Improvement of the dose assessment tools on the basis of dispersion of the⁹⁹Tc in the Nordic Seas and the Arctic Ocean

Abstract

Abstract. Compartment models are widely used for the evaluation of radiological consequences to man and biota in the marine environment over large spatial and long temporal scales. The model developed at the Norwegian Radiation Protection Authority (NRPA) is based on a compartment modelling approach that includes terms describing dispersion of radionuclides into oceanic space with time (non-instantaneous mixing in oceanic space). In this paper the latest modification of the NRPA model will be presented. The main improvement concerns the "time of availability" parameters (i.e. the times at which dispersed radionuclides reach compartment boundaries). The modifications have been implemented through the use of a comprehensive 99 Tc data set collected under the course of the project "RADNOR" and through comparison with the results of simulations provided by the 3D hydrodynamic NAOSIM model. The present version of the NRPA model describes the dispersion of 99 Tc in the Arctic Ocean and seas with a significantly improved precision for some marine regions. Results of the calculations indicate that defined "time of availability" parameters are in good agreement with transit times observed in the actual marine environment.

Modelling of marine radionuclide dispersion in IAEA MODARIA program: Lessons learnt from the Baltic Sea and Fukushima scenarios

“…Simulations over several months may be carried out for spatial scales of some hundred km. For even longer-term assessments (years to decades and thousand km), box models should be used (Lepicard et al, 2004;Iosjpe et al, 2009).…”

A comparison of radionuclide dispersion model performances for the Baltic Sea and Fukushima releases in the Pacific Ocean

“…This fact highlights that developing operational models for emergency management and decision-making support (which is one of the main application of numerical modelling) in these dynamic environments should be based on the reliable operational oceanographic model calibrated for this area. The same time it is important to note that the models that were integrated into the decision support system RODOS within EC project PREPARE -THREETOX and POSEIDON, that were refined within the project on the basis of the experience of the UVEV and Iosjpe et al (2009) model development, demonstrated during the described intercomparison study "the state of the art" level of the marine dispersion modelling.…”

Marine radionuclide transport modelling: Recent developments, problems and challenges

“…Box models are well suited for assessments of radionuclide dispersion involving large spatial and temporal scales (thousand kilometres; years to decades). Some recent examples of box models are POSEIDON-R (Lepicard et al, 2004;Maderich et al, 2014a,b;Bezhenar et al, 2016), models developed in NRPA (Iosjpe et al, 2002(Iosjpe et al, , 2009 and others (Sánchez-Cabeza et al, 2002;Håkanson, 2005;Smith and Simmonds, 2009; for instance).…”