a new suite of tools for the radioactivity measurements ... · a new suite of tools for...

A new suite of tools for Radioactivity Measurement Laboratories

João Abrantes, Gonçalo Carvalhal, Mário Reis

Instituto Superior Técnico, Universidade Técnica de Lisboa, Portugal Estrada Nacional 10, 2686-953 Sacavém (PORTUGAL)

Advances in Liquid Scintillation Spectrometry 18-22 March 2013, Barcelona

Laboratory workload

Advances in Liquid Scintillation Spectrometry

18-22 March 2013, Barcelona

• ~2500 samples/year • 10-12 assay methods (gross alpha/beta, H-3, Sr-90, Cs-137, Rn-

222) • Different sample types (water, milk, food) • Different detection systems (GPC, LSC) • Different measurement purposes (National Surveillance,

external clients, R&D, internal studies)

ISO 17025 accreditation

First steps



• Identify commom processes • Define workflow • Classify items

• Samples by class (cal. standard, background, blank, cert. ref. material, internal QC, …) and type (water, milk, food, …)

• Batches (ordered sequence of samples) • Analyses (ordered sequence of batches) • Measurements (associated to each analysis and detector

system) • Methods (assay/routine, reference/QC)

Requirements (development)



• Major tasks defined as modules • Easy to use • Easy to check/debug • Parameterizable • Rapid implementation

R: free software environment for statistical computing and graphics (http://www.r-project.org/) Data stored in ASCII files

http://www.r-project.org/










Requirements (outcome)



• Get data from measurements and samples • Perform activity calculations including uncertainties and

detection limits • Generate reports • Determinate ROIs for LSC • Calculate calibration parameters • Fit calibration curves • Estimate MDA from calibration curves • Check detector performance • Check method QC • …

Detector performance (I)



Reference methods defined for detector system • alpha/beta standards (GPC, LSC) • beta standards (LL LSC)

Standard sources and backgrounds assigned to detectors Am-241 (and BKG) on Tricarb 3170

Detector performance (II)



Ability to monitor tSIE for standard set kit (Am-241, Cl-36, BKG)

Method QC



For each method: • check background and

blank count rates • monitor tSIE

Sr-90 in food and milk

ROI determination in LSC



Loads standard and background files to determinate ROIs (from FOM)

Calibration



Uses standard (working) solution and standards data, measurement data to calculate activity, efficiency and interference (spillover/crosstalk).

Handles repeatability on measurements to calculate uncertainties (type A and B)

Fitting data (I)



Loads output from calibration, performs fit and plots calibration curves.

H-3 in water (LSC) Gross alpha (Am-241) in water (LSC)

Fitting data (II)



Also returns goodness of fit parameters for evaluation

Gross beta (K-40) in water (GPC)

MDA estimated after calibration



Gross alpha (Am-241) in water (LSC) (10x conc. @ top, no concentration @ bottom) H-3 in water (LSC)

Activity calculation



Implementation for: • Gross alpha/beta activities on water and suspended matter

(GPC, LSC) • Sr-90 in water (GPC) • Cs-137 in water (GPC) • Sr-90 in food and milk (LSC) • Rn-222 in water (LSC, 2 methods) • H-3 in water (LSC, 2 methods) • H-3 in RBA (LSC)

Returns all calculations to be used in uncertainty budget

Other tools



• Get data from detector systems (only Tricarb) • Send worklist to detectors • Create and fill batches and analysis • Generate report (ASCII) • Statistics on data (managment)

Conclusions



• Main laboratory procedures can easily be streamlined in a systematic, time-saving way

• Data and documentation traceability

• Quality of results assured

• Less error prone

Future work



• Database development • Graphical User Interface (integrating modules) • Sample data module • Extend capabilities to other detector systems • Spectra view • Statistical and database tools (managment) • …

Thank you for your attention.



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