The Chernobyl disaster occurred
at 01:23 a.m. on April 26, 1986 at the Chernobyl Nuclear Power Plant near
Pripyat, Ukraine, at the time part of the Soviet Union. Reactor 4 suffered a
catastrophic steam explosion that resulted in a fire, a series of additional
explosions, and a nuclear meltdown.
It is regarded as the worst
accident in the history of nuclear power. A plume of radioactive fallout
drifted over parts of the western Soviet Union, Eastern and Western Europe,
Scandinavia, the British Isles, and eastern North America. Large areas of
Ukraine, Belarus, and Russia were badly contaminated, resulting in the
evacuation and resettlement of over 336,000 people. About 60% of the
radioactive fallout landed in Belarus, according to official post-Soviet
data.
The world average annual dose
from natural background radiation is 2,400 microsieverts. The map shows, by
country and region, the average additional doses in the first year after the
Chernobyl nuclear reactor accident. As a result of fallout from the
accident, 31 people died and 135,000 had to be permanently evacuated.
Localized areas received much higher levels of contamination and it is
estimated that in the long term many thousands in Europe will suffer or die
from diseases caused by increased radiation. credit: United Nations
It happened in ... Chernobyl -
23 Jun 08 - Part 1
How many people died and how many more are likely to die in the future?
A reasonable central estimate is about 4,000 fatal radiation induced cancers
during the lifetime of the 600,000 most highly exposed individuals and
perhaps another 5,000 in more peripheral populations. The number is small
(representing a few percent) relative to the normal spontaneous risk of
cancer, but the numbers are large in absolute terms. Among the 4,000 is
included some 50 emergency workers who died of acute radiation syndrome and
nine children who died of thyroid cancer, and an estimated total of 3,940
deaths from radiation-induced cancer and leukemia among the 200,000
emergency workers from 1986-1987, 116,000 evacuees and 270,000 residents of
the most contaminated areas (total about 600,000). These three major cohorts
were subjected to higher doses of radiation amongst all the people exposed
to Chernobyl radiation. The estimated 4000 casualties may occur during the
lifetime of about 600,000 people under consideration. As about quarter of
them will eventually die from spontaneous cancer not caused by Chernobyl
radiation, the radiation-induced increase of about 3% will be difficult to
observe. However, in the most highly exposed cohorts of emergency and
recovery operation workers, some increase in particular cancers (e.g.,
leukemia) has already been observed. Confusion about the impact has arisen
owing to the fact that thousands of people in the affected areas have died
of natural causes. Also, widespread expectations of ill health and a
tendency to attribute all health problems to radiation exposure have led
local residents to assume that Chernobyl related fatalities were much higher
than they actually were.
What was the environmental impact?
Ecosystems affected by Chernobyl have been studied and monitored extensively
for the past two decades. Major releases of radionuclides continued for ten
days and contaminated more than 200,000 square kilometers of Europe. The
extent of deposition varied depending on whether it was raining when
contaminated air masses passed. Most of the strontium and plutonium isotopes
were deposited within 100 kilometers of the damaged reactor. Radioactive
iodine, of great concern after the accident, has a short half-life, and has
now decayed away. Strontium and caesium, with a longer half life of 30
years, persist and will remain a concern for decades to come. Although
plutonium isotopes and americium 241 will persist perhaps for thousands of
years, their contribution to human exposure is low.
It happened in ... Chernobyl -
23 Jun 08 - Part 2
What was the economic cost?
Because of policies in place at the time of the explosion and the inflation
and economic disruptions that followed the break-up of the Soviet Union,
precise costs have been impossible to calculate. A variety of estimates from
the 1990s placed the costs over two decades at hundreds of billions of
dollars. These costs included direct damage, expenditures related to
recovery and mitigation, resettlement of people, social protection and
health care for the affected population, research on environment, health and
the production of clean food, radiation monitoring, as well as indirect
losses due to removing agricultural lands and forests from use and the
closing of agriculture and industrial facilities, and such additional costs
as cancellation of the nuclear power program in Belarus and the additional
costs of energy from the loss of power from Chernobyl. The costs have
created a huge drain on the budgets of the three countries involved.
How many “Chernobyl-type” reactors are still operating in the world?
Chernobyl-type reactors are operating only in Russia and Lithuania. They
technically are known as “RBMK” or sometimes “LWGR” plants. They are
water-cooled and graphite-moderated reactors. RBMK is a Russian acronym for
high-power-channel reactor. Russia operates twelve such plants for
electricity generation at Kursk, St. Petersburg, and Smolensk; additionally
four small units remain in use for local heating and power at Bilibino in
Siberia. Lithuania’s plant is known as Ignalina. One of the two units has
been shut down, and the other is scheduled to close in the near future.
Credit: U.S. Department of Energy,
International Atomic Energy Agency, U.S. Nuclear Regulatory Commission,
Nuclear Science Division ---- Lawrence Berkeley National Laboratory, Penn
State Radiation Science and Engineering Center, American Nuclear Society,
European Commision
