@Dean - I have not seen air compressor or service air tanks in the main reactor building. But I haven't been looking for them either. Would they be like big LP tanks on their side or more like a big outside upright tank? There are small upright tanks in the middle alley between reactor and turbine IIRC?
by lillymunster 11/6/2011 2:39:50 PM
@LILLY most of the tanks I've seen are vertical standing tanks.. some of the accumulators for air on components have smaller tanks
by dean 11/6/2011 2:40:48 PM
@Edano, it would be nice to interview that operator who turned off the IC.. I'll bet his concern was for the thermal stability on the vessel
by dean 11/6/2011 2:42:10 PM
@dean
the upright tanks I saw that are outside remind me of upright oxygen tanks used at hospitals. I have not looked closely to see if they are liquid tanks or air tight type
by lillymunster 11/6/2011 2:42:32 PM
@Edano, doesn't only 1 have an IC? The operator said he closed the IC off because the reactor vessel was cooling too fast.
by lillymunster 11/6/2011 2:43:45 PM
@lillymunster @dean the article says they were shut right before the tsunami, so before heating up. there was only the scram.
by Edano 11/6/2011 2:45:04 PM
maybe there was really quake damage that made the operator shut the valve as emergency measure ?
by Edano 11/6/2011 2:46:13 PM
@Edano One IC at unit 1 didn't work. The other one worked but the worker shut it temporarily to hault cooling. Then they lost power to the valves and he couldn't open it back up.
by lillymunster 11/6/2011 2:47:13 PM
@Edano IIRC Unit 1 = IC all others = RCIC
RCIC being the newer technology?
by lillymunster 11/6/2011 2:47:32 PM
But operators soon noticed that the IC was cooling the core too quickly, which could stress the steel walls of the pressure vessel. So they shut the system down. It was a by-the-book decision, but the book wasn't written for the extraordinary events of 11 March.
by dean 11/6/2011 2:48:17 PM
@dean before tsunami.
by Edano 11/6/2011 2:48:49 PM
At 2:52 p.m., the shift supervisor overseeing the plant's oldest reactor, the 40-year-old unit 1, confirmed that a backup cooling system called an isolation condenser (IC) had started up automatically. This system didn't need electric power to cycle steam through a cold-water tank on a higher floor, or to let the resulting water drop back down to the pressure vessel.
by dean 11/6/2011 2:49:42 PM
Tsunami alerts flashed on TV screens, predicting a 3-meter-high tsunami for Fukushima prefecture. Although the coastal Fukushima Dai-ichi plant was 10 meters above sea level, nonessential personnel followed procedure and began evacuating the site.
At 3:27 p.m. the first tsunami wave surged into the man-made harbor protecting Fukushima Dai-ichi, rushing past a tidal gauge that measured a water height of 4 meters above normal.
by dean 11/6/2011 2:50:08 PM
i have the impression that #1 scram did not work properly. (???)
by Edano 11/6/2011 2:51:31 PM
RPV's have maximum cool down rates so operator was maybe thinking damage to the vessel
by dean 11/6/2011 2:51:35 PM
something does not add up.
by Edano 11/6/2011 2:53:29 PM
@Edano.. all indications are that it did.. but,,, still so much not answered as a result of the EQ and we saw severe damage in #2 from eq..
by dean 11/6/2011 2:53:42 PM
@dean the post quake scram was a "normal" scram like they did that 100 times before. but this time the vessel cooled down too fast ???
by Edano 11/6/2011 2:55:33 PM
so that they shut down a vital emergency system ?
by Edano 11/6/2011 2:56:11 PM
the scram was normal for the EQ and, there were likely many other scram signals tripped aside from the EQ, those scram signals and interlocks all played into the unfolding of the event. I belive the IC started due to low level in the reactor vessel which is automatic trip... the steam isolation valves closed and resulted in the RPV pressure surging which overwhelmed the system and caused the relief valves lift to blow down steam.. that in turn caused the vessel level to BOIL OFF and water level lower,, then at the certain level the IC pours cold water into the vessel and I imagine the operator saw the temps lowering and from that single observation.. closed off the IC.. probably thinking.. I will open it later
by dean 11/6/2011 3:01:53 PM
@Peter.. that's the number i was looking for.... in addition.. I'll bet those operators and super's were thinking .. get things in controll so we can restart.. thats the mental thoughts.. not that the reactor is ruined..
by dean 11/6/2011 3:04:14 PM
the operators would have been heading for normal HOT shutdown mode which is higher temps on RPV.. then cold is 100
by dean 11/6/2011 3:06:35 PM
I"ll be back. time to head out and drive folks ...
by dean 11/6/2011 3:07:34 PM
is there only "off" and "on", but not something like "reduced flow" ?
by Edano 11/6/2011 3:08:18 PM
@Edano The IC valves have big springs on them. They look like they could have more than on/off but I don't know what the control systems allow them to do. The ones I have pics of are steam isolation valves so these might be for the turbines not the IC.
by lillymunster 11/6/2011 3:27:09 PM
@Peter Melzer yes, and i am trying to find this particular system ..... :)
by Edano 11/6/2011 3:33:25 PM
TEPCO to review criteria for determining 'criticality'TOKYO, Nov. 6, Kyodo
english.kyodonews.jp by Edano 11/6/2011 4:06:32 PM
@MaryW tepco is good in redefining terms....
by Edano 11/6/2011 4:10:57 PM
as this catastrophe is a completely new thing, they could even invent some terms.
by Edano 11/6/2011 4:17:55 PM
like "coresearch", for example.
by Edano 11/6/2011 4:25:42 PM
hard core and liquid core.
by Edano 11/6/2011 4:26:45 PM
damn, the word "liquor" exists already.
by Edano 11/6/2011 4:27:28 PM
update on fuku workers tweets from rockhopper
Tonight, the Fukushima worker talked about 'graduating from nuclear
energy' and possibility of it in Japan. He assumed, if Japan did a
public vote like Greece, it would go for no-nuke power. But, he thinks
that a public vote would not happen in Japan, and that it's necessary
to have a leading party which is against nukes and have a PM out of
the party in order for Japan to go forward it. He wonders if Japanese
can accept the economical situation without nuclear energy. Without
it, industries would stagnate and tax would increase. Will it be OK? -
he wrote (I am sure that many of his followers feel upset this
comments, because so many no-nuke people believe that this is THE
pro-nuke's opinion to support the industry.) Another issue he raised
is about Pu reprocessing. Japan has to do it (at Rokkasho and Tokai
villages) because now no other countries would do it for us, and
because of the 'peace use of Pu' Japan has declared. He guesses that a
reason why Pu contamination is not on the news is because they don't
want people to oppose to reprocessing and MOX fuels. Simane and Ooma
reactors now under construction are all for MOX fuel. This is why they
don't want us to think about it. He wonders if no-nuke may not be
possible unless 'a revolution' happens in Japan. He wrote that many
adults in Japan, especially parents, seem to hope that they don't want
to leave nuclear reactors for future children. Then, he wrote at the
end that victims of Fukushima, including him, think that no-nuke is
not easy; to do that, all Japanese have to work together with a strong
determination, and Japan need a very strong PM.
by elainekirk 11/6/2011 4:51:18 PM
@Edano , according to the log the scram worked. The instruction manual tells the operator not to cool the RPV down faster than 55 degrees Celsius per hour. However in a situation like this, and the superintendent in the main command center may have had an inkling of the extent of the damage, they would have been better of to ignore this instruction for a while and see how the rate of change develops. I wonder whether the superintendent had access to ground motion readings.
@Edano You would think a company in charge of a nuclear power plant would KNOW the criteria of all policies and procedures in the 'manual'.by MaryW 11/6/2011 4:09:53 PM
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