A top secret Soviet nuclear complex contaminated its environs for 40 years, exposing thousands of people in the vicinity to radiation
MAYAK, a nuclear energy facility in the
former Soviet Union that remained
shrouded in secrecy for over 40 years
now, has been identified as perhaps the
most disastrous, according to a recent
research report. Though not as well-
known as the nuclear power plant at
Chernobyl, the Mayak complex is
responsible for a comparable environ-
mental legacy: more than twice the
amount of radioactive material released
in the accident at Chernobyl has been
dumped in a nearby lake since 1951
(Environment, Vol 39, No 1).
A relatively small lake, one km
long and half a kin wide, with a maximum depth of only six metres, Lake
Karachay is probably the largest open
accumulation of nuclear waste in the
world. According to measurements, the
level of radioactivity in the lake is as high
as 120 million curies (curie is the
standard measurement of radioactivity,
equal to the number of disintegrations
(3.7 x 1010) undergone by one gramme
of radium in one second).
The vast complex of Mayak, created
in the late 1940s to produce plutonium
for nuclear weapons, is situated near
the city of Ozersk in the southern
Ural mountains. It became operational
in 1948 and continued producing
plutonium for nuclear weapons until
1990. Since then, Mayak has been used
to reprocess fuel from nuclear reactors
and to produce special radionuclides.
Although current operations are on a
much lower scale, radio -contamination
problems remain.
The complex was a disaster from the
start. A design flaw in its radiochemical
plant forced workers to clean filters used
to separate the plutonium and uranium
by hand, exposing them to very high
levels of radiation.
Disposing of the plant's radioactive
wastes was also a major problem. The easiest way
out was to dump them in a lake, the Techa river, which
river flows through the area.
From March 1950 to November 1951, approximately 2.5 million curies
of radioactive waste was
released into the river.
From 1949 to 1956,
at Mayak released approximately 76 million cubic
metres of waste with a
total radioactivity of 2.86
million curies into the
Techa. As a result, 28,000
people living along the
river were exposed to substantial doses of radiation.
Even now, a number of large reservoirs
and dams along the Techa house
low-level nuclear refuse.
As many as 20 serious accidents are
known to have occurred at Mayak,
including seven 'criticality events'.
Criticality events, in which a spontaneous chain reaction releases lethal
neutrons and gamma radiation, are
relatively rare. Only 13 such events
occurred in the Soviet Union during the
40 years in which it was producing
nuclear weapons. In comparison, eight
such events took place in the us.
On September 29, 1957, a major
accident took place when a storage tank
containing high-level radioactive waste
exploded with a force equivalent to
70 tonnes of TNT. Approximately 90
per cent (18 million curies) of the
radioactive material released by the
explosion settled in the immediate
vicinity of the tank.
The level of wastes dumped into
Lake Karachay exceeds those released
into the Techa. These can pose a hazard
in the surrounding area by either 'resus
pension' in the air or by contaminating
groundwater. On windy days, large
amounts of radionuclides are lifted
from the surface of the lake in the form
of mist, which can travel long distances
before settling down. To prevent this,
Russian authorities are now covering
the entire surface of the lake with hollow
concrete blocks. The project should be
completed within a few years, and will
eliminate one source of contamination.
But groundwater contamination is a
more serious problem.
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