Addressing off-site consequence criteria using Level 3 PSA
Andrew Wallin Caldwell, Malin Angerbjörn, Gunnar Johanson, Jakob Christensen, Ilkka Karanta,
The goal of this project is to further Nordic understanding of the potential for Level 3 PSA to determine the influences and impacts of off-site consequences, the effectiveness of off-site emergency response, and the potential contributions of improved upstream Level 1 and Level 2 PSAs.
This status report summarizes the work performed during 2014, which mainly belongs to Task 4, the Pilot Application, which is separated into two parallel activities, the "Swedish" and "Finnish" Pilot projects.
The Finnish Pilot study demonstrates the application of deterministic and probabilistic methods in Level 3 PSA. The case considered applies the source term of the actual Fukushima Daiichi nuclear power plant accident, but without taking into consideration that the population was evacuated before the accident due to the tsunami
The population doses are analysed in the event trees, and uncertainty analyses are conducted on the weather variables, evacuation and sheltering success probabilities, and the effectiveness of sheltering. We find that, even under rather conservative assumptions, the radiological consequences are small. However, the results should be seen as only indicative due to simplifications made in modelling.
For the Swedish Pilot study, two major activities were completed during 2014: The Input Specification and the Scope of Analysis.
The input specification includes a discussion on the input data that will be used in this study. Here some justification for why the EPR reactor would be the focus of the source term development for the Swedish pilot project. Further input data, such as weather and population data, will be extracted from a Thesis work.
The proposed analysis scope will help the project to ultimately provide important insights related to the main project goals.
During 2015, the final year of the project, the pilot projects will be completed and the guidance document will be formulated along with the project stake holders. The working group will also remain engaged in international activities surrounding Level 3 PSA, the development of the IAEA Level 3 PSA TECDOC and the ANS/ASME Level 3 PSA Standard.