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-It is necessary to control and evaluate human factors to reduce economic loss by major accident in toxic gas facilities. Conventional works to evaluate hazards have been focused on mechanical and systematic failure, while only a little works have been studied on managing human errors. In this work, a classification system of performance shaping factor (PSF) was suggested to consist human error in managing accident in the toxic gas facilities. Four types of PSFs (human, system, task characteristics, and task environment) were collected, reviewed, and analyzed to be categorized selected according their characteristics of situational, task, and environmental parameters. The PSFs were further modified to set up PSF systems adequate to evaluate human error, and the proposed system to consist PSFs to evaluate human error was further studied through accident analysis in toxic gas facilities.

To assess downward positions of water spray for the small-scale release of chlorine gas, dispersion coefficients for the Gaussian dispersion model were validated at the small-scale release experiment. And the downwind distances of water spray were assessed with the simulated results. As results, the Gaussian plume model using the Briggs' dispersion coefficient well estimated the dispersed characteristics for small-scale release of chlorine gas. The best adequate downwind position of water spray is the position of the maximum concentration of chlorine at the ground level. And the adequate vertical and horizontal dimensions of water spray consider the maximum width and height of cloud.

To establish the necessary safety technology in high-pressure toxic gas facilities, especially for the corrosion, which is the main causes of toxic gas accident, this study adopts and investigates the API-581 procedures developed by the American Petroleum Institute (API). And the applicability of the 8-step analytical procedures of consequence analysis in API-581 is discussed, and a method for consequence analysis in high-pressure toxic gas facilities is suggested. Based on the discussion and results, the analytical procedure is simplified as the 6 steps in total for the effective application to high-pressure toxic gas facilities: Step 1 (determination of representative material),Step 5 (determination of release type), Step 6 (determination of phase of fluid), and Step 8 (estimation of damage range) are not applied: Step 3 (estimation of total amount of release) is applied only for the inventory group concept; Step 4 (estimation of release rate) only for the gas release rate; and all of Step 2 (selection of release hole size) and Step 7 (evaluation of post-release response) are applied. In the proposed method, the generally applicable method of CCPS is adopted as alternative method for Steps 5 and 8.