Publicatie Laka-bibliotheek:
The other report on Chernobyl (TORCH)

AuteurI.Fairlie, Greens in EP, EFA
Datumapril 2006
Opmerking Also available in Ukrainian: See for TORCH 2016

Uit de publicatie:


On 26 April 2006, twenty years will have passed since the Chernobyl nuclear power plant
exploded, releasing large quantities of radioactive gases and particles throughout the
northern hemisphere. While the effects of the disaster remain apparent particularly in
Belarus, Ukraine and Russia, where millions of people are affected, Chernobyl’s fallout
also seriously contaminated other areas of the world, especially Western Europe.

The Other Report on Chernobyl (TORCH) provides an independent scientific examina-
tion of available data on the release of radioactivity into the environment and subsequent
health-related effects of the Chernobyl accident. The Report also critically examines recent
official reports on the impact of the Chernobyl accident, in particular two reports by the “UN
Chernobyl Forum” released by the International Atomic Energy Agency (IAEA) and the
World Health Organisation (WHO) in September 2005 6 , which have received considerable
attention by the international media.

Many uncertainties surround risk estimates from radiation exposures. The most
fundamental is that the effects of very low doses are uncertain. The current theory is that
the relationship between dose and detrimental effect is linear without threshold down to
zero dose. In other words, there is no safe level of radiation exposure. However the risk, at
low doses, may be supralinear, resulting in relatively higher risks, or sublinear, resulting in
relatively lower risks.

Another major source of uncertainty lies in the estimates of internal radiation doses, that is,
from nuclides, which are inhaled or ingested. These are important sources of the radiation
from Chernobyl’s fallout. Uncertainties in internal radiation risks could be very large,
varying in magnitude from factors of 2 (up and down from the central estimate) in the most
favourable cases, to 10 or more in the least favourable cases for certain radionuclides.

The Accident
Early on April 26 1986, two explosions in Chernobyl unit 4 completely destroyed the
reactor. The explosions sent large clouds of radioactive gases and debris 7 - 9 kilometres
into the atmosphere. About 30% of the reactor’s 190 tons of fuel was distributed over the
reactor building and surrounding areas and about 1-2% was ejected into the atmosphere.
The reactor’s inventory of radioactive gases was released at this time. The subsequent
fire, fuelled by 1,700 tons of graphite moderator, lasted for eight days. This fire was the
principal reason for the extreme severity of the Chernobyl disaster.

How Much Radioactivity Was Released?
The World Health Organisation (WHO) has estimated that the total radioactivity from
Chernobyl was 200 times that of the combined releases from the atomic bombs dropped
on Hiroshima and Nagasaki. The amount of radioactivity released during a radiological
event, is called the ‘source term’. It is important because it is used to verify nuclide
depositions throughout the northern hemisphere. From these, collective doses and
predicted excess illnesses and fatalities can be estimated.

Of the cocktail of radionuclides that were released, the fission products iodine-131,
caesium-134 and caesium-137 have the most radiological significance. Iodine-131 with its
short radioactive half-life 7 of eight days had great radiological impact in the short term
because of its doses to the thyroid. Caesium-134 (half-life of 2 years) and caesium-137
(half-life of 30 years) have the greater radiological impacts in the medium and long terms.
Relatively small amounts of caesium-134 now remain, but for the first two decades after
1986, it was an important contributor to doses.

Most of the other radionuclides will have completely decayed by now. Over the next few
decades, interest will continue to focus on caesium-137, with secondary attention on
strontium-90, which is more important in areas nearer Chernobyl. Over the longer term
(hundreds to thousands of years), the radionuclides of continuing interest will be the
activation products, including the isotopes of plutonium, neptunium and curium. However,
overall doses from these activation products are expected to remain low, compared with
the doses from caesium-137.

The authors have reassessed the percentages of the initial reactor inventories of caesium-
137 and iodine-131 which were released to the environment. They conclude that official
figures underestimate the amounts released by 15% (iodine-131) and 30% (caesium-137).

Dispersion and Deposition of Chernobyl Fallout

During the 10 day period of maximum releases from Chernobyl, volatile radionuclides were
continuously discharged and dispersed across many parts of Europe and later the entire
northern hemisphere. For example, relatively high fallout concentrations were measured at
Hiroshima in Japan, over 8,000 km from Chernobyl.

Extensive surveying of Chernobyl’s caesium-137 contamination was carried out in the
1990s under the auspices of the European Commission. The largest concentrations of
volatile nuclides and fuel particles occurred in Belarus, Russia and Ukraine. But more than
half of the total quantity of Chernobyl’s volatile inventory was deposited outside these

Russia, Belarus and Ukraine received the highest amounts of fallout while former
Yugoslavia, Finland, Sweden, Bulgaria, Norway, Rumania, Germany, Austria and
Poland each received more than one petabecquerel (1015 Bq or one million billion
becquerels) of caesium-137, a very large amount of radioactivity. 8

In area terms, about 3,900,000 km2 of Europe was contaminated by caesium-137 (above
4,000 Bq/m2) which is 40% of the surface area of Europe. Curiously, this latter figure
does not appear to have been published and, certainly has never reached the public’s
consciousness in Europe. Also 218,000 km2 or about 2.3% of Europe’s surface area was
contaminated to higher levels (greater than 40,000 Bq/m2 Cs-137 9 ). This is the area cited
by IAEA/WHO and UNSCEAR, which shows that they have been remarkably selective in
their reporting.

In terms of their surface areas, Belarus (22% of its land area) and Austria (13%) were
most affected by higher levels of contamination. Other countries were seriously affected;
for example, more than 5% of Ukraine, Finland and Sweden were contaminated to high
levels (> 40,000 Bq/m2 caesium-137). More than 80% of Moldova, the European part of
Turkey, Slovenia, Switzerland, Austria and the Slovak Republic were contaminated to
lower levels (> 4,000 Bq/m2 caesium-137). And 44% of Germany and 34% of the UK were
similarly affected.

The IAEA/WHO reports do not mention these comprehensive datasets on European
contamination by the European Commission. No explanation is given for this omission.
Moreover, the IAEA/WHO reports do not discuss deposition and radiation doses in any
country apart from Belarus, Ukraine and Russia. Although heavy depositions certainly
occurred there, the omission of any examination of Chernobyl fallout in the rest of Europe
and the northern hemisphere is questionable.