Japan Earthquake: nuclear plants

swl

There have been plenty of fatalities related to the release of radiation from the three meltdowns, fires and explosions at Fukushima 1.

There was a huge evacuation as result of the ongoing radiation release. During this evacuation, many people died. It is readily apparent that there is a connection between these events.

http://mdn.mainichi.jp/features/arch...na006000c.html

It is obvious there has been tremendous property, and psychological damage as well.

I recommend the contamination & consequences thread if you are interested in learning about some of the dangers of nuclear power.

Astronuc

Some background recently published.
The units were mostly on annual cycles, although units 5 and 6 were managing 13 to 14 month cycle lengths.
Unit 4, Cycle 23 was ~14.5 mo, Cycle 24 was 12 month.

Refueling/Maintenance outages were long by current (modern) standards. The plants were operating at original ratings and had relatively low capacity factors by modern standards. I'll post the source later.

Yamanote

Are there any news about the cause of the explosion of unit3?

I didn't follow this issue for quite some time...
For units 1 and 4 I think the explosions were caused most likely by hydrogen within the reactor building.

r-j

Nuclear Disaster In Japan Could Have Been Mitigated, Say Industry Insiders

http://www.nytimes.com/2012/03/10/wo...pagewanted=all

zapperzero

http://pbadupws.nrc.gov/docs/ML1205/ML12052A109.pdf
NRC transcript from the 17th

jim hardy

Heavily redacted, lots of speculation , very much in line with chaotic conditions back then..

Misinformation about state of unit 4 spent fual pool, they thought it was gone
speculation on conditions

p 74, and i wouldn't bet much on that being accurate.


Even the Frontline show was silent on that one.

SteveElbows

Personally I don't see the point in taking any of those details from the early days transcript seriously. Because its an experience we all went through in our own way at various stages of talking about the events on forums such as this one. Loads of confused details, stuff that turned out to be dead wrong, or speculation that may have lead somewhere interesting but for which no subsequent evidence emerged with which to build upon.

Now its always possible that previously undisclosed information will be released that will give cause to reconsider something, but when it comes to stuff such as explosions I would think it more likely that the knowledge about this stuff will not be greatly expanded upon, not directly anyway. For example if you are interested in the reactor 3 explosion then Im not quite sure what you are hoping to discover about the explosion. The timing of the explosions at both reactors 1 & 3 happening not long after venting is pretty compelling, and there is an uncontroversial source of hydrogen, several ways for the hydrogen to get into the buildings upper floors, and well understood triggers for that hydrogen to explode. The most you will get is that one day we are going to hear some more detail about factor 3's spent fuel pool, and the state of the fuel there could potentially renew a discussion about this pool having played a role in events at reactor 3 building. And at some point we might get a little more info about containment failure.

jim hardy

Thanks for saying it more eloquently.

That's where i am at too, we just dont know.
I'm done with speculating.
Waiting to see what pans out.

zapperzero

All the other numbers I've seen in there jive with TEPCO/NISA and later reports. The interpretation is all NRC, of course, and some of it turned out to be quite wrong.

zapperzero

Well I happen to think I just posted such a detail.

SteveElbows

Well I was meaning new detailed information about the pool and its contents, but certainly the rate you mention is of interest to this question.

I'm not used to working with R per hour numbers, did a conversion but am unsure if I did it right or not. Is 375 R/hour = 3.75 Sieverts/ hour?

NUCENG

Your conversion is correct. 1 Sv = 100 Rem.

ZZ, your detail is without context . A radiation reading was taken above the Unit 3 and, and if correct, was recorded at 3.75 Sv/hr. That is the detail. The context requires interpreting what the detail tells us. Was the high radiation due to loss of shielding water level from the spent fuel pool? Was the level from a release plume from damaged fuel in the SFP? Was the drywell Cap displaced? Was the level from shine from the drywell? Was the level from an ongoing release plume due to containment leakage? If the radiation was from I-131 it would indicate recently irradiated fuel. If it was all gamma radiation it would indicate shine instead of a plume. What is the radiation level today? We don't know enough to really say what it meams.

zapperzero

It says "strong possibility of uncovered fuel" to me.

100 Rem is 1 Sv, yes.

zapperzero

There is at least some context - it was measured from a JSDF helo and so it is, must be, all gamma, because that's all the military cares about - how long can their soldiers operate the equipment. It's not likely at all that someone bothered to pop a probe out the window just for the thrill of counting beta decays. In fact, I'd wager good money that they were buttoned up.

Look at that anemic plume of steam, hard to believe that the helo is getting 3 Sv/h from that (and if it was, people on the ground would have been getting it too), it's not like they are flying directly through:

http://www.youtube.com/watch?v=00YjEOpnsCc

The reactor well cap was not displaced, that we know of.

As for the radiation level today, that is also unknown. There are reports of dose rates on-site decreasing very significantly after the pools were watered.

SpunkyMonkey

This may be the missing Unit 3 refueling crane fallen into the spent-fuel pool as seen in an April, 14 2011 image here:



The graphic shows similar objects between this piece of wreckage in the Unit 3 pool and the intact Unit 4 refueling crane. It also shows a similar spacial conjunction of similar objects, and this meta-similarity makes me confident we're looking at Unit 3's refueling crane.

There are many pre-tsunami photos of the refueling crane here.

Why isn't the proposed refueling crane also bright green? My guess is that the fire that blasted out the south side over the pool and thus onto the crane scorched off the paint.

SteveElbows

Thanks for the additional info. I'm sort of with NUCENG with this one, in so much as I am hesitant to attribute the reading to a particular source with any great certainty. Especially as they were high enough in the air that I cannot claim that they were only measuring stuff that must be related directly to reactor 3.

I'm basically still stuck at the point of being able to say that the fuel pools are still of interest, and that reactor 3's pool may be more interesting than reactor 4's. I expect that at some point we will learn more about this, but I doubt Im going to figure much more out in the meantime.

tsutsuji

Sorry for asking again what was probably mentioned a dozen times in this thread, but:

Was there no instrumentation telling the SFP water level in real time, or was that instrumentation broken ?

I have the same question about temperature instrumentation.

If the fuel uncovered, how ? Was the water splashed out during the earthquake ? Or during the explosion ?