Following the risk assessment training for the CP unit staff at RSS a Major Risk Analysis (MRA) was carried out on Ammonia Storage tanks at Jordan Phosphate Mines Company (JPMC) in Aqaba. MRA is a preventive approach to major accident with major impact beyond the boundaries of the factory. MRA sets and develops scenarios, evaluates the impacts on human health and the environment, calculates probabilities of an incident and sets mitigation measures for decreasing the risk. The work was done by CPU/RSS and JPMC staff under the supervision of Dr. Pablo Lerena, a Swiss expert from Swiss Institute for the Promotion of Safety and Security (SWISSI). The study was conducted according to the international standards using United States / Environmental Protection Agency (US-EPA) approved risk assessment modelling software (ALOHA).
The company has two vertical cylindrical single wall tanks for liquid ammonia with capacity of 30,000 ton and 10,000 ton with the additional ancillary equipments such as valves, control systems, instrumentation, electrical equipments and alarm/safety system. The tanks are made from cryogenic (treated) steel and are designed for the operating pressure and liquid head. Anhydrous ammonia is stored at nearly atmospheric pressure and a corresponding saturation temperature of –33.4°C.
The Industrial Complex is located about 20 km south of Aqaba city. The Complex and the ammonia tanks are located in the southern industrial area as far as possible from the residential areas and public buildings, taking into account the direction of prevailing wind which is north. The ammonia storage tanks are located at the south west border of JPMC Industrial Complex. Figure below shows the whole layout of the Complex.
MRA study is limited to identifying the major accident hazard of ammonia storage tanks (including cooling system) and pipeline from the Jetty.
The CP unit team together with JPMC has focused on studying the most critical scenarios with highest percent of occurrence or with highest possibility of causing major harm to a lot of people (severity) .