MW-RN-2020 (1)

Protocol for the Collection, Transfer and ANSI/AARST MW-RN 2020 Measurement of Radon in Water 28 10.3.4 Staff and procedures Each laboratory shall appoint a technical manager, who shall be a full-time staff member, and who shall exercise actual day-to-day operation of the laboratory, including reporting of results. The technical manager shall be documented (named), shall have a minimum of two years of experience in radionuclide analysis, and shall review quality assurance data for the laboratory. The name of each analyst that prepares or measures each water sample and the analytical methodology used shall be documented for each sample. The analyst and the analytical method utilized for intercomparison or proficiency testing shall be the same as that used for routine analysis of water samples. Only the named, properly-trained analyst(s) and approved method(s) shall be utilized to obtain reportable results for radon in water samples. 10.4 Approved laboratory method Validation of a proposed analytical method is the process by which a laboratory verifies the performance of the test method. Proposed test methods shall demonstrate that they have acceptable performance characteristics such as accuracy , precision, and detection capability for the measurement of radon. This is generally achieved by comparing the performance of the proposedmethod to that of existing approved methods and shall include results of recent performance testing and/or intercomparison studies. The applicant shall obtain (and provide if requested) sufficient data to allow determination that the performance of the proposed method is comparable to test methods already approved for radon measurements in water. The validation study shall include results for the reagent blank, detection limit, and method performance. 10.5 Intercalibration In lieu of a nationally recognized or federal primary reference that can be used for comparison across multiple methods to validate radon activity concentrations in water, the following generalized structure for developing a national reference for calibration and quality control is provided. 10.5.1 Reference for radon activity concentrations in water A radon reference can be developed using sources of both naturally-occurring (for precision) and man- made (for accuracy ) water samples containing 226 Ra and/or 222 Rn (radon) for intercomparison , calibration , and standardization purposes. Examples include: a) 222 Rn: Several states have identified groundwater sources containing 222 Rn at concentrations exceeding 100,000 pCi/L (3700 Bq/L). Sampling bottles, filled using techniques provided in Section 5 above, would need to be distributed quickly to participants. The advantages are ease and cost of sampling, no handling of radium standard, and a real sample scenario (decay); b) 222 Rn: The production of radon in sealed containers of water has been accomplished using both 226 Ra-impregnated resin and sealed filter sources. The dissolved radon remains in radioactive equilibrium until opened, and upon refill and closure of the container, equilibrium is re-established after 30 days, meaning the source is reusable. Easy to produce but includes handling of radium; c) 226 Ra: Some states have identified groundwater sources containing 226 Ra at concentrations exceeding 300 pCi/L (11 Bq/L). No special filling technique is needed, but a 30 day minimum is needed to obtain radioactive equilibrium of radon and its short-lived decay products in the water. Easy to produce but concentrations are often low; and d) 226 Ra: Water containing a known activity 226 Ra in equilibrium with radon can be produced using NIST- traceable standards. Although these are the best sources for a national reference, handling and distribution of 226 Ra poses potential contamination. Mineral-oil-based cocktails are usable up to one year.

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