So instead of just past midnight on March 13, 2011, the water may have stopped 6 hours earlier, on the night of March 12, 2011, a few hours after the Reactor 1 building blew up in an hydrogen explosion (which may have happened on the 4th floor instead of the 5th, top floor).
From Yomiuri Shinbun (3/24/2013):
３号機注水、１２時間途絶か…解析やり直しへ
Water injection into Reactor 3 may have stopped for 12 hours, analysis to be redone
２０１１年３月の東京電力福島第一原子力発電所事故の際、３号機の原子炉への冷却水注入が途絶えた「注水の空白」は約１２時間に及んでいた可能性が、東電などの調査で明らかになった。
It has been revealed by analysis by TEPCO and others that the blank in water injection into the Reactor 3 RPV may have been 12 hours in March 2011 in the Fukushima I Nuclear Power Plant accident.
３号機の「注水の空白」は従来、３月１３日未明から６時間半とされていたが、当時の運転員が記録した水位データが昨秋、新たに判明し、最大で約６時間早い１２日夜には注水が止まっていた恐れが出てきた。
The blank in water injection into Reactor 3 is said to have been for 6.5 hours starting in the early hours of March 13, 2011. However, the data on water levels recorded by the operator at that time surfaced in fall last year, which shows the water injection may have stopped max 6 hours earlier, on the night on March 12, 2011.
東電はこれまでの解析で、３号機の炉心溶融は１３日朝に始まったとしてきたが、注水が早く停止したという新しい条件に基づき、解析をやり直す方針。その結果次第では、放射性物質の拡散状況を推定する前提条件が変わる可能性もある。東電の調査に関して、政府の事故調査・検証委員会は昨年７月の最終報告書で「事故の解明は不十分で、検証すべき論点やデータが残っている」と指摘していた。
TEPCO's current analysis shows the core melt of Reactor 3 started in the morning of March 13, 2011. The company plans to redo the analysis based on the new condition that the water injection may have stopped earlier. Depending on the result of the new analysis, it is possible that the conditions to estimate the dispersion of radioactive materials will change. Regarding TEPCO's investigation [of the accident], the independent accident investigation commission set up by the Cabinet Office pointed out in the final report issued in July last year that "the investigation of the accident is not enough, and there are issues and data still to be studied".
All I can say is that the investigation commission is correct.
Even though there was no MOX fuel in the Reactor 3 Spent Fuel Pool at the time of the accident, it was in the Reactor Pressure Vessel, being used in generating power.
Back in May 26, 2011, Mainichi English reported that TEPCO admitted the pipe connected to the High Pressure Coolant Injection system (HPCI) for the Reactor 3 probably broke during the earthquake (see my post on that day).
On March 13, 2011 at 12:55PM, TEPCO discovered that 1.9 meter of the fuel rods in Reactor 3 were exposed, and at 1:12PM they started to pour seawater into the RPV (see my post that day). Well, that 1.9 meter exposure was false, in retrospect.
Earlier that day, the emergency battery power ran out for the High Pressure Coolant Injection System, and the system shut itself down at 2:44AM. At 4:15AM, the fuel rods started to get exposed as the water in the container started to boil and water level started to go down. Nuclear emergency was issued on 6AM. (See my post from that day.)
Now, TEPCO is saying the water may have stopped much earlier than 2:44AM on March 13, 2011 when the HPCI stopped. Or are they saying the HPCI itself stopped much earlier? Or are they saying water ran out (as the pipe to the HPCI had been broken in the earthquake) before the HPCI stopped?
I'm looking forward to TEPCO's new and improved analysis. I want to know the true timeline of events, which is clear as mud after more than two years since the start of the nuclear accident.
Whether you like it or not, TEPCO remains unfortunately the only source of information when it comes to Fukushima I Nuke Plant.
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9 comments:
I heard there were 32 assemblies in the spent fuel pool of No. 3, is this wrong? Were they actually in the reactor then? So how many MOX assemblies total at Fukushima Daiichi?
Criminal himself investigating the crime.
Other professionals in Japan is no more, it's obvious.
However, you will never know the truth.
... and while there is still so much to be understood about what went wrong the Abe administration is moving quickly to restart the nuclear machine in Japan.
Had nuclear powerplants been planes, they would be more cautious with the restarts; maybe because for planes the manufacturer and the operator are liable while for npps the taxpayer is liable.
Beppe
P.S. after reading again the statements made by Mr.Abe today it seems that his administration is heading towards returning the residents quickly to their villages (no mention of acceptable radiation limits); furthermore he is saying that recovery will be difficult unless reasonably priced electricity is available.
I might be wrong but I would interprete this as something like "you folks stop asking to be compensated for having your land and your homes contaminated and go back to your 20 mSv/yr villages now. Also, if you want to see any recovery money [recovery from the earthquake] you need to shut up and restart your npps."
Good old pro nuke LDP, did the Japanese miss it so much to vote it back into power?
Beppe
Nick, all 32 MOX fuel assemblies were in the reactor pressure vessel, NOT in the SFP. What you heard is wrong.
Fukushima Reactor 3 started "Pluthermal" - that's using MOX fuel, in fall of 2010, for the first time. There is no spent MOX fuel at Fukushima.
These MOX fuel assemblies were brought to Fukushima I in 1999, had been kept in the Reactor 3 SFP until 2010 when they were loaded in the reactor after more than 10 years of storage.
Beppe, as you know, LDP didn't need much support from the citizens. Half the population didn't vote anyway, and majority of those who voted did vote for parties other than LDP. LDP candidates happened to get the most vote, as people were baffled with parties they never heard of.
It's really amazing how old these MOX fuel elements already were.
They were way more than three years old. Mox "pluthermal" fuel is recommended not to be more than three years old because of their plutonium-241 decay, making them difficult to control because of its decay to the very dangerous Americium.
Americium in fuel in turn causes severe problems because of gamma and neutron decay. They are actually sort of permanent neutron source, which is very undesirable because this can start an unintended chain reaction easily (making reactor control very difficult).
The plutonium used in these elements was probably reprocessed in the mid-1990s in La Hague, so an age of around 15 years seems realistic. Thus there was plenty of Americium in the fuel.
The very high neutron activity of these fuel elements could possibly have contributed to a violent nuclear deflagration as seen when #3 went kaboom when it was reflooded with (sea)water.
Remember, the control rods had molten away already, so the combination of MOX and seawater cooling could have been like kick-starting the reactor without any brakes remaining, leading to a small nuclear explosion that was only stopped by the thermal expansion.
@1:59 while I agree it is not unreasonable to state that the LDP does not have a vast popular support I would maintain that the Japanese voters (those who voted and those who did not) bear the responsibilty of having put the LDP back in power.
Off topic, according to NHK Tepco will accept compensation claims basd on loss of sales caused by "damaging rumors", including sales losses of shiitake mushrooms from Kumamoto and expenses to measure radioactive contamination. I wish the bill were footed by cutting into nuclear subsidies rather than increasing taxes or electricity rates but maybe I am asking too much. Also, I wish these costs were taken into account when assessing the cost of different energy sources... asking too much again?
Beppe
http://areva.com/EN/news-9735/preparation-of-the-5th-mox-fuel-maritime-shipment-to-japan.html
he-he ) Nice!
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