Abstract: To enhance the intrinsic safety level of the station, the parameters and guiding words in the traditional HAZOP method are first improved. Then, the deviation degrees of parameters and countermeasures are weighted and combined to quantitatively process the deviations. Finally, the model is applied to the risk assessment of the internal detection operation process to obtain the risk concentration points. The results show that during the ball collection process, the risks are relatively high in scenarios such as insufficient venting, failure to open the vent valve and blowdown valve, failure to inject clear water, and failure to check the ball passage indicator. During the serving process, the combined deviation value of the blowdown valve not being closed, the serving cylinder not being emptied and the incorrect posture of the pigging device is relatively large, which belongs to the risk concentration points. It is recommended to enhance the training of operation personnel, establish an internal inspection operation ledger, set up an interlock control system and monitoring points along the line to reduce the number of false operation.

Key words: HAZOP, guide words, deviation, deviation degree, internal detection, risk assessment