Traceability is the property of a result of a measurement whereby it can be related to appropriate standards, generally international or national standards, through an unbroken chain of comparisons.
Reference sources and solutions supplied by Eckert & Ziegler Isotope Products are traceable to standards held by National Metrology Institutes (NMI´s) such as:
- the Physikalisch-Technische Bundesanstalt (PTB), Germany
- the National Physical Laboratory (NPL), UK
- the Laboratoire National Henri Becquerel (LNHB), France
- the National Institute of Standards and Technology (NIST), USA.
The National Metrology Institutes participate in validation and intercomparison exercises organized under the auspices of the International Bureau for Weights and Measures (BIPM) in France. Traceability to one NMI can often be accepted as attributing traceability to other laboratories. The administrative system to confirm traceability depends on the country to which traceability is sought. In particular, there are differences between the systems for Europe and the USA.
Traceability in Europe – Accreditation
Eckert & Ziegler Nuclitec GmbH, Eckert & Ziegler Isotope Product Laboratories Inc. and Eckert & Ziegler Analytics Inc. operate DAkkS (formerly DKD) accredited measurement laboratories in Braunschweig, Germany, Valencia and Burbank, California, USA and Atlanta, Georgia, USA respectively.
Accreditation is a system of assessment of laboratories by independent experts to the European standard EN ISO/IEC 17025. The assessments are carried out by experts representing the national accreditation body. The assessors check that the laboratories are meeting essential conditions, such as
- technical competence
- valid calibration methods
- traceability to national standards
- effective quality system.
If the laboratory passes the assessment and the surveillance visits, the laboratory is permitted to issue certificates of calibration marked with the symbol issued by the national accreditation body. The German Calibration Service (DAkkS) uses the DAkkS logo, the United Kingdom Accreditation Service (UKAS) uses the UKAS logo
The advantages of DAkkS or UKAS certificates are:
- assurance that work has been carried out to the required standard
- assurance that agreed methods have been followed
- assurance that measurements are traceable to national standards.
In turn, accreditation bodies such as DAkkS and UKAS are evaluated by a team of assessors from the European Co-operation for Accreditation of Laboratories (EA). The EA has set up a mutual recognition agreement, so a DAkkS or UKAS certificate has one further advantage:
- accepted in many countries world-wide.
For example, a DAkkS or UKAS certificate of calibration has the same status in France as a COFRAC certificate (the accreditation body in France).
Traceability in the USA – NIST
The requirements for traceability to the National Institute of Standards and Technology are set out in the American National Standards Institute standard ANSI N42.22-1995 ‘American National Standard – Traceability of Radioactive Sources to the National Institute of Standards and Technology (NIST) and Associated Instrument Quality Control’. The standard requires that source manufacturers meet certain criteria. The criteria fall under four main headings:
- quality assurance management system
- facilities and equipment
- participation in NIST measurement assurance program
- certificates of calibration.
Eckert & Ziegler Isotope Products reference sources and solutions satisfy the criteria for traceability as our measurement laboratories and production facilities meet the requirements of international standards (ISO9001:2008), but for the sake of completeness have also been audited against the specific requirements of ANSI N42.22 and found to be in full compliance.
Eckert & Ziegler Isotope Products: Eckert & Ziegler Nuclitec GmbH, Eckert & Ziegler Isotope Product Laboratories Inc. and Eckert & Ziegler Analytics Inc. are charter members of the Steering Group of the Nuclear Energy Institute NRMAP/NIST Measurement Assurance Program.
Eckert & Ziegler Nuclitec GmbH’s measurement laboratory carries out intercomparison exercises with NIST, and ensure that the results meet the acceptance criteria required by ANSI N42.22. The certificates of calibration provide the information required by ANSI N42.22.