Comparison of commercial and defence wastes

Commercial wastes are produced from a variety of sources but derive pre­dominantly through the generation of electricity using nuclear reactors. The exact nature of this waste is dependent on many factors, as the fuel and its cladding vary with reactor design.

Reprocessing spent fuel generates an acidic liquid HLW which contains the residue of the spent fuel following the removal of nearly all the uranium and plutonium via the Plutonium-URanium EXtraction PUREX process. This residue potentially contains a wide variety of elements derived from four sources, those initially present in the fuel and cladding, those formed during the fission process, a limited number of transuranics formed by neutron capture (e. g. Np, Am and Cm) and chemicals used in the reprocessing. Over the years, many methods have been investigated for the immobilization of commercial HLW, including cements, various glass compositions, glass-ceramics and SYNtheticROCk (SYNROC)-type ceramics, but the first-generation waste form choice was borosilicate glass (Donald et al., 1997).

Compared with the complexity of the commercial wastes, defence wastes are simpler. Generally, defence wastes do not contain the high concentra­tions of fission products found in commercial wastes, the exception being the calcined naval reactor wastes currently stored at the Idaho National Laboratory (INL), but destined for the Waste Isolation Pilot Plant (WIPP), in New Mexico, USA. They can, however, contain high concentrations of actinides which are not present in commercial wastes. Donald (2007) gave generic compositions for both commercial and defence wastes (see Table 25.2), and although there are very large compositional ranges for the con­stituents, it does highlight several important differences in addition to those described.

Table 25.2 Generic compositions of typical radioactive wastes streams

Constituent

Commercial waste (mass%)

Defence waste (mass%)

Na2O

0-39

0-16

Fe2O3

2-38

24-35

Cr2O3

0-2

0-1

NiO

0-4

0-3

Al2O3

0-83

5-9

MgO

0-36

0-1

MoO3

0-35

0-1

ZrO2

0-38

0-13

SO4

0-6

0-1

NO3

5-25

0

Fission product oxides

3-90

2-10

Actinide oxides

<1

2-23

Other constituents

17-27

© British Crown Owned Copyright 2007/AWE Source: Donald, (2007).

More specific waste stream compositions are given in Table 25.3 and actual compositions of the solid waste components of various waste streams based on calcine oxide compositions have been reported (Jantzen, 2011) and are shown in Table 25.4.

US wastes derived from the original production of plutonium contain a high concentration of sodium, which arose from the need to neutralize the acidic liquor before it could be stored in the carbon steel tanks built in the early days of the US defence programme at Hanford and the Savannah River Site (SRS). Although neutralization reduced the rate at which the tanks corroded it did not eliminate it entirely, and so these stored wastes contain contaminants from the steel, together with additional iron from the use of ferrous sulphamate in the PUREX process, small concentrations of nickel dissolved from the Ni-plated uranium targets irradiated to produce Pu, and some chromium. Wastes from the other countries involved in nuclear weapons programmes include those generated by the production of Pu and highly enriched uranium (HEU), together with various chemical and pyrochemical processes for reprocessing Pu.

Weapons programmes such as those in the US and the USSR were strictly military and the facilities built to support these programmes were clearly identifiable as were the wastes generated by them. The growing interest in nuclear power for electricity generation meant countries who started nuclear arms programmes only a few years later often had concurrent civil nuclear power and weapons programmes which used the same facilities. For example, in the UK, nuclear reactors at Windscale and Chapelcross were used to generate electricity but at burn-up rates optimized to maximize Pu production. Fuel from these reactors was reprocessed at Windscale along with fuel from other electricity generating reactors. Similarly the UK’s gaseous diffusion plant at Capenhurst was used to produce HEU but also lower enrichment grades for civil reactor fuel.

France also had concurrent programmes with the majority of product from its first plutonium separation plant at Marcoule being for military use. In anticipation of a global expansion in plutonium fuelled reactors for civil use, a second plant, at La Hague, was funded by the Commissariat a l’Energie Atomique ’s (CEA) civil and military budgets (Schnieder and Marignac, 2008). HLW reprocessing wastes in both France and the UK are being vitri­fied into steel casks and stored in purpose-built above-ground stores await­ing provision of suitable permanent repositories. In addition to the wastes generated during its production and those arising during the manufacture of warheads, there is also the plutonium which has been declared surplus to requirements following the decision by the US and Russia to reduce their warhead stockpiles. Under the 1993 Non-Proliferation and Export Control Policy (see http://www. fas. org/irp/offdocs/pdd13.htm), the US declared 55 tons of plutonium surplus to national security needs. A similar quantity was

Component

SRS

(USA)*

Hanford

(USA)*

Idaho Falls

(USA)*

Tokai

(Japan)

Sicral 1 (France)

Magnox

(UK)

Fanchow

(China)

Al

7.7

1.5

4.2

_

32.5

26.0

4.5

Na

5.9

4.1

3.1

44.5

20.5

31.0

К

0.3

0.9

0.6

Mg

0.2

4.0

30.0

Fe

29.7

6.1

8.4

16.0

13.0

13.5

Ni

2.8

0.6

2.2

1.5

1.4

2.9

Cr

0.3

0.1

2.2

1.5

1.6

1.2

Mo

0.2

0.2

10.8

0.7

Zr

0.6

3.4

11.4

11.8

0.7

Hg

1.8

Cl

0.9

0.1

so4

0.8

0.2

2.6

4.8

N03

4.2

2.8

12.5

11.0 mol

Fission

<3.0

<2.5

<1.0

49.0

24.5

2.7

products

TRU

<0.2

<0.1

<0.1

12.6

3.0

2.0

17.9

 

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* Defence waste. Source: IAEA (1992).

 

Component

DWPF

(Purex

HAW)

USA*

Hanford

76-68

USA*

West Valley,

NY

(USA)

Тока і (Japan)

UOX 1 (France)

Magnox

(UK)

Myak

(Russia)

ai2o3

5.99

_

2.39

_

_

19.60

_

CaO

2.46

Cr203

0.71

1.21

2.92

1.69

3.15

1.6

0.58

CuO

0.17

Fe203

50.64

29.09

50.30

9.02

18.06

10.0

6.07

HgO

0.33

K20

0.16

0.44

22.00

MgO

0.56

21.6

2.07

MnO

12.70

1.34

Na20

6.33

15.15

6.77

16.46

27.98

NiO

6.52

0.60

2.01

1.48

2.54

1.20

3.39

PbO

0.68

p2o5

0.28

1.52

11.09

0.93

1.76

Si02

1.35

ZnO

0.28

F

Cl

0.18

0.10

so4

0.72

1.02

Fission

2.71

38.48

3.16

65.01

72.24

44.40

37.91

products

Actinides

7.24

13.95

18.35

5.41

2.25

1.60

Source: Jantzen (2011).

Published with permission of Woodhead Publishers.

 

Подпись: © Woodhead Publishing Limited, 2013

also declared surplus by Russia. These quantities may be further increased following the 2010 US-Russia strategic arms reduction agreement (see http://news. sky. com/home/world-news/article/15583846).

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