Page 167 - Soil and water contamination, 2nd edition

154 Soil and Water Contamination

Carbon-14 can also be generated by neutron capture and subsequent alpha emission by
oxygen-17:

17 1 14 4
8 O + 0 n 6 C + 2 He (8.6)
Tritium is formed due to neutron activation reactions with lithium and boron isotopes
dissolved in or in contact with the reactor coolant (Aarkrog, 2001).
Radionuclides are also produced in cyclotrons, i.e. circular particle accelerators. In these
devices the nuclei of atoms are bombarded with accelerated and focused beams of charged
+
2
atomic particles (protons , deuterons ( H ), or alpha particles). They are primarily used
for scientific research in nuclear physics and for the production of short-lived isotopes for
medical treatment and diagnosis (e.g. technecium-99m (half-life 6.0 h) and iodine-131 (half-
life 8.04 d)). In general, the quantities produced are small.
During normal operation of nuclear reactors, only minor amounts of radioactivity are
released into the atmosphere and water. Airborne discharges involve tritium , radiocarbon,
131
radioiodine , and noble gases (e.g Xe). The airborne releases of I are in the order of 2.5–
14 GBq per GWy (GigaWattyear). Liquid discharges into water bodies are radioecologically
more important. For example, the liquid discharges of 137 Cs from reactors vary between
-1
15 and 2500 GBq GWy , depending on the type of reactor. Uranium and plutonium in
spent fuel from reactors are recovered in reprocessing plants like those in Sellafield , UK,
or La Hague, France. During the fuel reprocessing process the fuel is dissolved by strong
acids, from which the uranium and plutonium are recovered. If economic and institutional

Table 8.7 Major nuclear accidents (sources: Aarkrog, 1995; Aarkrog, 2001; ATSDR, 2013; Stohl et al., 2012).
Location Date Description Total Major radionuclides
radioactivity of radioecological
released concern
90
Chernobyl, 26 April 1986 Explosion of nuclear reactor 4 1–2 EBq 131 I, 137 Cs, 134 Cs, Sr
USSR (Ukraine) after engineering test; followed
by fire
Fukushima (Japan) 11 March 2011 Equipment failures and nuclear 15.3 EBq 133 Xe, 131 I, 137 Cs,
meltdowns at the Fukushima I 36.6 PBq 134 Cs
Nuclear Power Plant, following the
T hoku earthquake and tsunami
90
Windscale (now 10 October Fire in nuclear reactor 2 PBq 131 I, ( 137 Cs, Sr)
Sellafield) , UK 1957
Three Miles 28 March 1979 Core of the reactor became 378 PBq 133 Xe, 131 I
Island, overheated due to drainage of
Harrisburg, USA primary coolant
90
Kyshtym (Mayak/ 29 September Chemical explosion in a tank at 1 EBq 95 Zr, 144 Ce, ( Sr)
Chelyabinsk-40), 1957 the nuclear weapons plutonium
USSR (Russia) production site
90
Kyshtym - Groundwater pollution and 4 EBq 137 Cs, Sr
airborne resuspension from open (total
reservoirs for waste disposal of inventory)
high-level radioactive waste
Indian Ocean 21 April 1964 US satellite SNAP 9-A powered 0.6 PBq 238 Pu
by a radioisotope generator
re-entered the atmosphere
90
Northwest 24 January Soviet satellite Cosmos 954 0.2 PBq 131 I, 137 Cs, Sr
Territories, 1978 powered by a nuclear reactor
Canada re-entered the atmosphere

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