Radiation Levels During Shutdown in Boiling Water Reactors

To perform a realistic dose assessment, a data collection program was initiated to determine what balance of plant systems contribute to operational exposure. Six utilities that operate boiling water reactors participated in the program. As a result of the study, systems or components that were most important with respect to crud-based radiation were identified. The study focused on the following systems: residual heat removal, spent fuel cooling and cleanup, transverse in-core probes, flow and equipment drains, feed, reactor water cleanup, and steam systems. During the study, additional components or systems where no crud-based radiation was expected were identified, e.g., control rod drive pumps, scram discharge volumes, and certain condensate system equipment. It is expected that this information will help utility operators limit crud-producing radiation doses by providing prior knowledge of potential and buildup.