2007_6_Nr6_EEMJ

Methods and procedures for environmental risk assessment
Initiating
event
Upward
release
Immediate
ignition
Delayed
ignition
Flame front
acceleration
Final
events
Overall
probabilities
Fig. 2. Event tree diagram
4.2.7. Estimation of overall risk for population
By integrated the product of R by the local
population density over spatial coordinates, the global
risk for a given accident scenario is obtained. By
adding up the several R functions (one of each
scenario), a global risk function is obtained. In order
to estimate the number of injuries and evacuated
people, historical data were used. The average ratios
of injured people/evacuees to fatalities have been
estimated to the followings:
• 2.21 injured people for each fatality,
• 220 evacuees for each fatality.
This data were obtained from processing of
1033 port area accidents from which only 428
occurred during bulk hydrocarbon (un)loading and
tanker movement/maneuvers were retained.
The general ration should be used whenever
the present QRA conceptual approach is applied to a
port, because the scenarios, as they have been
designed and structured, entail both (un)loading and
ship maneuver/ approach operations. Nevertheless,
the operation specific values can be used for studies
that focus on a particular stage in port hydrocarbon
logistics.
5. Mathematic models for environmental analysis
and assessment
The modeling of the environmental systems
is a very difficult problem owing to their complexity,
as well to the complexity of their interaction with
different other systems, interaction that is sometimes
hard to be defined. In this paper, two environmental
mathematic models are described.
The first is a probabilistic model for risk
evaluation that uses a repartition function for a
random vector that describes the concentrations of the
atmospheric pollutant factors. The latter is an
optimization model based on multiple criteria, to
appropriate financial funds for pollution reduction.
For the second model, the solving modality consists
in reduction to an optimization problem with a single
objective function.
Environmental protection against pollution is
a priority not only for the European Union but also
for the countries that wish to joint to EU, countries
that make efforts for harmonization of the specific
legislation. The community environmental policy is
based on its integration within the EU sequential
policies, paying a special attention to the measures for
pollution prevention.
There are numerous concerns related to air,
water and soil pollution generated by exceeding the
limit concentrations of different pollutants, around the
whole world. For pollution reduction there were
conceived mathematic models by different
complexities. Most of them refer to air, soil, water,
air-water, air-soil, soil-water pollution. The main
types of models are based on differential
deterministic and stochastic equations (ordinary
differential equations, equations with partial
derivates), algebraic static equations, Petri networks,
mathematic or stochastic programming, optimal
control theory, Markov chains, Markov processes,
Monte Carlo simulation and models based on
mathematic equations (Radulescu, 2002).
Environmental risk management is a relative new
term in literature. This refers both to the risk and its
effects diminishing measures.
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