Fukushima Daiichi rated?

AntonL

There may also be other consequences by upgrading, dictated by economic consideration like insurances. Insurers may automatically increase their premium for aircraft and ships heading for Japan or even stop all cover while an ongoing level 6 is in progress. Once an aircraft or ship is contaminated it has scrap metal value.

M. Bachmeier

I could see why there would be an unspoken effort to delay status change, so as not to hamper relief efforts. But, the current evacuation zone seems inadequate.

clancy688

First post here - but what the heck... pls bear with my english. ;)


I think there should be some explanations of INES first - while INES is generally taken as a single assessment, it is in fact three:

1) People and the Environment (Maximum level of 7)
2) Radiological barriers and controls at facilities (Maximum level of 5)
3) Defence in depth (Maximum level of 3)

Every accident is rated in these three assessments. And the highest number is the final INES rating.

INES-Manual: http://www-pub.iaea.org/MTCD/publica...S-2009_web.pdf


As for Fukushima Daichi, Blocks 1-3 have only been rated in category two and three - they got a 3 for Defence in Depth and a 5 for Radiological Barriers, so the temporary rating is a 5. And since category 1 hasn't been rated yet, it can't go up any further.
Temporary INES-Rating of Fukushima Accidents as published on March 18th: http://www.nisa.meti.go.jp/english/f...20110319-6.pdf


Let's concentrate on category 1, impact on the environment. For INES levels from 5-7, INES-Manual gives us criteria of radioactive pollution to be met. The whole radioactivity release is converted into an equivalent activity of Jod-131. Other isotopes, such as Cäsium-137 for example, are multiplied by a factor (40 for Cäsium) which can be found on page 16 and added to the total number. These criteria can be found on page 17 (INES-Manual), but I will summarise:


INES 5:

Example (numbers given by the manual): Three Mile Island, 500-700 TBq Jod-131 equivalence


INES 6:

Example (numbers given by the manual): Kyschtym, 20.500 TBq Jod-131 equivalence


INES 7:

Example (numbers given by the manual): Tschernobyl, 5.400.000 TBq Jod-131 equivalence



Summary up to this point: Criteria 1 with a maximum level of 7 has not been rated yet for Fukushima, level 7 will be necessarily aquired after a release of 50.000-100.000 TBq Jod-131 equivalence.


So, what has escaped Fukushima? There are several different calculations, but none seems good:

Japan's nuclear safety commission expects a release of 33.000-110.000 TBq Jod-131. But I'm not sure if they are only referring to Jod, or if this is the equivalence.
Source: http://www.asahi.com/english/TKY201103250204.html

IRSN expects 90.000 TBq Jod-131 and 10.000 TBq Cäsium-137, converted into Jod-131 the number would be 490.000 TBq
Source: http://www.irsn.fr/FR/Actualites_pre...11-tableau.pdf

ZAMG expects between 10.000-700.000 TBq Jod-131 and 1000-70.000 TBq Cäsium during the first week. But all their plume simulations use a number of 100.000 TBq Jod-131 per day.
Converted into Jod-131 this would be between 50.000 and 3.500.000 TBq during the first week.
Source: http://www.zamg.ac.at/aktuell/index....-04-02GMT09:28


Which brings me to the conclusion, that the Fukushima Accident inevitebly has to be rated with INES-7 - if they are going to stick to the manual.
That's probably the reason why they still don't have rated category 1. Technically, the event is not over yet, so the radioactive release is still going on and you can't figure the final numbers.
But the numbers won't go down - regardless of how much radioactivity will be released during the next month, this accident reached the INES 7 category during the first few days.


Edit: Whoever corrected the chaos I created with my wild replies - thank you very much. :)

M. Bachmeier

Re: http://www.physicsforums.com/showpos...3&postcount=37 @clancy688

You make a very good argument. Some, like myself, have felt from the beginning that the potential worst case could force the redefining of the INES standard.

clancy688

Well, basically, not this accident is a problem for the INES scale. But Tschernobyl is.

With radioactivity releases measured around several ten- to hundredthousands of TBq, INES-7 fits perfectly for Fukushima.

But according to the INES-Manual, Tschernobyl released a hundred times the amount needed for INES-7.
If INES really is a linear scale, where each level is a tenfold increase in seriousness, then Tschernobyl should be rated as something between INES-8 or -9.

People are right if they say, that Fukushima isn't the same scale as Tschernobyl. But Tschernobyl was such a gigantic accident, that it popped the scale and compromised the level 7 rating...

NUCENG

What is the real utility of the INES rating?

Will having the event rated 6 or 7 help solve any problems? Will the Japanese feel better if it remains a 5? The Japanese people have lost thousands of lives and billions of dollars due to an earthquake and tsunami. Has anybody rated that?

A few years ago the State of Arkansas was rated 49th in a number of categories involving health, education, life expectancy, poverty, etc. Jokesters claimed that the Arkansas state motto was, "Thank God for Louisiana." (Louisiana was rated #50.)

Jimmy Carter claimed that George Bush was the worst US President of all time. True or not, Barak Obama seems to be trying to make them both look good.

My purpose is not to make this a political forum, it is to question why we always have to rate things. This is a disaster. What can be done to prevent another one? What can be done to help the Japanese recover? Those questions seem more imediate to me.

M. Bachmeier

A the time of my original post the INES scale seemed to be one 'objective' way to assess potential outcomes, and present threat levels in a way that would be accessible to a layman like myself.

Also, the objective was to allow knowledgeable contributors to present argument for an INES rating (past, present and future).

"My purpose is not to make this a political forum, it is to question why we always have to rate things." @NUCENG

Your frustration is understandable, but it would be irresponsible not to pay attention to these nuclear incidents, the INES ratings currently assigned and argument as to the correct application of the scale.

I don't believe there's any need to be concerned about making this thread political, because it's implied in questioning official ratings. However, any political assertions should be accompanied by sound argument and references to external sources of information.

NUCENG

You are right of course, I had just seen some of the most irresponsible speculation by some talking heads on TV about how many people were dead and didn't even know it yet. They totally ignored the loss of life from the earthquake and tsunami which are real and known in order to guess what might happen in the next 50 years. I was already frustrated and then saw this discussion on what seemed to be a trivial distinction. My apologies to anyone who felt I was disparaging their inputs. I wish people could keep the nuclear problems, as serious as they are, in context with the much larger destruction and loss of life.

clancy688

INES 7 on its way:

http://english.kyodonews.jp/news/2011/04/84721.html

Wow... so those 100.000 Tbq per day numbers by ZAMG may have been correct after all...

clancy688

And there it is... INES-7 declared for Fukushima by NISA:

http://english.kyodonews.jp/news/2011/04/84805.html

vanesch

I have a question regarding this.

When I look here: http://books.google.com/books?id=O0Y...page&q&f=false

I see that a typical "hot" and active 1 GW core has a fission product inventory of the order of 4.4E20 Bq (12 000 megaCi).

Now, I think that in Chernobyl, between 5% and 95% of the core went "airborne", so this comes down to at least 2E19 Bq.

This seems to be confirmed when looking at p 36 of:
http://puck.sourceoecd.org/vl=994441...92/v3n1/s1/p1l

(click on the pdf link, and look at the table at p35).

When you make the sum, you are above 10^19 Bq.

So how come we classify events with a release of the order of 10^17 and 10^19 at the same level ?

clancy688

Excellent question. I was asking myself the same thing. In my opinion, INES needs one or two levels more.

maxverywell

Yesterday it was rated as level 7!
Very bad, I think it will become worst than Chernobyl...

Dmytry

The question i have is.... where did this idea of converting Cs-137 (half life 30 years, distributes over muscle tissue) to I-131 (half life 8 days, concentrates in thyroid) came from ?!

clancy688

INES-Manual, therefore IAEO. ;)

Dmytry

A definite proof of utter incompetence, on record. Not exactly what OP was asking for, but very close.

On topic of the release.... I don't understand what's so scientifically outrageous about the estimate that the release would be on par with Chernobyl?

The fraction of Cs-137 released from each pellet would depend to it's temperature, the time spent at this temperature. The total would depend to the amount of fuel affected, and to what fraction of the Cs-137 gone into atmosphere (versus deposited on piping).

The primary perceived difference between this disaster and Chernobyl is that at Fukushima, 'containment' is intact [except for the spent fuel pools (which have virtually zero I-131 unless it gone critical)]
The 'containment', however, is being vented without any filtering. Sure some of the radioactive dust would deposit on the piping that the venting is done through, but I would doubt that it is significant, due to the sheer volume of steam that was and is being vented through same piping. Furthermore, spent fuel in spent fuel pool #4 had no containment and did reach at least zirconium-steam-igniting temperatures (as evident by hydrogen explosion) and was then further heated up by zirconium fire, followed by zirconium-uranium dioxide reaction.

It seems to me that knee-jerk rejection of Chernobyl level release has more to do with misunderstanding of difference between radiation, which the containment contains, and radioactive aerosols, which are being vented, than with any technological difference. Or perhaps misunderstanding of the mechanisms of containment and release of the Caesium and Iodine from the fuel (hint: it is not released by explosion. It is released by heat).

Also, lets compare apples to apples and strawberries to strawberries:
http://www.nisa.meti.go.jp/english/f...20110412-4.pdf
Announced by NSC, 1.2E16 Bq of Cs-137 , versus 8.5E16Bq of Cs-137 from Chernobyl.
Meaning, and this is official, long term effects of ~18% Chernobyl.

But this is still comparing apples to oranges! We are comparing final Chernobyl estimate done not by Soviet Union alone but internationally, to a preliminary Fukushima estimate done by Japan alone. Obviously, Japanese government has every incentive to be conservative with their estimates.
Then, we'd be comparing a case of fallout blown largely onto parties who performed independent measurements (Europe), to case of fallout blown into sea.