Reading the national report of Ukraine (2): Lessons from Chernobyl to Fukushima

I haven't finished reading the report document yet (totally over 300 pages), but in addition to the zone classification, there are other useful information and pedagogical analyses already in the first several pages.

In page 14, there is a paragraph saying:

The USSR undoubtedly achieved considerable success in developing nuclear science and engineering, especially in military industry. However, this success was too much politicized. At the same time, shortcomings and errors that led to large disasters both at civil and military nuclear facilities were concealed.  ----- All this resulted in the fact that infallibility moods become firmly established in the nuclear engineering. ---- "The Soviet nuclear reactors are the best in the worlds. " This (attitude) was also eloquently seen in response to the accident happened at the American Three Mile Island Nuclear Power Plant in 1979, when the leaders of the USSR nuclear industry announced that "such accident was impossible under socialism". -----

This analysis can be applied literary "exactly" to the Fukushima nuclear disaster, except the "under socialism" part, which should be replaced with "in Japan".

After nearly 30 years since the Chernobyl catastrophe, no Japanese politicians as well as bureaucrats learned the lessens from the Chernobyl. The ancient Romans used to say "Errare Humanum est", but this repetitive mistake by the Japanese government is too much and unacceptable to me.

Reading "National report of Ukraine: Twenty-five years after Chernobyl Accident"

I am reading now a report from Ukraine, "Twenty-five years after Chornobyl accident: Safety for the Future", which can be downloaded from here. (I did not know this until recently:  in Ukrainian, the correct spelling for "Chernobyl" is "Chornobyl". See Wikipedia.)  The reason for my reading of this document is that I wanted to know how the Ukrainian government set the radioactively contaminated zones.  There are four zones in Ukraine: (1) Exclusion zone, (2) Zone of implicit (mandatory) resettlement for more than 5 mSv/year, (3) Zone of guarantee voluntary resettlement for 1 to 5 mSv/year, (4) Zone of enhanced radiation monitoring for 0.5 to 1 mSv/year.

0.5 mSv/year corresponds to 0.06 μSv/h, which is observed everywhere not only in Tokyo, but in many parts in Japan (and maybe in many places in the world).  Usually, 0.06 μSv/h is regarded as a  "low" dose. When this zone classification was reported in NHK (Japan Broadcasting Cooperation), I thought something is wrong: 0.06 μSv/h is too low as a radiation monitoring district. That is why I decided to read the original report by myself.

First of all, I expected that the report is not open to public in the pdf format, so that I thought I might need to go to library to have a copy of the report. But to my surprise, the document can be downloaded in the pdf format! I appreciate those who allowed the download.

Anyway, I read the document, and found that the levels of the "dose" used for the zone classification turned out to be "additional" dose to the natural level. For example, if the natural dose is 0.06 μSv/h, then the No.4 zone (that is, the zone of enhanced radiation monitoring) should show the radiation level from 0.11 to 0.17 μSv/h. I agree that the places in Tokyo and its neighbours showing this level of radiation are surely contaminated by Cs-137, Cs-134, and other radioactive materials from the Fukushima nuclear power plant. My conclusion is that NHK misinterpreted the report issued by the Ukrainian government. As everybody says, it is important to check the original sources or documents so as to obtain correct information and knowledges.

As an example, a place in Chiba (East of Tokyo) shows 0.14μSv/h (with DoseRAE2 dosimeter). This place is near a small lake called "Inba-numa". See pictures and google map, below. The natural radiation level in this place is about 0.03 to 0.05 μSv/h. Therefore, the additional radiation is 0.09 to 0.11μSv/h (0.79 to 0.96 mSv/year), which satisfies the criterion for No.4 Zone.

Left: a view of "Inba-numa"
Right: radiation level measured in the place shown in the left picture.

View Larger Map

 To confirm how much the classification is reasonable, it is useful to measure the radioactivity of the soil in the place. The measurement should be done with the more sophisticated NaI scintillator (of course much more expensive than simple dosimeter such as DoseRAE2 in the above picture). Fortunately, I can access to one of such scintillators (Berthold LB2045), which  measures the radioactivity of soil samples in the unit of Bq (Becquerel, the number of radiation particles per second) . The measured radioactivity of the soil sample taken in Inba-numa is 318.2 Bq/kg (for Cs-137 and Cs-134). The corresponding gamma-ray spectrum is shown in the picture below.

Radioactivity (Caesium 137 and 134) of the soil sample
taken near the Inba-numa lake, Chiba.

The presence of three peaks in the 503 to 1025 keV energy region indicates that this soil is contaminated by Caesium 137 and 134. A small peak near 1550 keV shows a presence of K-40 (potassium 40, a natural radioactive material). CPS for the vertical coordinate means Count Per Sec. The value for Bq is calculated by integrating the spectrum in the relevant energy region. From this result, the 0.14 μSv/h means surely a contamination by Cs-137 and Cs-134.

A fairly large earthquake

A fairly large earthquake hit east japan this evening (around 5:30 pm).

I was outside, trying to observe Jupiter with a recently purchased big reflection telescope. This type of big telescope would be fantastic to enjoy the detailed surface of planets and subtle colouring of nabulae, etc. if the alignment of the autoguidance was perfectly set. Otherwise, this heavy chunk of metal is totally useless. It is likely to happen especially to most of beginners: the setting of the big telescope is very difficult. Last two days, I have been trying to see Jupiter with this telescope, but no success. Even a glance of Jupiter was not seen so far. Only a darkness...

Today, I followed the manual to set the alignment of the telescope with the help of the attached computer system for the control of the gears of the telescope mount. It was that moment when I felt a subtle shaking of the whole ground... It was just a beginning of another big Earthquake hitting Tokyo for the first time since the March 11, 2011.

The oscillation amplitude became larger and larger in time. I could feel the undulation movement of the asphalt itself. Looking up a building and a chimney tower in front of me, I noticed they were also oscillating slowly. The earthquake continued about a minute or so. Indeed, very long-lasting transverse wave it was! So scary. I run to the security office and asked an officer where the epicentre was. He said "Again in Tohoku. Almost the same area as the last big one happened. A Tsunami alert again along the all coasts in the north east Japan!"

Big earthquake, followed by Tsunami, which strikes Fukushima Nuclear Power station: this is the golden formula to destroy many parts in Japan. And I had a feeling that this could happen again. I try to gather the information about the No.4 reactor in Fukushima 1 nuclear power station. Because the spent-fuel pool placed on the top of the reactor has been tilting since the mega earthquake hit last year. Some scientists and engineers have warned that once the pool falls down to scatter the spent fuels, people in Tokyo need to evacuate from the capital immediately. I was so afraid of this possibility. I called my wife and told her to prepare for a possible evacuation in case.

Fortunately, this time, the spent-fuel pool survived the earthquake. But the Fukushima-2 Nuclear power plant, which survived the mega earthquake last year, underwent a minor emergency situation due to today's earthquake, allegedly to Mainichi Newspaper.  The met office (of Japan) announced that this evening's earthquake is an aftershock of the mega earthquake last year, so that it can happen again soon. I don't want to live with nuclear power stations under this sort of situation for long.

Tunnel collapses can happen again somewhere near the epicentre, I guess.

Tunnel collapse and SUBARU Impreza WRX

As reported (for example, in the Guardian), there was a tunnel collapse in a highway near Tokyo a few days ago. This collapse is not a total collapse of the tunnel, but the concrete ceiling panels fell down to crash several cars running below.  9 people were killed by this accident.

But there could be one more casualty: as mentioned in the article of the Guardian, a journalist working for NHK (Nihon Hoso Kyokai = Japan Broadcasting Cooperation) who happened to drive his SUBARU Impreza WRX under the collapsing tunnel, narrowly escaped the accident.

SUBARU Impreza that escaped the accident.
(Picture taken from here.) 

Many people in Japan believed that this escape was possible because it was Impreza, with high performance for a quick acceleration and good rigidity of the car body. If the car was Prius, then the driver would be dead now...