Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[zapperzero]

Is this the crane? I can't see it on the TEPCO feed. Screenshot taken at 09:45 GMT

 

[zapperzero]

Also, a report by TEPCO on the fact-finding expedition inside reactor #2.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110622_02-e.pdf

EDIT: 430 mSv/h at the bottom of the stairs leading to the first basement level.

 

[SteveElbows]

Also, a report by TEPCO on the fact-finding expedition inside reactor #2.

http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110622_02-e.pdf

EDIT: 430 mSv/h at the bottom of the stairs leading to the first basement level.

The water is a sinister colour.

As for the crane around unit 1, its been doing stuff almost every day at unit 1 for some time now - often appears to be dangling a probe of some kind, though in locations that are not intuitive to me.

 

[tsutsuji]

http://www.meti.go.jp/press/2011/06/20110622004/20110622004.html : The NISA agreed today with the request made by Tepco on 8 June to store more water in the Process main building :

OP5100 mm -> OP5600 mm
1.4 m above 1st basement floor -> 1.9 m
14,200 m³ -> 15,700 m³

http://www.bloomberg.co.jp/apps/news?pid=90920019&sid=a45S9fQOTF3A : this provides 5 more days of storing capacity, beyond the former 29 June expected overflow date.

http://www.yomiuri.co.jp/science/news/20110622-OYT1T00687.htm : the flows in the reactors are set as follows :

unit 1 : 3.5 tons/hour.
unit 2 : 4 tons/hour
unit 3 : 10 tons/hour

 

[SteveElbows]

Yep, water levels are now such an issue that they've been reducing the amount pumped into the reactors in order to buy themselves a bit more time.

 

[tsutsuji]

http://www.asahi.com/national/jiji/JJT201106220097.html : The filtration efficiency of the absorption facility and the coprecipitation facility put together was found to be OK in the tests with highly contaminated water. The efficiency of the absorption facility is lower with highly contaminated water than during the tests with low contaminated water, but that is still high enough.

 

[Atomfritz]

Also, a report by TEPCO on the fact-finding expedition inside reactor #2.

http://www.tepco.co.jp/en/nu/fukushi...10622_02-e.pdf

EDIT: 430 mSv/h at the bottom of the stairs leading to the first basement level.

Thank you for the link.

This weird color of the water looks to me like rust. It's just the same color you get when you have various sorts of scrap metal rusting in aggressive water.
Remember there are many different metals there and this can boost the rusting speed to a nearly explosive pace.
Just think of how fast the Komsomoletsk dissolved due to the titanium-steel rusting catalytics.

The saturation of the water with whatever dissolved in it appears quite high, as it is completely opaque.

Hope they will publish a chemical and radiological analysis of that liquid soon.

And, when I looked at the picture in detail, I noticed that the water level originally has been a few cm higher.
And the water apparently was originally not that intensely saturated with that brown stuff, as you can barely recognize the original flooding mark.

Could an explanation for these observations be that there is an opening at the height of the water level where the water flows off to somewhere else?
Could the observation of a higher original water level be caused by a widening of such an initial opening, maybe because insulation or other debris in the way has been swept away by the water flow?

 

[joewein]

This weird color of the water looks to me like rust.

There should be plenty of rust, given how salty the water is. I saw one report that the salt contents of the liquid in the basements still is 50-80% of that of sea water. Also, the relatively high temperature from the decay heat will accelerate the reaction speed.

Once they pump out salty radioactive water, treat it and pump it back as almost clean water, this will lower the salt contents, but will probably take a very long time to bring the NaCl concentration down to levels comparable to fresh water, as it will just dilute and dilute it.

Anything already touched by salt water will keep a slight salt crust when the liquid level drops. Anything already rusty will continue to draw moisture from the air (rust seeks moisture), which will keep the rust growing. I can't help wondering what the basements will look like in say 5 years from now. Will there be any metal staircases left?

The salt water contamination and resulting corrosion also has implications for units 5 and 6, which TEPCO has not officially written off as not restartable yet, and for Fukushima Daini which TEPCO would also like to bring online again ASAP.

And, when I looked at the picture in detail, I noticed that the water level originally has been a few cm higher.

Perhaps some water was pumped from the turbine hall basement, since the reactor building basement and turbine hall basements are connected.


The 430 mSv/h at the bottom of the stairs was pretty interesting. TEPCO is talking about drilling holes through the floor to near the torus, to fill the space around it with a cement/sand mix. A bit like drilling a hole down into hell...

 

[robinson]

The water is a sinister colour.

Doesn't that give a pretty good idea of where the reactor and the fuel ponds are, at least for building 2? The containment is structure is hug!

 

[zapperzero]

The 430 mSv/h at the bottom of the stairs was pretty interesting. TEPCO is talking about drilling holes through the floor to near the torus, to fill the space around it with a cement/sand mix. A bit like drilling a hole down into hell...

And a bit like pouring concrete over the scene of an accident while the investigation is ongoing.
EDIT: Can't be helped, I suppose, not if they want closed loop cooling. But still.

 

[tsutsuji]

http://www.asahi.com/national/jiji/JJT201106220097.html : The filtration efficiency of the absorption facility and the coprecipitation facility put together was found to be OK in the tests with highly contaminated water. The efficiency of the absorption facility is lower with highly contaminated water than during the tests with low contaminated water, but that is still high enough.

http://www.yomiuri.co.jp/science/news/20110622-OYT1T00967.htm provides filtration rates :

Kurion (absorption facility) : 1/50 (instead of the expected 1/1000)
Areva (coprecipitation facility) : < 1/400※ (expected 1/1000)

and a more prudent conclusion: "It is unclear whether putting both systems together can provide a stable water treatment".

※below the measurement limit.

EDIT : see also the measurement results in the following press release : http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110622_04-j.pdf : left column is before treatment, (1) is after the Kurion treatment, and (2) is after the Areva treatment.

 

[Astronuc]

Working conditions improve at Fukushima unit
22 June 2011
http://www.world-nuclear-news.org/RS-Working_conditions_improve_at_Fukushima_unit-2206114.html

Hopefully, we will learn more about the condition of the Units as TEPCO regains access.

The point of filtering the water is too clean up the radionuclides and reduce activity in the areas where workers ultimately must access. The collected radionuclides will obviously have to be consolidated and placed in a repository.

The cleaner water will provide shielding for subsequent work to remove the fuel from the SFPs and the damaged cores. However, it will take years to accomplish much of that.

 

[Bandit127]

Working conditions improve at Fukushima unit
22 June 2011
http://www.world-nuclear-news.org/RS-Working_conditions_improve_at_Fukushima_unit-2206114.html

The cleaner water will provide shielding for subsequent work to remove the fuel from the SFPs and the damaged cores. However, it will take years to accomplish much of that.

Hopefully the cleaner water will improve the high levels of radiation in the basement (430mSv(/hr?) in the top left stairwell and 388 mSv(/hr?) in the bottom right stairwell reported in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110622_02-e.pdf").

I really feel for those guys...

A technical question. If we assume that:
1. The general radiation in Unit 2 1st floor is ~30 mSv/hr.
2. The people working in there are wearing protective equipment (Tyvek coveralls etc.)

Does the dose received equal the radiation they are exposed to (e.g. if I were to walk about there for an hour, would it add 30 mSv to my dose). Or is there an attenuation due to some factor like the protective equipment I would be wearing? Or my (average) 1 m distance from the floor?

Thanks.

 

[MadderDoc]

Is this the crane? I can't see it on the TEPCO feed. Screenshot taken at 09:45 GMT
View attachment 36650

They are the cranes at quay, due to the different angle you can see them on the TBS feed. Here's the south view at 10:00 JST:
http://www.gyldengrisgaard.dk/tepcowebcam/tepcowebcam2/20110622100000.jpg

Edit: Sorry didn't see that yours is in GMT. Here's the south view at 10:00 GMT (19:00 JST):
http://www.gyldengrisgaard.dk/tepcowebcam/tepcowebcam2/20110622190000.jpg

 

[Astronuc]

Hopefully the cleaner water will improve the high levels of radiation in the basement (430mSv(/hr?) in the top left stairwell and 388 mSv(/hr?) in the bottom right stairwell reported in http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110622_02-e.pdf").

I really feel for those guys...

A technical question. If we assume that:
1. The general radiation in Unit 2 1st floor is ~30 mSv/hr.
2. The people working in there are wearing protective equipment (Tyvek coveralls etc.)

Does the dose received equal the radiation they are exposed to (e.g. if I were to walk about there for an hour, would it add 30 mSv to my dose). Or is there an attenuation due to some factor like the protective equipment I would be wearing? Or my (average) 1 m distance from the floor?

Thanks.

There would be attenutation with distance and shielding. The problem is mostly gamma radiation which is highly penetrating. Beta particles go a relatively short distance in air, and much less in metal.

A dosimeter measures at the location of the dosimeter.

With respect to any dose rate, I'd want to know the portion that is beta and the portion that is gamma.

 

[tsutsuji]

http://www3.nhk.or.jp/news/html/20110623/t10013703941000.html : alongside the poor decontamination factor at the Kurion facility, an unexplained phenomenon took place. Although the radioactive substances were expected to accumulate more in the first absorption tower upstream, it is in the last absorption tower downstream that a 3 mSv/h radiation was observed on June 21st or even 15 mSv/h on June 22nd.

 

[Bandit127]

There would be attenutation with distance and shielding. The problem is mostly gamma radiation which is highly penetrating. Beta particles go a relatively short distance in air, and much less in metal.

A dosimeter measures at the location of the dosimeter.

With respect to any dose rate, I'd want to know the portion that is beta and the portion that is gamma.

The sievert is (as far as i understand it) is a dose equivalent based on gamma. If the radiation were reported in grays, then you would indeed want to know the proportion of beta and gamma. But I am hoping we can ignore this for the sake of this question since the proportion should be accounted for.

Let us assume that the dosimeter was placed at my average height of (just under) 1m, then we can ignore height.

My question remains, if I stand in an area of ~30 mSv does this mean my dose is ~30 mSv?

I ask this beacuse 3 workers who stood in water containing 2-6 Sv were reported to have a recived a dose of http://www.cbsnews.com/stories/2011/03/24/501364/main20046609.shtml".

In fact, thinking it through as I am typing - perhaps I should ask a different question.

If I were a worker on Floor 1 of Unit 2 where the radiation appears to average ~30 mSv/hr, would I accumulate 30 mSv/hr of dose in 1 hour and therefore reach my annual limit after (250 / 30 = 8.333 hrs] 8 hours and 20 minutes?

 

[Jorge Stolfi]

A dosimeter measures at the location of the dosimeter.

Presumably workers wear their dosimeters inside their protective suits, whereas the ambient contamination measurements are taken with unshielded meters; is this correct?

 

[etudiant]

http://www3.nhk.or.jp/news/html/20110623/t10013703941000.html : alongside the poor decontamination factor at the Kurion facility, an unexplained phenomenon took place. Although the radioactive substances were expected to accumulate more in the first absorption tower upstream, it is in the last absorption tower downstream that a 3 mSv/h radiation was observed on June 21st or even 15 mSv/h on June 22nd.

Seems that there is considerable incremental performance potential once they get this system properly balanced.
TEPCO should be happy to have the performance starting at 99+% removal, simply to free up some space in the plant. Additional improvements will require tweaking the process.

 

[MadderDoc]

http://www3.nhk.or.jp/news/html/20110623/t10013703941000.html : alongside the poor decontamination factor at the Kurion facility, an unexplained phenomenon took place. Although the radioactive substances were expected to accumulate more in the first absorption tower upstream, it is in the last absorption tower downstream that a 3 mSv/h radiation was observed on June 21st or even 15 mSv/h on June 22nd.

Chromatography?

 

[SteveElbows]

My question remains, if I stand in an area of ~30 mSv does this mean my dose is ~30 mSv?

I ask this beacuse 3 workers who stood in water containing 2-6 Sv were reported to have a recived a dose of http://www.cbsnews.com/stories/2011/03/24/501364/main20046609.shtml".

In fact, thinking it through as I am typing - perhaps I should ask a different question.

If I were a worker on Floor 1 of Unit 2 where the radiation appears to average ~30 mSv/hr, would I accumulate 30 mSv/hr of dose in 1 hour and therefore reach my annual limit after (250 / 30 = 8.333 hrs] 8 hours and 20 minutes?

How long did they stand in the water for? You have already acknowledged that length of exposure time is an important factor, so should not miss it out of that example as it will be a huge difference maker.

The dose a worker receives will be based on what the dosimeter records, and this will reflect the changing levels of radiation depending on exactly where they are standing in relation to radioactive hotspots, not some average figure like the one you speak of. We have seen from various surveys of different reactors that the detected radiation levels have varied considerably in different areas, and a key to minimising workers exposure is to locate these hotspots and either avoid them or find ways to shield workers from them.

I doubt that dosimeters are perfect, and it is possible to imagine scenarios where they fail to capture a decent picture of the radiation a person is actually exposed to. Especially early on TEPCO struggled badly in this regard, since they were not even able to give each individual human their own device.

Despite protective clothing & breathing apparatus designed to guard against internal exposure, to evaluate workers exposure as best as possible they also need to do forms of scanning on people, and add any results to the ones from dosimeter history to get a persons total.

Finally, if the workers are involved in some sort of incident where solid data personal to them is not available, or is suspected of being inaccurate, it may be necessary to estimate doses based on whatever incident factors that are known and measured. I am not sure entirely how the dose was calculated for the workers who got their feet wet, but I tend not to lose too much sleep over it because at the end of the day these Sievert figures are not a perfect guide to the health consequences in any given person anyway, they just give us some sense of the magnitude of risk that people are being exposed to.

 

[MadderDoc]

Presumably workers wear their dosimeters inside their protective suits, whereas the ambient contamination measurements are taken with unshielded meters; is this correct?

I am not sure about that. I've seen them using meters packed in all kind of plastic and stuff, that ought to be protective against radiation in a fashion quite similar to the personal Tyvek suits.

 

[WhoWee]

Another quake with tsunami warnings
http://www.usatoday.com/news/world/2011-06-22-Japan-earthquake-tsunami_n.htm

 

[MadderDoc]

If I were a worker on Floor 1 of Unit 2 where the radiation appears to average ~30 mSv/hr, would I accumulate 30 mSv/hr of dose in 1 hour and therefore reach my annual limit after (250 / 30 = 8.333 hrs] 8 hours and 20 minutes?

Yes, that would seem to be the case, as a first approximation of the potential exposure it ought to do.

 

[Most Curious]

Also depends on the part of the body exposed. Say the feet vs whole body.

 

[joewein]

http://www.yomiuri.co.jp/science/news/20110622-OYT1T00967.htm provides filtration rates :

Kurion (absorption facility) : 1/50 (instead of the expected 1/1000)
Areva (coprecipitation facility) : < 1/400※ (expected 1/1000)

and a more prudent conclusion: "It is unclear whether putting both systems together can provide a stable water treatment".

※below the measurement limit.

I can see that the Kurion filtration rates are lower than expected, but the final outcome is "ND" (below detection level), which is presumably what you would want.

Lest anybody misread the above, the result for the Areva stage did not achieve a 1:400 instead of a 1:1000 reduction, it's input was 400 times as radioactive as the detection limit for the output (which came out ND), so it must have achieved at least a 1:400 reduction.

EDIT : see also the measurement results in the following press release : http://www.tepco.co.jp/nu/fukushima-np/images/handouts_110622_04-j.pdf : left column is before treatment, (1) is after the Kurion treatment, and (2) is after the Areva treatment.

The overall cesium decontamination factor came out as at least 1:20,000 on Cs-134 and 1:22,000 on Cs-137.

If they were expecting a higher decontamination factor, presumably they would have used a more sensitive test on the final output? Their cutoff was at 100 Bq/cm3, which still is 500 times the limit for drinking water, but then they're not hoping to be able to drink this, only use it for reactor cooling or perhaps send it by boat to a nuclear reprocessing plant.

 

[Astronuc]

Another quake with tsunami warnings
http://www.usatoday.com/news/world/2011-06-22-Japan-earthquake-tsunami_n.htm

They shouldn't get much of a tsunami from that.

http://earthquake.usgs.gov/earthquakes/recenteqsww/Quakes/usc0004e5w.php

A mag 6.7, close to the coast, 39.980°N, 142.247°E at a depth of 32 km (19.9 miles).

Edit: I looked up the location of Fukushima Daiichi:

Fukushima 37° 25' 17'' N, 141° 1' 57'' E
          37.421389, 141.0325

Then applied: Distance = sqrt(x² + y²)

where x = 69.1 * (lat2 - lat1)
and y = 69.1 * (lon2 - lon1) * cos(lat1/57.3)

x = 176.8, y = 66.65
distance (earthquake to Fukushima Daiichi) ~ 189 mi, 304 km.

The quake is a challenge to nearby structures, but not a tsunami threat.

http://ptwc.weather.gov/ptwc/text.php?id=pacific.2011.06.22.215933

EVALUATION

NO DESTRUCTIVE WIDESPREAD TSUNAMI THREAT EXISTS BASED ON
HISTORICAL EARTHQUAKE AND TSUNAMI DATA.

HOWEVER - EARTHQUAKES OF THIS SIZE SOMETIMES GENERATE LOCAL
TSUNAMIS THAT CAN BE DESTRUCTIVE ALONG COASTS LOCATED WITHIN
A HUNDRED KILOMETERS OF THE EARTHQUAKE EPICENTER. AUTHORITIES
IN THE REGION OF THE EPICENTER SHOULD BE AWARE OF THIS
POSSIBILITY AND TAKE APPROPRIATE ACTION.

THIS WILL BE THE ONLY BULLETIN ISSUED FOR THIS EVENT UNLESS
ADDITIONAL INFORMATION BECOMES AVAILABLE.

It's the vertical displacement of the sea floor or solid/liquid (crust/ocean) interface, particularly abrupt vertical displacement, that matters.

It's all about the physics (and the math)!

 

[Joe Neubarth]

Yes, that would seem to be the case, as a first approximation of the potential exposure it ought to do.

But the individual is also picking up exposure to ionizing radiation while on the Grounds of the plant and on the way to the plant.

 

[jim hardy]

""Presumably workers wear their dosimeters inside their protective suits, whereas the ambient contamination measurements are taken with unshielded meters; is this correct?""

common sense applies it's just a little hard when you are unfamiliar to know what makes sense.

where i worked we wore dosimetry outside protective clothing. Not for shielding value of the clothing ( basically zero) but so it'll be obvious if you lose it and your buddies will holler at you.. It goes at chest level so as to be not far from most of your organs.
If you're going someplace that's contaminated you put it in a teeny ziplock bag and affix that with masking tape and a twistie-tie, still on outside of clothes. The ziploc bag keeps the dosimeter from picking up radioactive dirt. It needs to be kept clean so you can take it to the clean area of plant at shift's end.


and to bandit's question regarding dose vs rate...

yes, in a 30 mr(or mSv) per hour field you will accrue that amount every hour and reach your limit in the time you proposed.

Standing water in a radiation area is a red flag - stay away because it may be chock full of Beta contamination.
Beta rays go only inches in air so at chest level your dosimiter may read safe while your feet are getting a pretty good dose. Survey meter won't see it either unless you put it right down at surface.
That's what happened to those poor guys laying cables - they just didnt know to stay away from water. Their feet took a big dose but fortunately Betas mostly go only skin deep. And there's not many important organs in our extremities, maybe a little bone marrow.

if i can help others with practical basics that's my contribution here.

old jim

 

[tsutsuji]

http://www3.nhk.or.jp/news/html/20110623/t10013703941000.html : alongside the poor decontamination factor at the Kurion facility, an unexplained phenomenon took place. Although the radioactive substances were expected to accumulate more in the first absorption tower upstream, it is in the last absorption tower downstream that a 3 mSv/h radiation was observed on June 21st or even 15 mSv/h on June 22nd.

http://www.tokyo-np.co.jp/article/national/news/CK2011062302000200.html : There was a mistake on a command panel. One or more bypass valves marked "closed" on the command panel were actually open, so one or more absorption towers were being bypassed.

http://www.asahi.com/national/jiji/JJT201106230039.html : As a result of the mistake, only 1 out of 4 cesium absorption towers was actually being used. After checking the valves and correcting the mistake, the test has been started again with a 50 ton/hour flow.

If my understanding is correct, what this Asahi/Jiji article is saying is that in a normal operation, one cesium tower is bypassed for maintenance, while the other 3 are active. As a result of the mistake, they were doing just the opposite. Yet only one valve was wrong.

Tepco provides a diagram explaining the mistake : http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110623_01-e.pdf