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 language | English |
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Publisher | VTT Technical Research Centre of Finland |
Number of pages | 21 |
Publication status | Published - 2015 |
MoE publication type | D4 Published development or research report or study |
Keywords
- level 3 PSA
- consequence analysis