The basics of risk theory 1. Concepts: risk, safety and stability of systems; crash; catastrophe

1. Concepts: risk, safety and stability of systems; accident; catastrophe

The 20th century brought not only new threats and risks to humanity [11], but also allowed us to outline common ways of confronting global threats.
The main one is the idea of ​​sustainable development - equality between peoples. Another way is strategic risk management, which
It is connected with the impossibility of abandoning many dangerous technologies.
The analysis of many accidents and disasters shows that their source is not the elements or equipment, but the person, that is, a significant part of the danger
nosti and risks - inside the person. The theory of safety and risk being created now is a generalized interdisciplinary approach capable of
play an important role in the development of civilization development algorithms.
Safety and sustainability of the development of society are two interrelated concepts that are important in choosing guidelines and paths
Achievement of high material and spiritual living standards of people.
In general, safety, including man-made, natural and environmental aspects, usually refers to the state of protection
human, society and the environment from excessively harmful
impacts of technogenic, natural and environmental factors [12]. At
This implies that conditions are provided under which the excess of scientifically substantiated acceptable levels of physical
fields, concentrations of harmful substances and dose loads.
Security level corresponding to a particular state
society, its scientific, technical and economic opportunities, has a stochastic nature and is determined by a number of random phenomena. In about-
In the present case, it is characterized by:
- the likelihood of man-made accidents, disasters, natural hazards and possible damage during these events;
- the degree of negative impact on humans and the environment
the environment of sluggish technogenic and natural processes while maintaining at the macro level the equilibrium state of ecosystems;
- the likelihood that the environmental situation will develop into a crisis and catastrophic and an emergency.
In accordance with modern views, risk is probabilistic
a measure of the occurrence of technogenic or natural phenomena, accompanied by the formation and action of harmful factors, and caused
at the same time social, economic, environmental and other types of damage. The general (34) and simplified (35) risk calculation formulas may
be presented as follows:

where R is the level of risk, i.e., the probability of causing certain damage to humans and the environment;
R 1 — probability of occurrence of an event or phenomenon that determines the formation and action of harmful factors;
R 2 - the probability of the formation of certain levels of physical fields, shock loads, concentration fields of harmful substances in various
environments and their dose loads affecting people and other objects of the biosphere;
R 3 - the probability that the indicated levels of fields and loads will lead to certain damage.

A quantitative measure of risk can be expressed not only by a probabilistic value. Sometimes the risk is interpreted as damage arising
in case of accidents, catastrophes and dangerous natural phenomena.
Determining the level of risk as a probabilistic category is more convenient and acceptable when solving a wide range of tasks
scientific and practical in nature, especially tasks related to the overall assessment of the level of security.
In determining the magnitude of the damage, it seems appropriate to take into account all possible types of hazardous events,
accidents and catastrophes for a given facility and risk assessment based on the sum of the products of the probabilities of these events
to appropriate damages. In this case, the following relationship is true:

where R is the level of risk expressed through damage;
R i - probability of occurrence of a dangerous event of the i-th type or type;
Y i - the amount of damage during the i-th event.
The following can be listed as an indicator of damage:
H - various types of damage to human life and health (quantity
dead, injured, evacuated).
T - technical damage (destruction of systems, certain types of accidents).
L - material loss of property, damage from interruption of production.
E - environmental impacts (amount of emissions into the environment
environment, contaminated area).
The latter interpretation of risk finds practical application. The indicated indicators of damage are calculated for each scenario of dangerous incidents, accidents, disasters along with the expected frequency of the scenario. The data obtained in the calculations are used to determine the risks.

2. The main sources of accidents and disasters

The main sources of accidents and disasters include the following damaging factors [13].

3. Classification of accidents and disasters

Consider the classification of accidents and disasters according to the following criteria:
- according to the scale of the countries and territories covered by technological accidents and disasters - these are global, national, regional,
local and object disasters;
- according to the degree of potential danger - these are accidents and catastrophes at nuclear facilities,