This thesis examines if the software AFRY Intelligent Scenario Modelling can be used to model for the purpose of a level 3 Probabilistic Safety Analysis (PSA). A Gaussian puff model is developed in AFRY Intelligent Scenario Modelling, capable of predicting the resulting ground deposition [Bq/m2] of the radionuclides I-131 and Cs-137 following a fictional accident at a Nuclear Power Plant (NPP). Inputs to the model are precipitation and wind conditions as well as a source term representing a release of radionuclides. In order to test the validity of the model, it is first run using weather data and source term from the Fukushima Daiichi NPP accident in 2011, and the resulting ground deposition is compared to empirical data. The comparison indicates that the model yields reasonable results. Then the model is applied to the Forsmark NPP, in order to simulate what the ground deposition of I-131 and Cs-137 would be two days after a fictive accident. Using probability density functions (PDF) for rain and wind conditions, as well as the source term from the Fukushima Daiici accident, the model is run probabilistically for different weather parameters. Furthermore, the model is extended to be able to calculate whole body effective dose [mSv] to a person of the general public at any given distance, up to 100 km, from the source term. These dose calculations were done around Forsmark NPP using the same conditions as above and even though the whole body effective dose to a person of the general public was low this could be explained through short time of exposure. Given this the exposure model was assumed to give reasonable results. The model has been shown being able to disperse radionuclides in the air and predict the resulting ground deposition after the validation. This in combination with being able to probabilistically calculate ground deposition and whole body effective dose to a person of the general public shows that AFRY Intelligent Scenario Modelling is suited for modelling to be used in a level 3 PSA.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:uu-533130 |
| Date | January 2024 |
| Creators | Lindberg, Thor |
| Publisher | Uppsala universitet, Tillämpad kärnfysik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | UPTEC F, 1401-5757 ; 24044 |
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