Fukushima No. 1 loss of coolant due to earthquake 7

[printing724]

Re exposure levels: electricpete's conversion is right on, 8217 microsievierts/hr is 822 mrem/hr.

(Disclaimer: what follows is from my Navy career which ended many years ago. I believe it to still be current)

To put that in perspective, the occupational limit in the US nuclear industry is 3,000 mrem (30,000 microsieverts) per quarter or 5,000 mrem (50,000 microsieverts) per year. This is based on a presumed "safe" level that does not add substantially to long-term cancer risks.

The Navy's limits when I was in were 300 mrem (3000 microsieverts) per quarter or 500 mrem (5000 microsieverts) per year.

Acute physical damage starts to occur at short-term exposure levels in the 50-100 rem (500,000-1,000,000 microsieverts) range. If the exposure level rises to 300-500 rem (3,000,000-5,000,000 microsieverts) the short-term survival odds drop to 50% or less..

At Fukushima, they reported a spike to 822 mrem (8217 microsieverts) at the perimeter, then decreasing to some level markedly lower. A worker would exceed his/her quarterly exposure limit in about four hours in that environment.

What we don't know is the source of the radiation. The significant decline indicates (to me) that it originated from a point source rather than area contamination. If it was from a point source, the exposure levels closer to the source go up as the square of the distance. If that is the case, workers nearer to the source will exceed their limit that much quicker.

It is possible that reducing the number of workers on site is a measure intended to miinimize exposure.

In any case, our hearts must go out to the workers at that site. They have suffered personal losses like everyone else who lives in the surrounding area, yet they are at work trying to keep a bad situation from becoming much worse.

Kevin Snyder
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[rasevskii]

for davefitz and jmw:

Yes you are missing something here: As I posted in the OilDrum thread, is that the auxiliary station service electrical supply was wiped out by the Tsunami, that is all the electrical equipment at a an elevation of few meters above Sea Level was flooded out by corrosive salt water, and was therefore rendered inoperable, and could not be re-energized from whatever source.

We are talking of 4.16 KV systems (possibly 6KV), 480V, and lower voltage systems. The outdoor sea water pumps. plainly visible in the aerial views. on all 4 units were flooded out, as well as the Diesels (several MW) and even the two fuel tanks for the Diesel station were carried away.

Al electrical equipment was rendered useless, instantaneously, that was flooded out by salt water. Unrepairable. Only replaceable.

Even the reportably "brought in gensets" could not be connected to the existing (ruined) switchgear.

Evidently some other MV large motors (feed pumps?) were also flooded out and were therefore made uselass, rendering the reactors without any cooling supply. This is conjecture on my part, not having seen any any elevation drawings or one-line electrical diagrams of the station. Such information would be useful in further analysis of the situation.

rasevskii

 

[unclesyd]

rasevskii

In this rather lengthy paper there drawing of the different Pressure Suppression water system on the reactor..

The case is thus or somewhat similar:
POGO

http://www.oecd-nea.org/nsd/docs/1986/csni86-126.pdf

 

[electricpete]

The good news: It seems the fire was at unit 4, and is out, not a concern.

Perhaps that was premature.

Would anyone venture a guess what's going on with this fire in unit 4?

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(2B)+(2B)' ?

 

[electricpete]

Apparently the fire broke out again, and there were reports of consideration for bringing in helicopters to dump water on it.

I can take a guess, but I'd rather hear someone else guess what this represents.

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(2B)+(2B)' ?

 

[unclesyd]

It just came across on the news that they are has the same problem with #5 and #6 as they are having on #4.

There was some Congressman on TV calling for all the US nuclear plants to be shutdown.

If I could only harvest all the hot going out today I could run a very big turbine. I've come to the conclusion that a bow tie makes one an expert.

Also today an expert said shutdown the nukes and use a renewable energy source, natural gas and others. He wouldn't name the others.

A person stated that all we needed was a smart electrical grid which would replace the Nukes. I've seen some numbers on a smart grid but nothing like the 20% from nukes.

 

[electricpete]

http://www.nzherald.co.nz/natural-disasters/news/article.cfm?c_id=68&objectid=10712720

3.41pm: Japan's top government spokesman says that a surge in radiation means workers are unable to continue even minimal efforts at Fukushima Daiichi. Chief Cabinet Secretary Yukio Edano said work on dousing reactors with water was disrupted when workers were forced to withdraw after radiation levels surged early in the day.

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(2B)+(2B)' ?

 

[unclesyd]

One way to resolve the worker's radiation exposure. one question is this an increase in the radiation field or total radiation to the body.

"On Wednesday morning, the Japanese government raised the permitted radiation exposure for plant workers by 2.5 times to allow them to work longer, according to NHK TV".

 

[electricpete]

It sounds a little bit like giving up. One would think there would be some reinforcements available, with radiation suits ....

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(2B)+(2B)' ?

 

[cloa]

This thread really should have been called Fukushima Daiichi as the plant at Fukushima Daini is well under control (cold shutdowns) and wasn't that bad to start with. Any thoughts about when they'll restart Daini as we really need the power?

 

[electricpete]

One would think there would be some reinforcements available, with radiation suits ....

I guess that technology is not here yet:

http://www.radshield.com/product_page_detail.asp?ProductID=985&ProductCatID=27&Search=

Tailored for evacuation in a dispersed low energy environment. The Demron™ Radiation Protection Suit is a full body suit complete with an integrated hood, heat-sealed seams, and seam seal tape for added protection. The suit was engineered to provide protection during the evacuation of a dirty bomb. Due to advanced molecular design, the Demron™ coverall allows for better heat dissipation than other impermeable protective fabrics, providing the user with a cooler core environment. The suit is an excellent shield of high-energy beta particles, such as those emitted from Strontium-90, and provides at least 50% shielding of gamma rays up to 130 Kev

I know 130kev = 0.13MeV is a fairly low energy gamma compared to certain like the N-16 6 MeV gamma. Are most fission product gammas also above 0.13 mev (?)

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(2B)+(2B)' ?

 

[unclesyd]

The latest update from Reuters.

http://www.reuters.com/article/2011/03/16/us-japan-quake-idUSTRE72A0SS20110316

 

[trottiey]

The increase in permitted dose sounds like a planned emergency measure. Please see my explanation about this in thread466-294445.

Radiation suits protect primarily against internal radiation exposures, although it does also block external alpha and beta. Personal protection against external gamma is generally not worth the weight. See my radiation protection thread for an explanation of the difference between internal and external exposure.

 

[Zogzog]

Anyone know the status of power? I heard they had some diesels on site but could not restore power because the switchgear had salt water contamination. I have a 1,000,000 sq-ft warehouse full of switchgear and am wondering if and how I can assist.

 

[MintJulep]

Where is all the sea water going?

Reports continue to say "injecting sea water".

The pressure vessel was full of water to start with. So where is all this water going?

There was some venting of steam, but how much water could that account for?

 

[Zogzog]

Recently my company refurbished approximately 75 portable 5kV generator sets that are used for general emergency and conflict situations and deployed and maintained by the Army’s 249 Engineering Battalion. Other users include FEMA and state governments.

Each unit is specially designed to be easily transported by C-17 military aircraft and all members of the 249th are fully trained on their operation and service.

Wonder why these units are not deployed there?

 

[guizmy]

Guys, pardon me to brainstrom on some of the worst scenario one can imagine.

Suppose the control of the situation is lost, and all reactors are lost with all nuclear material releasing radiations to atmosphere making a whole area of 500 km diameter having no more acceptable levels of radiation for any human being.

Question is : who will keep operating the remaning nuclear facilities in the affected critical 500 km area? are theses facilities equipped to withstand fulong shutdown period full autonomous mode?

 

[trottiey]

Zogzog, I suggest you contact the IAEA with your offer of assistance.

guizmy, I am not aware of any plausible scenario where a 500 km evacuation zone would be warranted for civillians, and a similar sized evacuation zone for nuclear workers is ludicrous. The appearance of Godzilla would seem more likely to me.

guizmy's second question is interesting, but I do not know the answer.

 

[rasevskii]

for Zogzog:

There appears to be a complete news blackout on the detailed status of anything at Fukushima. Some reports say that the workers are operating in complete station blackout conditions. It may be too late in any case for more generators to be sent in. I think that we have been talking about a complete loss of all station service due salt water intrusion into all equipment at near seawater level.

That would have been 4.16 KV (or 6Kv) and all lower voltage level equipment that was lost.

It is obvious that the outdoor seawater pump motors were all flooded out, and the Diesels in a building near the lower right had the same fate. Imagine the damage as the salt water flooded into the energized and operating plant...

In any case two fuel tanks seen in the Before views were not there in the After views.

Latest reports talk of reduced staff due high radiation levels.

BTW what KW are these Diesels that you refurbished? Are they 4160 60HZ or reconnectable for 50Hz and other voltage...(unless that is secret of course.) You said 5KV, was that a typo?

Obviously detailed incident info belongs to the plant owner, as would be in any organization. We can only conjecture based on our field experience in similar installations.

rasevskii

 

[trottiey]

You call this a "complete news blackout"? Really?

You can access all the press releases at this website:

http://www.nisa.meti.go.jp/english/

There have obviously been communication failures, but I'm guessing that the workers on site are a little to busy to do interviews right now.