This work presents the coupled development of hydrodynamic, dispersion and dose assessment
models to support nuclear emergency response consequence assessment.
High resolution 2D depth averaged hydrodynamic models incorporating wetting and drying
were developed for the Tamar estuary and Upper Firth of Clyde using the Thetis coastal
ocean model and validation against available tidal elevation and velocity data showed very
good agreement.
To facilitate their use in emergencies, harmonic analysis was conducted to enable the rapid
reconstruction of velocity and elevation fields. It was determined by sensitivity analysis
that the loss of certain high frequency flow features in the reconstructed flow was significant
to particle dispersion predictions. The novel application of Dynamic Mode Decomposition
techniques was trialled to resolve these issues; however, training stability and the loss of
temporal awareness using this technique were found to be limiting in its application.
A 3D Lagrangian particle model has been developed over a base particle trajectory solver
to enable the assessment of radioactive transport, including wind forcing, management of
radioactive decay and kinetic exchange of radioactivity between water and sediment phases.
A number of validation cases for the dispersion model are presented compared against a
tracer study.
A proof of concept directly coupled atmospheric and marine dispersion model was developed
and demonstrated. Testing identified that such an approach may not be suitable for small
domains due to the numerical limitations of Lagrangian simulations and representative exchange
lengths between phases.
Dose assessment tools have been developed, including the novel development of a full-field
gamma shine assessment tool incorporating buildup and air attenuation. Some considerations
for the best interpretation and communication of dose results in emergencies have also
been provided.
Sensitivity analysis of the combined model system has resulted in novel insights including
the insensitivity of immediate response phase models to sediment dynamics.