i didn’t realise it until i stumbled across an article on iol..
today (wednesday, 26th of april 2006) is the 20 year anniversary of the chernobyl disaster.
i looked up the incident on www.chernobyl.info and this is what happened:
on the night of the 25th april 1986 a crew began a test run on reactor 4 of the chernobyl nuclear power station.
they planned to see if the turbines could keep the coolant pumps running long enough while waiting for the emergency diesel generators to kick in.
to prevent interruption of the test, all of the safety systems were deliberately switched off.
to initiate the tests the power levels needed to be decreased to 25%.
something went wrong and the power levels dropped to 1%.
30 seconds after the test began an unexpected surge was encountered and a chain reaction started. since the safety systems were disabled the emergency shutdown failed (if it hadn’t it would have halted the chain reaction).
at 1:23.44 am the reactor blew and blasted off it’s 1,000 tonne sealing cap.
temperatures of 2,000 degrees celcius resulted in feul rods melting and the graphite cover of the reactor catching fire, creating an inferno which sucked radioactive materials into the atmosphere.
100 times more radiation than the bombs dropped over hiroshima was released.
about 135,000 people had to be evacuated from the surrounding area.
people trying to fight the blaze were fried on the spot by gamma radiation.
many firefighters and engineers at chernobyl died.
the reactor is currently enclosed in a concrete casing known (aptly) as the sarcophagus. the sarcophagus was meant to be a short-term fix and currently another casing (a 20,000 tonne structure) is planned to be completed in 2008 and should safely contain the reactor for another 100 years.
there are some pictures of chernobyl (some of which are in this post) by Waclaw Gudowski available through this link.
elena (the kid of speed) likes to ride her motorbike around the area and has some interesting facts on here page (available through this link.)
apparently a radiation level of 500 roentgens in 5 hours is fatal to a human (not counting cancer and whatnot), but it takes about 2.5 times that amount to kill a chicken, and over 100 times that to kill a cockroach.
some places around the reactor after the explosion were measuring 3,000 – 30,000 roentgens. your average european city has a background radiation of about 20 micro-roengens (20/1,000,000 of a roengen).
interestingly enough the roads in the area are in very good condition (no traffic) and since radiation lies in the soil and plants, not the asphalt, the radiation levels in the middle of the road are not too bad. they double at the edges of the road and are 4 or 5 times higher 1 meter off the road though.
one final link to another information site which has some news coverage in realplayer format (haven’t tried it myself): www.chernobyl.co.uk
this is the sort of thing that reminds engineers why safety is important.
i’m not normally the one to rant things like “this should always be remembered to remind us…” but i think this should.
but remember: the lesson here isn’t nuclear power is bad, the lesson here is that safety is paramount. it doesn’t matter what it is, if it explodes then safety is an issue. surprisingly the immediate deathtoll of this incident was actually very low (however cancer is a slow killer).
for a non-nuclear accident to illistrate this point even more, look at the disaster at bhopal, india. again safety systems had been neglected and ignored (they ignored the warning light and pressure gauges) resulting in 27 tonnes of a deadly gas (methyl isocyanate) leaking out over a sleeping city. people were killed while they lay asleep in their bed. the immediate deathtoll is estimated around 4,000 people. more than 120,000 people are still suffering concequences from breathing in the gas.
find more information on bhopal through this link, this link, and this link.