Improvements to a level 3 PSA event tree model and case study

Ilkka Karanta, Tero Tyrväinen, Jukka Rossi

    Research output: Book/Report › Report

    Abstract

    This report presents implemented and potential improvements to a level 3 PSA model and its analysis previously developed in the PRADA project. The model is an event tree model, where wind direction, wind speed, precipitation, success of evacuation and success of sheltering (if evacuation is unsuccessful) are the nodes. The case modelled was an alternative take on the Fukushima Daiichi nuclear accident: what adiological consequences would the accident have had if the population in nearby big cities had been in place and not dislocated due to the tsunami. The radiological consequences were found to be small even under rather conservative assumptions. The most important change to the event tree model introduced in this report is that wind speed is now drawn from a Weibull distribution in a Monte Carlo simulation. Also evacuation modelling was improved slightly. In the uncertainty analysis, the most important change concerns the handling of source term uncertainties. Population dose is composed from doses caused by each radionuclide, and thus the amounts of radionuclides in the release can be made random variables and subjected to Monte Carlo simulation. An uncertainty distribution was attached also to wind speed parameters and evacuation success probability in the uncertainty analysis. The radiological consequences to the general population were minor also in this study. This gives support to the hypothesis that the very small (according to UNSCEAR) radiological consequences to the general population in the Fukushima Daiichi nuclear accident were not a matter of good luck but rather something to be expected concerning the case.
    Original languageEnglish
    PublisherVTT Technical Research Centre of Finland
    Number of pages21
    Publication statusPublished - 2015
    MoE publication typeD4 Published development or research report or study

    Fingerprint

    nuclear accident
    wind velocity
    uncertainty analysis
    radionuclide
    tsunami
    wind direction
    simulation
    accident
    modeling
    dose
    distribution
    analysis
    city
    project
    parameter

    Keywords

    • level 3 PSA
    • consequence analysis

    Cite this

    Karanta, Ilkka ; Tyrväinen, Tero ; Rossi, Jukka. / Improvements to a level 3 PSA event tree model and case study. VTT Technical Research Centre of Finland, 2015. 21 p.
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    abstract = "This report presents implemented and potential improvements to a level 3 PSA model and its analysis previously developed in the PRADA project. The model is an event tree model, where wind direction, wind speed, precipitation, success of evacuation and success of sheltering (if evacuation is unsuccessful) are the nodes. The case modelled was an alternative take on the Fukushima Daiichi nuclear accident: what adiological consequences would the accident have had if the population in nearby big cities had been in place and not dislocated due to the tsunami. The radiological consequences were found to be small even under rather conservative assumptions. The most important change to the event tree model introduced in this report is that wind speed is now drawn from a Weibull distribution in a Monte Carlo simulation. Also evacuation modelling was improved slightly. In the uncertainty analysis, the most important change concerns the handling of source term uncertainties. Population dose is composed from doses caused by each radionuclide, and thus the amounts of radionuclides in the release can be made random variables and subjected to Monte Carlo simulation. An uncertainty distribution was attached also to wind speed parameters and evacuation success probability in the uncertainty analysis. The radiological consequences to the general population were minor also in this study. This gives support to the hypothesis that the very small (according to UNSCEAR) radiological consequences to the general population in the Fukushima Daiichi nuclear accident were not a matter of good luck but rather something to be expected concerning the case.",
    keywords = "level 3 PSA, consequence analysis",
    author = "Ilkka Karanta and Tero Tyrv{\"a}inen and Jukka Rossi",
    note = "Project code: 101958",
    year = "2015",
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    Karanta, I, Tyrväinen, T & Rossi, J 2015, Improvements to a level 3 PSA event tree model and case study. VTT Technical Research Centre of Finland.

    Improvements to a level 3 PSA event tree model and case study. / Karanta, Ilkka; Tyrväinen, Tero; Rossi, Jukka.

    VTT Technical Research Centre of Finland, 2015. 21 p.

    Research output: Book/Report › Report

    TY - BOOK

    T1 - Improvements to a level 3 PSA event tree model and case study

    AU - Karanta, Ilkka

    AU - Tyrväinen, Tero

    AU - Rossi, Jukka

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    PY - 2015

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    N2 - This report presents implemented and potential improvements to a level 3 PSA model and its analysis previously developed in the PRADA project. The model is an event tree model, where wind direction, wind speed, precipitation, success of evacuation and success of sheltering (if evacuation is unsuccessful) are the nodes. The case modelled was an alternative take on the Fukushima Daiichi nuclear accident: what adiological consequences would the accident have had if the population in nearby big cities had been in place and not dislocated due to the tsunami. The radiological consequences were found to be small even under rather conservative assumptions. The most important change to the event tree model introduced in this report is that wind speed is now drawn from a Weibull distribution in a Monte Carlo simulation. Also evacuation modelling was improved slightly. In the uncertainty analysis, the most important change concerns the handling of source term uncertainties. Population dose is composed from doses caused by each radionuclide, and thus the amounts of radionuclides in the release can be made random variables and subjected to Monte Carlo simulation. An uncertainty distribution was attached also to wind speed parameters and evacuation success probability in the uncertainty analysis. The radiological consequences to the general population were minor also in this study. This gives support to the hypothesis that the very small (according to UNSCEAR) radiological consequences to the general population in the Fukushima Daiichi nuclear accident were not a matter of good luck but rather something to be expected concerning the case.

    AB - This report presents implemented and potential improvements to a level 3 PSA model and its analysis previously developed in the PRADA project. The model is an event tree model, where wind direction, wind speed, precipitation, success of evacuation and success of sheltering (if evacuation is unsuccessful) are the nodes. The case modelled was an alternative take on the Fukushima Daiichi nuclear accident: what adiological consequences would the accident have had if the population in nearby big cities had been in place and not dislocated due to the tsunami. The radiological consequences were found to be small even under rather conservative assumptions. The most important change to the event tree model introduced in this report is that wind speed is now drawn from a Weibull distribution in a Monte Carlo simulation. Also evacuation modelling was improved slightly. In the uncertainty analysis, the most important change concerns the handling of source term uncertainties. Population dose is composed from doses caused by each radionuclide, and thus the amounts of radionuclides in the release can be made random variables and subjected to Monte Carlo simulation. An uncertainty distribution was attached also to wind speed parameters and evacuation success probability in the uncertainty analysis. The radiological consequences to the general population were minor also in this study. This gives support to the hypothesis that the very small (according to UNSCEAR) radiological consequences to the general population in the Fukushima Daiichi nuclear accident were not a matter of good luck but rather something to be expected concerning the case.

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    KW - consequence analysis

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    BT - Improvements to a level 3 PSA event tree model and case study

    PB - VTT Technical Research Centre of Finland

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    Karanta I, Tyrväinen T, Rossi J. Improvements to a level 3 PSA event tree model and case study. VTT Technical Research Centre of Finland, 2015. 21 p.

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