Since the Japan earthquake attain , it seems like the story surrounding the Fukushima Nuclear Power plant has changed every 10 minutes , make it tough to keep up on the latest developments . fortunately there ’s no famine of informed person and organizations keeping running of what ’s die on .
While the situation regarding the reactor explosions is still very serious , the general consensus seems to be that there ’s little menace of radiation exposure outside the nuclear nuclear reactor containment structures , and that any radiation emitted so far has n’t been wicked . But many have also gone to great lengths to explain the world-wide science behind the nuclear reactors . Here ’s the information you need from people who know …
BBC has a goodvisual breakdownof the Fukushima plant .
Boing Boingbreaks down the reaction appendage :
The fission response that happen are all about law of proximity . In a fuel gat , lots of uranium atoms can crash into each other as they break aside . tamp the fuel pole into an assembly , and lots more atoms can affect one another - which means the reaction can eject more vitality . Put several fuel fabrication into the core of a nuclear reactor , and the amount of energy released gets even high .
Proximity is also what makes the conflict between a atomic bomb calorimeter , and the hold fission reaction in a power plant . In the turkey , the reactions happen - and the energy is released - very quickly . In the power plant , that process is slowed down by control rods . These workplace like putting a while of cardboard between two Jenga tower . The first tower falls , but it hits a roadblock instead of the next tower . Of all the atoms that could be break open , only a few are allow to really do it . And , instead of an explosion , you end up with a realizable amount of heating system free energy , which can be used to boil urine .
PopScibroke down the safety systems normally found in nuclear great power plants :
At the onset of the earthquake , the plant life mechanically shut down the fission process , which unremarkably would leave the coolant system — both the main one and a backup source — still operational . But the tsunami wipe out mogul to the works , which took down the main coolant system of rules , and a wave destroyed the diesel - base backup organisation . Even though the fission had stopped , coolant is still very much require to keep the works safe .
That ’s due to the heat that rest in the nuclear nucleus , both from the of late - handicapped but still - hot fuel rods and from the various byproducts of the fission mental process . Those byproducts include radioactive iodine and caesium , both of which produce what ’s call “ decay heat”—essentially residual heat that very tardily dissipates . If the core is n’t unceasingly cooled , there ’s still enough heat energy that can still cause a nuclear meltdown even after it ’s been “ turn off . ”
Al Jazeera shows us what would happen in a worst type scenario if a meltdown were to happen :
TheNY Timesalso has a great synergistic graphic wear out down the robotlike closure system and nuclear meltdown threat .
The Atlanticclarifies the meaning of the terminal figure “ meltdown ” as it has been used in relation to the Fukushima power works :
Of immediate concern is the prospect of a so - called “ meltdown ” at one or more of the Japanese reactors . But part of the problem in understanding the likely dangers is extend indiscriminate use , by expert and the media , of this inherently terrible term without account or perspective . There are vary academic degree of melting or meltdown of the nuclear fuel rods in a given nuclear reactor ; but there are also multiple condom system , or containment roadblock , in a given plant ’s design that are intend to keep radioactive cloth from escaping into the general environment in the event of a fond or complete meltdown of the reactor essence . Finally , there are the steps study by a plant ’s operator to seek to bring the nuclear pinch under control before these containment barriers are go against .
In the Three Mile Island accident , a partial core nuclear meltdown occurred in one reactor social unit but stay for the most part within the plant ’s containment barrier and little radiation was release to the environment . The Chernobyl catastrophe , however , resulted in a massive environmental release of radiation syndrome following a effect meltdown . An crucial distinction is that the Chernobyl plant lacked crucial containment structures find at the Three Mile Island and Japanese plants .
accord to the International Nuclear and Radiological Event Scale , which rates the severity of nuclear tycoon plant incident on a graduated table from zero to 7 , Chernobyl was rated a 7 , the high grade of severity and the only such accident . Three Mile Island was rate a 5 , “ an accident with wide-cut consequence . ” Thus far , the Japanese atomic emergency at Fukushima Daiichi has been rated a 4 , an “ accident with local consequences , ” but this is of course a preliminary estimate .
New Scientisttells us about the health risks imply with nuclear radiation exposure :
asunder from the impairment because of fires and explosion , accidents also release radioactive materials which can make radiation malady . Radiation exposure above a certain threshold , usually only received by workers and pinch teams in a stricken flora , do acute radiation syndrome within hours of exposure . calculate on the battery-acid of radiation this ranges from hide rashes , vomiting and diarrhoea , to comatoseness and death .
Radiation scathe DNA , specially as it assembles in dividing cells . That means tissues which take many dividing cells , such as the gut lining , peel and bone gist , are most at risk of equipment casualty . High enough Department of State also damage head cell and such doses are always fatal .
Less severe damage can be treated , however . Gut wrong disturbs fluid balance and can guide to blood infection ; inwardness scathe intend no blood cells are farm for clabber and contend contagion . If those problems can be managed , people can be kept alive long enough for catgut and marrow to renew . A cloned human endocrine that boosts white stock cell product sometimes helps ; there is little else .
Brave New Climatehas a diagram of the Fukushima nuclear reactor intent , with an timeline of events provided by a secret diligence source :
Likely timeline of incident is :
a. Reactors 1 , 2 and 3 were in surgical procedure at Fukushima Daiichi atomic world power works when the earthquake struck .
b. all three reactors were exclude down and control rods were inserted when temblor strike .
c. Cooling was sustain to remove radioactive decay heat
d. decay heat drops rapidly on reactor shut down ( e.g a 3GW reactor will reduce to 200MW decay warmth after 1s and 50MW after 1 hour … But take long time ( 3 - 6months ! ) to reduce to paltry levels )
e. sometime ( ≈1hr ) later tsunami walk out and mains tycoon was lost to coolant circuit on Unit 1
f. Diesel generators also fail when tsunami collide with so cooling was run by backup batteries for 7 - 8 hour
g. Other parking brake diesel generator institute in but deficient to run pump
h. loss of coolant leads to fuel rods no longer being cool down by two stage flow ( it is a Boiing water Reactor ) and eventually get live enough to recat with steam to grow Hydrogen .
Our own Kyle VanHemert front into how bad theradiation news leak really are :
While it could get really bad really tight if one of the reactors themselves were to crack open - a full nuclear meltdown would release meaning amounts of radioactive elements like iodine-131 that disperse rapidly in air and water , greatly increase the chances for birth defects , thyroid Crab , and other trouble - health expert are currently cautiously optimistic . As of this weekend , radiation level in the industrial plant ’s control room were 1,000 times higher than normal but only eight time above normal in area surrounding the flora . According to Ron Chesser , director of the Center for Environmental Radiation Studies at Texas Tech University , both of those levels are technically good for humans , who immerse an norm of 360 millirems of radiation per twelvemonth from cosmic shaft and manmade source . Still , three elements in particular- iodine-131 , strontium-90 and cesium-137 - are troubling because they mime substances find out of course in the body .
Treehuggerputs the obvious into unmortgaged terms — nuclear power plant ca n’t detonate like bomb calorimeter :
Thankfully , it is physically insufferable for a nuclear power works to explode like a atomic turkey . It just does n’t have the right kinds of materials : A fission bomb use extremely enriched uranium or plutonium ( 90%+ of U-235 or Pu-239 ) , while a nuclear power place in the main uses Uranium that is only enriched to around 5 % ( sometimes up to 20 % in smaller enquiry reactors ) . A nuclear power post also miss all the other mechanisms that are necessary to create a nuclear explosion ( like for model the implosion or gunman - character assembly shape that allow supercritical mass to be reached ) .
BloggerJason Morganreached out to Dr. Josef Oehmen , a research scientist at MIT , who explain the fundamental component of the atomic reactor nitty-gritty :
Update : Salon has debunkedthe post by Dr. Joseph Oehmen . Oehmen is not a atomic scientist of any variety , but a business researcher at MIT advising companies on taking risks . MIT nuclear engineering science students havereposted his articletaking out its title Why I am not worried about Japan ’s nuclear reactors and any credit to the impossibility of meaning radioactive escapes . Since the time of Oehmen ’s claims , there have been many sack of radioactivity .
MIT Researcher Is Not a Nuclear Scientist , Radioactivity Claims debunk
The plants at Fukushima are so called Boiling Water Reactors , or BWR for short . Boiling Water Reactors are similar to a pressing cooker . The nuclear fuel heats water , the water boils and create steam , the steam then drive turbines that create the electricity , and the steam is then cooled and condensed back to water system , and the water commit back to be heat by the nuclear fuel . The pressure cooker manoeuver at about 250 ° C .
The nuclear fuel is uranium oxide . Uranium oxide is a ceramic with a very high-pitched melting decimal point of about 3000 ° C . The fuel is fabricate in pellet ( believe little cylinders the size of Lego bricks ) . Those pieces are then put into a long tube made of Zircaloy with a melting point of 2200 ° hundred , and seal tight . The assembly is called a fuel gat . These fuel rod are then put together to form larger packages , and a numeral of these packages are then put into the nuclear reactor . All these packages together are referred to as “ the core group ” .
( And for what its worth , Oehman imagine the prospect of a full - weighing machine nuclear meltdown occurring is slender . )
Update : TEPCO already has said that a partial nuclear meltdown of the heart and soul has most probably happened already , following the damage of70 % of the atomic perch in one reactor and 33 % on the other .
70 % Nuclear Rods damage on Fukushima Reactor 1 , 33 % Damaged on Reactor 2 , Partial Reactor Core Melting potential
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