[en] 1 - Description of problem or function: KRONIC calculates the annual external total body tissue dose from chronic release of radionuclides to the atmosphere. The code does not analyse release path phenomena; the release rate is given as a starting parameter. Atmospheric dispersion effects are estimated using data on joint frequency of occurrence of wind speed, wind direction and stability for a particular site. Each sector is considered to be a plume for which the centre line ground level dose is calculated for specified downwind distances. The result of the calculation is a table of annual dose rates as a function of direction and distance from the release point. The beta dose contribution is calculated using a semi-infinite cloud model; the range of beta particles in air is short compared to the dimensions of the plumes. The range of gamma rays is longer and a space integration over the plume volume is performed. The gamma dose is calculated as a tissue dose at the body surface, at 1 cm, and at 5 cm depth. The beta and gamma doses are reported separately or added together, as required. 2 - Method of solution: The program is divided into two separately executable parts. The first of these, FDOSE, computes gamma dose factors by a numerical volume integration of an expression involving the attenuation of gamma rays in air, modelled by a linear attenuation coefficient and a buildup factor, together with data specifying wind speed and direction, cross-winds, and the height and rate of radionuclide release. An eight point polynomial technique is used to perform the integration. These dose rate factors may be stored in a data library for future use, or passed directly to the second part of the program, CHRONI, which combines them with radionuclide decay data to generate doses and air concentrations. KRONIC uses three types of data library containing: - data on radionuclide decay schemes, half lives and beta energy production; - data on photon production; - dose rate factors, as calculated by FDOSE. The program includes libraries containing data for nearly 600 nuclides, including fission products and activation products. 3 - Restrictions on the complexity of the problem: A maximum of 8 wind speeds, 6 weather stability types, and 16 angular sectors can be specified