Nuclear emergency response is the last defence in nuclear safety, which is important for mitigating the consequences of a nuclear accident and ensuring the safety of the public. It involves complex physical-chemical processes associated with an accident, which happen both inside the nuclear facilities and in the open environment. Because of this complexity, nuclear emergency response has become an active multi-discipline research area, involving severe accident analysis, source term estimation, behaviour of radioactive aerosols, radionuclide transport, dose assessment, and radioactivity measurement. After the Fukushima accident, nuclear emergency response has received increased attention from the community and the public.

Despite great efforts, nuclear emergency response still faces challenges from a diverse range of areas. There are a variety of uncertainties in the modelling of the accident evolution process, radionuclide retention and removal inside nuclear facilities, radionuclide transports in different environmental media, and source term estimation in the presence of limited information. Additionally, new equipment is being developed to provide new opportunities to enhance the capabilities of nuclear emergency response, such as an unmanned aerial survey of radioactivity. Most importantly, the emerging small modular reactor (SMR) brings new requirements and philosophies for nuclear emergency response, which has become a key factor for the deployment of the SMR.

This Special Issue invites scientists and engineers from the whole nuclear community to share their latest achievements and important experiences on nuclear emergency response, to advance technologies for nuclear emergency response for the future. The scope of this Special Issue includes severe accident analysis, mechanism source term estimation, radionuclide transport inside and outside the nuclear facilities, dose assessment, and radioactivity measurement. Both original research work and critical review articles are welcomed in this issue.

Potential topics include but are not limited to the following:

• Accident (INES level 4-7) analysis: modelling, experiments, and code development
• Source term estimation based on mechanisms and inverse modelling
• Behaviour of radionuclides inside the nuclear facility
• Sensors, equipment, instrumentation, and facilities
• Radioactivity measurements: data, analyses, and practices
• Nuclear emergency preparedness and response: theory, development, validation and practices