Radon passive detectors intercomparison in the field: radiometric characterisation of the sites Enrico Chiaberto - ARPA Piemonte Intercomparison s working group: Filippo Berlier, Francesco Cardellini, Enrico Chiaberto, Daniele Giuffrida, Massimo Faure, Federica Leonardi, Mauro Magnoni, Gianfranco Minchillo, Anna Prandstatter, Elena Serena, Rosabianca Trevisi, Rosamaria Tripodi, Stefania Verdelocco, Miriam Veschetti Milano 21 september 2017
3 different sites 1- workplace on the ground floor in Ivrea (TO) 2- workplace on the basement in Ivrea (TO) 3- dwelling in Valle del Cervo (BI)
A list of problems can influence radon measurements in the field with passive detectors: Temperature, humidity, lightness Dose rate Altitude Long period of measurement (Ageing, fading, and track overlap in CR39, descharge of electrets ) Thoron Equilibrium factor Minimum exposure detectable Calibration using a continuous radon monitor instead should be added: Background of the instruments Long period (electronic problems: memory, AC Adapter )
We have found the same difficulties to obtain the reference values So we used in the field 4 radon continuous monitors and CR39 passive detectors calibrated in ENEA INMRI plus other instruments were tested in different radon and thoron chambers
Beginning of the exposures: brainstorming
Exposure 1: workplace on the ground floor in Ivrea (TO) altitude 253 m above sea level * dose rate during storage: 64 ngy/h ± 13% dose rate during exposure: 73 ngy/h ± 10% (TLD100) * equilibrium factor: 0.53 (spot measurements with EQF3220) * temperature: 20 C pressure: 989 hpa humidity rel.: 45 % (climatic data gathered by radon monitors)
Exposure 1: climatic data Temperature 26 24 22 20 C 18 16 14 12 10 0 500 1000 1500 2000 2500 3000 3500 h Pressure 1030 1010 hpa 990 970 950 0 500 1000 1500 2000 2500 3000 3500 h Umidity 60 55 50 RH% 45 40 35 30 0 500 1000 1500 2000 2500 3000 3500 h
Exposure 1: critical points Long period of measurement (Ageing, fading) Low concentrations Minimum exposure detectable Calibration and Background of the monitors
Exposure 1: Reference passive CR39 detectors kbqh/m 3 Exposure 1 - Passive detectors 400 350 300 250 200 150 100 50 0 1 2 3 4 5 6 7 8 9 10 position Rn CR39 detectors kbqh/m 3 unc. kbqh/m 3 254 22 218 21 218 20 249 22 236 21 247 22 239 21 230 22 248 21 244 22 Radon exposure Passive detectors Metrological and statistical Uncertainty 1σ kbqh/m 3 kbqh/m 3 238 22
Exposure 1: homogeneity of radon concentrations Standard deviation uncertainty of a singol detector
Exposure 1 Continuous radon monitors During the exposure Storage of the transits in 2 double radon proof bags
300 250 200 150 100 50 0 Exposure 1: radon concentration Radon concentration 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 AG1535 h Bq/m 3
Exposure 1 Reference continuous radon monitors Radon exposure Metrological and statistical Uncertainty 1σ Radon Concentration Metrological and statistical Uncertainty 1σ kbqh/m 3 kbqh/m 3 Bq/m 3 kbqh/m 3 225 50 61 13
Exposure 2: workplace on the basement in Ivrea (TO) altitude 253 m above sea level * dose rate during storage: 64 ngy/h ± 13% dose rate during exposure: 106 ngy/h ± 12% (TLD 100) * equilibrium factor: 0.56 (spot measurements EQF) * temperature: 21 C pressure: 997 hpa humidity RH%: 52 (climatic data gathered by radon monitors)
Exposure 2: climatic data Temperature C 30 25 20 15 10 0 500 1000 1500 2000 2500 3000 3500 h Pressure hpa 1010 990 970 950 0 500 1000 1500 2000 2500 3000 3500 h Umidity rel. 70 60 % 50 40 30 0 500 1000 1500 2000 2500 3000 3500 h
Exposure 2: critical points Long period of measurement (Ageing, fading) High concentrations Minimum exposure detectable Calibration and Background of the monitors
Exposure 2 kbqh/m 3 Reference passive radon detectors Exposure 2 - Passive detectors 2500 2000 1500 1000 500 0 1 2 3 4 5 6 7 8 9 10 position Rn CR39 detectors kbqh/m 3 unc. kbqh/m 3 1694 119 1681 117 1716 119 1733 119 1649 116 1646 117 1681 118 1713 119 1706 119 1677 121 Radon exposure Passive detectors Metrological and statistical Uncertainty 1σ kbqh/m 3 kbqh/m 3 1690 121
Exposure 2: homogeneity of radon concentrations Standard deviation uncertainty of a singol detector
Exposure 2 Continuous radon monitors During the exposure Storage of the transits in 2 double radon proof bags
1000 900 800 700 600 500 400 300 200 100 0 Exposure 2 Radon concentration 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 3400 3600 h AG1363 Bq/m 3
Exposure 2 Reference continuous radon monitors Radon exposure Metrological and statistical Uncertainty 1σ Radon Concentration Metrological and statistical Uncertainty 1σ kbqh/m 3 kbqh/m 3 Bq/m 3 kbqh/m 3 1731 152 469 41
Exposure 3: A dwelling in Valle del Cervo (BI) altitude 846 m above sea level * dose rate during storage: 64 ngy/h ± 13% dose rate during exposure: inhomogeneus (TLD 100) * equilibrium factor: 0.15 (continuous measurements with EQF) * temperature; 13.2 C pressure: 916 hpa humidity rel%: 75 % (climatic data gathered by radon monitors)
Sienite della Balma
Exposure 3: geology and lithology
Exposure 3: climatic data Temperature 18 14 12 10 50 100 150 200 h Pressure 925 920 915 910 905 0 50 100 150 200 h rel. Umidity 80 75 % 0 hpa C 16 70 65 0 50 100 150 h 200
Exposure 3: inhomogeneity of gamma dose rate The gamma dose rate in air changes for each SET of dosemeters
Exposure 3: critical points Humidity * High dose rate * Altitude * High thoron concentrations * Calibration (radon and thoron)
Exposure 3: Rn CR39 detectors kbqh/m3 kbqh/ m3 565 71 579 72 517 66 568 71 521 66 557 70 500 515 66 400 573 72 300 516 66 200 543 69 522 66 527 67 10 11 12 13 14 15 16 17 18 19 20 535 68 position 577 72 548 69 587 73 Metrological and statistical σ Uncertainty 1σ 557 70 532 67 kbqh/m3 kbqh/m3 539 68 547 73 574 51 Reference passive CR39 detectors Exposure 3 - Passive detectors 700 600 kbqh/m3 unc. 100 0 1 2 3 4 5 6 Radon exposure Passive detectors 7 8 9
Exposure 3: homogeneity of radon concentrations Standard deviation uncertainty of a singol detector
Exposure 3 Continuous radon monitors During the exposure A special thanks to Prof. Piergiorgio Albertazzi Storage of transits in radon proof bags in Ivrea
Exposure 3: radon concentration Bq/m3 Quittengo - radon concentration 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0 AG933 0 AG917 50 EQF 100 AG professional 150 h 200
Exposure 3: thoron concentration Quittengo - toron concentration 3000 2500 Bq/m3 2000 1500 1000 500 EQF AG professional 0 0 50 100 150 h 200
Exposure 3: reference continuous monitors Quittengo - Radon and Toron exposure Radon exposure 800 Toron Exposure 700 kbq/m 3 600 525 525 511 503 500 361 400 363 300 200 100 0 AG933 AG917 EQF Radon exposure Metrological and statistical σ Uncertainty 1σ Radon Concentration Metrological and statistical σ Uncertainty 1σ kbqh/m3 kbqh/m3 Bq/m3 kbqh/m3 516 85 2399 Agprof 394 THORON exposure Metrological and statistical σ Uncertainty 1σ THORON Concentration Metrological and statistical σ Uncertainty 1σ kbqh/m3 kbqh/m3 Bq/m3 kbqh/m3 362 84 1685 389
Conclusions Reference values : Radon and Toron Exposures kbqh/m 3 2000 1800 1600 1400 1200 1000 800 600 400 200 0 Continuous monitors Passive detectors Exposure 1 Exposure 2 Exposure 3 Radon Exposure 3 Toron Continuous monitors kbqh/m 3 unc. (k=1) kbqh/m 3 Passive detectors kbqh/m 3 unc. (k=1) kbqh/m 3 Exposure 1 Radon 225 50 238 22 Exposure 2 Radon 1731 152 1690 121 Exposure 3 Radon 516 85 547 73 Exposure 3 Thoron 362 84
Thank you