Activity measurements of a suite of radionuclides (90Sr, 137Cs, 210Pb, 210Po, 228Ra, 234U, 235U, 238U, 238Pu, 239,240Pu) in soil reference material (Rocky Flats II): CCRI(II)-S2

In 2005, the CCRI decided that a comparison undertaken from 2002 to 2007 by the NIST (SIM) in the development of a new soil (Rocky Flats II) standard reference material (SRM) was sufficiently well constructed that it could be converted into a supplementary comparison under CCRI(II), with comparison identifier CCRI(II)-S2, so as to support calibration and measurement capability (CMC) claims for radionuclide measurements in reference material (specifically, low calcium-content soils). Previous comparisons of radionuclides have been of single or multiple nuclides in non-complex matrices and results of such could not be extended to support capabilities to measure the same nuclides in reference materials. The results of this comparison have been reported to the participants, and have been used to determine the certified reference value of the SRM. The key comparison working group (KCWG) of the CCRI(II) has approved this approach as a mechanism to link all the results to certified 'reference values' in lieu of the key comparison reference value (KCRV) of these specified radionuclides in this type of matrix (soil) so as to support CMCs of similar materials. (authors)