LOW-LEVEL RADIOACTIVITY OCEAN SEDIMENT STANDARD REFERENCE MATERIAL

The National Institute of Standards and Technology (NIST), in cooperat ion with experienced international laboratories, will issue a low-leve l radioactivity Ocean Sediment Standard Reference Material (SRM) 4357 in 1996. The Ocean Sediment joins the NIST suite of six other 'natural matrix' environmental radioactivity Standard Reference Materials. Thi s family of natural matrix materials have already been used: (1) to de velop radiochemical procedures; (2) to test radiochemical procedures a lready in use for environmental and biokinetic evaluations; (3) to cal ibrate instruments; (4) to intercompare and evaluate radiochemical met hods; (5) to test competency of technicians to do radiochemical assays ; and (6) to demonstrate that data output is reliable. The participati ng laboratories provided data for the following 25 radionuclides: K-40 , Sr-90, (TC)-T-99, I-129, (CS)-C-137, Eu-155, Pb-210, Po-210, Pb-212, Bi-214, Ra-226, Ra-228, Ac-228, Th-228, Th-230, Th-232, U-234, U-235, Np-237, U-238, Pu-238, Pu-239+Pu-240, Pu-241, and Am-241. The data fo r many of these radionuclides are of sufficient quality to establish c ertified values and reasonable uncertainty limits given the relatively low concentrations of the radionuclides. The uncertainties for a numb er of certified radionuclides are non-symmetrical and large because of the non-normal distribution of reported values. Copyright (C) 1996 El sevier Science Ltd.