Taka Hiraishi
29th March 2013

Personal Assessment
This is a completely personal note, written largely for the purpose of brain storming!
Your shouts will be welcome! <taka_hiraishi@nifty.com>

For a long time, I did not update this file. (I did an update on 1st August 2011.) My excuse israther simple. I was devastated by my mistakes due to the lack of correct information. After the
Fukushima nuclear accidents, I dilligently monitored information available through the Internet,
including radioactivity monitoring resulsts, which was relatively accurate. In addition, I
continued regular surfing of the websites based on which I undertook my assessment of risks.
However, I was completely mistaken, or I would say, misled – for instance, through thewebsites, “measured” temperatures were regularly reported, and judging from them, I thoughtthat the large part of nuclear fuel rods are kept under water. However, most of the measurement
equipments, even the water level gauge, were not properly working, which was revealed only along time after the accident.
Even after two years of time, the situation is fat from “under control”. Dismantling those four
nuclear reactors will take decades of time. Final disposal of high level radioactive materials
remains century-long question. I am only hoping that technolocal innovations and dedicatedworkers on site will find certain solutions.
And most importantly, there are thousands of people who had to move away from their homeand had to find new life. My sympathies might not mean anything for them, and there is reallynothing that I can do for them.

11th August 2011
I have been completely occupied with my work with the IPCC, more than half staying out of Japan, and losing up-todate information on the Fukushima. I am trying to catch up . . .

Overall radiation
Except those areas close to the site, environmental radiation readings are nearly back to normal, I
think.

1http://www.mext.go.jp/english/incident/1303962.htm

Containment at the site
Thanks to the impressively dedicated and highly organised work, there have been steadyadvances on containment work. Facilities for the decontamination and re-circulation of water in thebuildings and outside trenches are working fairly well (though with a few minor technical problems, ofcourse), and external cooling systems for the spent fuel rods pool are being installed. However, thefeeding of cooling water to the reactors #1, #2 and #3 still continues (at a gradually slower rate as thegenerated heat from fuel is getting smaller) – this continuously generates contaminated water (luckily it is
now at less rate than that of the decontamination).

Residual radiation is a matter of serious concern
On the other hand, radioactive fallouts, probably largely from mid-March emissions, persist andare causing a wide range of potential health risks, most notably through beef production and marketing.
Somewhat mysteriously for me, risk of radioactive contamination of feeding hay was completely
overlooked and consequently a few lots of beef that exceed current food radiation standards (500 Bqs/kg)
leaked to the market. Naturally this caused nation-wide concerns among the consumers, which has forced
the authorities to introduce complete monitoring of all the beef cattle – thus consumers will be protected,
though at an enormous costs and time as well as the public feeling to reduce consumption of domestic
beef. A serious lesson was learned – a small oversight can be very costly.
High radiation has been detected from debris (from earthquakes), removed top soil and plants, aswell as waste water treatment sludge and waste incineration ash, and the volume of them is steadily
increasing. The Ministry of the Environment has issued a guideline that those wastes that do not go
beyond 9,000 Bqs/kg can be disposed of in regular “managed waste disposal sites”, and requested to store
the other wastes safely. As the amount is getting larger, the treatment of the latter is getting a challenge
for the region and the nation.

2

This image is a contour of recorded environmental radiation, shown at<http://kipuka.blog70.fc2.com/blog-entry-413.html>, which was based on the work of<http://www.nnistar.com/gmap/fukushima.html> (reflecting more than 26,000 measurement records since
March compiled by the Ministry of the Education and Science.).
Please note that this image is a compilation of results of a wide
range of different measurement schemes, and should not be used
as a basis of any decision-making unless all the measurement
parameters are individually considered.
I would not attempt to carry out a risk assessment based on thisbecause I do not have any exposure data of reasonable quality, but
I tend to believe that evacuation plans might need to be seriously
re-considered, without paying any attention to the cost that might
incur. Very detailed environmental measurements must be carriedout and we should not shy away from strong actions to protect
people’s long-term health damages.

3

Taka Hiraishi
25th June 2011

Personal Assessment
This is a completely personal note, written largely for the purpose of brain storming!
I have not been able to update this note because of difficulty of accessing the Internet while I was attending
the UNFCCC meetings held in Bonn. (Needless to say that most of my attention has to be paid to the negotiation of
future climate actions, even though the progress is extremely slow and frustrating …..)

Overall environmental radiation levels
Fortunately environmental radiation levels have been steadily lowering, which implies
that there has been no additional major emission of radio-nuclides. However, some spots aroundthe Fukushima reactors continue to show higher levels as shown below. The Government’s
general criteria contain 20 mili SV/year for evacuation and unfortunately some areas show
significant levels even 3 months after the mid-March major emissions. Contamination in the
coastal sea water shows declines.

Hot spots
As monitoring activities (both by Government agencies monitoring and private
activities) advance there are few spots outside the stipulated evacuation areas where high levelof environmental radiation has been recorded. The Government might need to address theseareas.
Schools
As I noted earlier, the Government has lowered the target levels, but public concernsand debates continue.
Health monitoring
In Fukushima Prefecture a wide range of health monitoring has started, which would
have to be continued for a long time span.

4

Food and water monitoring
Monitoring of food and water continues and a few cases of detection above the“provisional standards” and the required market restriction has been applied. My personalassessment is, however, in view of the overall environmental radiation levels and this situation
will not aggravate, though contamination of agricultural products from the nearby areas willcontinue a matter of concern.
Actions at the Fukushima Station
Water purification and re-circulation work is steadily progressing. Addition of coolingwater has to continue to the reactors and spent-fuel cooling pools as a must, and some 30-40
tonnes of water is added to them every day, especially to the reactor #3 of which temperature is
still high (around 150 degrees C – I do not know why #3 has higher temperature?). The total
amount of water thus accumulated in the tanks or underground structure so far has amounted tosome 120,000 tonnes which is termed, “highly contaminated”, and it is increasing day by day(and the rain season is here in Japan). TEPCO has constructed a purification process –containing (i) oil removal, (ii) Caesium removal, (iii) overall nuclides removal, and (iv)desalinisation. The facility is still being tested, but they have reported reduction to the level of
10,000th (by (i) though (iii)) which contains only two digits of Bq per Kg (please remember thatthe drinking water standard is 200 Bq/water). Thus, they are close to the final stage to the using
the purified water for cooling. One quantum step towards containment!

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5

Taka Hiraishi
2nd June 2011

Personal Assessment
This is a completely personal note, written largely for the purpose of brain storming!
Environmental radiation levels
Environmental radiation levels have been steadily lowering. Though rainy season ishere in Japan, radiation does not increase after rains – earlier we saw radiation peaks after rains.
This means that there havenot been any major new
emissions. However, higher
radiation still persists in theareas near the nuclear site,
especially in the North-west
direction from the Fukushima#1 nuclear station. (The twocircles show 20km and 30km
radius.) High radiation levelsin the North-west direction
have been continuously
observed since mid-March,probably due to the mainthemission of radio-nuclides occurred on 15 March. This image also shows high levels ofenvironmental radiation above the natural radiation level. (if you use my excel sheet, you can
see that one microSv/hour means 8.76 miliSv/year, and we casually use the figure of 1
miliSv/year as natural background.)Containment actions at the site
TEPCO’s fight against time still continues. While the reactor temperatures are relatively
under control, they absolutely need to continue cooling of three reactors, and a total of some 20
tonnes of water per hour is added to them and leaked out. Thus, the high radiation level water isincreasing every day, either in the ground rooms of the buildings or outdoor trenches. They are
constructing a French company’s water decontamination plant (scheduled to be completearound 15th June, but their water storage space for the high radiation water is getting shorter.
TEPCO says the construction is on schedule, but they do not hide their concerns. (Rain season
is here in Japan, and the roof of the three houses (#1, #3 and #4) were lost by the hydrogen
explosions in March!)
Food and water
Agricultural and fisheries products as well as water supply have been continuously
monitored, and there have been a small number of detection, and required marketing restrictions
have been enforced. Thus, I do not consider that there are imminent health risks for the public.

6

Nevertheless, consumers are concerned and sometimes results in reluctance from purchasing
products from nearby regions.
Remnant radiation
Cases of radiation measurements are increasing, in such areas as soil of schools andparks, agricultural soils, and sewage treatment sludge. Disposal of them is faced withdifficulties, and this will continue for some time, I am afraid. (Some cases will get less serious(I hope) because they are the result of mid-March major emissions.)

Afterthoughts and political debates
Often afterthoughts are useless, except they are remembered for the purpose of futureuse. Some notes follow.
Firstly, my own:
As you suspect, I have been regularly monitoring the reactor parameters from theTEPCO webpage and observing press conferences (by the Internet). Judging from the waterlevel, temperature and internal pressure, I had thought that the damages of the reactors andcontainers were not extensive. For instance, TEPCO data showed that half of fuel rods had been
covered by water (except a few instances). Only two weeks ago, they found that the water levelindicators were not functioning. Thus, my assessments miserably collapsed. Although nothing iscertain now, everybody believes that all the reactor cores have been extensively damaged, andfuel melt-down had occurred. One lesson: monitoring facilities should have backups…..
Evacuation actions
Government decisions on evacuation were obviously belated, and some were notscience-based. At a rather early stage the Government (on 1st April – this was ridiculously late)used 20-30km zones as evacuation area (20 for evacuation and 30 for warning), and later theyadded the scheduled evacuation zone (announced in May!). I wonder why they made thesedecisions so late – radiation monitoring started in March! I do not understand either why they
started with 20-30 when we all knew that the North-west areas showed higher radiation levels –we knew this in March.
More recently there are new debates on why the results of the SPEEDI (a computer
simulation model of environmental diffusion) were not used before the mid-March emission.
Though I personally tend to consider that this may be a typical afterthought, it was definitely
regrettable that scientific information was not used wisely and in a timely manner in thedecision making process at the top of the Government. Having said this, I should better add that
the SPEEDI has obvious limitations. It can calculate eventual radiation levels based on theassumptions (most importantly, weather conditions (wind direction, temperature andprecipitation) and amount of emitted radio-nuclides. It may provide useful predictions whensteady emissions and stable weather conditions continue, but it would not give any early
warnings. Clearly the latter was the case in mid-March major emission case. If you look into theSPEEDI calculations on 15th March, obviously they did not know how much of radio-nuclides
were about to be emitted. To make it worse, the wind direction changed a lot on that day – winddirection literally rotated. Thus, I would call the new debate an afterthought.

7However, however, I consider that Government’s decisions on evacuation were belated
and unscientific. Simply stated, the Government did not (and does not) have a proper decisionmaking process.

8

Taka Hiraishi
27th May 2011

Personal Assessment
This is a completely personal note, written largely for the purpose of brain storming!

Annual Radiation Level at School
The Minister for Education announced today, that they would aim at limiting the annual
exposure at school to 1 mSv. Earlier target of 20 mSv/yr was seriously criticised. The
announcement was accompanied by an explanation that the school kids’ total annual exposure
will be limited to 9 mSv. (I tend to believe that these figures do not contain natural radiationlevel – often 1 mSv/yr is mentioned as natural radiation.)
Cooling Water Input on Day 2 (12th March)“Interruption” of sea water feeding to the reactor #1 has been a subject of politicaldimension. An earlier announcement was that there was a 55 minutes interruption of sea water
feeding, which was severely argued by the opposition parties at the National Diet. However it
was revealed that the Director of the Fukushima Station unilaterally decided not to stop the sea
water feeding in disagreement with the agreement at the TV conference involving
representatives of the Government and senior staff of the TEPCO, where the Director himself
was present. (The reasoning for the “interruption” was a perception of a possibility of recriticality by adding sea water to the high temperature reactor core, but this is of course
completely un-scientific perception in most experts’ view. Continuation of cooling was a must.)
The Director’s unilateral decision must have been completely justifiable, but the misinformation(the Director reported the interruption in line with the agreement at the meeting, and then later
reported resumption of seawater feeding after the “55 minutes of interruption”.) to TEPCO has
been criticised by the Government. This is considered that the front line people did not havemuch confidence in the central discussions. This itself is something of a cheap drama, which
can be considered that the decision-making process at the top level seems to require morescientific grounds.
Fortunately in a sense, the further damage of reactor vessel could have been avoided by
the Director’s unilateral decision.

Leakage of High Level Water from the Storage Facility
Somewhat hidden behind the above politicised story, there was a more serious news that
the TEPCO found the leakage of high level water from the storage tank to the undergroundrooms of the Central Waste Management facility. Since this tank is collecting high level waterfrom underground rooms of the reactor #1, #2 and #3, and of their turbine houses, as well as
outdoor trenches, this leakage would cause difficulties in management (and re-circulation forcooling) of water.

9

Sporadic Detection of Radiation
The Greenpeace announced their monitoring results of sea fish and plants. Scientificassessment might be required (on such as high level reading of short-life radio-nuclides, but thisall implies that more extensive monitoring needs to be carried out. There have been someradiation measurement results (higher than the Government guidelines), and marketing has been
stopped. Very personally speaking the tea leaf guideline value of 500 Bq/kg of tea leaf seems to
be too strict (in comparison with 200 Bq/Kg of drinking water), but this also means that more
extensive monitoring needs to be conducted.
Ambient Radiation Monitoring
Broadly speaking ambient radiation levels continue lowering.

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10

Taka Hiraishi
25th May 2011

ICRP Recommendations
The following are reference materials issued by the ICRP in the context of evaluation of
long-term exposure limits.
-

2007 ICRP Recommendations (IARC Publication 103)
http://iopscience.iop.org/0952-4746/28/2/R02/pdf/0952-4746_28_2_R02.pdf
You may consider that Page 165, Table 4 is very relevant.

-2011 ICRP Publication 111 (Special Free Edition) on 2007 Recommendations
http://www.icrp.org/docs/P111(Special%20Free%20Release).pdf

You may find this section also informative.


ANNEX A. HISTORICAL EXPERIENCE OF LONG-TERM CONTAMINATED AREAS

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Taka Hiraishi
23rd May 2011

Personal Assessment
This is a completely personal note, written largely for the purpose of brain storming!

“Melt-down” debate
Last week I wrote about “melt-down” of the reactor #1, but the Government authorities
explained a few days later that it is likely that similar situation occurred also in the reactor #2
and #3. Miraculously again, “China Syndrome” did not happen. Immediately after theearthquake and tsunami, and subsequent total blackout of the station and consequent loweringof water which caused the fuel rods exposure above cooling water, the Government and TEPCO
accepted significant damages to the fuel rods. However, “meld-down” possibility was notannounced until last week. In discussing the situation, the definition of “melt-down” and “China
Syndrome” may be required. According to the press conferences, “melt-down” is used by theGovernment authorities to mean that a large portion of fuel rods are melt, a large part of reactor
core is destructed and contents of damaged fuel rods were dropped to the bottom of the reactor.
The bottom of the reactor vessel might have been damaged and thus melt-down fuel might haveleaked to the bottom of the container vessel. I consider that this definition is reasonable. I used
“China Syndrome” meaning that the bottom of the container vessel is also damaged and melt
fuel goes out of the container vessel.
These days there have been all sorts of discussions, including those at the National Dieton; when the melt-down occurred, why the cooling operation was interrupted, why thisinformation was not shared till now, but I personally do not believe that this kind of discussions
are very constructive. We should only thank God (see my notes of the last week), and focus on
how the situation can be contained, and how similar accidents can be prevented in the othernuclear stations.

Situation of the Fukushima plant
Cooling of reactors (#1, #2 and #3) has been relatively successful – by continued
addition of cooling water. However, addition of water means the increase of high levelcontaminated water in the reactor building, turbine house, and surrounding trenches. Some 200
tonnes of water is added everyday, and high level contaminated water is being accumulated.
TEPCO is constructing water purification and circulation system (differently from the normal
system (reactor is being cooled through small circulation <from reactor-heat exchange-back toreactor>, this un-experienced system is intended to circulate water< from reactor-leakage tobottom of houses/trenches-storage tanks-purification facility-back to reactors>) with the French
company technologies, but they are fighting against time – remaining space of temporarystorage tanks is getting less and less, while purification and circulation plant is still being built.

12

Environmental radiation levels
Although the leakage continues, the overall environmental radiation readings have been
lowering, including those of sea water. However, radiation levels of highly contaminated areas
continues in the nearby areas. TEPCO announced yesterday that they would assess the leakageof radio-nuclides to the surrounding environment. Quantitatively this may be small compared to
the large emissions at the early stage, but if this can not be contained it could mean significant
in a long term.

Food, water and fish
Intensive monitoring is being carried out by the Government authorities, and a very
limited range of products are banned from market. More serious impacts on markets areobserved by “rumours”.

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13

Taka Hiraishi
15th May 2011

Personal Assessment
This is a completely personal note, written largely for the purpose of brain storming!

I have not added my notes for two weeks. This does not mean that the situation issatisfactorily stable, nor I have lost my interested. I have been away on mission to Abu Dhabi toattend IPCC meetings, where I did not have good access to the internet. Having said this:Environmental radiation levels
As far as I have been monitoring, environmental radiation levels have not shown any
significant changes – overall environmental radiation levels have been declining, even thoughemissions have not been completely contained. Food and water levels have been continuously
monitored by government agencies, and necessary control measures have been taken, and thus
the consumers are not subject to any imminent risks because the food materials or drinking
water supply are not available in the market or water supply system.

Fukushima nuclear station (No.1 Station)
A few days ago, there was a new development in Unit 1, where the TEPCO found thatthe measurements of water level had been faulty. They have re-assessed the situation andannounced that there was a complete exposure of fuel rods in the early stage after theearthquake and have accepted that there was significant melt down of fuel rods. (I have been
regularly monitoring the reports at < http://www.tepco.co.jp/nu/fukushima-np/indexj.html#anchor02> and had had an impression that the Unit 1 had been rather stable, but theirdata now show that the measured water level is “down scale”. Apparently a large amount ofmelt fuel rods have dropped to the bottom of the reactor, and may have even escaped to thebottom of the container vessel. This is indeed a dreadful discovery but, awfully luckily “China
Syndrome” did not happen, and overall temperature is now low and the situation is now rather
stabilised. I am admittedly an atheist but I have to thank Gods. . .
They also found that a large of water has been leaked to the underground room, andthey have to find a new containment actions to deal with it. (The exact amount of this water,presumably of an extremely high radiation level, is not known but the recent reports talks ofsome 2,000 tonnes. Thus they would need to install a decontamination facility and to circulate
the water for cooling. Similar system had been discussed for Units 2 and 3, and thus they are
now faced with a serious dilemma that while they have to continue cooling, by adding a large
amount of water to the reactors, they have to construct a large decontamination scheme torecycle water for all the reactors, #1, #2 and #3. This development is not in a sense anything unanticipated, because everybody knew that the cooling water added those reactors could not have14

disappeared and must have been leaking to somewhere outside of the containment vessel. Now
we know where the water is.

Hamaoka reactors
Some 10 dyas ago, Prime Minister Kan announced that all the reactors at the Hamaoka
nuclear power station should be stopped. It was a conditional stoppage (till complete antiearthquake measures can be completed), but essentially, it meant that all those reactors will
never be used again. This drastic actions for the Hamaoka station is due to the recent discovery
that the station is located near the geological default, and these actions are exceptional ones only
for the Hamaoka station. However this might mean that many nuclear power stations (which do
not have such geological situation) will be subjected to very serious safety discussion for the
future. . . . IPCC’s recent report, Special Report on Renewable Energy Sources (SRREN)
should be a significant resource in this context.
<http://srren.ipcc-wg3.de/report/srren-spm-fd4>

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15

Taka Hiraishi
1st May 2011

Personal Assessment
This is a completely personal note, written largely for the purpose of brain storming!

Environmental Radiation Levels
Fortunately, environmental radiation levels are generally declining, including the insideof te Fukushima Daiichi Nuclear Plant. This must mean that there has not been any new major
release of nuclides. This does not mean, of course, no emissions. Three incidents of hydrogen
explosion scattered radioactive debris especially inside the plant, and contaminated water insidehas been increasing because of additions of cooling water to reactors #1, #2 and #3 and to fuelrods cooling pools for reactors #4, which all means potential increase of emissions.
Release of the SPEEDI results has given us some insights on the development of theaccidents, but the data on the emissions are yet unclear. Recent information that there is acontinuous release of radionuclides at the level of 157 teraBqs per day, but this would need tobe confirmed later. This figure appears small (See my assessment dated 13 April) but the
impacts are all depending on how long this level of emissions might continue.

Containment Actions being taken
A really good news was that they have been able to see the bottom of the reactor #1,
and no significant water leakage was observed. TEPCO is cautiously considering submerging
the reactor to water within the container vessel, which would hopefully stabilise the temperatureof the reactor. (Please note, however, addition of Nitrogen gas and water to the reactor does not
result in the increase of pressure nor much increase of water level within the reactor. This would
normally mean that there is a release of gases including water vapour.) TEPCO is carefully
monitor the reactor temperature and pressure, by decreasing addition rate of water to the reactor#1.
Reactors #2 and #3 has leakages and addition of cooling water must be causing increaseof high radiation water somewhere, either at the bottom (outside of the container vessel) or evenseepage to the trenches. TEPCO is moving the high level water from trenches and undergroundrooms to a large containment tanks, but they would need to consider expanding those tanks.
It is clear that cooling of reactors and pools must continue to be the top priority, though
the increase of high level water is an unavoidable consequences.

Evacuation Actions and Consequences
The “scheduled” evacuation zones are being implemented, which causes major
disruptions to the residents’ life and their activities. Provisional compensation payment has been

16

initiated. There have been a lot of discussions on the “20 mili-Sievert/year” criterion for theevacuation especially for the schools kids – some scientists argue that this level is too high anddoes not taken into account the internal radiation. Removal of top soil in two schools have been
carried out though the final disposal of collected soil has caused arguments among the residents
close to the disposal sites.
A large scale soil contamination measurement has started.

Contamination of Fish
Measurements of fish (and sea water) have shown general declining of radiation, butthere have been certain contamination detections, which led to marketing restrictions and intake
advice of certain mushrooms, sand eels (the local fishery association stopped their fishing forthe current season), and marsh grass from certain areas. These administrative actions (required
for the purpose of health protection) has a limited negative impacts but more significant impacts
on agricultural products via “unscientific rumours”.

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17

Taka Hiraishi
25th April 2011

Personal Assessment (25 April 2012)
This is a completely personal note, written largely for the purpose of brain storming!

Environmental Radiation levels in the vicinity
Having returned to Tokyo, I reviewed the press release of the radiation readings coveredin the press releases of the Ministry of Education, Culture, Sports, Science & Technology, Japan(What a long name! Let me call them “MOES”.) The summary of my work is already containedin the website. Unfortunately I was not able to find data for the area within 20 kms range, but
the highly contaminated area is limited to the North-west direction (high radiation was observed
between 20-30 km range). By the way, I have been informed that the radiation levels within 20
km are actually lower than those between 20-30 km range though the information did notcontain time-series of data. Thus, my layman’s guess is that; (i) the contamination in those areas
were caused by the high level emissions of mid-March, (ii) radio-nuclides fell in those limited
span of areas by rain or snow, and that (iii) subsequent emissions have been relatively smaller.
Thus, my optimistic views are, UNLESS there is further large scale emission (by, e.g, failure ofreactor container(s)); (a) high level contamination zones will not expand, (b) radiation levels
will decline in a long time span, (c) as environmental surveys advance, some evacuation areas
might be de-listed.
http://www.mext.go.jp/english/incident/1303962.htm

Radiation levels in the other areas
Environmental radiation levels are generally getting lower, even after recent rains. This
supports my thoughts that the higher radiation readings were actually caused by the mid-Marchemission incidents.

Marine sea water, drinking water, fish and agricultural products
There have been sporadic occurrences of radiation reports. Marketing of agricultural
products from certain limited range of areas are controlled by Government’s measurements andregulations, and thus do not cause any public risks.
Sea water has been monitored, and higher (than natural) readings in the nearby coastal
waters have been reported. This may need continuous monitoring.
Controls of marine fish do exist, though they are limited only to certain fish species.
Wider monitoring and measurements in the fish species at higher food chain will need to becarefully carried out.

18

Impacts on agriculture and fisheries are significant – but I would say, more by rumours
than actual radiation. The people have been faced with all the damages by the earthquakes andthe tsunami. Coastal farmers lands have been inundated by sea water. Irrigation system werelost, let alone transports and market systems. Many fishing ports were seriously damaged, andmajority of fishing boats gone. I would say that their additional economic loss by rumours isjust unfair.

Overall
Emergency containment works are still on-going on-site. Their cooling activities (whichhave to be continued at all costs) generates large amount of contaminated water that have to be
stored and eventually managed. Risk of physical breaks of facilities is not negligible. Lots haveto be done at the site – again I have to say that work has to be carried out at the workers’ health
risk.

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19

Taka Hiraishi
21st April 2011

Personal Assessment (21 April 2012)
This is a completely personal note, written largely for the purpose of brain storming!

Radiation levels
Since higher level recorded in mid-March, overall radiation levels have been steadily
going down, even in the vicinity of the nuclear plant site. This might mean that the major
emissions of 15th and 16th March there has not been high level of emissions.
http://www.mext.go.jp/component/english/__icsFiles/afieldfile/2011/04/21/1305097_042019.pdf

Evacuation area categories have been upgraded.
On 21st April, the area within 20 km radius was declared as a “Warning Zone” under the
Nuclear Safety Law. With this entry into the zone is now legally prohibited. This covers some
28,000 households, though limited visits will be organised.

High level water leak
It was announced that in the leakage of high level water into the sea (which is now
stopped) some 4.7^15 Bq was leaked out to the sea from the hole. (Fortunately the amount itself
was relatively small.)Overall containment actions
Reactor parameters are somewhat erroneous, and it is not easy to interpret.
http://toofuya-en.blogspot.com/

However, leakage appears continuing in the Reactors #1, #2 and #3, thoughenvironmental radiation levels have not been affected. A limited Visual images from Robots in
the reactor houses are now available, and removal of high level water from turbine houses andoutside trenches have been initiated. These activities can be considered significant progress incontainment activities. A long term plans have been now announced (Step 1 (3 months) andStep 2 (6-9 months) but they are all contingent upon (i) the status of damages on the facilitiesand (ii) absence of any major incidents (steam explosion within the container vessels or recriticality as a result of serious damages of fuel rods - Some experts consider that the detectionof 39Cl in the environment might mean it.)20

Taka Hiraishi
16th April 2011

Personal Assessment (16 April 2012)
This is a completely personal note, written largely for the purpose of brain storming!

Yesterday (15th April), Nuclear and Industrial Safety Agency (NISA) announced thatthe amount of radioactive substances contained in the low level radiation water released to theocean – 150 giga Bq. This is not a negligible amount of course, but if compared with theamount of atmospheric emission (500,000 tera Bq – this triggered the change of INES Level 5to 7) it is very small, which is a good news. This, however, does not mean the potential
emission to the ocean would be small. Future emission to the sea is all contingent upon the ongoing containment work.

Reactor parameters
Generally there has not been any major changes, though there appear to be some faulty
detectors.
http://toofuya-en.blogspot.com/

Recent monitoring readings
Overall, monitoring readings show gradual decline.
http://www.mext.go.jp/english/radioactivity_level/detail/1303986.htm

Containment work
The low level tanks are now emptied, but TEPCO is still inspecting these potential
recipient storage facilities so that high level water can be safely moved from underground rooms
and external trenches. This movement of high level water is a precondition for (i) inspecting ofreactor facilities and (ii) any containment work thereafter.

Recent news
14 April 2011BBC
http://www.bbc.co.uk/news/science-environment-13048916

CNN
http://edition.cnn.com/2011/WORLD/asiapcf/04/14/japan.nuclear.reactors/index.html?hpt=P1

21

Taka Hiraishi
13th April 2011

Personal Assessment (13 April 2012)
This is a completely personal note, written largely for the purpose of brain storming!

When I was wring yesterday’s assessment, I made one serious mistake. I was writing
the figures while listening the press conferences and I mis-converted Japanese numbers andinternational numbers. I am sure many of the readers have noticed my mistake andinconsistency in my yesterday’s text.
Correct figures of emissions:Chernobyl emission:

5,200,000 tera Bq.

Fukushima:

370,000 tera Bq - 670,000 tera Bq(i.e., in the range of 1/10 of Chernobyl as remarked by the Government.)

This means that in terms of emission amount, the Fukushima accident has emitted theamount that can be categorised as Level 7. I deeply regret my stupid mistake on this. However, I
would insist on my impression that the Fukushima and Chernobyl accidents are really different.
As the INES manual states, “Events are considered in terms of their impact on three different
areas: impact on people and the environment; impact on radiological barriers and controls at
facilities; and impact on defence in depth...”, and thus the INES rating is not only based onemission amount. In view of the fact that nobody has been killed by the radiation, and in viewof the low environmental radiation readings, the Fukushima situation is really different from thecase of Chernobyl. Thus, I still feel that the new INES rating of Level 7 was rather misleading.

-

22

-----

Taka Hiraishi
13th April 2011

Personal Assessment (13 April 2012)
This is a completely personal note, written largely for the purpose of brain storming!

Several hours ago, I wrote my personal assessments of 12th April. Due partly to the jet
lag after 4 weeks international travel, but more caused by my irritation I did not sleep well. So, I
decided to add one “sleep-writing” paragraph. I admit that this addition is something more
emotional than factual or scientific.

Levels:The level 6 or 7 question bothered my sleep. I wrote of a “cautious” declaration of level
7 yesterday. Level 7 was chosen though the results of estimation of past emissions are some tensof thousands of tera Bq. My guess was that since the emissions are still on-going, somebody
somewhere assumed in their assessment process that there would be sizable emissions in the
future. On the other hand, the NISA spokesman stated in a press conference that if they can
successfully continue containment activities they do not expect further major release ofradioactive materials in the future. Even if the NISA statement may be based on their hopeful
assumption, I feel that this assumption signifies their appreciation of the on-going containment
work at the site, being carried out by the dedicated workers who are literally risking their life.
From the trend of environmental monitoring,
there have been a few peaks in the past month probably
reflecting major emissions caused by hydrogen explosions,facility burst(s) and precipitation (the latter peak occurred
after the first heavy rainfall after the explosions. Morerecently, environmental radiation has been declining evenafter rainfalls. My way of thoughts tends to support NISA’s
assessment. Thinking of workers on site, I wonder why somebody assumed that there would besizable environmental emissions in the future?

New Evacuation policy
Yesterday, I wrote that the new policy is based on hitherto and anticipated annual
radiation level. Reportedly, the boundary criteria was actually 20 mili Sievert in a year.

23

Taka Hiraishi
12th April 2011

Personal Assessment (12 April 2012)
This is a completely personal note, written largely for the purpose of brain storming!

There have been two major developments, namely changing the INES level to 7 (fromearlier 5), and new evacuation policy. Other information is also added.

INES Level change
As it has been broadly broadcasted, the Government of Japan decided, on 12th April
2011, to change the INES (International Nuclear and Radiological Event Scale) from 5(“Limited release of radioactive material likely to require implementation of some planned
countermeasures” and “Several deaths from radiation” to 7 (“Major release of radioactive
material with widespread health and environmental effects requiring implementation of plannedand extended countermeasures”) as a “provisional assessment”. The Government alsoannounced that the release amount of radioactive substances has been around 10% of that of theChernobyl accident.
At the TEPCO press conference a spokesman said the assessment on the eventual total
release exists, and agreed that if the remaining all radionuclides in the reactors (of somethousand tera Bq) are released, the total emission might be similar or larger than the one of theChernobyl.
According to press conferences, the amount of release was estimated some 37,000 teraBq and 67,000 tera Bq (two different estimations using different methodologies by two
institutions. Cf: Estimation of Chernobyl emission is some 5,200 thousand Bq.)

My immediate very personal impression is this declaration is a very cautious one. If you
read the INES manual, shown below, and in view of the absence of any death incidents causedby radiation, the level could be rather close to that of level 6, very objectively speaking, but I
guess that this decision took into account the fact that the leakage is still ongoing in the
Fukushima case. (Actually, the Nuclear and Industrial Safety Agency (NISA) stated that if they
can successfully continue containment activities they do not expect further major release ofradioactive materials in the future – this is of course their hopeful expectation. The important
point is that these are all contingent upon the on-going and future containment activities.

INES Manual page 17. <http://www-pub.iaea.org/MTCD/publications/PDF/INES-2009_web.pdf>
24Level 7:“An event resulting in an environmental release corresponding to a quantity of radioactivity
radiologically equivalent to a release to the atmosphere of more than several tens of thousands ofterabecquerels of 131I.”
This corresponds to a large fraction of the core inventory of a power reactor, typically involving a mixtureof short and long lived radionuclides. With such a release, stochastic health effects over a wide area,
perhaps involving more than one country, are expected, and there is a possibility of deterministic healtheffects. Long-term environmental consequences are also likely, and it is very likely that protective action
such as sheltering and evacuation will be judged necessary to prevent or limit health effects on membersof the public.
Level 6“An event resulting in an environmental release corresponding to a quantity of radioactivity
radiologically equivalent to a release to the atmosphere of the order of thousands to tens of thousands ofterabecquerels of 131I.”
With such a release, it is very likely that protective action such as sheltering and evacuation will be
judged necessary to prevent or limit health effects on members of the public.

Expansion of evacuation policy
Yesterday, the Government announced its new evacuation policy. This policy now
covers evacuation areas based on hitherto and anticipated annual radiation level rather thanmechanistic identification of areas (e.g., 20 km or 30 km radius). My personal guess is that thishas become possible by accumulated radiation monitoring results and model dispersion modelstudies, such as the “SPEEDI”. Some areas (within 30 km radius) was not included in the newtarget areas, but some villages (administrative government areas) have been added, as“Scheduled Evacuation Plan Areas” from which “the residents were advised to move out in one
month time.” Naturally, this new policy has stirred bad feelings among many residents
concerned.

Environmental monitoring readings
There have been some rain in the Kanto areas, but fortunately there has been no
increase of radiation levels in the environment nor in waters.

Containment actions
Addition of cooling water contains in reactors #2 and #3, and nitrogen gas input (for the
purpose of avoiding any hydrogen explosion) to the container of the reactor #1. (Obviously thisall means that there is some leakage from these reactors.)
Conditions of the fuel rods cooling pools are stable (by addition of water).
There have been rather large aftershocks and the activities were interrupted, but havebeen resumed.
Management of contaminated water is slowly on-going, but high level radiation water
still hinders the inspection of reactors (reactor houses), turbine houses, and surrounding trenches.

25

-

----

26

Taka Hiraishi
10th April 2011

Personal Assessment (10 April 2011)
This is a completely personal note, written largely for the purpose of brain storming!

Having returned back home after 4 weeks of international travels (four meetings in four
countries), the following are my second notes mainly on the nuclear accident.

1. Environmental monitoring readings and environmental safety• Status remain the same – except the nearby localities radiation levels do notindicate any immediate health risks.
< http://www.mext.go.jp/english/radioactivity_level/detail/1303986.htm>• Certain areas close to the Fukushima Nuclear Station No. 1, however, showshigher radiation levels that needs attention. Some additional local actions mayneed urgent actions, including health protection actions for local people.
(Currently, evacuation for 20 km radius region, and “stay in house” for 30 km
radius region are implemented, but widening these areas need to be considered,in my personal view.)<http://www.mext.go.jp/component/english/__icsFiles/afieldfile/2011/04/10/13
04690_0919.pdf>• Radiation from tap water seems to be safe.
• Radiation from agricultural and fisheries products have been detected and anumber of administrative actions have been taken:
o Regulation on marketing of agricultural products from certain areas:
http://www.kantei.go.jp/saigai/20110408shiji_fukushima.pdf,
http://www.kantei.go.jp/saigai/20110323shiji_ibaraki.pdf,
http://www.maff.go.jp/noutiku_eikyo/index.html• Regulatory actions on fishery products have been very limited, but after the
release of low-level water (see below), market’s reactions have been significant.
In addition to the destruction of ports and fishing boats, fishing industry in thewide area is faced with major negative market reaction, and largely is inactive.
2. Containment work and safety measures• Reactors are broadly under emergency management, though (i) the reactor #1 is
yet unstable, (ii) reactors #2 and #3 appear leaking (due to the high radiation theexact status is not yet clarified), and (iii) fuel rod cooling pools for reactors #4,#5 and #6 needs continuous external cooling.

27

•

Original cooling systems are yet to be re-constructed, though external
electricity supply has been recovered.
• Treatment of high level radiation water (of different sources) is the central taskright now, and the ocean disposal of very low level water has been carried out
to obtain storage capacity of high level water. (Without this, access to the areas
near to the reactors will not be feasible.) As I wrote earlier, radiation of thereleased water (of some 11,500 tonnes) is low (somewhat comparable withdrinking water standards or some natural hot spa water), but this release caused
a wide range of international criticisms largely because of the sudden decision
and absence of international notification.) (As you might notice, I personallyappreciate, in view of the relatively small size of emission of radioactive
substances, the need of this decision so that a larger subsequent emission ofradio-nuclides can be avoided, but this is a matter of judgement.)• In a medium term, containment actions of several more months will be
important which will determine the future of the concerned areas, of decades.
3. Overall impacts (including the impacts of the earthquakes)• Having returned to Japan and viewing mass media in Japan, the seriousness of
impacts is enormous, starting with yet-unknown human loss, loss of areas (daily
life, culture, etc. etc), industries (which have major economic impacts on
Japanese industries, agriculture, fisheries, ….
• Goodwill extended from all sides, of all nature, is widely reported andappreciated.
4. Afterthoughts• As always, we see a lots of afterthoughts. Some are only trying to make excusesand completely un-constructive, but I am hoping for the better, drawn from thisextremely unfortunate accidents. Better safety standards, and no repetition ofthis situation.
5. Future tasks• Again, I believe that it is very premature to discuss the details of the future.
Containment is yet to be elaborated and implemented, and a long-termreconstruction has to be started.

I thank you for your attention.

Taka HIRAISHI

28

Taka Hiraishi
5th April 2011

This is a completely personal note, written largely for the purposeof brain storming!
Dear Friends,

This is an extremely, extraordinarily special issue. I am sending this mail to all my"Underground" mail friends this time, but I would send similar subsequent mail only to thosefriends who wish to be involved in the information exchange for the future.
The main reason or sending this mail to you is to share some updated information and mypersonal assessment on the situation. I have seen many international press articles, which I
consider unbalanced or misleading. Some talk of "domino melt-down", others talk of “leak ofmolten fuel though the bottom of nuclear reactor and container”, “diffusing high level radiationwater to the open sea”, so on and on. Such articles are, among many others:
http://www.guardian.co.uk/world/2011/mar/29/japan-lost-race-save-nuclear-reactor
http://english.aljazeera.net/indepth/features/2011/04/20114219250664111.html

This might be partly due to the absence of good information from the Japanese authorities andthe TEPCO. However, it may be unfair to criticise the Japanese side only because simply theymight not have good information themselves. Actually, TEPCO Press conference on U-stream
is an extremely useful, but it is in Japanese only.
http://www.ustream.tv/channel/iwakamiyasumi
Making this long mail even longer, let me make a personal confession. I am on my four week
mission, covering four countries and four meetings. I left Japan on 17th March, but I did thinkof throwing away all of responsibilities (of the IPCC, and the others) so as to stay on with myfamily. However, I concluded that the situation would not go to the worst, and fortunately I wasright. Thus, I am here in Bangkok, hoping that my conclusion of three weeks ago continues tobe valid for the future.
So, all started on that Friday afternoon, 11th March, with the largest-ever recorded earthquake(s)in Japan and historically not-well-known huge Tsunamis. Thanks to the Japanese TV system,
lots were televised live. Watching them, I wrote an email to my friends that it is not a wave. The
sea is moving over land, carrying cars, houses, ships, people and all sorts of debris. We are now
talking of close to 30,000 deaths. Many towns and villages vanished with their people, culture
and all those people had cherished. It would take decades, I feel, that we can calmly talk of
those calamities.

29Here, I wish to make a step aside from all these calamities and talk of nuclear reactors. First
simplest summary is that the earthquakes scrammed all those nuclear stations in the region(together with the other thermal power stations) - meaning loss of more than 10 GW/hour power
generation capability at once.
Among the nuclear reactors affected, there are six nuclear reactors at the Fukushima power
station No.1. Three of those reactors were in the process of regular inspection but the other 3, #1,#2 and #3 were in operation and scrummed down (safely). However it seems that their system,
including the core cooling facilities, did not activate themselves, because there were seriously
damaged or lost (some because of loss of external power supply, loss of subsidiary power
generation facilities (some engines or even fuel tanks were washed away by Tunamis. These six
reactors have six different stories afterwards. Since I am not completely informed of the detailsof the situation, I would limit myself to talking of a few specific issues rather than those six
individual reactors from now on.
1. Environmental monitoring reading and regional impacts.
• There are a number of website showing results of radiation monitoring, such as
http://www.mext.go.jp/english/radioactivity_level/detail/1303986.htm. This site
carries also radiation level of tap water. Monitoring results of many points inside
the power stations are also available.
• There were a few sharp peaks after the hydrogen explosions and subsequent
rainfalls, but since then environmental radiation levels have been slowly going
down.
• With the exception of few spots near the nuclear station No.1, most of monitoring
spots do not show the radiation level of immediate environmental hazards. (Theremay be differing views, but I usually consider those readings below 1 micro Sievert/hour something close to the range of natural background radiation.). If you apply
my standards (only tentatively), there are several locations (in the vicinity of thenuclear reactors), where long term health attention might be required.
• Overall, except those spots within the nuclear facilities, no immediate acute danger
from direct environmental radiation has been perceived. However, there have beena few instances of water contamination warning (vis-à-vis I-131 drinking water
standards of 300 Bq/kg (water) and 100 Bq/kg (of water) for less than one year oldbabies.), and contamination warnings and market regulations on several kind ofvegetables from neighbouring areas.
<http://www.kantei.go.jp/saigai/genpatsu_houshanou.html#shokuhin>• In this context, I have seen several cases of “safety statement”, saying radiation ofchest X ray is some 0.05 mili Sievert (per shot), and environmental radiation (of, forinstance, 10 micro Sievert/hour) is safe – but this is of course illogical. One year issome 8, 760 hours!
• We can not deny at all the serious impacts on the region. Many people have been
evacuated, and I personally believe that more evacuation is recommendable,
especially young children and ladies. Results of Japan’s computer model research,“SPEEDI” has been publicised. < http://www.nsc.go.jp/info/110323_top_siryo.pdf>
There are similar research, such as < http://www.newscientist.com/article/dn20285-

30

fukushima-radioactive-fallout-nears-chernobyl-levels.html>. As far as I understand,these research require many assumptions and I tend to consider that they are yetsomewhat indicative rather than quantitative. Because of extremely high sensitivity,
CTBT network’s “detection” may not mean much unless we know of the quantityof radiation. However, I believe that the Japanese SPEEDI can be useful as a guideof administrative preventive actions.
2. Core melt-down risk
• It is well known, that removal of decay heat is absolutely required. – For decay heat,“7% of thermal outputs from the reactor” (immediately after scrum) is used. (Please
note that “1GW” power station has 3 GW thermal outputs). Unless this heat isremoved, fuel rods will get damaged (melting point below 1,000 degrees C) andcontents will be dispersed to cooling (reactor) water, fuel rods cover material(zirconium alloy) will react with water and form hydrogen gas (three hydrogen
explosions occurred consecutively in #1, #2 and #4 turbine houses), and finally fuelpellets contained in the rods will melt (>2,800 degrees C) – this is so-called meltdown.
• Thus the cooling of the nuclear core is the first priority MUST. There were certain
times when the reactor water level went all the way down to expose fuel rods inreactor #2, became dry. Because of the insufficient availability of freshwater, theyused sea water for this purpose, which was later substituted by freshwater. To somereactors, Boron was added to avoid any re-criticality.
• Continuing the addition of cooling water and maintaining inside pressure was achallenge for #1 and #2, but while this process was ongoing, the internal (gauge)pressure of suppression chamber of #2 fell to near zero (this means that leakage
occurred). Later, internal gauge pressure of #2 and #3 reactors became near zero,and this means that these reactors have some leakage.
• METI is rather transparent on this and we can see the “parameters” of all six
reactors. It is in Japanese, but I guess you can understand this – for instance theinside temperatures are relatively low, and risk of steam explosion seems to be low.
From today (7th April, they started adding Nitrogen gas to the #3 container to avoid
any hydrogen explosion.)
http://www.nisa.meti.go.jp/earthquake/plant.pdf
3. Keeping Cooling pool cool.
- Fuel rods pools are usually cool with cooling facility, but after cooling facility has
been lost, temperature rise (and water loss by vaporisation) became problematic forreactors #4, #5 and #6. Addition of water by helicopter, by fire engine, and more
recently by concrete injection machines have been undertaken, but addition of waterin such manners might have increased the amount of contaminated water. Thoughoriginal cooling facility has not been recovered, further loss of water and eventualhydrogen explosion would be avoided.
4. Contaminated water- Yesterday (5th April) international mass media were full of the news of release ofsome 11,500 tonnes of “contaminated” water. The government’s announcement was31nearly silent about the quality of the water concerned, except there was mentioningof “tens of thousands higher level than regulatory standards on effluent”. The Chief
Cabinet Secretary Edano mentioned “some 8 Becquerels per cm3”, i.e., 8,000
Bq/kg (of water). I would not drink it, but I tend to think that this is really low level.
Of course, I should not defend any intentional leakage of radioactive substances,
but in view of the urgent needs, priority actions would need to be taken. If there is alarger risk (of environmental leakage of high level radiation water), accepting
smaller risk should be opted. (I would encourage my colleagues to compare thetotal amount of radioactive substances in this and the amount which is still kept in
the reactors and reactor containers, with a very thin and leaking walls. Total
emission has been still smaller than the other major nuclear accident cases.

5. Future?
- It is too premature to think of the future. The situation must be contained first. Anyeven tiny accidents, such as rupture of vessels or pipes, breaking of buildings,
hydrogen or steam explosion, or additional leakages . . . would completely change
the scene. In the meanwhile, we greatly owe to all the dedicated workers on site.
Damages will persist, both explicitly, implicitly and future of all of us will beaffected – some seriously, and some mildly. Japan will have to shoulder all of this.

<<<<<<<<<<<<<
Other issues will be added as required. My personal misunderstanding or preoccupation must be
rectified. Updating? Of course, as good news arrive.
>>>>>>>>>>>>>>>>

32

Addendum – my earlier e-mails:

From: Taka Hiraishi <hiraishi@iges.or.jp> To: " Date Fri, 08 Apr 2011 13:30:40 +0900
Subject: Fukushima Update

Dear Friends,

As many of you may know I am right now in Bangkok in the middle of UNFCCC AWG
meetings. Unfortunately I do not see much amazing new agreements here, though there are very
eager discussions. Actually today is my last day in Bangkok, and am returning home tomorrow
after my four weeks.
Of course, I have not forgotten Fukushima, and regularly monitor the environmental radiationlevels, public announcements by Governments and TEPCO, but there has not been no big news-- no news is genrally a good news (e.g., environmental radiation levels are declining at most of
locations, emergency actions on the site is steadily advancing, etc.)

Water release to the sea was a bad news, but very objectively speaking, the water (11,500
tonnes!) contains very low level of radioactive substances (only 8 Bq/cc - similar level as somenatural mineral spa water -- See: http://kadoyasan.com/radium-world.html or
http://ja.wikipedia.org/wiki/ラドン #.E3.83.A9.E3.83.89.E3.83.B3.E6.B8.A9.E6.B3.89), andthe release was, in my personal view, fully justifiable so as to prevent future eventual leaks ofhigher level water and to advance their containment activities on site.
#2 and #3 are, sort of, in stabilised condition (including continued leakage). I personallyconsider that the reactor #1 development needs some attention, but there has been little (or no)journalists' attention on this. See: http://www.nisa.meti.go.jp/earthquake_index.html
http://toofuya-en.blogspot.com/

My current short assessment is:a. Except the case of the reactor #1, they have gone through the emergency situation. (such as
so-called "melt-down" or large scale physical bursting of reactors or reactor containers.) (I amassuming that #1 can be somehow managed ....)

33

b. They are now moving into the second "containment" stage. Cooling must be contained,
hopefully, with recovered or re-constructed internal cooling system. Safe storage of debris,
contaminated water (every hour some 25 tonnes of water is added to the reactors, and the watermust be staying somewhere....) is a huge challenge for several months. We should not forget theneeds of local people, and their economy. A wider evacuation plan has to be elaborated andimplemented as a matter of urgency.
c. After b. a long-term reconstruction has to be done. . . This might take decades....
I am coming home tomorrow!

Taka

Attached:Taka&Nuclear.docx (some colleauges have seen this earlier.)----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Mon, 04 Apr 2011 21:21:29 +0900 Subject: Re: Fukushima
nuclear accident: (29th March) Corrected version.
,

You should have read this chain from the start. Today, TEPCO in agreement with theGovernment started releasing of 13 kilo tonnes of water (low level radiation water which had
been kept in their tank) to the sea. This water's radiation level is 8 Bq/cm3 (of I-131). (Some 40
times higher than the drinking water standards - only 40 times ..).
Of course I am not saying that they can release it because the radiation level is low. We need tothink of quantity of radioactive substances.
They have already been leaked to the atmospheric environment, and what we have to see iswhat this release to the sea means.
Chernobyl's release figure is a total (as expressed in I-131). Of course we do not know yet whatkind of amount of radioactive substances will be released from those six Fukushima reactor
facilities in the end, but the amount we are now talking as a release to the sea is a tiny, tiny
portion of "all potential release", and this "all" will be hopefully smaller than that of Chernobyl.
This is the reason why I shouted "this kind of unscientific news bewilders people.
Journalistic ...." There is no common sense in writing this kind of ridiculous article.
Will you recalculate it please?

34

Taka

----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: " Date Mon, 04 Apr 2011 14:24:08 +0900 Subject: Fukushima what is happening? (4 April 2011)

Dear Friends,

a. Generally, environmental radiation levels are slowly going down - generally going closer to"natural" levels. This is partly because the North-West winds have prevailed, and there has
recently been no rain, nor no new explosive additional emissions. Some locations near the
nuclear power station continue showing high level of radiation, which, in my personal view,
special actions.
b. At the site, cooling efforts continue, though the leakages are yet to be tackled. Facilities
connected to reactor #2 and #3 are definitely leaking, the high level radiation from water inturbine house underground water is not yet accounted, nor they do not know the cause of highradiation from water in trenches.
c. They found a high level radiation water leaking to the sea, which has excessively
monopolised the journalists' attention. I have heard a lot of extremely technical exchanges how
to stop the water itself, but nothing about where the radioactive substances in the water comefrom. (By the way, my understanding is that the water hole comes only in ebb time (and forhigh tide times, sea water must be seeping into the wall), but some people seem to have an
impression that contaminated water from reactor systems are "gushing out" to the sea. . . . ) We
need good answers to these points, before you formulate your impressions.
d. I am getting tired of observing the press conference. The press people ask for their articles,
but do not address the core questions, such as: - Where is the added water going? (They are
putting in close 10 tonnes per minute kind of cooling water to each reactor - where do they go?

- Not much discussions on the cause of high level radiation radiation of turbine house
underground. (10,000 times higher level that normal reactor water does not mean anything,because primary cooling water is nearly clean of radiation. I wrote of my guess on this earlier.) I
have been tired of hearing of the confusion of waters of reactor house and turbine house, andconfusing image connecting all three different water bodies, (i) reactor house, (ii) turbine house,(iii) trench water, and (iii) water in the inspection hole - the linkages between them are yet to beelaborated.

35

- There are still lack of understanding between radiation strength, radiation received in specifictime frame, and amount of radioactive substances. These are all related, but it is simply wrong
to compare the radiation received from chest Xray (- 0.05 mili Sv/inspection) with sub-micro
Sv/hour level environmental radiation. There have been too many "safety" declarations.
- The total amount of radioactive substances, which might have emitted already, which might
continue emitted, .... Without this, Japan will continue to be blamed as an historic polluter - shemight become one, though. ..
Taka@BKK----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Sat, 02 Apr 2011 17:27:54 +0900 Subject: Fukushima nuclear
accident: (2nd April)

Dear Friends,!

Absence of my mail does not of course mean that I have lost my interest in this. Simply stated I
have not been able to add meaningful analysis based on new quantitative information.
Since this morning, there were some international media coverage to the effect that a newleakage to the sea was found. But I am not able to assess the significance of this leakage qualitatively, yes, there seems to be a leakage, but it does not mean much unless we know theamount of radio-nuclides in the water flowing into the sea in a quantitative manner. There areleaks and higher radiation levels are known. Thus addition of radioactive substances to theenvironment has been known.
Thus, unless we know the quantity of radioactive substances leaking to the sea, this kind ofnews is meaningless. More important point is what caused this higher level of radiation in the"inspection pit" which is close to the sea. Where did they come from? Through electric power
cable piping? From the rainfall? There has been no explanation on possible leakage route "Morethan 1000 mili SV/hour in a semi-closed small space does not have much information.
QUANTITAVE discussion is necessary.
Apparently they do not have access to reactor houses, and therefore they do not know theleakage there. (Gauge pressures of #2 and #3 containers (not reactors) are nearly zero, and thismeans there is some leakage somewhere around. (This would mean, probably, leaks fromfacilities connected to the container.) They continue adding 7-9 tonnes of freshwater to #1, #2,#3 reactors but nobody explains (or asks) where this water is going?? The causes of the highly
contaminated water in the underground rooms of turbine houses have not been analysed. Till thewater is pumped out to tanks, they can not step in those houses, only after which they can obtainsome insights. (This would take, at lease, a few more days.)

36

Thus I am short of relevant information to write to you.
Otherwise, environmental radiation has been gradually falling in nearly all areas. Some areas
near the reactor site show high level of radiation.
Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To Date Thu, 31 Mar 2011 10:59:16 +0900 Subject: News on
Fukushima (31 March at 11:00 (JPN time)

Dear Friends,

Environmental radiation levels and their trends have not changed significantly - except in areas
near the reactors, environmental radiation levels are not extremely high level.
http://www.mext.go.jp/english/radioactivity_level/index.htm
http://www.mext.go.jp/a_menu/saigaijohou/syousai/1303747.htm

This can be considered a sort of good news among more alarming news.

The Nuclear Energy Safety Agency (let me call it "NESA" for the time being.) explained
yesterday night (Japan time):

a. They found a new water patches in th "Central monitoring .... Office", showing relatively low
radiation.
b. As for the water in the "trenches", they now consider that the water inside will be (i) tsunami
water, and (ii) subsequent precipitation (gathering radio nuclides from the environment). They
are talking of low radiation from this water.
c. Removal of water from #1 turbine house underground is temporarily stopped because thetank being used is nearly full. They are looking for the other tank(s).
d. Leakage from reactors #2 and #3 exists and they are faced with a serious dilemma - theyneed to feed cooling water, and at the same time need to deal with contaminated water. (I am
not aware of any clear explanation on the cause(s) of high radiation level of waters in the37

turbine house.) They are not able to identify the status of reactors, containers, suppression
chambers and any facilities connected to them - due to high radiation levels.

e. At the press conference, NESF talked of difficulties of cooling of #2 -- externally supported
pump failed, and then tube of fire engine failed....
The NESA spokesman was of the view that, though the problems still continue, the situation
has passed the extreme emergency situation which did exist.
Through the Ustream I can not see the interview scheduled at 10:00 (Japan time) -- it seems that
it is delayed by 60 minutes??? (I hope that this delay does not mean anything very serious. I
need to sleep.
Could somebody watch this . . .) http://www.ustream.tv/channel/iwakamiyasumi3

Since yesterday, I have not been able to find any interviews of TEPCO (which I consideredmost informative.)

Good night.
Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Tue, 29 Mar 2011 13:15:55 +0900 Subject: Fukushima nuclear
accident: (29th March)

Dear Friends, Good Morning!

1. Good news, first:

1-a. In Yokosuka, there was a hump on 27th March, but generally environmental radiation isdecreasing. Some of them may be considered close to "natural".

38

http://www.atom.pref.kanagawa.jp/cgi-bin2/telemeter_map.cgi?Area=yokosuka&Type=WM

1-b. Radiation through water supply does not cause major concern.
1-c. Overall, environmental monitoring trends are similar to the earlier situation. Generally
getting safer (except certain locations).
http://www.mext.go.jp/english/radioactivity_level/detail/1303986.htm

1-d. Freshwater (rather than sea water) is used for more reactors, and external electric power isincreasingly used. (This is being realised by dedicated workers in the hazardous environment, ofcourse.)2. Continued concerns:

2-a. Fukushima area - radiation at some points are high.
http://www.mext.go.jp/a_menu/saigaijohou/syousai/1303747.htm

2-b. Uranium has been detected in soil samples but the measured levels are found not to cause
hazards. TEPCO will continue monitoring.
2-c. Water samples from #2 turbine house have high radiation, and they also foundcontaminated water in trenches. They are trying to move the water to secure containers.

2-d. A high level of radiation within the houses continue, and work is restricted.
3. New information.
Following information is available on international spread of radiation.
(See the url, shown below and the attached file). These appear alarming, but in my humble
opinion, they tend to discuss together (without properly linking them) of (i) detection (at anextremely low level) by CTBT network, and (ii) model simulation of diffusion of contaminated
air mass, which gives an awful image. Basis of estimation of amount of potential emission is notvery clear either, but it is factually true that Fukushima reactors contain far larger radioactive
substances compare with Chernobyl, but that the leakage from them to the open environment isstill considered largely contained. I have not seen any estimation of potential amount of39

radioactive substances which may be leaking. I am sure that this information will become
available soon, so that we can see the situation in a more quantitative term.
http://www.newscientist.com/article/dn20285-fukushima-radioactive-fallout-nears-chernobyllevels.html

4. I regularly observe the press briefing of TEPCO, titled "iwakamiyasumi"
http://www.ustream.tv/chan. This is in Japanese, but informs details of technical difficulties. I
am impressed by the sincere attitude of TEPCO people, including Vice-President Muto. You
may find, as always, some irrelevant and irritating questions by journalists.
Taka-------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Mon, 28 Mar 2011 14:55:51 +0900 Subject: Re: Fukushima
nuclear accident (For your weekend!)

I know that they are now faced with the difficulty of storing contaminated water they found in
the underground floor of the turbine houses, and they are discussing usage of other tanks andeven constructing temporary (but sealed) tanks.
There seem to be five kinds of water.
(i) the contaminated water in the underground room of turbine house.
(ii) leaked water in the reactor container house (this has not been discussed yet, but since it has
been confirmed that the #2 reactor container has leakage, it is likely that there is somewater. . . ) (iii) Overflow water as a result of water addition to pools (by fire engine, etc.) (iv)condensation water.
(v) other un-detected water,

I have not found an answer to my question - where the cooling water is going. This morning at
TEPCO press conference they were talking of addition of a few tonnes of water per hour. They
also said that they are trying to reduce the addition speed only to the level of speed which keep
the water level in the reactor. This means to me that the added water vaporises and thencondensed back to water - somewhere, usually a condenser attached to the container. These
have not been asked, nor answered.
Taka

40

----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: " Date Mon, 28 Mar 2011 03:55:37 +0900 Subject: Fukushima
nuclear accident: 10 million times or 100 thousand times.
Dear Friends,

Since my mail of yesterday, there were some big news - ups and downs. Let me explain:a. I talked of 10 million times higher radiation levels and stated, "(i) normal level in the reactor
is actually very low in the Boiling Water reactors, and therefore the steam can be sent to turbine
for electricity generation. Thus, using "10,000,000" is not very informative." This was
confirmed by the TEPCO Vice-President, when they rectified that it was 100 thousand, not 10
million. Vice-President also said that usually the radiation level of reactor water is in the rangeof 1X E+2 Bq/cm3, 10,000 times lower than the Japanese regulation level. Thus, as I said
earlier, their comparison with normal reactor water is really misleading.
b. This detection error was due to the mistake of identification of peaks in the measurement
chart - I guess it is the chart of nuclear weight-spread gamma-radiation strength. They mistook
one peak of Caesium-134 for Iodine 134, and they found that there was no I-134. New detectedradiation was some 2 X E+7 Bq/cm3 (which was 2.9 X E+9, yesterday).
c. In the meanwhile, CNN jumped up, and one nuclear analyst stated that the current situationis unprecedented, even over Three Miles and Chernobyl. He talked of possible domino-melting
down of 4 reactors. It was really disgusting, I have to say. BBC is more restrained.
d. In Yokosuka, there was a hump on 27th March. Did it rain ?
http://www.mext.go.jp/english/radioactivity_level/detail/1303986.htm

e. Environmental monitoring trends are similar to the earlier situation.
http://www.mext.go.jp/english/radioactivity_level/detail/1303986.htm

Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: " Date Sun, 27 Mar 2011 16:58:14 +0900 Subject: Fukushima
nuclear accident (For your weekend!)

41

Dear Friends,

1. Yokosuka area's radiation continues declining: http://www.atom.pref.kanagawa.jp/cgibin2/telemeter_map.cgi?Area=yokosuka&Type=WM

2. Tokyo, Chiba, Ibaraki areas continues showing similar trends
http://www.mext.go.jp/english/radioactivity_level/detail/1303986.htm

3. There was a news on highly contaminated water in the turbine facility house of the reactor #2.

3-a. As I wrote yesterday, this does not necessarily mean that there is a new leakage route. It is
more likely that this leakage route has been there, but was not known. (My view is based on thefact that environmental radiation has not shown any new increasing trends.)

3-b. "More than 10,000,000 times higher than the radiation from the reactor water in normal
situation" sounds awful. Let me add some personal guesses -(i) normal level in the reactor is actually very low in the Boiling Water reactors, and therefore
the steam can be sent to turbine for electricity generation. Thus, using "10,000,000" is not very
informative.
(ii) By the lowering of water in the reactor pressurised vessel, fuel rods have been damaged andradioactive substances moved out to water, and the radiation from water in the reactor haveincreased to an "abnormal" level.
(iii) This high level radiation water was found in the turbine house, not in the reactor house.
This means that there is actually leaks from the primary steam circuit, which has not been
mentioned at all so far. It is known that #2 reactors's suppression chamber was damaged but I do
not believe that this leak caused high level water in the turbine houuse.
These are only my guesses, but I do have concerns that the similar situation might exist also for#1 and #3.

Let me again say that this news does not necessarily mean new leakage.

42

4. I am still curious - what is happening with the added water? They have added lots of water(sea water earlier, and now they switched to fresh water, not yet purified water.) but they nevermake it clear on where the H2O went. . . Salt must be in the reactor or reactor container, butwhere did steam or water go?

5. In the meanwhile, http://www.bbc.co.uk/news/world-asia-pacific-12872707

Wade Allison, University of Oxford is of the view that current standards for radiation is 1,000
times too stringent. I do believe that radiation standards are set at very cautious levels, but it isso because we do not have much experiences.
http://www.bbc.co.uk/news/world-12860842

Have a nice weekend!

Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Fri, 25 Mar 2011 15:05:13 +0900 Subject: My routine
monitoring on monitoring

Dear Friends,

Good news: 1. As I predicted, water radiation level in Tokyo has gone down to below 100
Bq/kg (water), though water radiation levels tend to be still high.
2. Environmental radiation levels are gradually decreasing (except areas close to the reactor
site.) (We need to see the radiation levels when rain comes.)

Bad news: 1. Judging from the industrial accidents, #3 reactor system has minor leakage. (Iwrote "minor", because the container has positive gauge pressure.)43

2. High level radiation has been detected at a large number of sites especially in Fukushima
prefecture, but some announcements seem to be misleading (to safe side).
3. "Detection of radiation" is reported increasingly widely - unavoidably.
Some materials: a. Attached is a set of useful monitoring sites (I routinely use this.).
Most of them are in Japanese, but I am sure you have other useful urls that you may wish toshare with colleagues.
b. INES Pamphlet: http://www.iaea.org/Publications/Factsheets/English/ines.pdf

Taka

Attached:Monitoring.lzh----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Thu, 24 Mar 2011 06:44:28 +0900 Subject: As rain has moved
away to the East, radioactivity level is settling down.
Dear Friends,

a. Radiation monitoring results at Yokosuka monitoring stations appear to be generally
declining, though they are still higher than 100 nano Sv/hour. But they are going lower!
<http://www.atom.pref.kanagawa.jp/cgi-bin2/telemeter_map.cgi?Area=yokosuka&Type=WM>

b. Overview of contamination: <http://atmc.jp/water/> This website may be of some use to see
overall contamination levels over Japan, even including the Fukushima reactor site (part of it,yet).
If you click on the small graphs, you can enlarge them. This sight gives you air, water,
precipitation (wet and dry) radiation values. (They are in Japanese, but translation seems to beavailable by pushing language button on top left of the page. Please note, as always, that thosenumbers are often peak levels.)

44However, because those pages are meant to give the overall views, precision might be missing.
For details, you may wish to check this or other more specific pages:
http://www.atom.pref.kanagawa.jp/cgi-bin2/telemeter_map.cgi?Area=yokosuka&Type=WM

One thing I noticed was that the 209 Bq/kg (water supply) level, which we extensively talked
yesterday) was an extremely high level, even higher than the water supply quality at
Hitachinaka area or Utsunomiya area. I would not call it a detection error, but logically speaking(according to my personal logicism!) that kind of level will not continue long.

Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Tue, 22 Mar 2011 22:45:41 +0900 Subject: Re: How to assess
the radiation levels and contamination of water and sea water

Dear Friends,

a. The attached two images show you past trends of radiation in the vicinity of the IGES. In my
earlier mails, I reported on two peaks and rather quick decline of environmental radiation.
However, I have noticed that from yesterday (21 March) , there emerged a new peak. The peaklevels are 157 nano Sv/hour and 114 in these cases. These levels are in the range similar to"natural radiation" and they are not something to worry about. I feel, nonetheless, somewhat
concerned, because I am not aware of any incidents involving pulse emissions from thosenuclear reactors in the last few days. (One possible explanation is that these peaks are related tothe change of wind direction, I guess.) We need to continue checking the change of these levels.
b. Contamination of water, vegetables and raw milk in Tohoku area is something un-avoidable,
and indeed the Government had to take legal actions to restrict the marketing of them. There
were reports on contamination of water even in Tokyo area, but the levels are very low andwould not cause any health impacts. Local sea water contamination around the reactors weredetected at a rather high level, but this is not something un-anticipated, and it will not cause any
immediate health impacts. Fish (both marine and lake/rivers) would need to be monitored in the
future though.
c. There has not been much news on reactors #2, #3 and $4, except cooling by fire engines andconnection of external power lines to the facilities. I am still concerned with in particular #2 and#3, and keenly awaiting good news on them.

45

Finally, I am attaching also an excel table (conversion tool) for your eventual use - to convert
hourly values to annual values so that you can see the significance of measured levels ofradiation. Please read the "Important Notes" section. Please do not conclude, for instance, that(i) compared with the X-ray radiation, environmental radiation is very high, or; the otherextreme: (ii) compared with current environmental radiation levels (which are not far away from"natural radiation" levels in Tokyo/Yokohama/Yokosuka areas, mammogram is very dangerous.
This table should not be used for risk assessment purpose, because impacts are not mechanically
proportional to the time and dose.
Taka

Attached:Nishi-Itsumi_0321_Month.jpg Attached:Highland_03_21_Month.jpg
Attached:Sv_Conversion_TH_expanded.xlsx----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Sat, 19 Mar 2011 16:39:28 +0900 Subject: Fw: How to assess
the radiation levels

Dear Friends,

Let me add a few pieces of information on radiation monitoring so that you can understand therisks and safety of environmental radioactivity levela. Basics a-1. You need to differentiate the strength radiation expressed usually by "per hour"(e.g., nano/micro/mili Sievert/hour), and the annual dose (often expressed in mili Sv per year.)
When you wish to understand monitoring results, please keep this in mind.
a-2. At an extremely high radiation level site (such as at a nuclear accident site), short term
exposure matters. Short-term health damage could result at an environmetnal radiation in therange above 100's of mili Sievert/hour level. Fortunately you would not experience this.
Hight level gamma ray radiation can be serious in the vicinity of irradiated materials.
a-3. Long-term impacts may be very broadly categorised into two different groups. One: longterm exposures through atmospheric contamination, and Two: long-term impacts ofcontamination accumulated in water, soil and food.
b. "Natural" radiation level b-1. Radiation comes from natural environment especially Radon in
the ground, etc. Thus "natural" radiation level differs among the locations, the famous highradiation locations are; Ramsar: 260 mili Sv/year, Garapari: 10 mili Svr/year. Ofen 2.4 mili46

Sievert/year is used as a typical "natural" radiation level. If you do a quick simple calculaion (bydividing them by 8,760 (number of hours in a year), you will get 29,700 nano Sv/hour, 1,140
nano Sv/hour, and 270 nano Sv/hour, respectively.
b-2. Environmental measurements showed: b-2-1. As your saw in the attachments of my earlier
mail, Kanagawa stations recorded two peaks or above 200 nano SV/hour, and subsequently
went down to below 50 nano Svt/hour level.
b-2-2. Some monitoring stations have records exceeding 1,000 nano Sv/hour level and someremains at the level of high hundreds of nano Sv/hour level. These levels look extremely high if we say that these hundreds nano Sv/hour can be hundreds times higher than "natural".
However, if you compare them with the b-1 cases, you may get to a different conclusion. (I am
not insisting that we can forget about those monitoring results, at all.)b-2-3. Often we hear statements that Xray examination 50 will be micro Sv, comparing it withenvironmental levels (two digits nano Sv/hour). This is somewhat un-understandable
comparison. You do not compare the car speed and distance the car is making.
b-2-4. For the big travellers: You will receive 45 micro Sv/hour of radiation - some 350 micro
Sv/flight (of 8 hours). If you have ten international missions per year, 7 mili Svt/year. You may
not wish to compare this is 2.4 mili Sv/year (natural radiation).
Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Fri, 18 Mar 2011 21:05:06 +0900 Subject: Re: How to assess
the radiation levels

Dear Friends,

I have just sent to my colleagues information on what INES means.
http://gnssn.iaea.org/regnet/Pages/INES.aspx If you want to know more details, http://wwwpub.iaea.org/MTCD/publications/PDF/INES-2009_web.pdf

This change of category does not change the contamination levels, of course. Contaminationlevels are those which have been monitored. I apologise in this context that in my earlier mail I
mentioned "micro Gy and Sv, but as you might have noticed in the photo image they are noano
Gy and nano Sv. I was confused with the higher level of contamination on sight. Again this does47

not change the status. Contamination levels in Kanto areas are what those images (or others, you
may wish to check from the website.)

Finally, a friend inquired into the possibility of accumulation of radioactive substances in theenvironment, such as soil, food or water.
I would say, it will occur, but we should always consider the level of contamination and thespecies. The AIST has uploaded the analysis on this question (There is a table talking of nuclear
species in the middle of the pate, though it is in Japanese).
http://www.aist.go.jp/taisaku/ja/measurement/index.html The message was that I-131 (highest
recorded) has a half-life time of 8 days, and Te-132, 32 days . Longer life species (Cs-137, 30
years, and Cs-134 30 years), needs careful attention. (I this table, I think the peaks (which I
mentioned in my earlier mail) are also recorded, and later radioactivity measurement havedeclined.

Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Fri, 18 Mar 2011 18:56:21 +0900 Subject: How to assess theradiation levels

Dear Friends,

I wish to share with you how I assess the current radiation levels.
Mass media carries often the news talking of only peak levels. If you see only those peak levels,
you might come to a conclusion that a wide range of areas have been contaminated.

Just wait! As you are fully aware, all the environmental pollution levels highly fluctuates as the
air mass moves around. Radioactive matters are also environmental pollutants and behaves
similarly like SOx, NOx or SPM in the air. Thus environmental experts use hourly values,
annual averages, 98 percentile figues, etc. etx of air pollutants. Depending on contaminants,
peak levels are not so relevant to health impacts. (One exception from this is the case of direct
gamma ray irradiation from certain radioactive matters, but this applies only when you are
physically very close to the radioactive solids (or sometimes liquids).

48

Mr Sato circulated guidance materials (in Japanese and English), which contained an url on
monitoring stations and their records.

http://maps.google.co.jp/maps/ms?ie=UTF8&brcurrent=3,0x34674e0fd77f192f:0xf54275d47c6
65244,0&oe=UTF8&msa=0&msid=208563616382231148377.00049e573a435697c55e5

Some of those stations have radiation level trends, and I am now attaching two image files of
the Nishi-Itsumi (?) Station in Yokosuka (one monthly trend and the other 24 hours trend.) The
monthly record shows,(i) natual radiation levels including those days even before the accidents are shown, and it saysthat natural radiation level is usually between 10 micro Gy/hour (please take it that Gy and Sv
are the same, for the time being). It shows also past few peaks correspond to rainfalls.
(Raindrops washes down natural radioactive substances to ground.) You may know that Japan is
not a country that has extreme high level of natural radiation level.
(ii) Two big peaks appeared between 15th and 17th (?) March. The peak levels are something
what we should be concerned, but environmental levels quickly fell down to below 50 micro
Gy/hour. More recent 24 hours records also show gradual decline. (My very, very personal
guess is that these two peaks are the results of two hydrogen explosions in Fukushima site, but I
do not have any means to confirm this.)From the above my current conclusions are:a. Unless there is any major additional leakage, environmental radiation level will not go
extremely higher than the natural level in Tokyo-Yokohama-Yokosuka areas. There may besome peaks still occurring but they would be smaller than those already observed.
b. Water supply to the reactor #4 cooling pool was a challenge (because physically waterbombing could have caused dispersion of significant radioactive substances, but fortunately
there was no major explosive incidents. No big peak has been recorded in the stations which I
have checked (this needs to be confirmed.) It was quite a relief for me, personally speaking.
c. There is no doubt that there is a leakage at the reactor #2 (its suppression chamber, to be
exact). With the initiation of cooling system using external power supply would reduce theoccurrence of further leakage, but we can not completely rule out the possibility of further leaks
as time passes. Environmental monitoring and relief actions for the neighbour areas should beinitiated.

49

d. Thanks to the devotion (literally "devotion") by the TEPCO on-site staff, self defence forces,
police and fire control officers, catastrophic accidents might have been prevented.

Let me again state that this is only my personal assessment. You may have yours.
Taka

Attached:Yokosuka_24hrs.jpg Attached:Yokosuka_PastMonth.jpg----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Thu, 17 Mar 2011 12:15:15 +0900 Subject: Re: Greetingsfrom …, Berlin

Dear …

Thank you very much for your mail and kind words.
It was really a major disaster. Probably more than 10,000 people perished, and a large area,
including several cities and townships were swept away to the sea. Aftershocks still continue.
Two nuclear power stations were seriously damaged, to the effect that the core cooling system isunstable in at least two nuclear reactors. There has not been any significant radioactive leakage.
As news reveals more damages, we recognise that Japan will face with major challenges recovery from devastating situation.
From climate viewpoint, Japanese people lost again their confidence in nuclear energy. At thesame time, Tokyo will face with major electricity deficiency - because these earthquakes mean
loss of several gigawatt per hour electricity power generation for the coming few years. (I think
my quick calculation is correct - it is so huge, and I can not be sure....) According to TEPCO,
Tokyo area is going to experience "scheduled power cuts".
Even in my life time, Japan has gone through a number of difficult times, and I sincerely hopethat we can again see miraculous recovery.
Taka

PS: There are reports on European mass-media, including German. Lufthanza apparently
decided that they avoid flying to Tokyo. There was a gossip that the German Emergency Rescue

50

Team sent to Japan after the earthquakes was sent to Osaka. Many Europeans only recall
Chernobyl - but fortunately (so far) the Fukushima incidents will be contained though withsome minor nuclides leakage - it is not an open fire of a nuclear reactor, but many Europeans
can not differentiate them. Sad, isn't it.
----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Wed, 16 Mar 2011 13:52:02 +0900 Subject: *** Very
Personally,

Dear ,I understand. . .

Apparently, European countries are very much concerned with the situation. As I have been
writing, I am not very optimistic about the situation. #2 reactor has a minor leak, #1 & #3 arenot yet stable, and #4 rod cooling pool is heating up. This morning's news, the "white cloud"from #3" was extremely alarming.
Howver, very objectively speaking, even in the worst case scenario, Fukushima will not
become Chernobyl, though it might go up a half step higher to Level 4.5. Again very objectively
speaking even in such a case, Tokyo will not be contaminated to the level of significant healthrisk.

Thus, it is understandable that some European countries have taken a very cautious approach.
Personally, I am leaving for an international mission for 4 weeks, starting tomorrow. I havebeen seriously thinking of staying with my family, deserting my IPCC responsibilities, but myassessment has not forced me to take such a decision.
We are all a small part of the history.

When I and you come back to IGES, let us drink and recall all the things that might have
happened.
Take care! Taka51

----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Tue, 15 Mar 2011 19:09:32 +0900 Subject: Re: [15 March
17:20 Update] Travel, Blackouts

This is an informative article. I also believe that there is no imminent risk at the moment, though
I would not say that "(T)he plant is safe now and will stay safe". It is too early to conclude so.
We need to address all the reactors separately.
#1: there was a hydrogen explosion. Dry fuel rods generated the hydrogen and it leaked out(through unidentified route such as de-gassing facility of primary water pipe or somewhere
unknown.) Later they decided to open the "vent" of the reactor container and to inject sea water,
and it appears that sea water is still flowing in. They believe that the situation is stable (this does
not mean it is completely safe.

#3: Situation is similar to #1.
#2: This is still not stabilised. Earlier there was an "explosion", but I tend to believe that it wasa physical rupture not an "explosion" (of chemical or nuclear reaction).These are two different
things. Later, Government's assessment said it appeared that leak of from heat exchange
connected to the suppression chamber.

My hopeful assessment is, thus, the pressurised nuclear reactor (that contains essentially all theradioactive substances) is not directly and widely open to the atmosphere. Nuclear reactor isconnected to the suppression chamber through controlled valves, and hopefully, the suppression
chamber is connected to heat exchanges (again through controlled valves), and the heatexchanges have rupture(s). There has not been clear announcement to say if my assessment iscorrect or not, but in view of the fact that subsequent environmental monitoring has not shown
any continuous extremely high level, I am assuming that there is no major leakage from nuclear
reactor to the environment. However, there is a leakage after the rupture . . . Government's mostrecent assessment was that they can not be certain if the sea water injection operation is stably
on-going. This is definitely a matter of concern.
#4: There was a fire (not hydrogen explosion), and they have yet to establish the cooling poolof spent fuel rods has enough water inside.
It has been taking a long time for them to confirm this - some concerns.

52

There have been reports that temperature of the other spent fuel rods cooling pools is rising.
This may be less urgent issue compared with the others, like #2 case, but I hope some attention
will be made to avoid another hydrogen explosion.
Environmental monitoring results indicate that there is some sporadic high level ofmeasurements, especially one spot near #4, which prevented the workers access.

Otherwise, radioactivity has been detected very widely, but they are very low level, which does
not pose health risk. Of course, basically, no additional radioactivity is the best, though.
Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Tue, 15 Mar 2011 16:58:17 +0900 Subject: Re: radiation
precautinary measures

My quick impressions are:a. Obviously 400 mSv/hour is an extremely high level. More recent assessment says that thiswas probably caused by the remnants of debris from reactor #3 facilities (there was an explosion
there yesterday), and the authorities' current assessment says that it is likely that this was causedby continuous emission of radio-nuclides or no increase of leagkage. Since the location shows
this high level workers are not able to work in the area. (We need to understand that the local
direct radiation from broken construction materials (which does not move) and long-reangeobservation of radio activity are of completely different nature.) A measurement at the gate once
showed above 1 miliSv/hour level but later it went low to hundreds micro-Sv/hour level) (I haveto think that there is continuous leakage of un-known rate.)b. Subsequent environmental measurements in power generation site have all shown lower
radioactivity.

c. Measurements in Sendai, Tokaimura, Tokyo and Yokosuka (US base) show very low level ofradiation but all are very low and do not pose any human health risks.

53

d. Fortunately there is a good monitoring capability by US Navy (up-wind from Hayama), andit will be unlikely that equipping IGES with measurement facility would have any value.
e. I do not have any strong views on work-at-home. It might reduce the risk of exposure(though extremely minor) in commuting, but Yokohama is closer to Fukushima, I think.
f. At present leakage of radio-nuclides is very low - no comparison with Chernobyl (Onecomplete reactor exploded (or two - I do not remember well) released accumulated radionuclides!). It is far lower than the Three Miles case.
Touch wood, though.
I can not say Japan is completely safe, but the risk seems to be really negligible -- so far.
Taka----------------------- Original Message ----------------------- From: Taka Hiraishi<hiraishi@iges.or.jp> To: Date Tue, 15 Mar 2011 11:31:04 +0900 Subject: Re: [15 March
10:45 Update] Travel; Blackouts; Fukushima Nuclear Plant

Good information service, which I highly appreciate.
This morning news were alarming. There is now leakage from "suppression chamber (pool)" of
the reactor #2 of the Fukushima Power station #1, though the leakage level is not yet clarified.
This "suppression chamber" is connected to the "container" through control valve, and thecontainer contains the nuclear reactor (pressurised and sealed body), which has a controlledconnection with the rest to the container. Thus, the reactor itself does not have direct connection
with the open air.

Right now Prime Minister Kan revealed that fire broke out at the reactor #4. Increased leakageof radioactivity has been observed. Chief Cabinet Minister Edano explained that #4 had notbeen functioning even before the earthquakes, and the fires are not related to nuclear activities.
Residents of 20 -30 kms range were advised to stay in their houses.
Edano explained that it seems that the leakage of #2 was through the heat exchange facility
connected to the suppression chamber (TH: this was a relief for me because the leakage was notdirectly from the suppression chamber nor from the reactor vessel). He also reported high levelof radioactivity (hundreds of milli Sievert level (not micro-Sv, which has been used earlier on
the environmental measurements levels) near the reactors - Edano said this high level isconsidered to be related to the #4 fire. He explained that thanks to diffusion, it it expected that
their impact would not be health-hazardous beyond 20 kms.
Taka
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