World-Wide Radiation Metrology:

Role of the CIPM MRA

Lisa R. Karam Chief, Radiation and Biomolecular Physics Division

National Institute of Standards and Technology +1 301-975-5561

lisa.karam@nist.gov

What is the CIPM MRA? • Paris 14 October 1999

• 40 entities originally, now 74 (plus designated)

• Mutual recognition of

– National measurement standards

– Calibration and measurement certificates

• Structure

– RMOs

– Member States

– Associates of the CGPM

– Designated Institutions

Origins and Function

• Growing importance of metrology

– Enable world trade

– Overcome technical barriers

– Recognized foundation for variety of scientific and societal activities

• Secure technical foundation for wider agreements

• NMIs of Member States of the Metre Convention or Associate States (economies) of the CGPM

• “Consultative committees” focus on metrology in sound, length, mass, electricity/magnetism, time, thermometry, photometry, chemistry, and ionizing radiation (CCRI)

• Sections I (P. Sharpe), II (L. Karam) and III (D. Thomas)

CIPM MRA Participants in the Americas Country Institute Date Signed

Argentina INTI (CNEA designate) 14 Oct 1999

Bolivia* IBMETRO 16 May 2008

Brazil INMETRO (LNMRI/IRD designate) 14 Oct 1999

Canada NRC-INMS 14 Oct 1999

Caribbean Community* Designates in 11 countries 12 Oct 2005

Chile INN 18 Oct 2000

Costa Rica* LACOMET 6 Oct 2004

Cuba (COOMET)* NC (CENTIS and CPHR designate) 18 June 2001

Ecuador* ININ 15 April 2001

Jamaica* BSJ 21 July 2004

Mexico CENAM (ININ designate) 14 Oct 1999

Panama* CENAMEP AIP 16 Sept 2003

Paraguay* INTN 27 Oct 2009

Peru* INDECOPI 17 Nov 2009

USA NIST 14 Oct 1999

Uruguay LATU (MIEM/Lab. Tecnogestión designate) 14 Oct 1999

International Organizations IAEA; IRMM 14 Oct 1999 *Associate of the CGPM

SIM Signatory Labs in Ionizing Radiation

Country Institute Field

Argentina CNEA Dosimetry, Radioactivity

Brazil LNMRI/IRD Dosimetry, Radioactivity, Neutron measurements

Canada NRC-INMS Dosimetry, Radioactivity, Neutron measurements

Mexico ININ Dosimetry, Radioactivity, Neutron measurements

Uruguay MIEM/Laboratorios Tecnogestión

Dosimetry

USA NIST Dosimetry, Radioactivity, Neutron measurements

Quantities of Interest

• Neutron Measurements – Absorbed dose and dose rate to

graphite, tissue, water, other – Ambient dose equivalent and rate – Emission anisotropy – Emission rate – Fluence and fluence rate – Personal dose equivalent and rate

• Dosimetry – Absorbed dose/rate to air,

graphite, tissue, water, other – Air kerma area product – Air kerma length product – Air kerma/rate – Ambient dose equivalent/rate – Directional dose equivalent/rate – Personal dose equivalent/rate,

penetrating or superficial

• Radioactivity – Activity – Activity per unit area, mass,

volume – Efficiency of contamination

monitors – Efficiency of gamma-ray

spectrometers (versus energy) – Efficiency of ionization chambers – Emission rate, rate per unit solid

angle – Surface emission rate, rate per unit

area

n0

Calibration and Measurement Capabilities (CMCs)

• Initially, synonymous with “Best Capability Measurement” used in accreditation

• In 2008, BIPM, ILAC and RMOs agreed to a clarified, common, annotated definition:

“A CMC is a calibration and measurement capability available to customers under normal conditions

(a) as published in the BIPM key comparison database (KCDB) of the CIPM MRA; or

(b) as described in the laboratory’s scope of accreditation granted by a signatory to the ILAC arrangement”

Where the term NMI is used, it is intended to include

Designated Institutes (DIs) within the framework of

the CIPM MRA

Published CMCs in SIM: 30 in dosimetry, 515 in radioactivity, 10 in neutrons

Structure and Character of CMCs for Ionizing Radiation

• Supported by approved quality system

• Validated through comparisons, other published results

• Delineated by quantity of interest, range of measurement, measurement conditions, uncertainty

• Searchable at the CIPM MRA appendix C site (http://kcdb.bipm.org/appendixC/default.asp)

Calibration or Measurement

Service

Measurand Level or

Range

Measurement

Conditions/Indepen

dent Variable

Expanded Uncertainty

Reference

Standard used

in calibration

Comparisons

supporting this

measurement/

calibration

service

Services Administration

Quantity Instrument or

Artifact

Instrument

Type or

Method

Minimum

value

Maximum

value Units Parameter Specifications Value Units

Coverage

factor

Level of

Confidence Standard

Source of

traceability

NMI Service

Identification

Service

Category NMI Comments

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

air

kerma

rate

ionization

chambers

(other

dose/rate

instruments

in special

tests)

Calibration

in air

against

national

standard

9E-09 3E-02 Gy s-1

x rays,

10 kV to

50 kV

Conform to

ISO 4037/1

(2000)

1 % 2 95 %

free-air

chamb

ers

NIST

Rapport BIPM-

99/05 (1999) J

Res NIST 104,

135 (1999)

Draft report for

Metrologia

Technical

Supplement on

BIPM.RI(I)-K2

2003

SIM-RAD-

NIST-1001 1.6.4 NIST

29 W-anode beam

qualities; 11 Mo-anode

beam qualities; 6 Rh-anode

beam qualities; see

http://ts.nist.gov/ts/htdocs/2

30/233/calibrations/ionizing-

rad/x-gamma-

ray.htm#46010C for list.

Classification of RI Services

Role of Comparisons

• Key component of CMCs

– Guidance on uncertainty expectations (uncertainty budget is crucial)

– Aid in review process

– Published results improve metrological rigor

– Key and supplementary both useful

• Allows improvements in methods

• Contributes to planning for future comparisons (optimizing resources)

• Successful participation to support “equivalency”

Comparisons in Dosimetry http://kcdb.bipm.org/appendixB/KCDB_ApB_search.asp

• Currently, 43 comparisons in x and gamma rays, and electrons measurements (dosimetry) are listed in the Key Comparison Database (KCDB; Appendix B)

• Comparisons include – SIM, EURAMET, COOMET, APMP,

CCRI(I), BIPM

– Planned, in progress, measurements complete, Draft B, approved/published, equivalence

– Absorbed dose to water, absorbed dose rate for beta, air kerma (low and med energy, Co-60), personal dose equivalent

Recent Comparisons with SIM Participation Dosimetry

Comparison Description Institutes Time

BIPM.RI(I)-K1 Co-60 air kerma NIST Submission anticipated in 2011

BIPM.RI(I)-K2 Low-energy x-ray air-kerma NIST Submission anticipated in 2011

SIM.RI(I)-K3 Calibration Coefficients at Radiotherapy Level for Orthovoltage X-ray Beams

NRCC, NIST, ININ, LNMRI/IRD, CNEA

2007-2011 (Draft A review)

SIM.RI(I)-K3.1 Piggy-backed to K3 NIST, KREB (Kenya) 2009-2010

BIPM.RI(I)-K5 Cs-137 air kerma NIST Submission anticipated in 2011

BIPM.RI(I)-K6 Absorbed dose to water in high-energy x-ray beams NIST In progress

BIPM.RI(I)-K7 Mammography x-ray air-kerma comparisons NIST 2009 (in progress)

CCRI(I)-S2 Measurement of absorbed dose to water NIST 2009 p

EUROMET.RI(I)-K1 Measurement of air kerma for Cobalt 60 NRCC, NIST, LNMRI/IRD, CNEA 2005-2008 p

EUROMET.RI(I)-K4 Measurement of absorbed dose to water for Cobalt 60 NRCC, NIST, LNMRI/IRD, CNEA 2005-2008 p

SIM.RI(I)-S1 Air kerma from radiation protection level Cs-137 and Co-60 gamma ray beams

NIST, IAEA 2009-2010 p

SSDL (IAEA/WHO) Calibration Coefficients for Therapy-level ionization chambers (Co-60)

CNEA 2009

SSDL (IAEA/WHO) TLD powder (Co-60) CNEA 2009, 2010

BIPM Air kerma Ir-192 HDR brachytherapy NRCC Planned in 2011

SIM.RI(I)-K4

• Measurement of absorbed dose for Co-60 to water

– Run in 2002 along with SIM.RI(I)-K1

– Three cavity ionization chambers used as transfer instrument

– Key comparison

– Series of bilateral comparisons between NRC and participating countries

Participants

CNEA National Commission of Atomic Energy; Argentina, SIM

IAEA International Atomic Energy Agency; International Organization

ININ Instituto Nacional de Investigaciones Nucleares; Mexico, SIM

LNMRI Laboratorio Nacional de Metrologia das Radiaçoes Ionizantes, IRD; Brazil, SIM

LSCD Laboratorio Secundario de Calibracion Dosimetrica; Venezuela (Bolivarian Republic of), SIM

NIST* National Institute of Standards and Technology; United States, SIM

NRC* National Research Council; Canada, SIM

*laboratory holds primary standard to

allow link to the BIPM

Procedure • Cylindrical A12 Ionization chamber

• Comparison of absorbed-dose-to-water standards made indirectly by comparing the calibration coefficients (ND,W) of the three chambers as determined by the individual lab

• NIST and NRC standards based on water calorimeter; BIPM based on graphite (to which the secondary labs are traceable)

Results

• BIPM absorbed-dose-to-water value taken as the KCRV • Degree of equivalence defined as difference between the

absorbed-dose-to-water as measured and the KCRV, divided by the KCRV, and the expanded uncertainty of this difference

• Uncertainty of a given result is obtained by combining the reported calibration coefficient uncertainty, the absorbed-dose-to-water uncertainty of the BIPM standard, and the uncertainty of the link between the NRC and the BIPM (including correlation effects)

• Details published in Metrologia, 2008, 45, Tech. Suppl., 06011

Comparisons in Radioactivity http://kcdb.bipm.org/appendixB/KCDB_ApB_search.asp

• Currently, 128 comparisons in measurement of radionuclides (radioactivity) are listed in the Key Comparison Database (KCDB; Appendix B)

• Comparisons include – SIM, EURAMET, COOMET, APMP,

CCRI(II), BIPM (including TI)

– Planned, in progress, measurements complete, Draft B, approved/published, equivalence

– A variety of radionuclides for health, security, environmental protection, metrology; single and multiple

– Many matrices (from solution to soils)

Recent Comparisons with SIM Participation Activity

Institution Comparison Description Time

CNEA CCRI(II)-K2.H-3 Tritium in solution 2008-2009

IAEA-CU-2009-04 Environmental samples (filters) 2009-2010

IAEA-CU-2009-02 Environmental samples (soil and water; EA ARCAL Project 2/014); 2009-2010

IAEA-CU-2009-03 Environmental samples (soil, water and grass) 2009-2010

CSN - CIEMAT: ashes Alimentary diet 2010

IAEA-CU-2010-04 ALMERA proficiency test on the determination of natural radionuclides in water and Ra-226 in soil

2010-2011

IAEA-CU-2011 Environmental samples Planned in 2011

SIR Co-60, Am-241 and Eu-152

NIST Unregistered? APMP? Cs-137 and K-40 in Rice Powder Reference Material 2009

CCRI(II)- K2.Pu- 241 Pu-241 in solution 2009-2011

BIPM.RI(II)- K4.Tc-99m Transfer instrument 2009

CCRI(II)-S8 Cs-137, K-40, Sr-90 activity concentrations in IRMM-426 Bilberry Reference Material

2011

CCRI(II)-S10 Source emission rate for the calibration of surface contamination monitors

Planned in 2011

SIR Ga-67, Co-57 2010 (?)

LNMRI/IRD BIPM.RI(II)- K1.Lu- 177 Lu-177 in solution 2010

BIPM Y-90 in solution Planned in 2011

Rationale

• Radioactivity CMCs are nuclide specific

• Currently in excess of 1000 different combinations (quantity/nuclide/matrix) in CMCs

• Comparison results (quantity/nuclide/matrix) valid for “limited” time (eventually will be 10 years)

• Need to cover more than 1 quantity/nuclide/matrix with each comparison

• Primary methods of radionuclide metrology can be grouped according to nuclide characteristics and behavior

• In principal, one comparison could support dozens of CMCs at a time

Scheme

• Categorized by – Radiation-type – “Primary” measurement method

• Degree of difficulty color-coded – Red: most difficult – Yellow: moderately difficult – Green: least difficult

• In general, CMCs can be supported by comparisons results – If red: all red, yellow and green nuclides in method – If yellow: all yellow and green nuclides in method – If green: only all green nuclides in method

• In general, results using one primary method can not support claims (for the same nuclide) by another method

• Secondary methods not grouped

• Uncertainties are NOT benchmarks, but are “reasonable” to expect (for CMC reviewers’ aid)

Special Notes and Considerations

• Matrix of generic groupings (and comparisons based on it) are a tool to support CMCs

• Matrix, assignation of difficulty, and “reasonable” uncertainties prepared by working groups (key comparisons, uncertainties) of CCRI(II) (radionuclide metrology)

• All CCRI(II) asked to contribute and evaluate

• CCRI(II) members had been asked to look again at radioactivity CMCs to see if there are comparisons to be added to support them

• Active participation in future comparisons will help fill out the matrix

• Matrix is a “living” document (i.e., changes are expected with time)

Comparisons in Neutrons http://kcdb.bipm.org/appendixB/KCDB_ApB_search.asp

• Currently, 28 comparisons in neutron measurements (fluence, fluence rate, emission rate, ambient dose and survey meter) are listed in the Key Comparison Database (KCDB; Appendix B)

• Comparisons include – SIM, EURAMET, COOMET, APMP,

CCRI(II), BIPM; generally fewer labs

– Planned, in progress, measurements complete, Draft B, approved/published, equivalence

– A variety of neutron energies reflecting various applications

Recent Comparisons with SIM Participation Neutrons

Comparison Description Institutes Time

CCRI(III)-K9.AmBe Comparison of emission rate CIAE, CMI, KRISS, LNE-LNHB, LNMRI, NIST, NPL, VNIIM

1999-2005

CCRI(III)-K8 Thermal Neutron Fluence Measurements NIST had intended, but had to back out due to planned reactor shut down

SIM Neutron fluence (two possible comparisons)

NIST, LNMRI/IRD Planned in 2012

CCRI(III)-K9.AmBe

Participants

CIAE China Institute of Atomic Energy; China, APMP

CMI Czech Metrology Institute; Czech Republic, EURAMET

KRISS Korea Research Institute of Standards and Science; Republic of Korea, APMP

LNE-LNHB Commissariat à l'énergie atomique / Laboratoire National Henri Becquerel; France, EURAMET

LNMRI Laboratorio Nacional de Metrologia das Radiaçoes Ionizantes, IRD; Brazil, SIM

NIST National Institute of Standards and Technology; United States, SIM

NPL National Physical Laboratory; United Kingdom, EURAMET

VNIIM D.I. Mendeleyev Institute for Metrology, Rostekhregulirovaniye of Russia; Russian Federation, COOMET

• Measurement of neutron source emission rate — International comparisons

are staged infrequently and take many years to perform

— The emission rate of an 242Am-Be(α,n) source was measured by 8 participants

— Key comparison

Procedure

• All participants used the manganese bath technique to measure the neutron emission rate

• All groups except NIST calibrate their baths with calibrated solutions of activated MnSO4.

• NIST compares unknown sources to a standard Ra-Be photo-neutron source NBS-1 whose stable emission rate was previously measured

NIST Mn bath

Results

• The results of CIAE and LNE-LNHB were not included in the KCRV because they were considered to be outliers. Later the two groups found errors which when corrected brought their values into agreement with the KCRV

• Today the leading source of uncertainty comes from energy-dependent cross section uncertainties for certain key fast neutron reactions (e.g. 16O(n,a))

• Details published in Metrologia, 2011, 48, Tech. Suppl., 06018

• Radiation Physics (Radiation-interaction cross sections; Monte Carlo code development; Quantum metrology)

• Radiation Dosimetry (Brachytherapy; Mammography; Radiation processing (high dose); Worker protection)

• Medical Physics and Nuclear Medicine (Diagnostic; Therapeutic; Quantitative Medical Imaging)

• Decontamination (Industrial processing; Mail irradiation (anthrax); Luggage decon)

• Fundamental Neutron Physics (Weak nuclear interactions; Neutron lifetime; Neutron fluence; Calibrations)

• Neutron Science and Applications (Imaging; Interferometry)

• Radionuclide Metrology (Radionuclide standardization; SRMs; Calibrations)

• Environmental Radiometrology (Radiochemistry; protocols; Natural matrices; Bioassay; Environmental stewardship for nuclear power)

• Homeland Security (Measurements/standards for x-ray screening; Fast neutron spectrometry; Standards for radioactivity and neutron detection; Calibrated test sources; Validation testing; Evaluation

Protocols; Guidance to DHS)

Ionizing Radiation Metrology at NIST

Finally

• Measurement traceability enables international trade

• World-wide metrology supports legal and regulatory aims

• “Mutual Recognition” and “Equivalency” allow comparability within stated uncertainties

• Comparisons provide basis of analysis and confidence to customers

• International approach brings robustness and validity to measurements

NMI/DI

secondary

Stakeholders

secondary