HAZOP study and SIL assessment on yellow cake dissolution process at BATAN's uranium refining and conversion facility

Purification and conversion facilities at BATAN’s Uranium Refining and Conversion Facility are used to purify uranium concentrate (yellow cake) from impurities and convert it to uranium dioxide powder that meets the criteria for nuclear grade. Yellow cake dissolving process is one of the main processes in uranium refining and conversion facilities. The use of nuclear materials and nitric acid solution in this process may cause radiological and chemical hazards from concentrated nitric acid as well as exothermic dissolution processes that may affect both the operator and the environment around of the facility because yellow cake nuclear material emits (alpha) radiation which can be an internal emitting material in the human body. In addition to radiological hazards, occupational accidents caused by equipment failure or human error may also occur. Therefore, it is necessary to identify this potential hazard, which can be done by using the hazard and operability study (HAZOPS) method then assessing the risk using a risk matrix based on AS/NZS Standard 4360:2004 and determining the SIL (safety integrity level) value to determine the level of system safety and security already installed. From the identification that has been carried out, 6 nodes are obtained and then a risk analysis is carried out which results in 10 deviations caused by 12 damages and or equipment failure. The risk assessment of 12 damages resulted in 1 potential hazard risk categorized as low risk, 10 potential hazard risks categorized as medium risk, and 1 potential hazard risk categorized as high risk. The low hazard risk category can be overcome by routine handling such as performing periodic preventive maintenance and calibration of devices within a certain period of time or when problems are encountered as the existing programme. For the category of moderate hazard risk, in addition require recommendations such as low hazard, it is also needed other recommendations in overcoming deviations that might be occur according to the type of deviation. Risk control for the high hazard risk category relies at the pressure, in addition to require equipment maintenance recommendations such as medium hazard risk categories and add with other recommendations to overcome the deviations that might occur. The results the SIL determination obtained 1 protection system that has been installed in this process, namely a protection system for the steam system with a SIL value at level 1, so that it is necess