Japan says it may take months to end radiation leaks (Reuters) - Are fission products still being released?
Japan says it may take months to end radiation leaks (Reuters) - Are fission products still being released?
Japan says it may take months to end radiation leaks (Reuters)
Reference:
http://news.yahoo.com/s/nm/ts_nm/us_japan
Fukushima Nuclear Accident Update Log, Updates of 3 April 2011
"On 2 April, deposition of iodine-131 was detected in 7 prefectures ranging from 4 to 95 becquerel per square metre. Deposition of cesium-137 in 6 prefectures was reported on 2 April ranging from 15 to 47 becquerel per square metre. Reported gamma dose rates in the 45 prefectures showed no significant changes compared to yesterday."
Reference: http://www.iaea.org/newscenter/news/tsunamiupdate01.html
Are fission products still being released? Previously, it was stated that, once control rods are inserted, fission would stop and there would be no further release of fission products. However, we now know there has been core melt in the reactors and core melt on fresh air in the fuel pools.
Reference:
http://www.nytimes.com/2011/04/03/science/03meltdown.html?pagewanted=1&r...
What is the difference between reactor contents, fuel and fission products? What is being released at this time? In particular, is Iodine-131 still being released?
Dr. Chivers, would you please explain.
They have no idea what's
They have no idea what's going on at the reactors because they can't even get close:
A radiation monitor at the troubled Fukushima Daiichi nuclear power plant says workers there are exposed to immeasurable levels of radiation.
The monitor told NHK that no one can enter the plant's No. 1 through 3 reactor buildings because radiation levels are so high that monitoring devices have been rendered useless. He said even levels outside the buildings exceed 100 millisieverts in some places.
Pools and streams of water contaminated by high-level radiation are being found throughout the facility.
The monitor said he takes measurements as soon as he finds water, because he can't determine whether it's contaminated just by looking at it. He said he's very worried about the safety of workers there.
Contaminated water and efforts to remove it have been hampering much-needed work to cool the reactors.
The monitor expressed frustration, likening the situation to looking up a mountain that one has to climb, without having taken a step up.
Tuesday, April 05, 2011 19:51 +0900 (JST)
http://www3.nhk.or.jp/daily/english/05_38.html
I'm a news guy, not a
I'm a news guy, not a scientist. However, here are a couple of things to consider:
Neutron emissions have been recorded coming out of the reactors. IIRC, that means fission is happening in open air.
The 'ethereal blue flash' has been observed, also indicating open-air fission.
I have to say that the whole
I have to say that the whole thing about neutron emissions and blue flashes seem confusing to me. I'm not saying that these things did not happen, but it just does not gist with my experience and knowledge of how fission chain reactions occur. To get a significant amount of fission occurring to produce enough neutrons to be detected by neutron detectors, one would have to have a high density of fissile atoms (U-235 or Pu-239) coupled to a moderator (usually water) to slow down fission neutrons to enable the production of additional fission. Also, blue light is normally associated with what is called Cherenkov radiation which is caused when a charged particle (usually an electron) travels faster than the speed of light within a medium other than vacuum (usually water). Reactors are normally associated with Cherenkov radiation because we can observe the effect in pool-type reactors with your naked eye (see Wiki Cherenkov Radiation). But, in open air and at an intensity so that one can observe it? Does not make sense to me.
In describing the
In describing the criticality accident with the infamous "Demon core" of plutonium on the Manhatten project, the incidents were said to produce blue light in open air.
The videos from Arnie Gundersen of Fairewinds associates said that he believes the sea water is modulating a core that is nolonger in a proper geometry, and that the chlorine-38 proves this.
Thanks a lot for responding.
Thanks a lot for responding. The neutron story seemed odd due to the use of the word "beams" which might have been a poor translation. Regardless, it does seem that neutrons have been detected, and if that can only happen if a certain level of fission is reached, then once again I suspect that we are not being told the full story.
Same for the blue flash. If both of these are actually occurring, as has been reported, there is a lot more going on in those reactors than we are being told. On the other hand, we've seen disinfo from day one of the crisis as well (the hoax radiation map comes to mind).
Clarification
Hi Dr. Chivers,
Thank you for your explanation. But to clarify, does this mean that the West Coast and the rest of the US will continue to have radioactive isotopes coming our way for months?
Please see my response
Please see my response below.
Te-129
Dr. Chivers -
Given that TEPCO detected Te-129 on March 31, which has a half life of approximately 70 minutes, doesn't this indicate that there is at least localized criticality?
That may very well be and
That may very well be and there are scientists here working on analyzing that aspect of the Japanese data in collaboration with the University of Tokyo. This is not really my department, so I will not speculate on this. However, yes, a short-lived isotope being detected long after shutdown may indicate localized criticality occurring due to geometry changes. This is assuming that Te-129 was actually the correct analysis of the data which is not always a foregone conclusion even if it was reported in the media. The situation is obviously very complex and it seems we are not out of the woods just yet.
Thank you ...
... for the response. It sounds like TEPCO is suggesting that the Te-129 detections may have been caused by methodological errors. Please pass on anything you learn from the analysis in your lab.
I did hear that some peaks
I did hear that some peaks were misidentified, but I was unsure of which ones. Unfortunately, there is software out there than can identify peaks automatically and the efficiency is not always perfect. We always do a sanity check on all identified peaks to check for correlated peaks (secondaries that also show up) and ensure the peak ratios make sense before we call it identified. This takes some specialized skills to do.
In general (and very basic),
In general (and very basic), once control rods are inserted, there is no sustained fission chain reaction. This essentially means that fission is still occurring but at an extremely low rate and that on average each fission rarely results in a second fission. Fission products are the "fragment" (usually two) atoms resulting from the splitting of uranium (or plutonium) and are usually highly unstable to radioactive decay. These fragments decay into other atoms by emitting alpha (helium nucleus) and beta (electron) particles and decaying to get more stable. These processes result also in gamma radiation as they "relax" into more stable configurations in the nucleus. After shutdown where control rods are inserted, the fission products that have built up in the fuel from normal operation remain and are highly radioactive for months until the bulk have decayed to more stable elements. During this time, all of that decay is releasing energy and all of these alpha, beta, and gamma radiation produces heat and this is called decay heat.
Now, this is all normal stuff and normally one would not experience any release of these fission products as these are contained within the fuel elements and the decay heat is taken care of by active cooling. However, if the cooling is removed, which is what happened in this case when power was removed by the tsunami taking out the diesel generators, then the core can heat up. Eventually if cooling is not re-introduced, the cladding, which is a metal barrier made of a zirconium alloy separating the fuel from the cooling channels, may fail and fission products will be released. From this point, there are many different scenarios that can lead to release of these radioactive elements to the environment. I'm not sure we have the full factual story from Fukushima yet, but it is clear that we have had a minimum of cladding failure and most likely a partial meltdown where some portion of the core has changed geometry due to to becoming partially or fully molten. From here, we see I-131 due primarily because it has a large inventory within the core combined with it being very volatile (i.e. converting to gas at low temperatures). Now, if the Japanese are trying to cool these reactors with sea water, they need to depressurize the containment so to be able to push water in. The bleeding of pressure will produce releases of these volatile elements that are now in the water that is being used to cool the reactor decay heat. I see no way around this for months. In addition, there may be small leaks in piping from the primary that was caused by the earthquake that can also provide a pathway.
We may also see a primary containment breach which would introduce more radioactive elements if they become airborne.
Hope that was not too technical.
If, as you say, these
If, as you say, these releases are going to continue for months, then I am confused why on the FAQ page it states that monitoring will continue until the levels of radioactive particles start to dissipate, "perhaps sometime in Mid-April."
I'm just trying to get a grip on the actual scenario we're facing. It's very confusing. Also, if an actual expert like yourself recognizes the grave danger posed by this situation, I wonder why the U.S. isn't getting more involved. It seems that there is a humanitarian crisis in Japan at least as serious as the one in Libya. Whatever effects we experience here will be trivial compared to the looming catastrophe it seems they are in for. I assume the Berkeley team is sharing their research and analysis with governmental authorities?
Hi ck, Sorry for the delay
Hi ck, Sorry for the delay as I am on travel at the moment. The FAQ does say that these particles will dissipate perhaps in Mid-April and this is assuming that we do not have any very large releases like we witnessed early on. In Japan, I think we will see releases at lower levels due to two reasons: 1) The large amounts of iodine gas inventory was released once the pathway was introduced from the core to the environment and as long as we are still in a controlled cool-down situation I expect the amounts of the release to be much less than before, and 2) the half-life of I-131 is around 8 days which means at this point the I-131 is reduced to 5% of the original inventory. The 95% has now decayed to Xe131 which is a stable atom. This does not mean that we may not see larger releases in the future, but it is becoming more unlikely as time moves on. We are now having to sample larger volumes of water and air along with counting for longer times while trying to reduce our normal background to see the I-131 signature. At this point it is still detectable, but barely. My hope is that by mid-April we will be below minimum detectable activity and be can begin to try to understand all of this data in a more rigorous way. This is when the real work for us begins.
Hi DChivers, Thanks for
Hi DChivers,
Thanks for clarifying this. I had not realized that the levels were on the decline and barring any further large explosions they will continue to reduce. Great news.
After the levels have diminished will you begin working out estimates of how much radiation we have received?
Thanks - I really appreciate all the work you and your team are doing.
I see; I hope the controlled
I see; I hope the controlled cool-down is maintained and this predicted scenario plays out as you have described.
Thanks for the speedy reply, and for all the information you and your team are providing us. It's great to be able come to this site and get information from credible sources, including hard data on precipitation, air levels, etc. (I have not been able to make head or tails out of the RadNet graphs on "gross gamma radiation.")
I really appreciate it. Take care.
And once again... Thanks
I would like to "second" ck's thanks, Dr. Chivers, and the entire Berkeley Lab staff.
If you're by any chance traveling through or near North Texas, I'd be happy to buy you a coffee or a Shiner Bock, or whatever else you drink, sir.
(Shortest post ever by me; I want that noted by somebody!) LOL...
Rick Cromack.
Allen, Texas
www.facebook.com/lonestarplano
RichardFCromackJr@gmail.com
972-746-8575
No, not too technical...
...Just very, very scary. If the U.S. Government knows all this -- and I have to assume it does -- why, WHY aren't potassium iodide tablets, and Prussian Blue, being distributed among the general population, given that we're likely to CONTINUE to experience radioactive contamination for a period of AT LEAST several months? Has anyone contacted the DoE or EPA (or, heck, Homeland Security -- this falls well within their mandate) about this stunning lack of responsible governance?
...I just can't believe this is playing out like this. I thought I was a cynical sonufagun when it came to appraising the qualities of our nation's government... But this is just beyond anything.
Rick Cromack.
Allen, Texas
www.facebook.com/lonestarplano
Ok
An additional question(s):
If there is a primary containment breach, are the levels we are seeing now going to climb? (Understanding that what we see here is subjected to weather patterns and the jet stream...)
Also, if you don't mind:
Why is everyone freaking out about the Xe-133 levels? Could you explain why there seems to be an seeming downplay to this element under Cs and Iodine? I'm just trying to understand all of this better so I don't ask stupid questions in the future. :o)
- Jen
D. Chivers, time to reply?
D. Chivers,
If you have time to answer this question, I would be very interested in hearing you thoughts. From what I gather the explosions are what caused the fallout out to make it to the United States,. I'm just trying to get a sense if there is a primary containment breach, might are levels climb? Or would that be more likely to happen only if there was another explosion? Thanks again for all you're doing to keep the public informed.
The explosions we saw at the
The explosions we saw at the beginning of this event were actually hydrogen explosions caused by a sequence of events beginning with the water within the core cooling channels being removed, the core heating up to high temperatures, then a reintroduction of water creating high pressure steam which then interacts with the zirconium alloy cladding (metal separating fuel from cooling channels) to produce ZrO2 (zirconium-oxides) which emits pure hydrogen (2*H20 + Zr --> ZrO2 + H2). I think that is right,...,I am far from a chemist. The hydrogen builds builds up in the secondary containment building and if it is not dissipated, there is an explosion risk. Usually, there are things called sparkers that are used to produce many "small" hydrogen ignitions if the hydrogen levels increase to a certain level in order to lower the hydrogen concentration. It seems these did not work probably because they required power to operate which was not available. Now, these explosions essentially removed the secondary containment that could have controlled the release of iodine, cesium, and tellurium. If there is a primary containment breach, this is the thick reinforced concrete barrier between the core and the outer building, we may not necessarily see high level releases because we may have seen the bulk of the volatile elements being released already. It is really hard to predict at this point, our hope is that we have seen the worst of this.