###### Abstract  
Supercritical water oxidation is a promising technology for decomposition of industrial wastewater and sludge. However, the system is operated under high temperature and pressure (usually higher than 500 \({}^{\circ}\)C and 25 MPa). Corrosion of component materials and salt deposition may lead to leakage or even the burst of the pressure vessel in the SCWO system, resulting in a high level of worry about the safe operation of the system. In this paper, the safety management and accident-control strategies are introduced according to a commercial-scale SCWO plant in China. The safety management strategy refers to the special design and operation strategies of some facilities. Different types of potential accidents are analyzed and the coping strategies for accidents of different levels of severity are described in detail. The strategies are valuable for the safe operation of commercial SCWO plants and other plants operated in high temperature and high pressure.  
supercritical water oxidation; corrosion; salt deposition; over-heating; accident; industrial sludge +
Footnote †: journal: Medical  
Many commercial companies constructed industrial SCWO plants for organic waste treatment [12; 13; 14], such as General Atomics [15], SRI International [16], Innoveox [17] and Hanwha [18]. However, some of the plants were forced to shut down due to the severe corrosion of component materials or blockage of pipelines caused by salt precipitation, which are the two obstacles impeding the commercialization of the SCWO technology [19]. Meanwhile, there are some new industrial SCWO plants under construction, such as the 50 t/d SCWO plant for sludge in China, which is designed by our research group [20; 21].  
Since the SCWO concept was proposed by [PERSON] in the 1980s, many aspects related to this technology have been studied, including reaction kinetics [22; 23; 24], corrosion behavior of construction materials [25; 26], salt precipitation problem [27], reactor design concepts [28], system design [29] and low-cost start-up strategies [30]. These studies mainly focus on reaction mechanisms of different kinds of organic matters, dissolution and precipitation behaviors of inorganic salts, and corrosion mechanisms of alloys in SCW. However, few articles are focusing on the safety concept of the SCWO system.  
The SCWO process can be considered as the first system that is operated in a high-temperature and high-pressure environment with highly corrosiveness, high abrasiveness, and a high flow-rate feedstock. There are many potential safety risks during the operation of the SCWO plants; for example, unpredictable bursts of pipelines caused by corrosion, pipeline blockage caused by salt precipitation, and flammable- and combustible-gases leakage caused by valve failures. Therefore, safety management and accident control are vital for an SCWO plant, and can effectively avoid damage to equipment and loss of property.  
Currently, a commercial-scale SCWO plant for mixed sludge is under construction in China, designed by our research group. The novel design concept applied in this plant has been introduced in our previous articles [20]. In this paper, the safety management and accident control strategy for this commercial SCWO plant is introduced. The unique features of the SCWO system that related to safety scope are analyzed. the special design of facilities and operating methods to avoid accidents is introduced. Different types of potential accidents are analyzed, and coping strategies for accidents of different orders of severity are described in detail. This information is valuable for the safe design of commercial SCWO plants and other plants operated in high temperature and high pressure.