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International Intercomparison of Radon Reference Facilities (Chambers)

International Intercomparison of Radon Reference Facilities (Chambers). melinda ronca-battista. What do estimates of risk, decisions to mitigate, reassurance that mitigation is not necessary, the success OF mitigation, and the livelihood of this industry all depend on ?.

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International Intercomparison of Radon Reference Facilities (Chambers)

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  1. International Intercomparison of Radon Reference Facilities (Chambers) 2018 International Radon Symposium™ melinda ronca-battista

  2. What do estimates of risk, decisions to mitigate, reassurance that mitigation is not necessary, the success OF mitigation, and the livelihood of this industry all depend on?

  3. What is a true 1 pCi?How do we know our results really ARE 1 pCi? • About 130 radioactive decays in 1 pCi every hour • Different methods measure differently—some can detect only about 2 out of these 130 decays • Aka “efficiency” or calibration factor • Some measure alphas, some the betas and alphas, and some just the gammas

  4. Calibrations and spikes conducted in reference chambers • We calibrate our field measurements in our reference chambers, but… • How do our standard reference chambers know for sure that what they measure as 10 pCi in their chamber really IS 10 pCi??

  5. NIST=National Institute of Standards and Technology • Sells over 1300 “standards” used to calibrate measurement devices • Called Standard Reference Materials (SRMs) • SRM alcohol solutions to calibrate breathalyzers, cylinders of CO to calibrate CO analyzers • Even long lived radioactive SRMs like C-14 • But there are NOSRMs of radon

  6. Instead, like ozone, radon gas must be generated in reference chambers using Radium-226 • NIST Standard Reference Materialradium-226 sources emit radon-222 gas atoms at a known rate dependent on the # of curies in the SRM • This “perfectly known” # of radon atoms are then mixed with an extremely accurately known volume of air to produce a “true” pCi/L concentration

  7. The EPA’s lab in Montgomery generates “true” concentrations using a NIST SRM • EPA then intercompares with the US Certified Secondary Chambers in Ohio (BMI) and Kansas (KSU) • Secondary Chambers compare with Tertiary Chambers

  8. How do US secondary chambers compare with the rest of the world?andHow do all the US tertiary chambers compare with each other? • The first question is being answered with an International Intercomparison Project sponsored by COIRA

  9. UK Radon Association (UKRA) Nordic Group Radon Association (NGRA)

  10. Radon Chamber IntercomparisonProgram Goals • Consistency of radon measurements • Reference instruments shipped between each of the participating chambers • Each facility’s radon concentration is compared to the reference instrument in a blind exposure • Maintain anonymity & publish results in a peer reviewed scientific journal

  11. Project Design • Develop/Approve Procedures (SOPs) • Specifications for Reference Instruments • Identify Chamber Candidates • BMI, KSU in the US • SURO (Czech Republic), BfS (Germany), SSM (Sweden), PHE (UK), Pylon and Canada-Radiation Safety Institute in Canada

  12. Reference Instruments • High efficiency • Rugged and extremely stable • Large memory retention • Proven in previous intercomparisons • Software versatile and secure • Calibrations, equipment, and software donated • Alpha Track Detectors donated as trip blanks

  13. September 2018 Status • SOPs drafted and approved • US exposures being conducted • Preliminary US results indicate almost unbelievable agreement between chambers

  14. October 2018 • Set of instruments being shipped to Canada • After Canada, to Europe • Study duration 2-3 years • Preliminary results reported in 2019 • Expected to demonstrate close agreement

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