Japan Fukushima nuclear thread

[Globs]

grumbledoak said:

Or should we be scared just in case?

grumbledoak said:

Pompous tt.

Ok.

[hairykrishna]

Globs said:

Watch the video, listen to the counter, read my post, note my opinion.

You can be scared if you like BTW, I'm not sure why you'd think of being scared though. Are you easily scared? Does talking about something on the other side of the planet usually scare you?

It doesn't sound at all scary to me, but I have operated a rate meter before. He appears to have the scale on microsieverts and the alarm configured extremely low. It's hard to tell from the stty quality video though.

What's scary about it in particular?

Edit - Sorry. I didn't see that you hadn't used the phrase 'scary'. What about that video leads you to suspect significant contamination of the area?

Edited by hairykrishna on Tuesday 12th April 20:21

[llewop]

MOTORVATOR said:

The general level for the area is still elevated at 1.94μSv/h.

http://www.meti.go.jp/english/earthquake/nuclear/p...

LLewop would be best placed to determine whether the rate of fall off is significant or not.

The emergency recording equipment still records as under survey for some reason.

http://www.bousai.ne.jp/eng/

So anyones guess what levels they get locally.

Reuters report that remote controlled dozers are removing soil around the grounds of the plant to reduce levels. Don't know what they do with the soil mind.

I'm not sure I can add much to the decay heat thing - just been looking for some figures and can't really say what it would be by now. But even if it were only, say 1% of full power - for unit 1 that could still be something like - 4-5 MW, so far from insignificant. But that is only a semi-informed guess on the current power/cooling need, could be a mile off!

The radioactive half-life of one of the main isotopes of interest - Iodine-131 - is so short (8 days) that even now, the amount there will be reducing significantly ~ 4 half lives means 2x2x2x2 times less: factor of 16 reduction in activity since the time of the earthquake: only 6% of what was there originally. But that is only part of the story, the cocktail released won't just be I-131, Cs-137 and Cs-134 have been reported so they'll be there, there will be others to varying extents, but to be honest you tend to focus down onto just a few when it comes to dose: the ones that contribe the most. Cs-137 is generally the main one for external dose: and we're not even 1 half live down at Chernobyl (30 year)

The video is intersting for the earthquake and tsunami damage in the area around the plant - puts into context some of the difficulties they've had - just trying to get hardware on the scene must be a nightmare! I wouldn't (personally) put too much store on a noisy 'geiger' counter; you can get some amazingly noisy ones when not much is going on.... Having said that, he quoted 120 microSieverts per hour, which is not something you'd want to hang around in!

ETA: HK reminded me of something I was going to mention: those instruments would not be giving much of a clue of what level there was in the air or for that matter on the ground - in terms of what would pass into food chain - you need lab analysis for that on the whole.

Edited by llewop on Tuesday 12th April 20:40

[Globs]

hairykrishna said:

What about that video leads you to suspect significant contamination of the area?

It was mainly the geiger clicking - it almost reached a tone at one point, it was quite a bit of activity from something on a dashboard.

However I could not tell if that was from a big particle or two that came in from the vent and landed on the sensor or from background - I could only think gamma could get through the windscreen and car, unless beta/alpha was flying in through the open windows. I guess beta may get through glass (can it?) so maybe particles were building up on the windscreen.

Regardless of the reason for the high count you could drive the length and breadth of England and stop for a picnic at Windscale and still register about one count a minute so it's evidence of quite a serious amount of contamination in my view, even if the exact nature and spread is obscured.

[hairykrishna]

Globs said:

It was mainly the geiger clicking - it almost reached a tone at one point, it was quite a bit of activity from something on a dashboard.

However I could not tell if that was from a big particle or two that came in from the vent and landed on the sensor or from background - I could only think gamma could get through the windscreen and car, unless beta/alpha was flying in through the open windows. I guess beta may get through glass (can it?) so maybe particles were building up on the windscreen.

Regardless of the reason for the high count you could drive the length and breadth of England and stop for a picnic at Windscale and still register about one count a minute so it's evidence of quite a serious amount of contamination in my view, even if the exact nature and spread is obscured.

That detector will only be detecting gamma. Beta and particularly alpha meters are more specialised; wandering/driving around with such a meter would be bugger all use. 10's to 100's of counts per minute is actually what you'd tend to register as background depending on where you are and the size of the tube in the meter. As I said the clicking in that video doesn't seem that alarming - it's probably not that much above background. You can get meters that sound like the end of the world when they're only picking up natural radiation from a persons body. We used to have one lying around we'd use to scare school kids on UCAS visits.

There may well be significant land contamination but I don't think that video demonstrates it.

[grumbledoak]

Globs said:

Regardless of the reason for the high count you could drive the length and breadth of England and stop for a picnic at Windscale and still register about one count a minute

This is utter rubbish.

[llewop]

Globs said:

It was mainly the geiger clicking - it almost reached a tone at one point, it was quite a bit of activity from something on a dashboard.

However I could not tell if that was from a big particle or two that came in from the vent and landed on the sensor or from background - I could only think gamma could get through the windscreen and car, unless beta/alpha was flying in through the open windows. I guess beta may get through glass (can it?) so maybe particles were building up on the windscreen.

Regardless of the reason for the high count you could drive the length and breadth of England and stop for a picnic at Windscale and still register about one count a minute so it's evidence of quite a serious amount of contamination in my view, even if the exact nature and spread is obscured.

some beta's could maybe get through the glass, but probably what was being detected was gamma - I didn't recognise the instrument to comment further on that.

but: you can set an alarm on an instrument almost anywhere you like, to alarm at background levels for instance. Also - I've used instruments that indicate 1000 counts per second for 1 microSievert per hour, that gets pretty noisy! Then on the other hand even getting a single click or two from an alpha probe is more of a concern.

[Globs]

llewop said:

some beta's could maybe get through the glass, but probably what was being detected was gamma - I didn't recognise the instrument to comment further on that.

but: you can set an alarm on an instrument almost anywhere you like, to alarm at background levels for instance. Also - I've used instruments that indicate 1000 counts per second for 1 microSievert per hour, that gets pretty noisy! Then on the other hand even getting a single click or two from an alpha probe is more of a concern.

Cheers for that (and your info Hairy). About 2:45 you can start to hear the clicks coming thick and fast - I was ignoring the alarm as I did not know the threshold.

Interesting to know it was gamma - Caesium 137 or others do you think?

[hairykrishna]

This appears to be the full video;

http://www.youtube.com/watch?v=yp9iJ3pPuL8

I haven't watched it yet as youtube's a little flaky here.

[llewop]

Globs said:

Cheers for that (and your info Hairy). About 2:45 you can start to hear the clicks coming thick and fast - I was ignoring the alarm as I did not know the threshold.

Interesting to know it was gamma - Caesium 137 or others do you think?

most likely Cs-137 - there will be others for sure, but at Chernobyl for instance, if we put a gamma spectrometer on it: near enough all Cs-137, maybe shielding or skewed a bit, but still caesium.

One thing he mentioned I think in the video was the variability in levels - for instance some patches higher further from the plant - not unusual - will depend on the release characteristics, wind directions, strength etc during the releases also what the weather was doing at the time - more rain = more deposition.

[grumbledoak]

hairykrishna said:

This appears to be the full video;

http://www.youtube.com/watch?v=yp9iJ3pPuL8

Top comment gives a sense of proportion.

[MOTORVATOR]

grumbledoak said:

Top comment gives a sense of proportion.

So there's no need for the evacuation zone at all?

[grumbledoak]

MOTORVATOR said:

So there's no need for the evacuation zone at all?

Berk.

[MOTORVATOR]

grumbledoak said:

MOTORVATOR said:

So there's no need for the evacuation zone at all?

Berk.

No it was a serious question, I wasn't taking the piss but it seems if we believe every statement about there being no effect on human life then you have to question why the Japs have displaced some 70,000 of their citizens and told another 136,000 not to go outside their homes. You'd think they'd have other more pressing worries on their mind.

[grumbledoak]

MOTORVATOR said:

No it was a serious question, I wasn't taking the piss but it seems if we believe every statement about there being no effect on human life then you have to question why the Japs have displaced some 70,000 of their citizens and told another 136,000 not to go outside their homes. You'd think they'd have other more pressing worries on their mind.

Of course they have moved people away! They don't know what will happen, if they even know the situation that well now. I'd imagine it is still all hands and stay away.

But we need to keep a sense of perspective too. If you want extra fingers/toes/eyes go to Norfolk.

[llewop]

MOTORVATOR said:

No it was a serious question, I wasn't taking the piss but it seems if we believe every statement about there being no effect on human life then you have to question why the Japs have displaced some 70,000 of their citizens and told another 136,000 not to go outside their homes. You'd think they'd have other more pressing worries on their mind.

I don't think that anyone would still be in the category of 'don't go outside' - sheltering is generally a short term countermeasure, you can't ask people to do that for more than a few hours/days and expect it to happen - if it get more long term, then evacuation is logically the option.

The curious trick always with a countermeasure is there are often clear references for putting them in place (if X exceeds Y do Z) but it is not always as clear on how/when to lift them - so the answer to your question is complicated. Factors that come into play are how long you consider as being relevant - a countermeasure is supposed to provide a benefit, in this case, saving dose, but there is a cost, people being displaced, foodstuffs not being able to be consumed etc. What actually matters is: is there still an ongoing release from the plant? I've not tried to get my head round that for a couple of days, so I don't know. If they have established good cooling at all the units and all the fuel is covered again, then the releases may have stopped - that then gives you a baseline of 'what is there is what we have to consider' - if releases continue, then the potential exposure is going to keep increasing. Certainly it would appear that the perception is the response is moving from crisis management to situation management, ie maintaining status quo - but that might just an impression rather than fact - especially if there is still material being released.

[MOTORVATOR]

llewop said:

MOTORVATOR said:

No it was a serious question, I wasn't taking the piss but it seems if we believe every statement about there being no effect on human life then you have to question why the Japs have displaced some 70,000 of their citizens and told another 136,000 not to go outside their homes. You'd think they'd have other more pressing worries on their mind.

I don't think that anyone would still be in the category of 'don't go outside' - sheltering is generally a short term countermeasure, you can't ask people to do that for more than a few hours/days and expect it to happen - if it get more long term, then evacuation is logically the option.

The curious trick always with a countermeasure is there are often clear references for putting them in place (if X exceeds Y do Z) but it is not always as clear on how/when to lift them - so the answer to your question is complicated. Factors that come into play are how long you consider as being relevant - a countermeasure is supposed to provide a benefit, in this case, saving dose, but there is a cost, people being displaced, foodstuffs not being able to be consumed etc. What actually matters is: is there still an ongoing release from the plant? I've not tried to get my head round that for a couple of days, so I don't know. If they have established good cooling at all the units and all the fuel is covered again, then the releases may have stopped - that then gives you a baseline of 'what is there is what we have to consider' - if releases continue, then the potential exposure is going to keep increasing. Certainly it would appear that the perception is the response is moving from crisis management to situation management, ie maintaining status quo - but that might just an impression rather than fact - especially if there is still material being released.

I did come across this interesting site LLewop where a guy has attempted to grapgh all available info. He seems to have got hold of a good source of figures that don't seem to be in the public domain. Albeit I'm wondering if we don't get them all as they aren't all translated.

http://fleep.com/earthquake/

Unfortunatey he has said he won't update past 9/4 as he states it's really the Jap governements to do it.

There's definitely some conflict in reports with the company saying the plant surroundings are back to normal levels whilst governement are extending evac zones.

They've started intervention around the plant grounds with remote controlled dozers and no doubt they will need to have at least some intervention within the evac zone before it is cleared for rehabitation but as you say until they categorically say releases have finished then no point in trying to identify those areas.

Reading the latest statement from TEPCO then it would appear by inferrence they have not got no 1 under control yet and releases are still occurring.

http://news.xinhuanet.com/english2010/world/2011-0...

Also on Friday they identified radiation leaks from Onagawa plant and it is easy to forget that there are still other plants struggling that could add to the problem.

I don't know whether they have finished discharging contaminated water yet but they have identified Caesium contaminated fish just above safety levels now as well and the statement of how big the ocean is going to bite home. Fish swim large distances and sit within an oceanic food chain where it will concentrate up through the chain.

A long way to go yet I imagine.

[rhinochopig]

llewop said:

I'm not sure I can add much to the decay heat thing - just been looking for some figures and can't really say what it would be by now. But even if it were only, say 1% of full power - for unit 1 that could still be something like - 4-5 MW, so far from insignificant. But that is only a semi-informed guess on the current power/cooling need, could be a mile off!

The radioactive half-life of one of the main isotopes of interest - Iodine-131 - is so short (8 days) that even now, the amount there will be reducing significantly ~ 4 half lives means 2x2x2x2 times less: factor of 16 reduction in activity since the time of the earthquake: only 6% of what was there originally. But that is only part of the story, the cocktail released won't just be I-131, Cs-137 and Cs-134 have been reported so they'll be there, there will be others to varying extents, but to be honest you tend to focus down onto just a few when it comes to dose: the ones that contribe the most. Cs-137 is generally the main one for external dose: and we're not even 1 half live down at Chernobyl (30 year)

The video is intersting for the earthquake and tsunami damage in the area around the plant - puts into context some of the difficulties they've had - just trying to get hardware on the scene must be a nightmare! I wouldn't (personally) put too much store on a noisy 'geiger' counter; you can get some amazingly noisy ones when not much is going on.... Having said that, he quoted 120 microSieverts per hour, which is not something you'd want to hang around in!

ETA: HK reminded me of something I was going to mention: those instruments would not be giving much of a clue of what level there was in the air or for that matter on the ground - in terms of what would pass into food chain - you need lab analysis for that on the whole.

Edited by llewop on Tuesday 12th April 20:40

Guessing at thermal power is irrelevant really as it depends on the thermal roll-over point (i.e. the point where decay heat is equal to or lower than the heat removal from convection, radiation, etc. through the RPV and primary systems). Different designs have different roll-over points. It could be producing 400mw but as long as the reactor has rolled over then it's not a problem.

Haven't seen the video, but where they not using PAS then?

[llewop]

MOTORVATOR said:

A long way to go yet I imagine.

for sure

the link you gave is interesting - does look like most areas away from the plant the dose rates are not really that far away from pre-accident levels (thats not to say there isn't contamination on the ground which could result in other countermeasures being relevant). The dose rates on site probably don't tell the whole picture - some of the values (actually many of them) are such that they wouldn't be able to sustain work there, so presumably they are not actually representative of working areas, either that or the figures we've been given so far on worker exposures are not being updated.

The daily deposition figures suggest at least one leak is or was still ongoing, at least until Sunday/Monday, in fact seeming worse on those days than for the preceeding period.

Ploughing in or removal of surface layers makes sense as a simple way to reduce/remove the impact of the deposited layer, if nothing else that will make life easier for the workers on site to stay there and get on with things, without exceeding dose limits (extended ones if necessary) - although it does seem that to some degree they are now getting towards the tipping point between emergency response (when higher doses can be justified) and recovery (when increased dose limits are less likely to be justified/justifiable)

[MOTORVATOR]

llewop said:

MOTORVATOR said:

A long way to go yet I imagine.

for sure

the link you gave is interesting - does look like most areas away from the plant the dose rates are not really that far away from pre-accident levels (thats not to say there isn't contamination on the ground which could result in other countermeasures being relevant). The dose rates on site probably don't tell the whole picture - some of the values (actually many of them) are such that they wouldn't be able to sustain work there, so presumably they are not actually representative of working areas, either that or the figures we've been given so far on worker exposures are not being updated.

The daily deposition figures suggest at least one leak is or was still ongoing, at least until Sunday/Monday, in fact seeming worse on those days than for the preceeding period.

Ploughing in or removal of surface layers makes sense as a simple way to reduce/remove the impact of the deposited layer, if nothing else that will make life easier for the workers on site to stay there and get on with things, without exceeding dose limits (extended ones if necessary) - although it does seem that to some degree they are now getting towards the tipping point between emergency response (when higher doses can be justified) and recovery (when increased dose limits are less likely to be justified/justifiable)

From the Guardian so must be accurate.

"To cope, the plant's operator, Tokyo Electric, has downgraded safety baselines both for the workers and the surrounding environment.

With the approval of the Japanese government, it has increased the permissible radiation exposure level for the Fukushima workers from 50 millisieverts a year to 250. This raises the risk of cancer by about 1.25 percentage points above the population average."

"Yet even working in short shifts at this increased level, the radioactivity is so high in some areas, such as the No 3 reactor, that plant managers say humans may never enter again."

"Plans are now underway to find a long-term solution. Four of the General Electric-made reactors have been condemned, but they need to cool before they can be made safe. This is likely to take months. Engineers from Toshiba, Westinghouse and Babcock & Wilcox have reportedly begun looking at the options to remove the spent fuel and seal the plant."

This bit seems incredulous though.

"Elsewhere, the workers are kitted out in protective suits, masks and breathing apparatus, but there have been accidents. Two workers had to be hospitalised for radiation burns after stepping in highly contaminated water without boots. For more than a week after the accident, most did not have dosimeters for measuring background radiation. The government has provided more and the US has donated devices, but conditions remain tough."

No dosimeters and workers without boots. Tepco really don't look good in this.