Laboratory requirements for ISO/IEC 17025: accreditation of radon indoor measurements based on CR-39 nuclear track detectors S. Bucci, F.Cioni, S.Gambi,

Laboratory requirements forLaboratory requirements for ISO/IEC 17025: ISO/IEC 17025:

accreditation of radon indoor accreditation of radon indoor measurements based on measurements based on

CR-39 nuclear track detectorsCR-39 nuclear track detectors

S. Bucci, F.Cioni, S.Gambi, R.Magnanelli, I.Peroni and G.Pratesi

ARPAT, Enviromental Protection Agency – Department of FlorenceTuscany Region

Via Ponte alle Mosse, 211 – 50144 Florence Italy

24th ICNTS Bologna, 1-5 September 2008

What is ARPATWhat is ARPAT Regional Enviromental Agency estabilished since

1996 with 10 Departments (one for each Province of Tuscany)

Many institutional customers Monitoring of :Water, Soil and Air quality,

electromagnetic pollution, enviromental noise, food safety, waste control…..

Laboratory of radioactivity : spectrometry, liquid scintillation spectrometry…..

…..Radon measurements


WHY accreditationWHY accreditationARPAT performs enviromental monitoring of

many parameters and controls the respect oflegislation 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


Laboratory Accreditation:Laboratory Accreditation:STANDARD ISO/IEC 17025:2005STANDARD ISO/IEC 17025:2005

General requirements for the competence of testing and calibration laboratories

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)

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).


.

STANDARD ISO/IEC 17025:2005STANDARD ISO/IEC 17025:2005General requirements for the competence of testing

and calibration laboratories

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.


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”

ISO/IEC 17025 :ISO/IEC 17025 :Accreditation RequirementAccreditation Requirement

Management 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

Technical Requirements

- 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


ARPAT and ISO/IEC 17025ARPAT and ISO/IEC 17025ARPAT has more than 60 laboratory methods since 1998 accredited for chemical, biological and physical enviromental tests.


SINAL performs periodic visits in ARPAT (typically 1/year) for assessment of the technical and organisational requirements.

Accreditation is granted on the basis of examination of documentation and the results of assessment visits.

Our laboratory of radioactivity has 3 accredited methods:spectrometry on food and milk2) Radon indoor measurements (2006)

Technical requirement for accredidation of Technical requirement for accredidation of radon indoor measurements based on CR-39 radon indoor measurements based on CR-39

nuclear track detectorsnuclear track detectorsPoint 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)”


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 NaOH bath.

Technical requirement for accredidation of Technical requirement for accredidation of radon indoor measurements based on radon indoor measurements based on

CR-39 nuclear track detectorsCR-39 nuclear track detectors5.4 Test and calibration methods and method validation


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


CR-39 nuclear track detectorsCR-39 nuclear track detectors5.4.5 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




0,0

2000,0

4000,0

6000,0

8000,0

10000,0

12000,0

14000,0

16000,0

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Rn Exposition (kBqh/m3)

Tra

ck

de

ns

ity

(N

/cm

2 )

Calibration :Periodic check yearly repeated in the samebatch or with new batch of CR-39 detectors


Interlaboratory comparison (if you get A) is a track to achieve laboratory accreditation (not sufficient but necessary…)We partecipate to HPA intercomparison 2007 (A)

Exposure at CESNEF Politecnico of Milano



(5.4.6) Uncertainty: obtained from the following contributions- Background counts- Counting statistics- Calibration- Repeatability

Repeatability has been valued by means of different- chemical etching bath (same temperature and NaOH concentration)- detectors (within the same batch)- different microscope scans

0

2

4

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120 400 2550Rn exposure (kBqh/m3)

CV

%


Repeatability ofmicroscope scans as a function of exposure level




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 the thermal bath thermometer-Temperature uniformity in the thermal bath- International standard traceable calibration of hydrometer measuring NaOH solutiondensity CR-39 exposed to Am-241

0

0,05

0,1

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0,25

4 8 12 16 20 24 28 32 36 40

diameter (n)

freq

eun

cy

Minimum 2 detectors exposed to Am-241 in a fixed configurationare etched every bath. Control on:

- number of the tracks- morphology of the tracks



(5.4.5) Robustness against external influences and/or cross-sensitivity against

interference from the matrix of the sample/test object

NaOH thermal bath concentration

-10,0

0,0

10,0

20,0

30,0

40,0

50,0

5 5,5 6 6,5 7 7,5

NaOH /NC

V %

Influence of the etching thermal bath time

Influence of the etching thermal bath NaOH concentration

Influence of the etching thermal bath temperature

Influence of the number of detectors in each thermal bath


WHAT IS CRITICAL TO GO AHEADWHAT IS CRITICAL TO GO AHEAD

1. Tracebility of calibration to international reference standards2. 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 tracksnumber 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 )


ConclusionsConclusions 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 economicalresources. 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 controlThis stimulates a continuos improvement from a technicalpoint of view, giving better quality of data and guarantee to customers

Extra SlExtra Sl

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

Documents

Laboratory requirements for ISO/IEC 17025: accreditation of radon indoor measurements based on CR-39 nuclear track detectors S. Bucci, F.Cioni, S.Gambi,