Since 2011, many major chemical companies have reported several major fire and explosion accidents. This indicated that risk assessment in terms of chemical handling was insufficient, owing to a lack of understanding of their chemical reactions, which was a common point of the cause and background of the major accidents. Therefore, it is necessary to promote a proper understanding of the chemical reactions of these substances to carry out an appropriate risk assessment.

However, obtaining information on heat and gas generation resulting from chemical reactions is often difficult due to lack of sufficient resources to actual measurements. In addition, a detailed risk assessment method that considers logical and effective risk-reduction measures requires significant specialized knowledge and effort; therefore, there is a possibility that scenarios that lead to fires and explosions (hereinafter called scenarios) and risk-reduction measures will not be effectively studied. Further, since specialized knowledge is required to identify the chemical reactivity hazards and to examine the scenarios and risk-reduction measures, effective communication of the information regarding such studies may not be conducted. As a result, it is difficult to implement the measures outlined in the appropriate risk assessments of the chemicals, to prevent fires and explosions. Therefore, to carry out more appropriate risk assessments and thereby establish a safe working environment, it is necessary to provide the following information at the implementation stage of a logical risk assessment and risk reduction: the identification of chemical reactivity hazards and a list of sample scenarios and risk-reduction measures.

This document provides the reference information for carrying out risk assessments to prevent fires and explosions owing to runaway reactions and incompatibility, targeting the batch/ semi-batch processes. Based on the premise that the risk assessment and risk-reduction measures are carried out following the procedure compiled by JNIOSH, this document compiles the following reference information at the implementation stage of the risk assessment and risk reduction: the identification of chemical reactivity hazards, sample viewpoints on considering the scenarios, typical scenarios, and risk-reduction measures to prevent fires and explosions owing to unintended chemical reactions. It also introduces support tools, databases, and accident cases that can be used when identifying the chemical reactivity hazards and scenarios in fires and explosions owing to runaway reactions and incompatibility.