An Approach for Estimating the Total Effective Dose at Atmospheric Nuclear Weapons Test Sites

Decisions about the response actions to be taken at several sites containing surface soils that were contaminated from historical atmospheric nuclear tests at the Nevada Test Site must be made. The regulatory framework for these decisions is described in a Federal Facility Agreement and Consent Order for the test site. Through agreement with the stakeholders, a decision criterion was established as a Total Effective Dose (TED) of 0.25 milli-sieverts per year (mSv/yr) to a receptor under three established exposure scenarios. Several historical sources of information regarding the distribution of radioactive contamination (which included actinides) and the areal concentration of that contamination are available, but none were found to be of sufficient quality for decision-making. In addition, traditional dose estimates using soil sampling and the RESRAD computer code would likely overestimate the internal dose due to the presence of significant amounts of trinity glass with large particle sizes. One site was selected for investigation and decision-making. The approach evaluated internal dose separately from the external dose and generated data that could be used to allow for improved confidence in the use of historical sources of information. (authors)