Page 306 - Materials Chemistry, Second Edition

290 4 Life Cycle Impact Assessment

importance for rare invents with a very high potential of harm, as, for example, in
nuclear electricity production.

4.5.5.2 Radioactivity
Without this impact category and the category ‘casualties’ nuclear power would do
quite well in the impact assessment. The greenhouse effect and most chemical
emissions related to the energy output are small compared to thermal power
generation with fossil sources of energy. The risk of a maximum credible accident
remains that is hardly to be calculated according to the classical ‘insurance formula’
Risk = extent of damage × probability of occurrence
because

• the extent of damage is extremely large but cannot be quantified;
• the probability of occurrence is >0 but very small, and cannot be verified
statistically.
Statistical material at the basis of insurance mathematics is therefore missing.
As a substitute an attempt is made using general technical knowledge including
modelling as a basis for reasoning by analogy to make risk calculations, which
are however very controversial. Furthermore, the problem of the final disposal of
radioactive waste is not yet solved (anywhere in the world).
Incidents and leakages of nuclear power and reprocessing plants can be consid-
ered by impact assessment. Emissions under normal operation conditions should
be considered in the toxicity impact categories. A first quantification attempt of
the impact category radioactivity is based on the number of radioactive decays
pertimeunit 361) originating from the emissions. The SI unit of radioactivity 362) is
the Becquerel named in honour of the discoverer A. H. Becquerel (1852–1908).
It signifies the number of radioactive decays per second. The conversion into the
former unit Curie is done according to
1Curie (Ci)= 3.7 × 10 Becquerel (Bq)
10
The unit Becquerel has the disadvantage that further important information con-
cerning the impact of nuclear radiation like radiation type (α, β, γ) 363) , the energy per
particle or quantum and the half-life of radio active atomic nuclei is not considered.
For aggregation the non-weighted inventory data Bq per fU can be chosen.
A characterisation beyond this non-weighted aggregation has been described in
literature. 364) It takes into account that hard radiation can not only harm human
health but also the environment and that radionuclides can accumulate in the
environment with a well-known possibility of transfer to humans, for example, by
contaminated nutrition.

361) Suter and Walder (1995) and Guin´ ee et al. (2002).
362) ISO (1981) and Deutsche Normen (1978a,b).
4
363) α-radiation consists of He -nuclei, β-radiation is high-energy electron radiation, γ-radiation is
extremely short-wave electromagnetic radiation; the three radiation types mainly differ by their
energy content and particularly by their ability to penetrate matter, which increases from α to γ.
364) Solberg-Johansen, Clift and Jeapes (1997).