Environmental Engineering Reference
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theory of risk and safety should be carried out. On this basis, one could
rank the scientific problems in the order of their importance, set priorities
and formulate a number of specific tasks to assess the necessary costs
Z
(
t
)
and their effective use. Their solution would figure out how the results
change ways of achieving the goals. This part of the study could be called
analysis and synthesis of technologies of protection against risks. On this
basis we could adjust long-term goals, meanings, values, and the desired
future. Also, we can return to the definition of expected parameters of the
technosphere, predict future changes in the social sphere and the biosphere
and redefine the corridor of our ability. The circle is now closed.
Unfortunately, this simplest and most logical way of constructing a
theory is difficult to implement at the moment. First of all, while there
are also problems with the definition of long-term strategic objectives, it
is difficult to take into account the likelihood of dangerous states
P
(
t
) and
associated damage
U
(
t
).
Many events that generate threats, dangers, risks
R
(
t
), the probability
P
(
t
) and losses
U
(
t
), can be described by a large number of probability
models. However, these probabilities are themselves often subject to very
definite deterministic laws. Therefore, they can be assessed taking into
account the prior history of the systems, the measures, a wide range of
different factors, and can be manipulated. This gives a new probability
of direct quantitative approaches to the prediction of emergencies,
technological and sociogenic hazards, the new algorithm to improve
security in contingency, emergency and catastrophic situations of many
complex systems and provide a given level of human security, facilities
and environment.
An example of applying the theory to address the operational risks of the
problem at the Ignalinal nuclear power plant is given in sections 7.2 and 7.3.
2.5 Accounting for ageing in formal mathematical
models
A detailed review of the ageing processes in models of reliability of
components and systems of nuclear power plant safety was published in
Ref. 31.
It is shown in Ref. 31 that most of the PSA carried out to date for
existing, under construction and planned nuclear power units in the
simulation of emergency consequences, unpreparedness of the safety
functions (systems) and personnel actions, use the assumptions and results
of the deterministic analysis based on a conservative approach. It is
assumed that the strength and reliability safety margins for the components
and the chosen strategy of maintenance are conservative enough to ensure
reliable operation of the components during the entire period of service
under any of design conditions (maximum design-basis accident is regarded
as the most severe emergency mode). In this case, the majority of emergency
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