Page 168 - Soil and water contamination, 2nd edition

Radionuclides 155

conditions permit, the recovered uranium and plutonium can be recycled for use as nuclear
fuel. The residual liquid is still highly radioactive and part of this radioactive waste is released
as effluent . During the 1970s and 1980s, these liquid discharges (excluding tritium) from
-1
reprocessing plants normalised per TBq GWy were more than a thousand times greater than
liquid discharges from nuclear reactors (UNSCEAR, 2000). However, the discharges have
been greatly reduced since the mid-1980s, thanks to the introduction of improved waste-
treatment practices.
The spent fuel from reactors or, if the fuel has been reprocessed, wastes from reprocessing
plants are high-level radioactive waste s. The spent fuel is mostly stored within the reactor
basins or at aboveground waste storage facilities. Releases of radionuclides from these storage
facilities are negligible. However, in the long term these materials must also be safely disposed
of and isolated from the biosphere until the radioactivity they contain has diminished to a
safe level. Currently a preferred option is for the ultimate disposal of the wastes in solid form
in licensed deep, stable geological structures.
8.3.2 Accidental releases

The exploitation of nuclear energy has been accompanied by a number of accidents, resulting
in radioactive contamination of the environment. Most of these accidents have only been

kBq/m 2
1480
185
40
10

2

Chernobyl

6642

Figure 8.3 Cs- 137 deposition in Europe after the Chernobyl accident in April 1986 (source: DeCort et al., 1998).

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