**4. Modelling the effects and impacts of the accidents**

The current software tools used for modelling the effects and impacts are on a very good level. Their main task is to simulate (based on the models) the formation and development of the accident. These simulated accidents are subsequently

#### *Risk Management in the Area of Major Industrial Accident Prevention in the EU… DOI: http://dx.doi.org/10.5772/intechopen.98406*

included to the map material which can show us the impact of the accident in dependence on time and quantity. Thanks to these software means it is possible to identify the negative effects of the accidents and take the necessary preventive measures. These simulation programmes work with various databases thanks to which we can simulate the accidents as realistically as possible.

However, it is necessary to say this software cannot create a fully accurate model of the real world and define all parameters, e.g. the structure of the terrain, location of the buildings and equipment, etc.

Today there are a lot of simulation programmes determined for simulating the accidents, e.g. ALOHA, EFFECTS, BREEZE, TEREX, ROZEX, SAVE II, etc. They can be used for various types of accidents – the simulation of explosions, fires, leakages of hazardous substances to the air, evaporation of the hazardous substances, etc. [28, 29].

In the Czech Republic they most frequently utilise the simulation programme EFFECTS but the programmes ALOHA and SAVE II are also used. Only exceptionally they make use of the programmes TEREX and ROZEX. On the contrary, in Slovakia we often utilise ALOHA.

For simulating the type scenario in the emergency plan framework we chose the software ALOHA, particularly the version 5.4.7. The faculty student Lukáš Dančo participated in realising this simulation. The software simulated a leakage of a hazardous substance from a storage container. The software MARPLOT that is directly connected with ALOHA was subsequently used as a map basis for transferring the graphical outputs from ALOHA and thus for depicting the expansion of the hazardous substance fumes.

The particular company deals with manufacturing the basic chemicals and chemical products and its basic products are the essential amino-acids. Based on exceeding the threshold value of the hazardous substance present in the company, it belongs to the B SEVESO category.

Particularly, it is the hazardous substance ammonium hydroxide – the ammonia.

The ammonia stored in this company has a concentration higher than 25%. It presents a risk for the life and health of people only in the case of leaking from the storage containers or pipelines due to releasing the gaseous ammonia bound in water. The gaseous ammonia or the anhydrous ammonia (according to the law about MIA prevention) is the hazardous substance mentioned in the law in the Appendix 1, part 2. The substance is dangerous based on its classification as the toxic and ecotoxic material.

It is a caustic liquid with bad smell. Its colour range is from colourless to yellow or slightly turbid. This substance causes failures of the central nervous system and irritates mainly the respiratory system. The gaseous ammonia released from this liquid can be easily recognised already in a low concentration thanks to its strong odour. The exposure to a high concentration of the gaseous ammonia can cause the respiratory arrests.

The leakage of this hazardous substance can develop either in the storage containers or during pumping the hazardous substance from the tank truck. We aim at the storage containers, particularly at one of the containers, during the simulation of the hazardous substance.

We chose this device due to the fact it is the only storaging object in the company with a larger amount of the hazardous substance and it is the most dangerous equipment in the enterprise.

#### **4.1 Input data**

For us to be able to simulate the type scenarios we needed to define the input data in the software. The data about the territory were defined on the basis of the approximate position of the hazardous equipment. It is a locality in the Banská Bystrica region with an altitude of 370 metres above the sea level. The time and date of the emergency was fictitious only for the needs of the simulation – 14th May 2020 at 11:00 am (**Table 4**).
