Massively Parallel Transport Model for Radioactivity from Produced Water on the Norwegian Continental Shelf

Oil platforms on the Norwegian shelf discharge large volumes of pro-
duced water which is enriched in radioactive nuclides like ²²⁶Ra. A mas-
sively parallel Lagrangian particle model has been implemented, and used
to simulate the transport of ²²⁶Ra from all produced water sources on the
Norwegian continental shelf over a period of 5 years. We have considered
two scenarios; one where all ²²⁶Ra is released as dissolved matter, and
one where ²²⁶Ra is released as solid matter bound in the lattice of BaSO₄ .
Concentrations in the water column, and deposition to sediments have
been calculated.

We find that when ²²⁶Ra is released as dissolved matter, radioactive
concentrations fall off rapidly with distance from the release site, although
for some platforms concentration levels about 1mBq/L persist for some
kilometres. When ²²⁶Ra is released in solid form, concentrations in sed-
iments are found to reach up to 15 Bq/kg. With resuspension and re-
deposition of sediments over time, concentrations could potentially reach
much higher levels than this.

When simulating on the order of 100 simultaneous releases, over a pe-
riod of many years, the required number of Lagrangian particles becomes
very large. By using a parallel model, and running the simulations on a
cluster, simulations with hundreds of millions, or even billions, of particles
can be carried out efficiently.