QA/QC Procedures, Validation Method, Traceability and Intercomparisons

Methods developed to redetermine the 76As half-life were applied to four additional radionuclides. Several gamma-spectrometers were used to follow the decay of pure sources during 4-14 half-lives, comparing with a pulser stable to better than 2 . 10-8 per day. Complementary measurements (also for 76As) employed a pressurized ion chamber. Several least-squares methods were used to derive the best value of each decay constant. We find the half-lives to be 14.959±0.009 hours for 24Na, 12.339±0.011 hours for 42K, and 2.6924±0.0011 days for 198Au, where the uncertainties are the combined standard uncertainty u.