Tag Archives: Tokyo

An Explanation about Radiation

Today, I found an interesting article explaining how to understand the risk of radiation, but unfortunately, it was in Japanese and I can’t find a translated post in English. I am going to translate it into English as much as possible. There is anything you found, my mistakes or anything you feel it difficult to understand, please let me know.

Qestion1) Radiation decreases inverse proportion  to square of the distance. (right) Then, does it become 1/4 you move from 10 km point to 20 km point?

Answer) Radiation decreases like that in a vacuum. If it is filled with air ,the space between 10 km point to 20 km point, it works like a wall to block the radiation. That’s why it is impossible to reach  the surface of Earth for Gamma ray from Space. About radiation in Tokyo right now, it is provided by radioactive materials flying from Fukushima Nuclear Power Plant. In this case, the amount of radioactive materials / a square will decrease in distance, but those materials keep providing radiation.

Question 2) It is 8 days a half-life of Iodine-131. Then, is it safe 8 days later?

Answer) Both yes and no. Iodine131 lost its half power in 8 days. That’s true. But, if there are 4 times of safe limits for Iodine-131, there are still twice of safe limits 8 days later. So, you need 16 days to have safe limits of Iodine-131 in this case. And, Iodine-131 changes to Xenon-131m while providing Beta ray, and Xenon-131m changes to Xenon-131 while providing Gamma ray. A half-life is 11.84 days. So, it is impossible to say something is safe 8 days later.

Question 3) Is it more dangerous to be exposed a little every day from inside of your body by a radioactive material which comes into your body than to be exposed to more radiation only once.

Answer) It depends on how much radiation you are exposed in a moment. It is similar to the risk of having salts. In Japan, it is OK with an adult to have 10 g of salt / a day. Then, it won’t cause a problem on your health if you had 10 g of salt / a day for 20 days, but it is not good for you if you had 200 g of salt at a time. About Radiation, it is less effective for your health to be exposed to 6 micro SV of radiation for 42 days (1000 hours) than to be exposed to 6000 micro SV of radiation by 1 time CT scan.

Question 4) Experts say, “it doesn’t mean to cause a problem to your health right now.” Does it mean it will be dangerous later?

Answer) It is again similar to the risk of salt. It is safe to have 10g / a day, and it won’t be dangerous to have 20g if it is once or so. But, it will be dangerous for your health if you keep having 20g of salts everyday for a long time. It is the same with those vegetables or tap water that show much radioactivity than the safe limit. If you ate those vegetables or drank such tap water once or so, it won’t be dangerous just like 20g of salts won’t be dangerous if it was once or so. It will be dangerous if you eat/drink much everyday for a long time, again just like the salts, then, Japanese government announced the warning not to eat/drink as much as possible.

Those questions and answers are very understandable and seems rational for me. I hope I translated well.


Posted by on April 7, 2011 in Disaster, Science, Uncategorized


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Short Note from Japan on April 4

Well, I think you want to know how dangerous it will be for you the radioactively contaminated water which was released from Fukushima Nuclear Power Plant into the pacific ocean yesterday.

TEPC said it would be 0.6 milli SV/year of expose if you eat fished or seaweeds everyday which is caught or  collected around there. Our policy is, I am not sure it is international policy or not, but at least Japanese policy is set safe limit to general people as 1 milli SV/year, and it is impossible to catch any fishes nor seaweed around there right now. So, TEPC said it won’t be so dangerous even for us Japanese.

I think it won’t be so dangerous at least to the world if it is only one time release.
The water included low level radiation. It is 100 times higher than usual safe limit, but you know, pacific ocean is very large and every radioactive materials lost its power in time and distance. It is very high in limited space and water, but it will be less high once it is mixed with seawater of pacific ocean. While the materials traveling from Japan to your county by the ocean, the materials will make distance among them loosing its power in time. It will be bit higher than usual the radiation level of seawater around your country, but I am sure it won’t be so high to cause a problem on your health.

But, what if TEPC needs to do again? How many times they will need?  That is the question.

Right now, many experts from all over the world come to support us. I hope they will find a way more safe way to the world.

Believe me, all of us Japanese feel very sorry for what is going on. Natural disaster is something we can’t control and there is no way other than to accept and rebuild. But, the nuclear accident is different. I am sure TEPC and Japanese government have been trying hard their best, but it seems not enough. I am so sad we failed to keep a nuclear plant in safe. It is our own fault not to have more reliable way to keep a nuclear power plant in safe even with such a huge earthquake and tsunami as we know they happened very often in Japan, and, we knew how dangerous radiation is since 1945. We should be more careful.

I apologize as a Japanese to the world about that our country bring great fear to the world on the Earth. I promise we will find better way to be a reliable county.

Well, I might be sound bit pessimistic, I guess, but actually not. I keep my trust to our technology and friendship with many countries. I don’t think all the experts all over the world can’t find even a way to make the situation a little better. It won’t be so soon, but I believe we will find a way, maybe a tough and difficult way, but find a way with hope.


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Radiation Effects Research Foundation

Radiation Effects Research Foundation

A Cooperative Japan-US Research Organization

You can get more information about radiation effects there.

I am now trying to write a post about what happened today, April 4, but it was too complicated to me to explain in English. Give me a time, please.


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A Column about Vegetables from Fukushima

Craving Spinach After Fukushima Nuclear Scare: Paul Blustein


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Bloomberg says, “Radiation From Cornwall to Hong Kong Beats Tokyo Amid Nuclear Plant Scare”

Radiation From Cornwall to Hong Kong Beats Tokyo Amid Nuclear Plant Scare

I thought it interesting.

Again, I believe it is impossible to anybody to let all the medias, experts make the same lie with Japanese government.


Posted by on April 4, 2011 in Disaster, Hiroshima, Uncategorized


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Advice from IAEA

It is already April Fool here in Japan, but I am going to write what truly happened March 31 in Japan.

Today, IAEA found out there were 2 million Bq of radiation/ 1 square meter at Iidate-mura, 40 km away from Fukushima Daiichi Nuclear Power Plant. IAEA said it is 2 times higher than one of their refuge guideline.  Depending on this, IAEA gave an advice to Japanese government that they should watch carefully the radiation level there. IAEA suggested that they think it is dangerous to stay there.

Right now, Japanese government made the order that 1) to be away from the plant more than 20 km, 2) to stay inside as much as possible if you are from 20 km to 30 km.

Mr. Edano, the chief cabinet secretary, said that Japanese government have keep detected radiation level very carefully including Iidate-mura, and they put great respect to IAEA, but as they detect radiation different way, Japanese government didn’t think to widened the refuse area right now.

Well, what I understand is, IAEA got the amount by checking radiation by dusts on leaves. I mean, IAEA collect some dusts from leaves of trees, plants, etc. and check how much radiation those dusts included. On the other hand, Japanese government is checking radiation by the dust on the air, or the dust on the foods like vegetables. NISA said they think that their standard and technique are more precise about how dangerous the radiation level will be to one’s health than the standard of IAEA. The government and NISA (Nuclear and Industrial Safety Agency) also said that they set limits for when a person stayed outside all day, means 24 hours, but in reality, it is impossible to stay outside 24 hours, then, it is not so dangerous yet.

Seems to me, IAEA is bit too pessimistic and Japanese government is bit too optimistic. It is nucleuses. Yes, radiation is very dangerous when you are exposed very strongly in a moment, but not so dangerous when it is weak even if it is long time. But, it is yet radiation expose, it could be dangerous if there are enough radioactive materials, especially the ones which keeps its power for a long time. It won’t be good for your health.

I don’t think it is dangerous in Tokyo, but it seems bit dangerous in Iidate-mura. Up to now, there are very few people who were exposed dangerously and all of them were the engineers who worked at the plant, not the people who were living in around the plant. (Please mind that the engineers had already discharged from Hospital because they show no sign of damage because of radiation.) And, I think it would be true that Japanese government have been doing what they believe which is right, but it could be wrong in this situation, so I think it is time to take too much security on people’s health. I have heard so many sad stories which seemed to be caused by radioactive expose here in Hiroshima, not only the stories in Hiroshima or Nagasaki, but the stories of Chernobyl, Bikini archipelagos, or Kazakhstan. We already have enough Hibakusha in this world, don’t need more.


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Short Note from Japan on March 29

I am going to write some of my thoughts. Please don’t think it as what Japanese government announced or Japanese media reported. I am getting those information and my thoughts would be effected by them, but what I am going to write is only what I am thinking and feeling.

  • I think you should be careful about the yellow sands from China rather than the radioactive materials from Fukushima if you are in the west of south part of Japan as there is the Prevailing westerly around the Northern Hemisphere. I think there is very small possibility for the radioactive materials to reach Hiroshima because of the wind, but we couldn’t stop yellow sands to reach here because of the wind. We have been warned sometimes to stay inside when so many yellow sands reached Japan if you have a problem on your bronchus.
  • Well, it is possible for the radioactive materials to reach North America, Europe etc. because of the wind, but I believe it won’t be so dangerous when nuclear authorities say it is not dangerous by my own experience. When Chernobyl nuclear power plant accident happened, I was a girl, maybe 13 years old or so, (don’t guess how old I am now! lol ), and the distance between Hiroshima and Chernobyl is shorter than the distance between North America and here, but we were not warned any way and most of us are healthy adults now. I said “most of us”, not “all of us”, yes, but I believe you have lost some of your friends with any reason if you are older than mid 30.
  • If you are in the Northern Hemisphere and your country has nuclear weapons, especially that if your country has taken a test for a new nuclear weapon inside of your country, I recommend to make sure to live west edge of your country.
  • I have been frustrated about belated announcement by the government or TEPC, etc. I think there might be many things they didn’t say in front of camera among what they already knew, but I feel they didn’t make lies. They know very well that we can get any information on the internet, even in foreign language.
  • I hope you don’t think me supporting Japanese government, nuclear power, TEPC. No. I don’t support them, but I think it is not a time to point a finger and yelled at them, but a time to let them put all their wisdom and power to make our situation better. We can do anything when everything is settled down, including to change our prime minister.
  • I should say that I am bit mentally insecure since the disaster. I have recalled many memories of what I have heard about the bomb, what I experienced in Kyoto as a collage student living alone separated from the rest of my family when a big earthquake attacked Kobe in 1995, and what I saw and felt when I visited the Ground Zero in NYC. Sometimes, I can’t sleep well or can’t stop myself tearing when there is no reason to cry. I hope you don’t have such a mental problem.

Well, it’s time to go. Wish you a nice and pleasant day!


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