Changing patterns of radionuclide distribution in Irish Sea subtidal sediments.

This paper presents new data on the distribution of long-lived radionuclides in Irish Sea subtidal sediments, contaminated as a result of the BNFL Sellafield discharges. The results from different sampling campaigns in 1999 have been combined to assess the extent of radionuclide mobility relative to earlier surveys, in both the eastern and western Irish Sea areas, and to investigate changes in radionuclide distribution over time. The results appear to confirm the trend of continuing re-distribution and transfer of contamination away from the English coast. West of the Isle of Man, radionuclide concentrations and inventories have remained more or less constant. The inventory of radionuclides in sandy sediments in the eastern Irish Sea is still under-represented by current sampling, but could be improved by deeper and more extensive vibrocoring.

NIST radiochemistry intercomparison program: a summary of four-year performance evaluation study. National Institute of Standards and Technology.

This paper summarizes the methods currently applied by the National Institute of Standards and Technology (NIST) for the preparation and verification of environmental and radiobioaasay performance evaluation materials for the traceability testing of low-level radioactivity measurements. The evaluation of measurement quality of the all participants indicated that over 90% of the intercomparison results complied with ANSI N42.22 and/or HPS N13.30 standards. Overall, the differences from the NIST values observed for all test nuclides and matrices are less than -7%, with a typical measurement precision better than 10% (1 s). The dependency of measurement quality on the test radionuclides, sample matrices, and radiochemical methods is identified by statistical analyses.