CONSULTING

a source of carbon dioxide to smother the fire. Lead was included as a radiation absorber, as well
as sand and clay, which it was hoped would prevent the release of particulates.
A system was installed by 5 May to feed cold nitrogen to the reactor space, to provide cooling and
to blanket against oxygen thus avoiding further hydrogen explosions. By 6 May when most of the
graphite had burned, the core temperatures fell and there was a sharp reduction in the rate of
radionuclide releases. In addition, work began on a massive reinforced concrete slab with a builtin
cooling system beneath the reactor. This involved digging a tunnel from underneath unit 3. About
400 people worked on this tunnel, which was completed in 15 days, allowing the installation of the
concrete slab. This slab would not only be of use to cool the core if necessary, it would also act as a
barrier to prevent penetration of melted radioactive material into the groundwater.
In addition to the two workers that had died from the explosions on the day of the accident, by the
end of July, six firemen, a further 21 plant staff and a visitor had died of acute radiation poisoning
as a result of the accident.
Following the accident and the large contamination by the radioactive cloud, a 2,800 km 2
exclusion zone designated for evacuation has been established and placed under military control.
More than 130,000 people were moved out of their homes and villages in the immediate
aftermath of the accident. But many more people were eventually displaced. The U.N. Office for
the Coordination of Humanitarian Affairs (OCHA) stated in 2004: “Nearly 400,000 people were
resettled but millions continued to live in an environment where continued residual exposure
created a range of adverse effects.” 240
While units 1, 2, 3, unaffected by the explosions, resumed operation a few weeks later, the
Soviet army engaged (and poorly trained) more than 550.000 workers called the “liquidators”,
who were engaged in the disaster management. Their tasks included evacuation of contaminated
debris, cleaning emergency areas, repairing equipment and buildings etc.
Dispersion of Radioactivity
The graphite fire at unit 4 caused the ejection of radioactive gases, aerosols and particulates high
into the atmosphere. These were distributed in plumes by prevailing winds and rainfall throughout
Europe and eventually across the northern hemisphere. The consequent caesium-137 fallout
patterns in Europe were later measured by the European Commission (see Figure 28).
In total, 40 percent of Europe’s land area was contaminated significantly (>4,000 Bq per m 2 ) by
Chernobyl’s fallout. 241 The most seriously affected countries (ranked by magnitude of Cs-137
fallout) were the former USSR Republics adjacent to the stricken reactor—Belarus, Russia and
Ukraine.
Other seriously affected countries were, in area size order, former Yugoslavia, Finland, Sweden,
Bulgaria, Norway, Romania, Germany and Austria. Although former Yugoslavia was not measured
by the EC teams (because of the Balkan civil war), earlier measurements had been made by the U.S.
Department of Energy.
240 UN-OCHA, “Chernobyl: Needs great 18 years after nuclear accident”, 26 April 2004, see
http://reliefweb.int/report/belarus/chernobyl-needs-great-18-years-after-nuclear-accident, accessed 1 July 2016.
241 Ian Fairlie, “TORCH-2016—An independent scientific evaluation of the health-related effects of the
Chernobyl nuclear disaster”, 31 March 2016, see
https://www.global2000.at/sites/global/files/GLOBAL_TORCH%202016_rz_WEB_KORR.pdf, accessed 4 June 2016.
Mycle Schneider, Antony Froggatt et al. 78 World Nuclear Industry Status Report 2016