MS-QA_06-2019 rev5

ANSI/AARST MS-QA 2019 8 Radon Measurement Systems Quality Assurance Definitions measurement system. In some cases, spikes can be used as laboratory control samples . Typical spiking operations disclose the radon concentration to the sender of the device. However, for a blind spike , the radon concentration is withheld until after the client reports the radon value back to the chamber for independent verification. Results of spikes are assessed using the RPE statistic (also known by IPE, see definition), which is the degree from which each single measured value (spike) deviates from the chamber’s average concentration during the exposure period. Standard Test Atmosphere for Radon (STAR): A standard test atmosphere for radon, often called a “radon chamber” and termed STAR by ISO/IEC standards, including the standard for generating reference radon atmospheres (IEC 61577-4 2009). The STAR is defined as being sufficient in size and configuration and radon concentration range and controls such that: 1. At least three simultaneous and independent radon concentration measurements can be conducted at the high and/or low limits of radon concentration ranges (e.g., in pCi/L) or integrated concentration (e.g., in pCi-d/L), during which time the conditions in the STAR are as constant as practicable . 2. Devices are being tested for their ability to measure radon concentration. 3. Temperature, relative humidity and radon concentration are recorded hourly or more frequently by devices with NIST-traceable annual calibrations (traceable as defined in this standard) and documented uncertainty estimates. If the devices being exposed are documented to have insignificant response to changes in temperature or relative humidity (see below), hourly monitoring of these parameters is not necessary but is recommended, and only the average temperature and relative humidity during exposures must be documented. 4. Barometric pressure in the STAR at local conditions is recorded or otherwise available and included in exposure reports. 5. Temperature and relative humidity are controlled to this standard’s limits for the particular operation being conducted. 6. The uncertainty of the average radon concentration during the exposure period is calculated using methods recommended by NIST (JCGM 2008; Taylor and Kuyatt 1994), published and reported with each exposure, and the one-sigma total uncertainty of the average radon concentration during any duration of 48 hours or longer is less than 8%. 7. The STAR is operated under a documented quality management system, which is consistent with recognized international standards such as ISO 9001 (ISO 2015). When the term “STAR” is used within this standard, it refers to accredited chambers known as Secondary or Certified Reference Chambers and tertiary chambers such as manufacturer or laboratory chambers that are equipped specifically for calibrating a specific device or method device. Those that are tertiary chambers are only required to track hourly temperature and relative humidity (RH) environmental conditions when conducting s pikes or calibrations if the integrated measurement results are affected by hourly shifts in either environmental condition. Such chambers are, however, required to track hourly radon concentrations and verify agreement no less than annually by intercomparison with a Secondary or Certified Reference Chamber STAR. Traceability: Property of the measurement result that can be related to stated references, usually national or international standards, through an unbroken chain of comparisons, each of with their own stated uncertainties. The concept is often expressed by the adjective “traceable.” The unbroken chain of comparisons is called a traceability chain (JCGM 2008b; ISO/IEC 17025; ANSI N42.22 1995).