Research on Liquefied Natural Gas(LNG) inland river transportation security risk assessment and security technology based on risk management

Using the Analytic Hierarchy Process and taking a certain section of the lower reaches of the Yangtze River as an example, this paper analyzed and identified the risk of inland river transportation of LNG, established the risk assessment criteria. According to the assessment results, it can be concluded that the current security risk situation of inland river LNG transportation is between "general" and "higher", and puts forward corresponding suggestions to


Introduction
In recent years, with the accelerated implementation Inland waterway operation is a sustainable mode of transportation and an important part of China's modern comprehensive transport system, accounting for nearly 40% of China's water transport. It is a convenient way to transport LNG from coastal receiving stations to demand terminals in central and western regions by inland waterway transportation. Because of its high risk of fire and explosion, the domestic understanding of its inland waterway transport safety is insufficient, and the lack of records of large LNG ships, and designs a saving channel width algorithm for large LNG ships. The evaluation results show that the scheme not only meets the safety requirements, but also saves engineering funds. Hu Huiguo et al. [5] constructed an optimization method of LNG ship entry and exit organization scheme based on lattice order decision theory. Zhang Xiaodong et al. [6] proposed a queuing model considering non-simultaneous and simultaneous interference types to simulate the passage status of waterway vessels and effectively evaluate the safety and efficiency of LNG ships entering and leaving the port. Li Hongliang et al. [7] calculated the influence of LNG ships on the main channel capacity of Gaolan Port by using the navigation impact rate model and the channel occupancy rate model respectively. Wang Hairong et al. [8] used the method of fuzzy analytic hierarchy process to determine the weight vector and the fuzzy evaluation matrix, calculated the decision vector, and realized the quantitative risk identification of LNG receiving station. Wang Qingfeng et al. [9] quantitative calculated and analyzed of typical leakage and diffusion of inland river thin film LNG carrier and the consequences of fire and explosion accidents by using PHAST risk analysis software, considering the actual situation of inland river waters in China. Dou Xu et al [10] carried out numerical study on structural damage caused by collision of small LNG ships during inland navigation.
Wang Kan et al. [11] proposed an optimization fireball model by introducing the atmospheric transmission rate τ into the original TNO dynamic model.  on the residential population can be neglected. NWAOHA et al. [19] used risk matrix method to identify the main hazards in LNG ship maneuvering process, in which the transmission arm LNG overflow and control system failure have the highest hazard level. Further, through fault tree analysis of its causes and fault logic, the method of fuzzy logic reasoning was used to determine its safety level. Kim [20] analyzed the failure behavior of LNG sealed cargo hold under impact.

LNG transportation risk analysis and identification 2.1 Risk analysis of LNG ships
Chinese "Statistical Measures for Marine Traffic Accidents" will be included in the statistics of water traffic accidents into collision accidents, grounding accidents, reef-striking accidents, damage accidents, wave damage accidents, fire and explosion accidents, wind accidents, self-sinking accidents and other water traffic accidents causing casualties, direct economic losses and so on.

Risk identification of LNG ships
Explosion or leakage is common in LNG waterway transportation. Explosion or leakage has a great destructive effect, and accompanied by air and water pollution, it brings great economic losses to society.  Table 1.

Determining the weight of risk factors
The results of expert consultation collected are sorted out and the weights of factors at different levels are calculated respectively. Following is an example of the first level risk factors set. By calculating the first level of risk factors, the second level of risk factors can be obtained, as shown in Table 2. Therefore, the consistency checks of the judgment matrix of the first level risk factors set can be judged, and the weights of the factors u1，u2 and u3 can be obtained, as shown in Table 3.

Recognition of calculation results
Taking the navigation safety index system of LNG ships in a certain section of the lower reaches of the Yangtze River as an object of study, consulting relevant experts and professionals to determine the value of the evaluation index, the evaluation index affecting the navigation safety of LNG ships in this section can be obtained, as shown in Table 4.
Similarly, the evaluation vectors B2、 B3、 B4 can also be obtained for the channel condition.

Security management
In Establishing a scientific, systematic and procedural safety management system to ensure the institutionalization and standardization of maintenance, maintenance and troubleshooting.

Emergency plans
In accordance with the requirements of the guidelines for the preparation of emergency plans for production security accidents in production and operation units,

Conclusion
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