Laboratory requirements for ISO IEC 17025 accreditation of radon

Laboratory requirements for ISO/IEC 17025: accreditation of radon indoor measurements based on CR-39 nuclear track detectors S. Bucci, F. Cioni, S. Gambi, R. Magnanelli, I. Peroni and G. Pratesi ARPAT, Enviromental Protection Agency – Department of Florence Tuscany Region Via Ponte alle Mosse, 211 – 50144 Florence Italy 24 th ICNTS Bologna, 1 -5 September 2008

What is ARPAT Regional Enviromental Agency estabilished since 1996 with 10 Departments (one for each Province of Tuscany) l Many institutional customers l Monitoring of : Water, Soil and Air quality, electromagnetic pollution, enviromental noise, food safety, waste control…. . l Laboratory of radioactivity : g spectrometry, liquid scintillation spectrometry…. . l …. . Radon measurements 24 th ICNTS Bologna, 1 -5 September 2008

WHY accreditation ARPAT performs enviromental monitoring of many parameters and controls the respect of legislation limits This implies the necessity of a good quality of data Control of laboratory by an independent third organization provides a guarantee to users (customers) of the competence and impartiality of laboratories 24 th ICNTS Bologna, 1 -5 September 2008

Laboratory Accreditation: STANDARD ISO/IEC 17025: 2005 General requirements for the competence of testing and calibration laboratories Accreditation Body provides a guarantee of the competence and impartiality of laboratories in performance of the accredited tests by means of periodic technical assessments (assessment visits). In Italy this function is performed by SINAL (National System for Accreditation of Laboratories) which assesses and exercises continuing surveillance over the compliance of the laboratories with standard ISO/IEC 17025. (Note that several ministerial italian decrees make reference to ISO/IEC 17025 and SINAL accreditation). 24 th ICNTS Bologna, 1 -5 September 2008

STANDARD ISO/IEC 17025: 2005 General requirements for the competence of testing and calibration laboratories 17025 contains “all of the requirements that testing and calibration laboratories have to meet if they wish to demonstrate that they operate a management system, are technically competent and are able to generate technically valid results” The ISO 17025 standard itself is comprised of 5 elements: 1. Scope 2. Normative References 3. Terms and Definitions 4. Management Requirements 5. Technical Requirements Elements 4 and 5 contain the actual accreditation requirements. 24 th ICNTS Bologna, 1 -5 September 2008

ISO/IEC 17025 : Accreditation Requirement Management Requirements Technical Requirements (same as ISO 9001) - Organization - Quality system - Document control - Review of requests, tenders and contracts - Service to client - Complaints - Corrective action - Preventive action - Control of records - Test and calibration methods and method validation - Equipment - Measurement traceability - Sampling - Handling of test and calibration items - Assuring the quality of test and calibration results - Reporting the results 24 th ICNTS Bologna, 1 -5 September 2008

ARPAT and ISO/IEC 17025 ARPAT has more than 60 laboratory methods since 1998 accredited for chemical, biological and physical enviromental tests. Accreditation is granted on the basis of examination of documentation and the results of assessment visits. SINAL performs periodic visits in ARPAT (typically 1/year) for assessment of the technical and organisational requirements. Our laboratory of radioactivity has 3 accredited methods: 1) 2 g spectrometry on food and milk 2) Radon indoor measurements (2006) 24 th ICNTS Bologna, 1 -5 September 2008

Technical requirement for accredidation of radon indoor measurements based on CR-39 nuclear track detectors Point 5 of ISO/IEC 17025 “Many factors determine the correctness and reliability of the test and/or calibrations performed by a laboratory. These factors include contribution from: human factors (5. 2) accomodation and enviromental conditions (5. 3) test and calibration methods and method validation (5. 4) equipment (5. 5) measurement traceability (5. 6) sampling (5. 7) the handling of test and calibration items (5. 8) assuring the quality of test and calibration results (5. 9) reporting the results (5. 10)” 24 th ICNTS Bologna, 1 -5 September 2008

Technical requirement for accredidation of radon indoor measurements based on CR -39 nuclear track detectors 5. 4 Test and calibration methods and method validation Since standards methods for radon indoor measurements are under development (11 UNI - Italian National Standards Body, member of ISO – working group) the method ARPAT employed for radon indoor measurements is a non-standard method (5. 4. 4) based on a track analysis system TASL of CR-39 Tastrack detector chemically etched in a Na. OH bath. In a non-standard method some requirements are to fullfilled and specially: - Detailed description of the procedure - Description of parameters or quantities to be determined - Detailed description of the procedure for estimating uncertainty 24 th ICNTS Bologna, 1 -5 September 2008

Technical requirement for accredidation of radon indoor measurements based on CR -39 nuclear track detectors 5. 4. 5 Validation of methods : “the confirmation by examination and the provision of objective evidence that the particular requirements for a specific use are fullfilled” Determination of the characteristics of the method: - Calibration using reference standard or reference material - Comparison of results achieved with other methods - Interlaboratory comparisons - systematic assessment of the factors influencing the results - assessment of uncertainty of the results 24 th ICNTS Bologna, 1 -5 September 2008

Technical requirement for accredidation of radon indoor measurements based on CR -39 nuclear track detectors Calibration : Periodic check yearly repeated in the same batch or with new batch of CR-39 detectors Exposure at CESNEF Politecnico of Milano Interlaboratory comparison (if you get A) is a track to achieve laboratory accreditation (not sufficient but necessary…) We partecipate to HPA intercomparison 2007 (A) 24 th ICNTS Bologna, 1 -5 September 2008

Technical requirement for accredidation of radon indoor measurements based on CR -39 nuclear track detectors (5. 4. 6) Uncertainty: obtained from the following contributions - Background counts - Counting statistics - Calibration - Repeatability has been valued by means of different - chemical etching bath (same temperature and Na. OH concentration) - detectors (within the same batch) - different microscope scans Repeatability of microscope scans as a function of exposure level 24 th ICNTS Bologna, 1 -5 September 2008

Technical requirement for accredidation of radon indoor measurements based on CR -39 nuclear track detectors 5. 5 Equipment : Equipment shall be calibrated or checked before use “Records shall be maintaned of each item of equipment and its software significant to the test and/or calibration performed” Etching equipment check by means of: - International standard traceable calibration of thermal bath thermometer -Temperature uniformity in thermal bath - International standard traceable calibration of hydrometer measuring Na. OH solution density Minimum 2 detectors exposed to Am-241 in a fixed configuration are etched every bath. Control on: - number of the tracks - morphology of the tracks 24 th ICNTS Bologna, 1 -5 September 2008

Technical requirement for accredidation of radon indoor measurements based on CR -39 nuclear track detectors (5. 4. 5) Robustness against external influences and/or cross-sensitivity against interference from the matrix of the sample/test object üInfluence of the etching thermal bath time üInfluence of the etching thermal bath Na. OH concentration üInfluence of the etching thermal bath temperature üInfluence of the number of detectors in each thermal bath 24 th ICNTS Bologna, 1 -5 September 2008

WHAT IS CRITICAL TO GO AHEAD 1. Tracebility of calibration to international reference standards 2. Calculation and data trasnfer subject to appropriate checks in a systematic manner (i. e. computer software suitably validated (5. 4. 7)) (TASL system is not trasparent enough: algorithms to calculate tracks number are not open source: therefore it is not really possible to keep under control the process) 3. Technical point: Management of aging and fading (The two effects are under progressive study, this implies however long time ) 24 th ICNTS Bologna, 1 -5 September 2008

Conclusions l We showed laboratory requirements for ISO/IEC 17025 accreditation for radon indoor measurements based on CR-39 nuclear track detectors with same pratical examples Accreditation needs a big effort and human and economical resources. The wide experience of the Agency on other test methods helped us very much However we are convinced that Accreditation is worth while for two reasons: The periodic visit of SINAL 1/years allows us to mantain all the system under control This stimulates a continuos improvement from a technical point of view, giving better quality of data and guarantee to customers 24 th ICNTS Bologna, 1 -5 September 2008

Extra Sl Standardization diminishes trade barriers, promotes safety, allows interoperability of products, systems and services, and promotes common technical understanding.