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RADON FILM-BADGES BY RADIATORS WITH NANOHOLES VERSUS EXISTING PASSIVE MONITORS L. Tommasino

RADON FILM-BADGES BY RADIATORS WITH NANOHOLES VERSUS EXISTING PASSIVE MONITORS L. Tommasino THL, Via Cassia 1727, 00123 Roma, Italy ltommasino@gmail.com. Rn atoms are nanoparticles .4 nm wide for entering nanoholes with .4 nm aperture

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RADON FILM-BADGES BY RADIATORS WITH NANOHOLES VERSUS EXISTING PASSIVE MONITORS L. Tommasino

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  1. RADON FILM-BADGES BY RADIATORS WITH NANOHOLES VERSUS EXISTING PASSIVE MONITORS L. Tommasino THL, Via Cassia 1727, 00123 Roma, Italy ltommasino@gmail.com

  2. Rn atoms are nanoparticles .4 nm wide for entering nanoholes with .4 nm aperture Rn nanoparticles move through nanoholes in liquids and solids (Eyring, 1936)

  3. Rn-monitors by diffusion chambers

  4. Absorber Thickness Part. Coeff. α CR-39 1 mm 0.06 Polycarbonate 0.3 mm 8 Holder-plastics 3 mm 0.5-0.75 (From More and Hubbard, 1997)

  5. (From Pressianov and others)

  6. LIQUID–LIKE POLYMERS (T>Tg) (Rubber, polyethylene) Transient nanoholes GLASS–LIKE POLYMERS (T< Tg) (Polycarbonate) Frozen nanoholes THERMOSETS-(CR-39)

  7. Frozen nanoholes as sorptive sites Diffusion by molecular-induced jumps

  8. EQUILIBRIUM SAMPLING: Fast Rn-absorption time Equilibrium time (Barrer, 1939): T=d2/6D d the film thickness D the diffusivity

  9. For a 300-μm-thick PC-film (CD) T=~ 30 days Non-equilibrium sampling For a PC-film thickness < 50 μm T < 5 hours Equilibrium sampling

  10. CR-60 absorptive radiators • with bulk-distributed nanoholes for: • - obtaining compact and easy-to-deploy radon film-badges • - increasing the response linearity of passive monitors • -measuring soil-radon under equilibrium conditions • measuring radon directly in water. • CR-60 Definition respectively for: • - having a radon-diffusion length of about 60 μm at environmental temperature • - being a Carbonate Radiator (CR) with a solubility of 60 ± 20 (i.e. in the range 40-80) • -degrading maximum alpha-particle energy by a 64 μm-thick film • - having a film-thickness not greater than 60 μm. • CR-60 Characteristics depend on: • - the polymer structure and morphology • - the manufacturing processes • - the shelf-life • - the thermal history, etc.

  11. Two responses in one monitor Response Tracks.m3/ (cm2.kBq.h) Passive chambers 2.8 ± 0.7 (with CR-39) CR-60(20 µm Makrofol N)0.2 ± 0.03

  12. Radon film badge for in-soil and in-water measurements Two Radiators PE Bag CR-39

  13. Large tubes are conducive to errors (Tanner, 1991)

  14. Different volumes-Same responses

  15. [CRn]water =α (T) [CRn]air [C]Rn α (T) [C]Rn

  16. For large exposure measurements: • Film-badges by absortpive radiators with bulk-enclosed nanoholes • For low exposure measurements • of one week or less: • Film-badges by adsortpive radiators with surface-distributed nanoholes

  17. ADSORPTION Non-equilibrium sampling -activated-charcoals Equilibrium sampling -solid layers with surface-distributed nanoholes having very large surface to volume ratio.

  18. CR-2000 adsorptive radiators with surface-distributed nanoholes for: - measuring indoor radon-exposures for one week or less. CR-2000 Definition: -equilibrium Rn-adsorption of radon up to a concentration 2000 times of that present in the surrounding air. CR-2000 Characteristics depend on: - the manufacturing processes - the shelf-life - the storage environment

  19. Sampler Response Tracks.m3/(cm2.kBq.h) - CR-2000 (Adsorptive radiator)20 ± 4 -Passive chambers 2.8 ± 0.7 (with CR-39)

  20. Uniquely-compact radon-film-badges with absorptive- and/or adsorptive- radiators for: • - indoor measurements for days, • months, and years • - using as a back-up monitor • - correct soil-measurements • direct-in-water measurements

  21. CR-0 bags for storing all types of monitors prior to and after • the exposure are: • - radon-proof bags • radon-free bags • bags sealable by pressure-type devices

  22. CR-60, CR-2000, CR-0 available through a centralised distributionbecause of the: - need of custom-made radiators with desired characteristics - large cost of minimum-orders consisting of stocks up to 1000 kg - difficulty in handling and storing large volumes of materials in suitable low-radon environments Luigi Tommasino THL, Via Cassia 1727 00123 Roma, Italy ltommasino@gmail.com

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