Underground radionuclide migration at the Nevada Test Site

This document reviews results from a number of studies concerning underground migration of radionuclides from nuclear test cavities at the Nevada Test Site. Discussed are all cases known to the Department of Energy`s Hydrology and Radionuclide Migration Program where radionuclides have been detected outside of the immediate vicinity of those nuclear test cavities that are identifiable as the source of the nuclides, as well as cases where radionuclides might have been expected and were intentionally sought but not found. There are nine locations where source identifiable radionuclide migration has been detected, one where migration was purposely induced by pumping, and three where migration might be expected but was not found. In five of the nine cases of non-induced migration, the inferred migration mechanism is prompt fracture injection during detonation. In the other four cases, the inferred migration mechanism is groundwater movement. In only a few of the reviewed cases can the actual migration mechanism be stated with confidence, and the attempt has been made to indicate the level of confidence for each case. References are cited where more information may be obtained. As an aid to future study, this document concludes with a brief discussion of the aspects of radionuclide more » migration that, as the present review indicates, are not yet understood. A course of action is suggested that would produce a better understanding of the phenomenon of radionuclide migration. « less