A comparison of emerging gamma detector technologies for airborne. radiation monitoring

Transcription

1 A comparison of emerging gamma detector technologies for airborne ANSRI Dublin May radiation monitoring Steven Bell

2 Contents Airborne radioactivity MetroERM Gamma spectrometers Experimental method Spectra Resolution Efficiency Linearity Internal radioactivity MDA Follow-on project

3 Airborne radiation Particulates: sub-μm to sub-mm contaminated with fission products (e.g. 137 Cs and other volatile species) Gases: 3 H, 14 C, 85 Kr, 133 Xe Background radon/thoron and progeny Inhalation of radioactive airborne particulates (aerosols) and gases pose a serious health risk Emissions from nuclear facilities must be monitored National early warning networks provide extra layer of monitoring

4 MetroERM Metrology for radiological early warning networks in Europe National early warning networks provide near real time measurements to allow governments to respond during emergency situations Measurements of ambient dose rate and airborne radionuclide activity concentrations Accurate, coherent and complete data is required Outcomes: optimisation and harmonisation of measurements New technology is key to achieving outcomes

5 EURDEP Network European Radiological Data Exchange Platform (EURDEP)

6 EPA Network, Ireland Gamma dose measured near UCD campus recorded during ANSRI 2015 (ave. ~0.1 μsv/hr) Geiger-Muller tube Environmental Protection Agency, Ireland -

7 MetroERM On-line aerosol particulate spectrometer Portable and rapidly deployable monitor for incident response Developed by IJS (Slovenian national measurement institute) CeBr 3 detector slotted inside concertina filter Custom digital signal processing 3G mobile network connection

8 Gamma spectrometers Detector Size (mm) Model HPGe 85 x 30 Ortec Detective 200 p-type coaxial CeBr 3 38 x 51 Saint Gobain LaBr 3 (Ce) 38 x 51 Saint Gobain CdZnTe 10 x 10 x 10 Kromek GR1 CsI(Tl) 25.4 x 25.4 x 51 Kromek Sigma 50 * LaBr and CeBr coupled to Hamamatsu R9779 PMT and CAEN digitiser. CsI coupled to SiPM

9 Radionuclide Energy Am Cd Co Ce Cr Sn Sr Cs Mn Y Zn Co Co Y Filters 3g of mixed nuclide solution drop deposited evenly over 20x10 cm 2 area Mass deposited within 8 subsections recorded to ensure uniformity Activity levels chosen to mimic the activity collected on a filter over 48hr or 12hr with an assumed air sampling rate of 1,000 m 3 /hr in an environment of 0.03 Bq/m 3 of Cs- 137 (minimum European reporting level) High activity filter = 30 kbq (1.5 kbq Cs-137) Low activity filter = 6 kbq (0.3 kbq Cs-137)

10 Filters

11 Spectra

12 Energy resolution

13 Detection efficiency

14 Proportionality

15 Background

16 Minimum detectable activity

17 Minimum detectable activity

18 MetroERM II Metrology for mobile detection of ionising radiation in the aftermath of a nuclear or radiological incident Drone/helicopter-borne spectrometers Rapidly deployable monitors Crowd sourced dose measurements If submission is successful, project will commence Summer 2017 and finish Summer 2020 Please contact steven.bell@npl.co.uk if you are interested in joining the project

19 Summary MetroERM is a pan-european project with the aim of harmonising the measurement and interpretation of data during radiological early warning events NPL are committed to investigating new and existing technology for the measurement of gamma-emitting airborne radioactive particulates Currently drafting proposal for follow-up project. Involvement of stakeholders is vital (e.g. governmental bodies, end-users, instrument manufacturers)

20 Thank you for listening I would like to acknowledge the work of my colleagues Sam Beeke (Surrey MSc) and Paris Aitken-Smith (NPL) and funding through the UK s NMS and Euramet s EMRP programme The National Measurement System delivers world-class measurement science & technology through these organisations

21 Most importantly Thank you Paddy!