Laboratory%20requirements%20for%20ISO/IEC%2017025:%20accreditation%20of%20radon%20indoor%20measurements%20based%20on%20CR-39%20nuclear%20track%20detectors

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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
24th ICNTS Bologna, 1-5 September 2008
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What 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 g spectrometry,
  liquid scintillation spectrometry..
• ..Radon measurements

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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
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Laboratory AccreditationSTANDARD ISO/IEC
170252005
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)
.
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STANDARD ISO/IEC 170252005
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.
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ISO/IEC 17025 Accreditation 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
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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)
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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)
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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 NaOH 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
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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
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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)
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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

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

Repeatability of microscope scans as a function
of exposure level
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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
  the thermal bath thermometer
• Temperature uniformity in the thermal bath
• International standard traceable calibration of
  hydrometer measuring NaOH 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
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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

• 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

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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 )
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Conclusions

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