There are several factors that - through their implications to nuclear accident consequences - may affect level 3 probabilistic safety assessment (PSA) results significantly. For example, now, ice cover and frost may affect the transport of radionuclides; an initiating event, such as tsunami or loss of external electric power, may cause the population to be evacuated before release or impede evacuation; extreme snow as an initiating event implies that the season in
question is winter, and therefore winter weather should be used in atmospheric dispersion calculations. In this report, such factors are called seasonal and contextual factors (SCF). These factors are not systematically taken into account in level 3 modelling currently.
This report makes an overview of possible SCF’s and their potential impacts to accident consequences and level 3 analysis. SCF’s are listed together with their implications. SCF’s affect many important level 3 phenomena such as aquatic dispersion, transport of radionuclides in the environment and biosphere, population demography and behaviour, and attenuation of ionizing radiation. These, in turn, affect level 3 analyses concerning population dose, evacuation, sheltering and distribution of radionuclides in the environment.
Ways of incorporating SCF’s in level 3 analyses are discussed. For example, they affect dose assessment parameters, use of weather data, and estimation of contaminated land area. Constructing a framework for incorporating SCF’s in level 3 analyses, in a manner similar to those widely used for external events, would make this incorporation easier.
Systematic research is needed to find out which SCF’s are significant enough to merit incorporation in PSA, and how to incorporate them in a reasonable manner. This will involve multidisciplinary modelling, analysis and experimentation.
|Publisher||VTT Technical Research Centre of Finland|
|Number of pages||19|
|Publication status||Published - 2018|
|MoE publication type||Not Eligible|
|Series||VTT Research Report|
- probabilistic risk assessment
- nuclear accident consequences