THE MODELLING OF GRAVITATIONAL SETTLING IN THE ASSESSMENT OF THE CONSEQUENCES OF ACCIDENTAL RELEASES OF RADIOACTIVITY
This work examines modelling approaches for incorporating the gravitational settling of particles into the dispersion - deposition module of a consequence assessment code. The investigation arose from a perceived requirement that such codes be able to handle a coarser aerosol than hitherto envisaged, if all types of accident arising in any component of the nuclear fuel cycle are to be considered. Particular attention has been given to approximations which are compatible with the widely used Gaussian model of dispersion. A number of techniques (both conventional and newly proposed in this work) have been investigated theoretically and their limitations discussed. An attempt has been made to quantify the accuracy and ranges of validity of Gaussian "fix-ups" using the Eddy diffusivity theory as a framework, albeit with due recognition of the limitations of this basic approach. A number of new results have been obtained, and the investigation has led to practical recommendations (subject to the limitations of the framework used). Models have been compared with a rather sparse data base: although the broad features of the recommendations are supported by the experimental evidence, there are insufficient data points to make detailed quantitative checks on the limitations of the various approaches. A number of suggestions have been made for possible future work.
Bibliographic Reference: EUR 10097 EN (1985), FS, 155 P., BFR 500, EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
Record Number: 1989124033300 / Last updated on: 1987-01-01
Available languages: en