Environmental Engineering Reference
In-Depth Information
AMAP examined two studies published in the mid-2000s that attempted to use
plutonium isotope ratios (
240
Pu :
239
Pu) to investigate whether Mayak discharges had
reached the Ob estuary and the Arctic Ocean. However, the results still do not settle the
issue. If you are interested, take a look at the references by Lind and colleagues and Skip-
perud and colleagues listed in the bibliography. Whatever the historical situation may have
been, monitoring indicates that the three large nuclear sites are not at present contributing
significant levels ofradionuclides totheArctic OceanviatheObandYenisei riversystems.
The Thule aircraft accident:
On January 21, 1968, a B52 strategic bomber from the
U.S. Air Force with four nuclear bombs on board crashed onto the sea ice in North Star
Bay just after taking off from the airbase at Thule in north-west Greenland. During the ac-
cident and subsequent (nonnuclear) explosion, some plutonium from the bombs was dis-
persed onto the ice. Most of this inventory was quickly recovered, but some of the ice-em-
bedded material was lost into the water column when the ice melted later that summer. It
was estimated following the cleanup that about 2.5-3.0 kilograms of plutonium were lost.
Sediment core studies have shown that this corresponds to roughly the amount that lies in
marine sediments around the crash site. The reason that the lost inventory has remained
so close to the site of its original deposition is that plutonium adheres (or partitions) very
strongly to sediment particles. However, the distribution of plutonium in sediment samples
collected in 2003 was found to be very patchy and some lateral transport of up to 17 kilo-
metres from the impact location has occurred. Despite this pattern, most of the lost invent-
ory lies within a radius of 4 kilometres from the point of impact. The plutonium also ap-
pears to be relatively unavailable to biota because bivalves living buried in the sediment
carry plutonium levels several times lower than are found in the sediments, although they
are above background concentrations. The situation at Thule is not considered to present
risks to human health even if local shellfish are consumed.
Komsomolets
submarine:
In April 1989, the Soviet nuclear submarine
Komsomolets
caught fire following an explosion and sank 180 kilometres south-west of Bear Island in
the Norwegian Sea. The wreck lies at a depth of about 1,650 metres. The single nuclear
reactor shut down safely during the accident and was estimated to contain an inventory at
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