In order to prevent occupational accidents caused by chemicals, the Ministry of Health, Labour and Welfare (MHLW) has mandated that enterprises implement risk assessments and risk reduction measures for substances subject to preparation and implementation of safety data sheet since June 2016. Furthermore, the MHLW amended the order for enforcement and ordinances to introduce so-called "autonomous management," and these amendments were fully implemented in April 2024. Under autonomous management, enterprises must consider and implement measures necessary for occupational accidents prevention based on the results of their risk assessments. Consequently, the importance of risk assessments and related measures has increased.
The National Institute of Occupational Safety and Health, Japan has published the methodology for implementing risk assessment and risk reduction measures to prevent process accidents (JNIOSH method) following the approach outlined in the Guideline of Investigation of Danger or Harmful Effects of Chemical Substances of MHLW. Additionally, as reference information for implementing the JNIOSH method, the scenario diagram summarizing scenarios leading to fire and explosion due to runaway reactions and examples of risk reduction measures, and a list of key considerations for identifying scenarios involving reactive chemical hazards and examples of risk reduction measures associated with those key considerations has been created and published. To effectively utilize the developed scenario diagram and the list of key considerations in implementing risk assessments to prevent fire and explosion accidents, it is necessary to provide application examples that utilize the scenario diagram and the list of key considerations in order to deepen understanding of them.
Therefore, we show an application example demonstrating the application of the scenario diagram to identify scenarios and consider risk reduction measures. Moreover, we show an application example using the list of key considerations to review the results of scenario identification and risk reduction measure consideration using the JNIOSH method.

Keywords: Risk Assessment to Prevent Fire and Explosion Accidents, Identification of Fire and Explosion Accident Scenarios, Risk Reduction Measures, Examples of Risk Assessment