The HARP system is the final version of SW product developed and finalized within the grant project VG20102013018 supported by Ministry of interior of the Czech Republic. The product was solved in the Institute of Information Theory and Automation of the ASCR in the period 2010 - 2013. The innovated version of the product is a complex software tool for purposes of modelling of the radiological consequences of radionuclide releases due to the normal and emergency operation of a nuclear facility. Aerial transport of discharged radionuclides is studied up to the 100km from a source of pollution. Dispersion, deposition and successive radioactivity migration towards the human body is simultaneously modelled. As the system contains a database of demographical data on the area of interest, it can evaluate the major radiological quantities and a radiological burden of population due to different pathways of irradiation in both the early and the late phases of a radiation accident.
The core of the system is an atmospheric dispersion model. Generally, the modular architecture of the system enables for insertion of an arbitrary dispersion model. The default is segmented Gaussian plume model. Even simple, the Gaussian model is consistent with the random nature of atmospheric turbulence and it is an approximative solution of the Fickian diffusion equation. Proved semi-empirical formulas are available for approximation of important effects like interaction of the plume with near-standing buildings, momentum and buoyant plume rise during release, power-law formula for estimation of wind speed changes with height, depletion of the plume activity due to the removal processes of dry and wet depositions, radioactive decay and creation of daughter products, dependency on physical-chemical forms of admixtures and land-use characteristics, plume lofting above inversion layer, etc.
A special emphasis is laid on the proper treatment of types of input parameters fluctuations in sense of differentiation between variability and uncertainty. Some model uncertainties arising from the conceptual limitations could be roughly estimated on basis of the ensemble-based approach with alternative parametrization of physical effects taking place in the atmospheric dispersion. The system offers extensive interactive graphical user interface for presentation of a wide range of outputs important for decision makers. The system also incorporates a simulation and training tool enabling responsible staff to improve their knowledge and perception of the problem details. The HARP code has been proved in the fields of evaluation of environmental impact assessment (EIA) and probability safety assessment (PSA) studies, where the influence of operation of a nuclear facility on the surrounding environment is appraised.
Advanced data assimilation methods based on Bayesian filtering developed within the grant project are incorporated into the assimilation subsystem. It means, that the system offers a framework for embodiment of relevant information from different sources, such as measurements and expert judgements, in a statistically optimal way. Provided that the system is connected to a monitoring network, it can be used to recursive re-estimation of the initially ill-defined parameters regarding the release scenario (magnitude of release etc.). This assimilation methodology can be also used as a tool for testing of different topologies of a monitoring network and selection of the best one with regards to its functionality and economical and other constraints.
The HARP system was tuned and tested in the cooperation with National Radiation Protection Institute of the Czech Republic in Prague, where the product is connected to a database server providing up to date short term meteorological forecasts on a three dimensional grid.