2016년 7월 12일 화요일

Natural radiation

Natural radiation

The natural radiation (I do not thank it for natural one) is the generic name of the radiation that originally there is in the natural world even if there is not human activity [1]. Among the radiation exposure caused by the natural radiation, the radiation exposure caused by the radiation amplified by human activity may be classified in artificial radiation exposure. I refer to a classification of the radiation exposure by United Nations science Committee (UNSCEAR) about the influence of the atom radiation.

I refer to "the environmental radiation"

Table of contents

General statement

There is the classification method of the natural radiation in various ways. For example, I can classify it in two of the radiation from (1) cosmic rays (2) nature radionuclide (mainly a primitive radionuclide) if I pay my attention in the origin and classify it [1].

The breakdown of the radiation exposure caused by the radiation of nature which a human being receives catches the external exposure of 480μSv a year (= 0.48mSv) from the natural radionuclide from approximately 390μSv a year (= micro sievert, = 0.39mSv), the earth crust, building materials from cosmic rays [2]; [3]. And I receive internal exposure of approximately 290μSv a year (= 0.29mSv) from a natural radionuclide (potassium 40, carbon 14) which there is in the body. In addition to these, I receive radiation exposure of approximately 1,260μSv a year (= 1.26mSv) from radon included in the air. Will receive radiation exposure about 2,400μSv a year (= 2.4mSv) for world average in total from the natural world [4]; [5].

((1988 estimate) [6] that there is fewer it in Japan, and originally is only considered to be 1,400μSv a year (= 1.4mSv).)

And and [outside the body radiation exposure from the earth crust] is equivalent to it [7] when they pay their attention to the thing from a natural radionuclide (natural radionuclide) among natural radiations [internal radiation exposure] most move to potassium 40. Because the element called potassium exists abundantly during environment, and it is the element which is important to a creature, and potassium 40 occupies a little over 0.01% of naturally occurring potassium, potassium 40 is taken in by all means in the body when a creature takes potassium [7]. The natural radionuclide bringing radiation exposure next to potassium 40 is a nuclide of radon [note 1]; [7].

Thing by cosmic rays

The numerical value to be considered to be radiation quantity to come flying from the space varies according to a document and is considered to be 0.39mSv (= 390μSv) [9] for 2.5mSv a year (= 2,500μSv) [8], "basic knowledge of the use of radiation" by approximately 300μSv a year (= 0.3mSv), the documents of the Joseph vice by the documents of Ichikawa.

When altitude rises, the radiation from the space is increased approximately two times every 1,500m because shielding called the air decreases. I relatively strongly receive emission to fly substratospheric altitude by the jet of the international airline for a longer time than a domestic airline. If because the normal flight altitude is around 10,000m [10], I calculate from these values

I will be exposed to radiation to a radiation dose of approximately 100 times of the と ground.

I am said to receive a radiation of 0.2mSv (= 200μSv) by the round-trip flight between Narita - New York [11]. In addition, with the report that really fit a radiation exposure dosimeter to a plane crew boarding it between Narita - New York, and it is to approximately 3mSv a year (= 3,000μSv) as for the exposure dose when after measuring it, board it for 800-900 hours in a year [12].

The exposure dose of the astronaut during International Space Station stay to go around at a height of an altitude of around 400km that is a terrestrial magnetic field range becomes the 1mSv (= 1,000μSv) degree per day [13]. The exposure dose is said to be 1mSv (= 1,000μSv) degree per day equally in the outer space of the terrestrial magnetic field outside [14].

Is launched in Soyuz TM-18 on January 8, 1994, and stay in Mir LD-4 437.7 days, and I Lee ポリャコフ of the astronaut has a record for the longest space sojourn time in the single mission [15]; [16]. It is estimated that the exposure dose by this space trip exceeds 400mSv.

When solar flare occurs, many X-rays, gamma beam, a high energy charged particle occur. In addition, with flare, there is many that a material in sun corona is released in the interplanetary space (kolo null trout エジェクション (CME)). In addition, in the terrestrial magnetic field outside (at the time of a, for example, lunar stay and Mars existence person flight), X-rays in the flare, radiation exposure by the gamma beam may exceed the fatal dose of the person [17].

Thing from a natural radionuclide (natural radionuclide)

Radiation from natural radionuclides in the earth crust

A radiation of the 0.48mSv a year (= 480μSv) degree [9] is generated from radioactive material included in the earth from the basement. For example, a radiation becomes slightly strong in the tunnel to be strengthened when this becomes the basement.

The radiation material of the underground is included a lot in granite, and a nature radiation becomes strong in many areas of this rock. The radiation from the earth is the main factor that the strength and weakness of the radiation are over by an area.

Food and drink

Because the radionuclide of the infinitesimal is included in water and the food which a person usually eats, it may be said that the body is always exposed to radiation. This exposure dose is considered to be 0.29mSv a year (= 290μSv) degree [9] for [7], "basic knowledge of the use of radiation" that are approximately 250μSv a year (= 0.25mSv) by the documents of Ichikawa.

A main internal exposure source includes a naturally occurring radioisotope such as potassium 40 and the carbon 14. It is said that the human body weighing 60 kg in weight has a natural radiation material of 2,500 becquerels with 4,000 becquerels, carbon 14 with potassium 40 [18].

The radiological quantity varies according to a kind of the food, and a banana, a potato, a haricot bean, nuts, the kind of the sunflower have slightly a lot natural radioactivity [19]. It is Brazil nut that there is the most natural radioactivity and there is 244.2 becquerels per 1 kg [20], but is only the level that there is not of the influence in the human body even if I eat every day.

Atmospheric source

There is radiation exposure of 1.26mSv a year (= 1,260μSv) [9] from air. Gas such as radon which leak, and goes out of the inside of the earth, and exists naturally is feeble emission sources. I appeal for attention saying that the radiological intakes such as radon from all over the air have an influence on the respiratory system and can become the risk factors such as the lung cancer so that within it, indoor radon density reduces 100 becquerels/m3 in the World Health Organization [21].

Local to be known by the high natural radiation

Footnote, source

[Help]

Note

  1. In a nuclide of radon saying ^ here, radon 220 to produce in decay series of radon 222 occurring in decay series of the uranium 238 and thorium 232 exists

Source

  1. ^ a b Atomic energy encyclopedia ATOMICA [natural radiation (ability)]
  2. ^ http://home.hiroshima-u.ac.jp/er/EV_H_S1.html
  3. ^ http://www.asahikawa-med.ac.jp/hospital/hoshasenbu/qa.html
  4. ^ http://www.chuden.co.jp/energy/nuclear/nuc_hosha/nuch_sizen/index.html
  5. ^ United Nations science Committee (UNSCEAR) 2000 report (collection of "atomic energy, energy" drawings 2009)
  6. ^ University combination use engine corporation High Energy Accelerator Research Organization＞Radiation science center ＞Radiation in the living＞Natural radiation quantity
  7. ^ a b c d Of Sadao Ichikawa "the global environmental disruption from environmentology - gene destruction" (the third edition) in the site of Hiroshima University the introduction page of contents
  8. ^ Joseph vice work, Honda power reason "introduction to nuclear fusion energy" Hakusuisha, May 30, 2004. ISBN 4-560-05875-X
  9. Written by ^ a b c d Kazuko Tojima "basic knowledge Kodansha of the use of radiation", December 20, 2006. ISBN 4-06-257518-3
  10. ^ Hiromi Iida edition "radiation outline" trade and industry Kenkyusha, July 20, 2005. ISBN 4-86045-101-5
  11. ^ http://www.fepc.or.jp/learn/houshasen/seikatsu/shizenhoushasen/index.html
  12. ^ http://tech.eng.niigata-u.ac.jp/pdf4/014.pdf
  13. ^ http://iss.jaxa.jp/med/research/radiation/
  14. ^ http://www.rist.or.jp/atomica/data/dat_detail.php?Title_No=09-01-06-04
  15. ^ Encyclopedia Astronautica http://www.astronautix.com/astros/polyakov.htm]
  16. List of records of the ^ space trip
  17. ^ solar flare
  18. ^ natural science study mechanism - National Institute for Fusion Science
  19. ^ http://www.ocrwm.doe.gov/curriculum/unit2/pdf/lesson3activity3.pdf (PDF)
  20. ^ http://www.orau.org/PTP/collection/consumer%20products/brazilnuts.htm
  21. ^ "WHO HANDBOOK ON INDOOR RADON". World Health Organization (2009). May 28, 2011 reading. Japanese translation by the National Institute of Public Health: WHO indoor radon handbook

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