Determination of radioactivity distribution in nuclear power plant systems

When introducing radiation protection considerations into the design of nuclear power plants, additions to such plants, or backfits for regulatory or operational reasons, one is immediately faced with the necessity of determining the sources giving rise to the radiation field to be expected. In this context, fluids may be liquid or gaseous, and systems may include connected rooms in the plant as well as connected pipes or ducts. In most cases, one cannot rely on existing operating data, either because the facility has operated for only a relatively short period of time so that it is still clean, or because no data exist for the proposed modification and analogs are not available. It is then necessary to calculate the distribution of radioactivity throughout the proposed system or facility. This paper describes a computer program developed by the Tennessee Valley Authority to perform such calculations.