power cable to the damaged facillity suggesting the level of difficulty they are working under.

I don't underestimate the nature of the disaster but I take some comfort that the the reactor containment has survived so far as it was designed to (Chernobyl had no containment), there are very high levels of radiation around two of the reactors (probably due to the loss of the shielding effect of the water) but very little spread of radioactive material and that newer reactors are designed to withstand this level of event.

Best regards

Roger
 18 March 2011 04:01 PM
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dvaidr

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Japan has raised the alert level at its quake-damaged nuclear plant from four to five on a seven-point international scale of atomic incidents.

The crisis at the Fukushima Daiichi site, previously rated as a local problem, is now regarded as having "wider consequences".

BBC World Service at 2:40 this afternoon...............


http://www.survivalblog.com/20...lear_incidents_in.html
http://www.iaea.org/
http://allthingsnuclear.org/

Edited: 18 March 2011 at 04:40 PM by dvaidr
 18 March 2011 08:37 PM
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poo

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This site http://www.noneedfornuclear.or...rticle&id=56&Itemid=69 is worth a look.
Do we really need to split the atom to heat my bath water? Is there a less dangerous way of me keeping clean? Do we want to load the responsibility of managing the high level radioactive waste onto our grandchildren and beyond?
We don't have the right to do that.
50 years on and we still don't know what to do with the waste. It is a failed technology that eats public money.
The nuclear industry has abandoned the lie that nuclear power is cheap and now we are told it is "green". How can it be green when it leaves such a toxic mess behind for future generations to sort out?
 19 March 2011 08:12 AM
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dvaidr

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Poo, You're just a sensationalist! Roger informs us that radioactivity decays. Arsenic is forever. Therefore we should get rid of all these nasty chemicals and stick with radiation!
IET » Energy » Japan Earthquake

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