C-14/I-29 Preservation and Hold Time Survey

Abstract

Preservation and hold time of radionuclides must account for both nuclear half-lives and nonnuclear loss mechanisms, but variations in the latter are often neglected. Metals-based defaults are inappropriate for long-lived non-metals C-14 and I-129, which are vulnerable to chemical and biological volatilization. Non-acidification is already widely practiced for them. Recommended addition measures from radiological and chemical literature include glass containers where possible, water filtration where possible, headspace minimization, light shielding, cold (4°C) storage and unfiltered water hold time of 28 days. Soil hold time may need to be shortened when waterlogged , excessively sandy, or still adjusting to significant new contamination. Table 1 below summarizes recommendations. Table 1: Summary of C-14/I-129 Preservation and Hold Time Guidance Matrix Collected Fraction Preservation Hold Time Water Total Min. headspace, 4±2°C, amber glass or glass/PTFE stored dark 28 days Dissolved (0.22μ or 0.45μ filter) 180 days Soil: watery, very sandy, or newly contaminated Total Min. headspace, 4±2°C, amber glass or glass/PTFE* stored dark 28 days Soil: other/typical Min. headspace, 4±2°C, glass/plastic* 180 days * Normal soil self-shields for light, but small volumes may need control via container or dark storage.