လတ္တေလာ ဂ်ပန္မွာ ျဖစ္ေနတဲ့ ႏ်ဴကလီးယား အၾကပ္အတည္းကို ဂ်ပန္ ထိပ္တန္း တကၠသိုလ္တခုမွာ ပါရဂူဘြဲ႔လြန္ တက္ေနတဲ့ ျမန္မာ သုေတသီတဦးက ေရးသားေပးပို႔လိုက္တာပါ။ သူ႔ရည္ရြယ္ခ်က္ကေတာ့ အနည္းဆံုးအားျဖင့္ ဂ်ပန္ေရာက္ ျမန္မာေတြ အေျခအေနကို ေရေရရာရာသိေအာင္ဆိုတဲ့ ရည္ရြယ္ခ်က္ပါတဲ့။
အခု ဧရာဝတီ သတင္းဆိုဒ္မွာ တင္ထားပါၿပီ။ (ဒီမွာ ဖတ္ပါ)
တဆက္တည္း အခုျပႆနာျဖစ္ေနတဲ့ ႏ်ဴစက္႐ံုကို တာဝန္ယူလည္ပတ္ေနတဲ့ TEPCO ရဲ႕ တျခား အလားတူစက္႐ံုမ်ိဳးကို သူ႔ရဲ႕ တကၠသိုလ္က ပါေမာကၡေတြ ကိုယ္တိုင္ သြာေရာက္ေလ့လာၿပီး ေရးျပထားတဲ့ ရွင္းလင္းခ်က္ကိုလည္း ေပးပို႔ထားပါတယ္။ ဧရာဝတီ သတင္းဆိုဒ္မွာ မတင္ထားေပမယ့္ ဒီေနရာမွာ အဂၤလိပ္လို မူရင္းအတိုင္း ေဖာ္ျပေပးလိုက္ပါတယ္။
On current nuclear crisis: an explanation by XXXX University’s professors’ to the faculty staff members and students
● Structure of nuclear reactor and safety: XXXX SDM teachers and students visited N-Power plant of Tokyo Electric Power Company at Kashiwazaki-Kariha. We observed an interior of a container; we stood by the wall of a high pressure vessel containing fuel rods.
N-reactor consists of a high-pressure vessel made of thick stainless steel, a container made of steel and an outer container made of concrete which absorbs neutron effectively because of its main chemical composition of calcium carbonate.
Using this structure, nuclear fuel and neutron are triply enclosed. This structure is completely different from that of the Chernobyl reactor, which utilized graphite as a neutron de-accelerator. Graphite is easy to burn.
● What happened after earthquake
However, water cooling system stopped, because emergency power supply did not work due to Tsunami attack at Fukushima. Then, they started cooling using sea water by auxiliary pump. However, pumping capability was so small and amount of water was not enough. During this process, nuclear fuel cell appeared out of cooling water level in the high-pressure vessel due to its heat and insufficient cooling.
A fuel rod reacted with water, i.e., formation of hydrogen. Hydrogen concentration was high near the ceiling of the building and exploded due to some reason, probably due to exceeding the explosion limit with an air.
Note that this is NOT NUCLEAR EXPLOSION such that at the Chernobyl N-Power station, but a simple explosion of hydrogen, although this shocking image was broadcasted on TV repeatedly all over the world.
DO NOT WORRY, this is just an explosion of HYDROGEN!
Fortunately due to this explosion, a ceiling of a building was removed, and a satellite sent us a top-view of an image of a container made of concrete. It was NOT DAMAGED. This container was designed so that it can stand with attack of a bomb.
This suggests that by supplying water continuously, temperature of nuclear fuel can be lowered with boric acid, which is a decelerator for neutron. We have to be patient.
● Used Fuel at the Reactor No.4
Used fuel contains huge amount of radioactivity. Cooling water decreased and parts of used fuel are supposed to be above the water level; it is dangerous. The riot police of Tokyo Metropolitan Police Department will join fire extinction operation, using a high-pressure pump. We hope this would be successful.
● Unit of radiation: Sievert
Many people feel difficult to understand unit of radiation, i.e., Sievert (Sv) or Sievert/hr (Sv/hr).
Sievert is defined as an equivalent dose to a tissue. Rate of dosage is written using milli-Sievert/hr, micro-Sievert/min and so on.
Concept of Sievert and Sivert/hr corresponds to that of km and km/hr. In TV news, they were confused.
Amount of dosage in our daily life is, e.g., 200 micro-Sivert for a return trip between Tokyo and NY, 600 micro-Sievert for Roentgen inspection of our stomach. Natural dosage in our daily life is 2400 micro-Sievert a year.
TV reported 11,930 micro-Sievert/hr at the main gate of the first nuclear plant on 15 March. This is really high. This value means amount of dosage for a person who stands there for an hour,
As reported by TV, this value fluctuates. Suppose you drive a car at high speed or slowly. This is fluctuation. High radioactivity corresponds to sudden scavenge due explosion. Value was lower after that. Note that RADIOACTIVITY DOES NOT INCREASE CONTINUOUSLY. This fact makes us tranquil.
● Distance and wind
Suppose there is a radioactive material at a certain point. Radioactivity degrades in proportional to square of distance. This is also the case for intensity of light as well.
The effect of wind is so small. XXXX University (located in Tokyo, Yokohama) is sufficiently far from that hot spot.
Distribution of radioactive material can be estimated by computer simulation; at the point over 20km from the hot spot, the effect of radioactivity is so small for the short time period.
For the people in Tokyo and Kanagawa, the effect of radioactive materials from the N-power station of Fukushima is considered so small.
Furthermore, radioactive potassium K40 is contained in table salt. This suggests that taking small amount of radioactive material does not cause a big problem.
Hazard due to radioactivity is negligibly small, as long as we are in the Tokyo and Kanagawa area. So, please DO NOT WORRY ABOUT RADIOACTIVITY.
For further learning,
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