Page 307 - Materials Chemistry, Second Edition

4.6 Illustration of the Phase Impact Assessment by Practical Example 291

For a deduction of an indicator model an equation essentially the same as
Equation 4.30 is chosen, combining mass, impact and fate. The so-called envi-
ronmental increments (EIs) 365) have been proposed as EFs for an environmental
load. Such factors have been deduced for the most important radionuclides in
radioactive waste. From experience it is known that even in natural surroundings
a very small exposure of organisms occurs, and species and ecosystems obviously
can cope with it. 366) EIs of individual nuclides are determined, not completely
without certain arbitrariness, because of their natural variability of occurrence in
ecosystems (minimum area 1 ha, minimum time period 1 a). They serve as a proxy
similar to ‘No Effect Concentration’ in ecotoxicology. 367) For artificial radionuclides
EI values with more or less plausible assumptions were applied.
For an application in the impact assessment a media related indicator model
must be developed for terrestrial, air-related and aquatic exposition.
The simplest application of the EI method (fate factor = 1) formally resembles a
‘c.V.’ (Section 4.2):
( )
1
C = m (4.32)
i i
EI i
where
m mass of the released nuclide i (into the regarded medium), for which an EI i
i
was determined, per fU
C possible contribution of nuclide i
i
M mass i per functional unit
i
EI Environmental Increment of i ((Bq kg −1 soil), (Bq m −3 water) or (Bq m −3 air)).
i
These partial amounts can, as with the chemicals, be summed to an overall
potential.
In order to also include the life time and distribution of the nuclides (fate)
simple exposure models can be used. The human toxicity of radioactive emissions
is quantified according to Solberg-Johansen et al. (1997, loc. cit) by non-weighted
Bq but not characterised.
For radioactivity also, as in the case of other rarely applied impact categories (see
Section 6.3.1), advancement in methodology, harmonisation of different variants
and testing in real LCAs should have a high priority.

4.6
Illustration of the Phase Impact Assessment by Practical Example

Requirements of the impact assessment are divided into mandatory and optional
elements. For an elaboration of optional elements clearly more degrees of freedom

365) Amiro (1993).
366) The method was developed for emissions from nuclear plants and nuclear waste and is therefore
closer to a threshold-thinking than to the ‘less is better’ of classical LCA, Amiro and Zach (1993).
367) Solberg-Johansen et al. (1997).