20.08.2015   Nuclear Power and the Environment

Nuclear Fuel Cycle

The other major source of radioactive waste and contamination is the nuclear fuel cycle.2,7 By volume, the largest source of contamination arises from uranium mining and milling.15 Uranium mining has produced an estimated 937 x 106m3 of tailings, with activities ranging from <1 to > 100 Bq g 1.16 The waste contains not only uranium, but also uranium decay products, including radon, a radioactive gas. Although current tailings are well maintained, there are many old abandoned sites, particularly in eastern European countries and the former Soviet Union that require remediation.4,16

Contamination also arises from the handling and reprocessing of spent nuclear fuel (from either civil or military programmes) and can cause high localised levels of contamination.1,17 Release to the environment can arise from authorised discharges to the atmosphere and to surface and groundwater (see Tables 2 and 3), accidental release and leakage of storage tanks.18 21 At the Sellafield site, UK, authorised discharges to atmosphere and sea have occurred for over 40 years.2 Historically, the major sources of liquid effluent for dis­charge (via pipelines into the Irish Sea) were process liquors from reprocessing and fuel storage pond water; discharges for selected radionuclides from 1952 to 1992 are shown in Figure 2.22 The level of activity discharged to sea peaked in the mid to late 1970s, and in most cases has been declining ever since.

Leakage from storage facilities can also cause significant localised con­tamination. At the Hanford site (a former plutonium production facility) in the

Year

C-14

H-3

I-129

Kr-85

Total b/g

Total a

1999

2719

3.2 x 105

33.47

3.86 x 108

3.64

0.22

2000

2676

2.85 x 105

32.06

3.08 x 108

3.00

0.13

2001

972

3.05 x 105

24.42

3.31 x 108

2.88

0.11

2002

857

3.17 x 105

31.49

3.46 x 108

2.84

0.07

2003

737

4.41 x 105

22.26

3.72 x 108

3.91

0.17

Table 2 Airborne releases of carbon-14, tritium, iodine-129, krypton-85, total

p/у emitters and total a-emitters, from European spent fuel repro­cessing sites from 1999 to 2003.21 Values given are in GBq per annum. Total p/у excludes 14C, 3H and 129I.

Year

C-14

H-3

Total b/g

Total a

Uranium

1999

1.57 x 104

1.54 x 107

1.48 x 105

217.75

545.86

2000

1.31 x 104

1.28 x 107

1.15 x 105

206.16

614.70

2001

1.67 x 104

1.22 x 107

1.63 x 105

279.30

392.84

2002

2.09 x 104

1.52 x 107

1.69 x 105

495.22

444.64

2003

2.57 x 104

1.58 x 107

1.25 x 105

503.55

488.38

Table 3 Liquid releases of carbon-14, tritium, total p/у emitters, total a-

emitters and uranium from European spent fuel reprocessing sites from 1999 to 2003.21 Values given are in GBq per annum, except for uranium which is in kg per annum. Total p/у excludes 14C and 3H.

USA, an estimated 570 m3 of waste containing 3.7 x 104 TBq of radioactivity has been released into the subsurface from leaking underground storage tanks.7

Releases to the atmosphere arising from the nuclear fuel cycle are lower than from nuclear weapons, but can arise from several stages of the cycle. Uranium mining and milling releases radon gas and windborne dispersion of waste materials can also spread contamination.23,24