Assessing the Health, Safety and Environmental Risk of Ammonia and Urea Units Using the Integration of Shannon Entropy and WASPAS Based on Fuzzy Logic

Due to the scope and volume of activities, the petrochemical industry has a high potential risk to humans and the environment. This study aimed to evaluate and rank the health, safety and environmental risks caused by the ammonia and urea production process.

The Preliminary Hazard Analysis (PHA) method was used for qualitative risk analysis and screening of the health, safety and environmental risks identified in the follow-up phase. The severity and probability of occurrence of risk factors were calculated using PHA tables, and the level of risks was determined. To rank the final risks, the criteria “severity,” “probability of occurrence,” “probability of detection,” and the “extent of contamination” for environmental aspects and the criteria “severity,” “probability of occurrence,” “probability of detection,” and the “exposure” were first weighed by the fuzzy Shannon entropy method. Then, each risk was prioritized based on the mentioned criteria and using fuzzy Weighted Aggregated Sum Product Assessment (WASPAS).

According to the results, among 24 environmental aspects, CO2 emissions from the disposal tower with a value of 0.702 and among the 36 safety and health risks, falling from a height with a value of 0.713 have the highest score.

Finally, suggestions were made to correct and mitigate the high-level risks. Also, the research results showed that using the multi-criteria decision-making technique in the fuzzy environment increases the study’s accuracy and facilitates access to the knowledge of experts.