Modeling of the EMRAS urban working group hypothetical scenario using the RESRAD-RDD methodology.

The RESRAD-RDD methodology was applied to model the short- and long-term radiation exposures after a hypothetical radiological dispersal device (RDD) event in an urban environment. It was assumed that an RDD event would result in outside surface contamination of the exterior walls and roofs of surrounding buildings, as well as associated paved areas and lawns. The contaminants also might move inside the buildings and deposit on floors and interior walls. Some important input parameters include occupancy factors, building characteristics, and weathering of surface contamination. The modeling results include predicted external dose rates, relative contributions from important surfaces, annual and cumulative doses, and radionuclide concentrations. Potential countermeasures evaluated include grass removal, soil removal, and washing of paved areas.

U.S. Department of Energy policies, directives, and guidance for radiological control and release of property.

U.S. Department of Energy (U.S. DOE) regulates its operations with a system of rules, directives, and guidance under the Atomic Energy Act. U.S. DOE's policy is to conduct its radiological operations in a manner that ensures the health and safety of its employees, contractors, and the public. U.S. DOE uses an annual dose limit of 100 mrem (1 mSv) with an "as low as reasonably achievable" (ALARA) process to achieve radiological protection. The primary directive for radiation protection of the public and the environment is DOE Order 5400.5. It contains requirements for the protection of the public and the environment from routine operations, including controlling and releasing property. Since the publication of Order 5400.5 in 1990, U.S. DOE has issued guidance for meeting requirements under it; Guide G 441.1-xx consolidates this guidance. DOE applies a dose constraint of 25 mrem y (0.25 mSy y(-1)), plus ALARA, for the release of real property, and 1 mrem y(-1), plus ALARA, for release of personal property. Models and guidance to develop the needed documentation for release of property are easily available and user-friendly. While achieving protection of human health and the environment, U.S. DOE's dose-based release process has resulted in significant cost savings. U.S. DOE has recently adopted a management systems approach for general environmental and public protection programs. The integration of the radiation protection program into this new approach is a high priority.

A kinetic-allometric approach to predicting tissue radionuclide concentrations for biota.

Allometry, or the biology of scaling, is the study of size and its consequences. It has become a useful tool for comparative physiology. There are several allometric equations that relate body size to many parameters, including ingestion rate, lifespan, inhalation rate, home range and more. While these equations were originally derived from empirical observations, there is a growing body of evidence that these relationships have their origins in the dynamics of energy transport mechanisms. As part of an ongoing effort by the Department of Energy in developing generic methods for evaluating radiation dose to biota, we have examined the utility of applying allometric techniques to predicting radionuclide tissue concentration across a large range of terrestrial and riparian species of animals. This particular study examined 23 radionuclides. Initial investigations suggest that the allometric approach can provide a useful tool to derive limiting values of uptake and elimination factors for animals.

Radiosilver (Ag-110m) concentrations in Chesapeake Bay oysters maintained near a nuclear power plant: A statistical analysis.

An ongoing biomonitoring program using oysters (Crassostrea virginica) was implemented in 1978 to monitor radionuclide releases from the Calvert Cliffs Nuclear Power Plant located on Chesapeake Bay. The program involves quarterly removal and replenishment of oysters located in a tray about 0.2 km from the effluent discharge. Radiosilver (Ag-110m) concentrations in tray oysters (pCi/kg ww) were analyzed using ANCOVA-like models with plant releases of Ag-110m in the present and immediately preceding quarters and season of exposure as explanatory variables. Hypothesis testing based on the estimated models and comparison among model predictions under hypothetical release scenarios showed that season of exposure was important in influencing Ag-110m concentrations, with exposure during the Fall and Summer seasons resulting in significantly higher Ag-110m concentrations in tray oysters than exposure during the Winter and Spring seasons. From a management perspective of minimizing Ag-110m concentrations in oysters located near the plant, Winter and Spring are the preferred seasons for plant releases.