10-13 chernobyl vs fukashma Flashcards
where and when chernobyl
1986
close to the belarus border in ukraine
not a huge demand for land
reactor chernobyl
reactor type wouldn’t be allowed
water to cool and different material to moderate it
control rods come from the bottom
uses uo2 (like everyone)
reaction hot -boils water -steam turns turbines
chernobyl graphite in reactor
moderateor blocks
built really fast
block has holes in it on longitudonal axis for fuel and control channels
max temp for graphite is 730oC
chernobyl disaster build up
doing test- to see if they can turn it off, need to take the heat out
strict rules so test a nigh
bring power down during day- bring in more water
shift change at 12
more control rods in- absorbs neutrons- power dropped more the expected
before test they removed come control rods to increase the power
connect fourth main cooling pump to left loop of system
chernobyl disaster test
not enough control rods- TEST START
brought steam in- more reactions more fission- not enough control rods
power kept increasing- runs away- superheated
pushed emergency button which brought in control rods
control rods didn’t come in all the way as rods bent as so hot
graphite catches fire (first thermal explosion)
then explosion
chernobyl Zenon pit
zenon fission product- iodine decays into zenon
normally gets burnt by neutrons
stable zenon
if turn reactor off- no neutrons so zenon levels increase (big neutron absorber)
zenon decreases power-then decays increaseing power
chernobyl full core breach
moderators on fire
beam of light- fluorescence of excited oxygen and nitrogen atoms in the air
volatile radioisotopes of caesium and iodine were carried away by plume
chernobyl first response
block roads to plant
first responders- no protection
took them ages to enter emergency state
day later still fire- dumbed sand, clay and lead on the core
Pripyat evacuated (115,000 ppl)
chernobyl rad spreads across europe
explosion released 190 tones of rad gasses into atmosphere
fire 10 days
Russia kept it quiet
people worried about what element
iodine short half life so most worried about it -immediate aftermath
take pill to saturate your thyroid o can’t take in radioactive iodine
chernobyl main plume line
travelled far as flat topography
headed towards europe- west
turned forest red
chernobyl longer response, clean up
bulldozed lots- red forest bulldozed and put more trees on top
villages bulldozed
not allowed to grown in zone
life stock put down
lots of buried and abandoned things
exclusion zone-2600km^2
chernobyl elephants foot
large mass of corium formed during core melt down
flow done into basment
smaple each year
chernobyl human error
- Isolation of the emergency core cooling system
- Unsafe amount of control rods withdrawn
- Connection of the four main cooling pumps to the right and left of the system
- Design error in having a graphite tip on the control rods
- young inexperience operators as took longer than expected
chernobyl aftermath
soluble products leached into surrounding and soil
corium leaks down the core and melts everything in path
chernobyl sarcophagous
enclose core, concrete structure, huge block lifted into place in a month
30yr later concrete cracking
chernobyl new safe confinement
hermetically sealed
detectors can get data of radiation levels inside, moderate humidity inside
encasement leads to just enough water for fission to occur again but moderated and dried out
dismantle sarcophagus-cranes in roof
chernobyl exclusion tourism
bull pull for economy
Pripyat abandoned
can’t eat of drink in zones
clean everyone on exit
chernobyl red forest remediation
wild fire issue, windy and flat
keep dumping sand as keeps blowing away
chernobyl radiation mapping
people got a lot of rad dose as they did mapping
hotspots- some from debris being piled up and covered in sand
hasn’t been mapped at ground level so hotspots can be smoothed out and not detected
Fukushima set up
6 reactors
boiling water reactor
near the coast-colling ponds
safe as water is moderator as well
1,2,3 producing power at time of accident
1,2 running on UO2
3 running on MOX (PuO2/UO2)
enormous structures
control rods from top
Fukushima earthquake
subduction zone, earth shifted by 10cm
2.46pm-school run
mag-9
many shocks
35mins after first quake -Tsunami
19000 dead or missing
seawall next to power plant not high enough
Fukushima response after quake
control rods dropped once quake detected
power lines destroyed and all back up power- monitoring equipment needs power (1 out of 24 monitoring working)
reactor still hot but knocked out core colling
emergency cooling water brought in by fire trucks
Fukushima loss of coolant incident
no water to cool
clad fuel in zr
Zr reacts with water to create hydrogen when hot
1600oC
hydrogen pressurises inside reactor
BANG
Fukushima reactor damage
reactor 4 linked to 3, so explosion in 4 from hydrogen flowing in from 3
reactor 3&1 big explosion
reactor 2- intact, no explosion but hissing out and biggest release of material
Fukushima and Chernobyl level
both major accident -7
Fukushima is up there as it was so complicated and multiple reactors involved and over many days
Fukushima releases
10% of chernobyl
but mainly nobel gasses I131 and Cs137
hard to know as no monitoring
explosion at different times-different wind directions
original 20km radius exclusion zone had to be expanded to the north do to wind and plume
Fukushima doseage
very small dose
nun attributed to rad sickness
2 died as they were underneath reaction as Tusnami hit (draund)
Fukushima cost
81000 evacuees still displaced- get 1000 dollars a month in psychological suffering compensation
suicide biggest killer as generational homes taken away -elderly population
rad not main issue the evacuation was
Fukushima Remediation
lots of remediation as a lot of money into economy, ppl jobs
if you lived in the Fukushima fall out zone your life expectancy would decrease by
2-4 weeks
Fukushima and chernobyl primary dose contributor
Cs137
long half life
Fukushima provenance
can pin point where the plume came from
ash particles spread as far as Tokyo (2microns)
Fukushima particulates
fission products- gaseous high temp
Cs swaps out for other ions and sticks (clay rich soil issue)
type A- <10um (as far as Tokyo)
type B- pumice had high density U in it, vesicle, bits of concrete, uranium that had been exploded into the enviro
Fukushima soil
has clay rich soils so Cs sticks more
turned over soil on top so no Cs
Cs is mobile, sicks into the soil and can’t get it out
I135
turns into
Xe135
problem with detecting U+Th in Unmanned Ariel Vehicles
release beta and alpha -very little gamma
so can’t be detected by drone
B.J.Howard 2016 paper
comparison of the remediation in cher and fuk
Cs 134+7 were most important longer term dose
chernobyl had to remediate agriculture a lot as more animals in the area
Fuk had to remediate the paddy fields and remove plants
cher took longer to remediate
in both most of the radioactivity released was due to
volatile radionuclides (noble gases, iodine, cesium, tellurium)
Steinhauser et al (2014)
Steinhauser et al (2014)
chernobyl released more
refractory elements
