Fukushima: day 146 to 151

Dear Colleagues:

48th-151st day!

I. Radiological Safety Evaluation Report (draft) by FoodSafety Commission
The Food Safety Commission (FSC, http://www.fsc.go.p/english/index.htm)
has been taking a very important role in defining rdiological safety
criteria related with the Fukushima Daiichi disaster. On uly 26, they
compiled and posted, for public comments, a draft Evaluation Rport on
Assessment of Radioactive Materials Contained in Foods in Japanese, 226
pages). On this report, the Chairperson Naoko Koizumi, MD,as released a
message in English
http://www.fsc.go.jp/english/emerg/radiolog_iincho_danwa.pdf as attached as
radiolog_iincho_danwa.pdf
It is very intereting to read that the FSC is trying to introduce a
cutoff dose rates forlow level radiation risk at 100 mSv, through
reviewing 51 scientific papes including the following three reports:
(1) Nair RR et al. Background radiaton and cancer incidence in KeralaIndia-Karanagappally cohort study, Health Physics, 2009 Jan; 96(1): 55-66.
(2 Preston DL et al., Studies of mortality of atomic bomb survivors, Report
: 160 (4): 381-407.
(3) Shimizu Y et al., Life Span Study Report 11 Prt 2. Cancer Mortality in
the Years 1950-1985 based on the recently Revised ses (DS86). 1988.
Although I also share a need for introducing a cutof for low level risk,
I do not believe that the quoted major references alo are strong enough to
argue against the LNT hypothesis as discussed in arthquake (51) in May 1,
under the title of "Adequacy of 20 mSv and LNT hypthesis." In addition,
the FSC's report appears to be avoiding discussions ofthe most
controversial issue among young mothers, the dose limit for childre, since
there are not sufficient epidemiological data. However, I believeit is
urgent to establish a age-dependent radiation risk, such as done by ICRP
Pblication 72, ³Age-dependent Doses to the Members of the Public from
Intae of Radionuclides - Part 5 Compilation of Ingestion and Inhalation
Coeffcients, ICRP Publication 72 Ann. ICRP 26 (1), 1995.
I believe that the age-dependent effects can be simplified by a factor
of (organ doses in Gy, which is inversely proportional to weigt of
individuals) x (sensitivity differences of organs in ages). If w apply
this method, the children)'s dose limit should be reduced to 1 mSv/,
corresponding to the 20 mSv of the first year doses for adults.
I have submitted 8 detailed comments to the FSC, although it is
questionabe whether they pay attention to my comments, since they are
dominated by epidemiologists. I believe risk studies are needed now,
istead of literature survey.

II. City-wide decontamination in Minami Souma-shi
Since the Government is now coordinating, with local governments, toward
early relaxing of restrictions imposed on the 20-30 km "Emergency
Preparedness" Zone, Minami Souma-si, which is located in the north of
Fukushima Daiichi, launched a cit-wide decontamination in two months. This
project is assisted by Proessor Tatsuhiko Kodama of the Radioisotope Center
of University of Tokyo. The project consists of (1) development of
contamination density maps, (2) the identified hot spot regions will be
decontaminatd by the city, such as by cleaning catch basins of rain sewage,
high pressure water cleaning of school buildings, removal of surface soils
from school grounds followedwith deep burying under the ground, (3)
recruiting volunteers for privae housings. The initial costs of the
decontamination will be 9.6 billion ye (approx. $123M). From the city,
nearly a half of the citizens (33,600 resients) have already evacuated to
the other regions, reducing its population own to 37,900 and it is urgent
to demonstrate a feasibility of rehabilitation The total area of the
Minami Souma-shi is 398.50km2, although not all ofthis area needs
decontamination.

III. Update of the water purificatin system
The unstable and resultant low availability operationcontinue in the
water purification system. At 8:07m AM on August 7, a chemcal circulation
pump tripped in the AREVA's co-desition process due to an overloading. It
was at 3:31 PM, the system went back for water processing. Also at 7:05 AM,
apump in the Curion's cesium sorption facility tripped inced by a
malfunction of its electronic circuits. Fortunately, the evaprator
purification system, which is decontaminating the primary side discarge of
the RO system started to operate. An illustrative schematic diagra is
attached:
http://www.tepco.co.jp/nu/fukushima-np/images/hndouts_110808_01-j.pdf
At 8:20 AM of August 9, a lightning induced faiure of power units to
the pump from the SPT purified water extraction pmp as well as two level
gauges, one for the SPT receiver tank as well as SPT(B) for two hours. From
the announcement it appears that the cause of theloss of power is due to an
lightening-induced surge current.

It was also rported that the capacity went back to 50tons/h when the horses
were replaceto reduce the flow resistance.

Well, let me stop here tonight!

Gnn Saji
__________________________________________________________________________
(Previous e-mail sent at 10:01 PM on Aug 6 as Earthquake (40, August 2-6)
Dear Collgues:

145nd-148th day!

I. Update of the highest contamination detected
This survey was motivated from the unexpectedly low dose rate of air
samling taken from the 1F1 Reactor Containment Building as introduced in
Eartquake (139), which showed that it was not much different from what was
monitred in the Reactor Building. Let me recap the relevant radioactive
concentrtion information as attached. As to the concentration of
radioactive specis inside of the 1F1 Reactor Building, measured on May 5,
the results indicate approximately 0.08 Bq/cm3 for Cs-134+Cs-137. The
measurement of the air samling from the Reactor Containment Vessel was
introduced in Earthquake (18) as summarized below.
Species Bq/cm3
Cs-134 17
Cs-137 20
I-131 UD
These values are only 500 timeslarger than those at the Reactor Building.
It the reactor core has actuall molten through, the dose rates should have
been larger by several orers of magnitudes.
Since it was identified that the hot spots are relaed with the route of
venting through the Reactor Building Reactor Room Heting and Ventilation
System, through Emergency Gas Processing System, he survey appears to be
performed along this route. Although there were heavly loaded redundant
filtering units, consisting of dehumidifire units, heatin coils,
pre-filters, HEPAs and Charcoal filters, some of them may not hae worked
as intended under the station blackout situation. Nevertheles, these
filtering units should have removed a significant portion of the released
radioactive secies resulting in highly radioactive. This unit should have
worked for mtigation of some portion of the released radioactivity through
ventin. As a matter of fact, the dose rate records of the temporary
monitoring tations indicate that the dose rate due to venting is much
smaller than that following the hydrogen explosion as well as the subsequent
large release due to, potentially, a "spontaneous hydrogen explosion." The
venting was not the largest release from 1F1 as shown in the attached graph
showig a correlation of Monitoring-Events. There is also a possibility of
bck flow through a ventilation duct to the rom discharge ports to the Fuel
Handling Room, resulting in retention of the effluent through venting.
On August 4, TEPCO released a photo of another 3.6 Sv/h hot spot,
located at the bottom of the Common Exhaust Stac shared between 1F1 and
1F2. It is from a rain water dran line from the stack as attached
downloaded from:
http://www.tepco.co.jp/nu/fukushima-np/images/handouts_11005_02-j.pdf. It
appears to indicate that there is a pool of condensed highly contaminated
waterreleased by venting at the bottom.

II. Remote hot spot measurement of entire eastern region of Japan
The Gvernment decided to initiate an Overall Integrated Radiation
Monitorng Project, covering Tokyo and 21 Prefectures of eastern Japan.
This project is to respondto the public's anxiety agait local hot spots.
The detection will use airplane, whose effectiveness has been demonstrated
by the US DOE/NNEA dose maps and soil contaminationmaps.
This project is prudent, I believe, since the highly contaminated sewage
sludge have ben reported from NW areas around Tokyo where no contamination
maps are available.

III.Relaxing the 20-30 km "Emergency Preparedness" Zone
The Government is currently investigating toward early relaxing of
restrictions imposed on the 20-30 km "Emergency Prepares" Zone, such as
by producing detailed dose maps. On August 4, Nuclear Safety Commission
(NSC) released their view for this direction. The new guideline will be;
(1) A possibility should be bnignly small for future emergency evacuation
from this zone.
NISA/TEPCOassured that the current most critical issue is continued
water injection ito the Reactor Pressure Vessel. Even in severe
malfunctions, they should e able to recover the current essential safety
functions within three hours,such as by having fire-engines in standby.
(2) Dose rates from the time of r-habitation to this zone in the coming one
year should be less than 20 mS and will be expected to be reduced below 1
mSv/y in long time, through evironmental monitoring and decontamination.
For the reqrement of the Point (2), the below 20 mSv/y may be easily
achievable, however the below 1 mSv/y in the long range future is expected
to be extremely diffcult. Even if the "Scheduled (and organized)
evacuation" zone is not included, there are several hot spot areas in
Kuzuo-mura, Tamura-shi, Kawauchi-mura as wellas Iwaki-shi, due deposition
of Cs-134 1/2=2.01a) and Cs-137 (T1/2=30.0a), whichmay not decay for a
long time. A very high dose rate corridor is stretcing as far as 60 km
towards the NW direction from the Fukushima Daiichi. Th hot spots areas
appear tomount to nearly a half of the residual zone. This
characteristics are clearly shown in the US DOE/NNEA dose maps
http://energy.gov/articles/us-department-energy-releases-radiation-monitoring-data-fukushima-area

It appears like many scientists are making a mistake since te current high
air dose rates are not from effluent released from the damage plants rather
it is due to ground shine from the soil contamination

IV. Update of the water purification system
The unstable and resultant low availability operation continue in the
water purification system. On August 5, a worker found approximately 700
liters of the flushing water leaking from a line used for decontamination of
the sorption tanks. The activation level is of the same order of magnitude
as the highly contaminated wter, although there was no external release
from the Centralized Waste rocessing Building. Earlier to this, the
system stopped for 2 Hours repotedly due to a freeze of a portable computer
used for process control.
TEPCO is trying to replace two horses, one from the Kurion's process to
the AREVA's co-deposition process and the other from that to the treated
water storage ank (SPT). They appear to believe firmly in that the flow
decrease is due o deposition of sludge, although no chemical sampling data
has been release from them.
Although it was planned to start the overall commissioning est of the
new zeolite sorption facility, TEPCO decided to process the almostfully
accumulated highly contaminated water being stored at the basments of
Centralized Waste Processing Facility. The water has acumulated as high as
30 centimeters from the storage limit. The new faility is being
constructed by Toshiba in collaboration with Shaw Group.

V. pdate of internal exposure in live stocks
Since I covered this subjec in July 30 as Earthquake (134), this issue
has been the major topics i many Japanese media. The Government decided to
dispose all 3500 live socks which have been traced to be fed with the
contaminatedtraw feed. They have been thinking of putting them in storage
for several months waiting for detailed screening by dosimetory, however
they dged that the consumer may refrain from buying the sceened beef meat
even after found below 500 Bq/kg of cesium. All of them will be incinerated
for disposal.

Let me stop here tonight!


Genn Saji