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

This article compares radon film badges with nanoHoles to existing passive monitors for radon detection. It discusses the different types of radiators, sampling methods, and their characteristics. The article also introduces CR-60 and CR-2000 film badges and their applications in indoor, soil, and water measurements. Additionally, it mentions CR-0 bags for storing monitors and the challenges associated with their distribution.

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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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