Radioactivity standards for environmental monitoring. II

The current environmental-monitoring-standards efforts of the low-level-radioactivity laboratory in the Radioactivity Group of the National Bureau of Standards are described. The calibration efforts include traceability programs, natural-matrix Standard Reference Materials, alpha-particle-emitting standards, and international radioactivity intercomparisons. New radiometrology efforts under development include a prototype radon-222 in water standard, γ-ray emission-rate measurement techniques in the 60-keV region, and atom-counting techniques for radioactivity measurements.