[Territori_energia_resistencia] Fwd: [eco-eco] IMPORTANT: Situation at Fukushima 1 NPP worsens + Uncertainty on the radioactivity level

[Pere Ariza]

Col·legues,
Passo informació de François Diaz-Maurin, de l'ICTA-UAB, ex-enginyer
nuclear, que està fent una interpretació interessant, informativa i
traductora del que va passant a Fukushima.
Us passo la informació des de la més recent a la més "antiga"... el boom
d'informació a vegades fa antic allò que acaba de passar fa unes hores!!!
Crec que pot ser d'interés per entendre detalls tècnics.
Records i abraçades,
Pere

3) IMPORTANT: Situation at Fukushima 1 NPP worsens + Uncertainty on the
radioactivity level

Dear everybody,

I am very sad and sorry to have to send you again another update about the
nuclear crisis in Japan but the most recent events at the Fukushima I NPP
are very worrisome. To make things even worse, it is really hard to get
information about the current state of the plant reactors. So my analysis is
relying on what TEPCO is eager to release.


*Situation at Fukushima 1 NPP worsens:

*There is now a cascade of problems ongoing at the plant site:
- a new hydrogen explosion at unit 3 this occurred morning, as it has
already been the case at unit 1 on Saturday.
- apparently unit 2 is also experiencing injection of sea water and boric
acid (BBC information, not confirmed by TEPCO to my knowledge), which was
only the case of unit 1.
sources: http://www.tepco.co.jp/en/press/corp-com/release/11031312-e.html ;
http://www.tepco.co.jp/en/press/corp-com/release/11031402-e.html ;
http://www.bbc.co.uk/news/science-environment-12726628

I want to highlight again the difference between "shutdown" and "cold
shutdown". A rector is "cold shutdown" (completely off) only when the
nuclear fission reaction in the core is completely stopped. However,
although all 6 units of Fukushima I are "shutdown", units 1 to 3 are still
not "cold shutdown" meaning that a significant amount of heat is still being
produced in the core as the chain reaction is not completely stopped. The
time difference between "shutdown" and "cold shutdown" can take several
days, weeks or even months if no sufficient cooling is supplied (and so does
the number of partial discharges of radioactive materials in the air). Note
that the nuclear fission chain reaction is a self-sustained reaction that
would last a long period of time unless it is stopped by external
intervention (cooling). If the cooling fails, the reaction does not stop by
itself and the related problems remain (or worsen).

The explosion at unit 3 is technically the same as Saturday's one at unit 1
(hydrogen explosion). However, its effects will not be the same as the fuel
used in the reactor is different. Indeed, (unfortunately) unit 3 has been
the first reactor from TEPCO to use reprocessed fuel, the so-called MOX
(mixed oxyde) fuel, since August 2010.
sources: http://search.japantimes.co.jp/cgi-bin/nn20100823a7.html ;
http://www.japantoday.com/category/technology/view/mox-fuel-loaded-into-tokyo-electrics-old-fukushima-reactor

MOX fuel is used in nuclear thermal reactors for two main reasons : (1) it
allows using the weapon-grade plutonium in an attempt to reduce the nuclear
weapon arsenals; and (2) it allows reprocessing (not "recycling"!) the spent
nuclear fuel of other reactors to avoid having to store the waste (which is
today one of the main unsolved issue of the nuclear industry). Reprocessing
used fuel corresponds to switch from the once-through nuclear fuel-cycle (or
opened cycle) to the closed fuel-cycle. However, it is well known that the
closed-fuel cycle is not a preferred solution as it increases the risk of
nuclear proliferation while saving only up to 25% of uranium mining (see the
2010 MIT report on the nuclear fuel cycle).
source: http://web.mit.edu/mitei/news/spotlights/nuclear-cycle.html

Nevertheless, Japan was apparently planning to have one third of its
reactors using MOX by the end of 2010 in an objective to switch towards a
close-fuel cycle solution (information not sourced). Also, note that MOX is
not reprocessed today, so that we definitely cannot speak of "recycling"
when dealing with the closed-fuel cycle (even if the industry is using that
word).


*Uncertainty on the radioactivity level:*

I did not found much information and knowledge about the toxicity of MOX
fuel compared to regular spent nuclear fuel. In general terms, the shorter
the "half-life period" is (the time necessary for the radioactivity to be
reduced by 50%), the more hazardous the product is. This is due to the fact
that short half-life products are more active than long half-life products,
such as depleted uranium (U-238) with an half-life of 4.5 billion years
(practically stable, i.e. not active). In MOX fuel, Curium-242 may be
produced as a by-product of the fission reaction with potential harm as it
has a short half-life of 150 days or so. Another indicator of the potential
toxicity of MOX is that, in France, operating licenses do not yet allow MOX
fuel to remain on site, contrary to uranium fuel.

For now, TEPCO is reporting an equivalent radiation dose rate of 0.02 mSv/h
in the surroundings of the plant. This means that if one stays 1 hour
exposed to this radiation level, it receives about 0.02 mSv to its entire
body. For instance, a Paris-New York flight corresponds to a dose of about
0.06 mSv. So if the dose rate remains stable during one week, the people
around the plant would receive a dose of 7*24*20μSv/h = 3.36 mSv, so about
56 Paris-New York flights! For now, there is no reason to say that the
radiation level will drop. Indeed, it would be good news if it would remain
stable.
source: http://www.tepco.co.jp/en/press/corp-com/release/11031402-e.html

Another source of information tells me that 2km from the Fukushima 1 plant,
a radiation dose rate of 0.1 mSv/h has been measured by journalists. Other
measures talk about dose rate between 0.02 and 1 mSv/h! FYI, in February
2011, the radioactivity dose rate measured by the same journalist was about
0.04 mSv/h in Chernobyl. Also FYI, the annual dose of an individual living
in France is 2.4mSv (average rate of 0.0002 mSv/h).
So, if this information is true, the situation in Japan is dramatic.
source: Information from http://www.sortirdunucleaire.org/ in personal
communication (website unaccessible)


To conclude, the situation has now become critical as a cascade of adverse
events is currently happening at Fukushima 1 NPP, worsened by the high
uncertainty we face in respect to the radioactivity that is actually
released there.


François Diaz Maurin
Ph.D. Candidate
Research group on Integrated Assessment
Autonomous University of Barcelona (Spain)

Institut de Ciència i Tecnologia Ambientals (ICTA)
Economía Ecológica Despatx QC 3091 – Escola Tècnica Superior d'Enginyeria
(ETSE)
Universitat Autònoma de Barcelona (UAB)
08193 Bellaterra (Cerdanyola del Vallès) – Barcelona
Tel. (+34) 93 586 81 02
Fax. (+34) 93 586 80 08
http://www.eco2bcn.es/

2) UPDATE and CONCLUSION: Fukushima Nuclear Power Plant Events

Dear all,
This is will certainly be my last email covering the current events at
Fukushima nuclear power plants in Japan as the situation seems now to be
stable. Nevertheless, note that the only "reliable" source of information is
coming from TEPCO, the operating company of Fukushima nuclear power plants,
as they are the only one to have access to the plants, and thus to know what
really is going on. All information depends on what they share with the
outside world.

*Table of contents:*
*1. Quick summary of the current situation at Fukushima 2 (or Fukushima
Daini) (4 units)
**2. Quick summary of the current situation at Fukushima 1 (or Fukushima
Daiichi) (6 units)*
*3. Specific summary of the current situation at Fukushima 1 - Unit 1*
*4. Risks and prospects of the future situation at Fukushima 1 - Unit 1*
*5. Conclusion and potential effects on the civilian nuclear industry

*
*1. Quick summary of the current situation at Fukushima 2 (or Fukushima
Daini) (4 units)*
- According to TEPCO, all 4 units have been shut down and their reactor
water levels are stable.
- However, only unit 3 is "cold shutdown" (under full control). The others
still being cooling the reactor core one way or the other.
- All 4 units are releasing partial discharges of air containing radioactive
materials in order to maintain the pressure in the containment building down
(to avoid meltdown of the core due to high pressure & temperature).
- Those releases have been the decision of TEPCO operators.
- The evacuation zone is 10 km from the nuclear power plant.
- The situation can be considered under control as TEPCO operators "do not
believe there is leakage of reactor coolant in the containment vessel" for
all 3 remaining units that are still not cold shutdown.

source: http://www.tepco.co.jp/en/press/corp-com/release/11031233-e.html


*2. Quick summary of the current situation at Fukushima 1 (or Fukushima
Daiichi) (6 units)*
- According to TEPCO, all 6 units have been shut down.
- Units 4, 5 and 6 were on outage (shut down) at the time of the earthquake
and TEPCO operators "do not believe there is leakage of reactor coolant in
the containment vessel".
- On unit 2, the water level is stable (although low). On unit 3, there is
still injection of water inside the containment building to lower the
pressure.
- Both units 2 and 3 are releasing partial discharges of air containing
radioactive materials (for the same reasons as on Fukushima 2 NPP). Those
releases have been done *under the instruction of the national government*.
- The evacuation zone is 20 km from the nuclear power plant.
- The situation can be considered under control as TEPCO operators "do not
believe there is leakage of reactor coolant in the containment vessel" for
units 3 to 6 although they are not cold shutdown.
- No more information for unit 2, but it sounds like an explosion like the
one which occurred at unit 1 could happen at unit 2.
- For unit 1: see below.

sources: http://www.tepco.co.jp/en/press/corp-com/release/11031301-e.html ;
http://lci.tf1.fr/science/environnement/2011-03/accident-nucleaire-au-japon-un-autre-reacteur-en-difficulte-6308683.html


*3. Specific summary of the current situation at Fukushima 1 - Unit 1*
- Unit 1 is shutdown but the core is still hot with a risk of meltdown.
- Sea water and boric acid which absorbs neutron (responsible for the
fission chain reaction) are thus injected into the reactor core to lower its
temperature.
- The explosion which happened in the containment building has been damaging
*only the roof of the building* (made of concrete I think)*, the steel
containment layer remaining intact.*
- The successive layers of protection from inside to outside are the
following: 1) Reactor core (probably partially meltdown); 2) Reactor vessel
(state unknown but should be OK if core not fully meltdown); 3) Containment
steel layer (intact); and 4) Containment building (broken).
- The explosion is due to a contact between hydrogen from the containment
building and the oxygen from the outside. The hydrogen has been formed
between the steel layer and the building as a result of a lack of water in
the reactor building.
- Unfortunately, TEPCO on-site webcam is really not of help to visually
understand the situation as the power plant is hidden by trees...
http://www.tepco.co.jp/nu/f1-np/camera/index-j.html

sources: http://www.tepco.co.jp/en/press/corp-com/release/11031301-e.html ;
http://www.reuters.com/article/2011/03/12/japan-quake-reactor-idUSTKZ00680620110312


*4. Risks and prospects of the future situation at Fukushima 1 - Unit 1*
- Current situation at Fukushima 1 - Unit 1 is already the second worst
civilian nuclear accident after Chernobyl in the relatively short history of
the nuclear industry.
- Consequences of a meltdown at unit 1 would "only" be local (although being
dramatic for the immediate environment) as no explosion of the reactor
vessel or of the steel containment layer is expected (design different from
Chernobyl, so this scenario is to be excluded).
- However, in the case of full meltdown, the core in "fusion" would probably
go through the containment building floor and release radioactivity into the
ground. This scenario cannot be fully excluded for now.
- But chances are that the operators will manage to cold shutdown the
reactor.


*5. Conclusion and potential effects on the civilian nuclear industry*
- The Nukushima accident would certainly have immediate effects on the
discussion about nuclear energy and its potential role as an alternative
energy source. All this will depend on how the public opinion reacts after
the accident.
- We can be expected that the nuclear industry will soon focus on the
natural disaster cause of the Fukushima accident, saying that new plants
(such as Areva's EPR) are designed to sustain such seismic events. This is
true. However, given the fact that upmarket designs (1300MW and more) are
uneconomical, the trend is to build cheaper new plants (1000MW and less).
But such plants do not necessarily benefit from the same design features (as
being a trade-off between economy and safety).
- As far as having small modular reactors (300MW and less), the consequences
of an accident would be less than in a bigger plant but the overall risk of
accident (= consequence of one accident * likelihood) would be the same or
even higher depending on the number of those SMRs that are deployed...
- Nuclear fusion for commercial use is not to be considered as a significant
alternative energy source (if it is to be the case) before the end of the
century (according to my study) so that the current nuclear fission
technology is likely to remain the only available solution we can
realistically account for in the discussion about imminent energy supply
issues.

Sincerely,

François Diaz Maurin

1) UPDATE: IMPORTANT: About the Effect of the Earthquake on Nuclear Power
Plant in Japan

The situation at Fukushima-Daiichi nuclear power plant is becoming serious
(but not "critical" in technical terms).

*Explosion:*
It sounds like the explosion that occurred at the plant is an hydrogen
explosion outside the reactor building. So neither the reactor vessel
(second layer of protection), nor the containment building (third layer)
have been damaged due to this explosion.
http://www.nytimes.com/2011/03/13/world/asia/13nuclear.html

*Radioactive leaks:*
For units 1, 2 and 4, the TEPCO press release says that "partial discharge
of air containing radioactive materials" have been released.
http://www.tepco.co.jp/en/press/corp-com/release/11031221-e.html

The evacuation zone has been extended from region #1 to region #2 (10 km
around the plant) due to the release of radioactive materials in the air. If
no more release is performed, people could come back home as soon as the
concentration of those materials is diluted in the air.

This information is confirmed by media (I follow mostly Matthiew Wald from
NYTimes and Reuters)
http://www.nytimes.com/2011/03/12/world/asia/12nuclear.html
http://in.reuters.com/article/2011/03/12/japan-quake-leakage-idUSTKB00729820110312

According to Reuters, the evacuation zone has been now extended to 20 km.

*Reactor cores:*
In the last press release from TEPCO, they indicate that all units have been
correctly shut down. However, having the control rods down (which stop the
chain reaction) does not necessarily mean that the core temperature is not
rising. Among all 4 units, only unit 3 is cold shut down (= under full
control).
As far as the others reactor cores, their high temperature is damaging the
core so we can expect (at least) a partial meltdown if this situation
continues. If a meltdown occurs, it will damage the reactor vessel and only
the containment building will remain between the core and the environment. A
meltdown core can potentially damage the containment building (due to a
specific reaction between the core and the concrete) with severe
consequences on the environment.

This is the most important risk of Fukushima nuclear power plant. And the
probabilities are multiplied by a factor of 3, as 3 units out of 4 are
concerned.

Regards,

*0) Primer mail enviat:*

Dear colleagues and friends,

As a former engineer in the US and French nuclear industry, I can tell you
that what is currently happening at the Fukushima-Daiichi nuclear power
plant is really important.

The safety reactor coolant systems are mal-functioning (normally activated
by safeguard diesels that are now out of order), so that the reactor core
cannot be cooled normally. As a result, the temperature of the core is
rising (with an increased risk of melting) and so does the pressure inside
the containment building. If this pressure is becoming too high, there is a
risk of explosion of the containment. Although the design of the plant is
not the same as the one in Chernobyl, there are still "chances" that such a
worst case scenario happen at Fukushima plant if the pressure inside the
containment is not lowered. The only way to keep the pressure down to a
certain level is to release some gases into the atmosphere, but those gases
are most probably with a high level of radioactivity.

Last news here: http://live.reuters.com/Event/Japan_earthquake2

> * Power company TEPCO says it has lost the ability to control reactor
> pressure at Fukushima No. 1 and No.2 reactors. A spokesman said pressure is
> stable inside the reactors but is rising in the containment vessels. He said
> it is not known if there will be a need to release pressure at the plant at
> this point. That would involve a release of radiation.*
>

At the present time, only the engineers on-site know exactly what is going
on (and what to do). Unless the operators can one way or the other have the
safety reactor coolant system working again, they most probably chose the
option of successive gas releases until they can cool the core and shut down
the reactor.

It sounds like the US Air Force is shipping in emergency some generators to
help restart the coolant systems (pumps).

Be sure that all countries will do everything possible to prevent a worst
case scenario from happening. A severe accident at the Fukushima-Daiichi
nuclear plant, and it will be the cause of a new human and environmental
disaster which will certainly marks the end of the nuclear industry.

All this depends on the current decisions made by the crew of the Fukushima
power plant.

Hopefully they stay clever.
Sincerely,

François Diaz Maurin
-- 
"En la plenitud de este acto de amar, en su existenciación, en su praxis, se
constituye la solidaridad verdadera."  Paulo Freire

Pere Ariza-Montobbio
931825776
ICTA-UAB 93 586 81 02 //93 581 29 74. pere.ariza a uab.cat
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