Main Research Area and International Activities of the Radionuclide Metrology

Laboratory from IFIN-HH

Maria Sahagia“Horia Hulubei” National Institute of Research and Development for Physics and Nuclear Engineering,

IFIN-HH, Bucharest, Romania  

Second workshop for radioactive Decay Data Evaluators, DDEP 2008

Bucharest, Romania, May 12 – 14, 2008

Subjects to be treated

• General presentation of the Radionuclide Metrology Laboratory (RML)

• Main research areas

• International cooperation of RML

History

•IFIN-HH was founded, under the name of “Institute for Atomic Physics”, in 1949.

•Name IFIN was given in 1977, what became IFIN-HH (Horia Hulubei) in 1996.

• Radionuclide Metrology Laboratory (RML) was created in early sixties.

The founder is Dr. Enric Leon Grigorescu.

Official Status of the Laboratory

• Absolute (primary) standardization in the field.

• 2005-Protocol, National Metrology Institute (NMI) -Romanian Bureau of Legal Metrology (BRML) and IFIN-HH:

- IFIN-HH - owner of the Primary Standard of Activity Unit (Becquerel) and derived units

- BRML designated IFIN-HH: participant in International Committee for Weights and Measures - Mutual Recognition Arrangement (CIPM-MRA) ionizing radiations, CIPM-MRA, Annex A.

- BRML appointed IFIN-HH: representative in the Technical Committee for Ionizing Radiations (IR-TC) of EURAMET (EUROMET)

• BRML authorizes RML for legal metrology activities and attests it , as a calibration laboratory

Infrastructure and personnelRML- part of the IFIN-HH Radioisotope Department (RD) - Facilities for safe operation of sealed and open radioactive sources: radiochemistry laboratory, a balance room, two measurement laboratories, auxiliary rooms; - Separation from the RD crossing activities. Climatic regime and radiation background control-recently improved. - As a part of IFIN-HH, RML has access to all the available facilities, library, computing and communication network •RML Staff: 5 permanent and 1 associate members2 PhD, 1 PhD student, 1 Scientific researcher, 1 young physicists, 1 technician.

Thanks are due to Dr. E.L.Grigorescu, who retired.

Main research areas

• Methods and equipment for absolute standardization

• Methods and equipment for spectrometry and for relative standardization

• Methods and equipment for preparation of radioactive sources

• Metrology services and assurance of traceability

Absolute standardization:

• 4πPC-γ coincidence method

• Liquid Scintillation Counting

4πPC-γ coincidence methodStandardization of radionuclides emitting several coincident radiations and of pure beta emitters, by the tracing method. - First system, manually operated, constructed during sixties, contains a home made Proportional Counter (PC) - flow type, pure methane , and a NaI(Tl) detector. -Electronics is NIM modular of types Nuclear Enterprises and Canberra.

The method and equipment were verified in international comparisons

X, gamma - X, gamma coincidence detection block - two thin NaI(Tl) detectors - standardization of 125I, M. Sahagia et al. Appl.Radiat.Isot.3986/2008, under print.

Main Romanian contribution in the development

of the method (i) Dead time and coincidence resolution time corrections, E.L. Grigorescu, Mesucora Congress, Paris 1963;(ii) Measurement of beta, electron capture-gamma emitters, by the efficiency extrapolation: E.L. Grigorescu, Nucl.Instrum.Meth. 112(1973)151 ; E.L.Grigorescu, et al. Nucl. Instr.and Meth A369(1996) 414-420 and subsequent papers;(iii) Efficiency tracer for pure beta emitters and extrapolation for emitters with transition to the ground level. M.Sahagia, Marianske Lazne , Symp., 1979, Proc., 2/5, pp.180-187, and followings;(iv) Standardization of special radionuclides, 99mTc, M.Sahagia, Appl.Radiat.Isot. 64(2006)1234-1237.

New coincidence system

• The Research project, supported - Romanian National Authority for Scientific Research (ANCS), 2006-2008,

• New 4πPC-γ coincidence system: a Proportional Counter, two NaI(Tl) detectors and new electronic modules, ORTEC type or home - IFIN-HH made, operated in a semi automatic regime - constructed, is under testing :

C.Ivan et al. IFIN-HH Internal Rep. 2007. • Thanks are due to the Bureau International des Poids

et Mesures (BIPM), ENEA (Italy) and Laboratoire National “Henri Becquerel” (LNHB) from CEA-Saclay, France, for their help in designing the new system.

Liquid Scintillation Counting

•Liquid Scintillation Counter, principle of the Triple to Double Coincidence Ratio (LSC-TDCR): Detection block with three photomultipliers and associated electronics• Contribution of the LNHB-France and RC-Poland LSC-TDCR method implemented, and the system used for standardization of : H-3, C-14, P-32, Ni-63, Sr-89, Tl-204, Am-241, Cs-137, Fe-55•Method and system - verified by bilateral or key comparisons. A.C. Razdolescu and P. Cassette, Appl. Radiat. Isot. 60 (2004) 493-497; A.C. Razdolescu, et al, Appl. Radiat. Isot. 64 (2006) 1510-1514.

ANCS project – LSC improvements under way:

(i) New photomultipliers, type Burle 8850

(ii) A new detection block with 6 Channel Photomultipliers (CPM)

(iii) A NaI(Tl) probe for the application of the 4πLS-γ coincidence method.

(iv) The LabVIEW operation software - under installation.

Methods and equipment for spectrometry and for relative standardization

• Spectrometric methods

• Equipment and methods for relative (secondary) standardization

Spectrometric methods - Traditional work: GeHP gamma-spectrometer of the RD

- Contribution in development of the spectrometry method: (i) Use of the coincidence and Compton suppression anticoincidence for the low level activity measurements. E.L.Grigorescu, Nucl.Instrum.Meth. A 369 (1996) 574-577; A. Luca et al., Appl. Radiat. Isot. 53 (2000) 221-224; E.L. Grigorescu et al., Appl. Radiat.Isot. 61 (2004) 191-195; (ii) Studies on the shape of the gamma-ray background under the total absorption peaks, A.Luca et al., Appl.Radiat.Isot. 60 (2004) 233-237; (iii) Measurement of the X- and gamma-rays emission intensities for Zn-65, Sb-124 M.M.Be, ICRM2005, Appl.Radiat.Isot. 64 (2006)1396;

Content of the system Three detection blocks:(i)Gamma-ray detector: coaxial HPGe type, ORTEC model GEM-25P4, relative efficiency 30% (60Co); resolution 0.62 keV for 122 keV and 1.67 keV at 1333 keV; energy interval: 30 keV - 3 MeV. Shield: old lead, copper and a 1 mm thick tin foil - under construction(ii) X-ray detector - Si(Li), CANBERRA : energy interval 1 keV-50 keV, resolution 166 eV at 5.9 keV(iii) Alpha spectrometry chamber - surface barrier silicon detector, and vacuum system.All the three detection blocks are compatible (or adapted) to the analysis system, ORTEC, consisting from a digital spectrometer, connected to a personal computer.

Software facilities :

ORTEC GammaVision-32 (Model A66-B32), version 6.01, Advanced Measurement Technology, Inc. (AMETEK), USA; ORTEC MAESTRO-32 (Model A65-B32), version 6.06, Advanced Measurement Technology, Inc. (AMETEK), USA; GESPECOR, Romanian (Prof. O. Sima) - German (Dr. D. Arnold) - calculation of coincidence summing corrections and transfer of efficiency calibration between various geometries and matrices.

Equipment and methods for relative (secondary) standardization

Well-type ionization ionization chamber CENTRONIC IG12/20A

Transfer instrument, for secondary standardization of radioactive sources and solutions.

Calibration of the chamber.

Calibration figures were assigned for Various Gamma emitters and various geometries

(i)High activity sealed sources: certified by other producers - 241Am, 137Cs, 60Co.

(ii)Solutions vials: 2ml , PTB, Germany; 3.6 ml, BIPM - SIR; 5 ml , for radiopharmaceuticals; response is dependent of the volume of solution, mainly for low energy gamma-rays emitters.

Calibration for solutions

•Calibration with solutions absolutely standardized in RML by 4πPC-γ coincidence method , for 17 radionuclides: 54Mn, 57Co, 65Zn, 99mTc, 124Sb, 131I, 133Ba, 134Cs, 137Cs, 152Eu, 153Sm, 169Yb, 177Lu, 186Re, 188Re, 192Ir, 241Am. Uncertainty, U, for k = 2: U < 1.0% ( 2.1% for 99mTc)

•10 radionuclides: 54Mn, 65Zn, 131I, 133Ba, 134Cs, 137Cs, 152Eu, 169Yb, 192Ir, 241Am, verified in Key comparisons. RML values compared with calibration figures assigned, according he Key Comparison Reference Values (KCRV). Maximum difference: 241Am (1.1%)

•Calibration performed in 2001 at PTB, Germany, by Dr. H. Schrader, A.Luca and Al. Druker (NMI), using PTB - 2ml vials with standard solutions, for 19 radionuclides, 11 being common. PTB - IFIN-HH comparison : results agreed within uncertainties.

•Special attention for 131I , Sahagia et al. ARI 66(2008)539-544

Improvement of the electrometric system of the chamber

• Traditional electrometric system : a set of 0.1 nF, 1nF, 10 nF and 100 nF capacitors.

- Separate calibration figures, expressed in, mV s-1 MBq-1 for the capacitors, had to be determined, to be used for various activity intervals.

• Since 2006, an electrometer type Keithley 6517A has been operational.

- Parallel registrations, with both electrometers, and precise determination of the capacitors values - performed .

- The capacitor , 1 nF - value was determined with an uncertainty uc = 0.15%.

• The calibration figures were transferred to the new units, pA MBq-1.

Large area multiwire, sealed proportional counter

• Used for large surface alpha and beta sources used for measurement of surface contamination.

• Calibration - performed in terms of activity and particle emission rate in 2πsr geometry.

- calibration in activity was performed by using standard sources, gravimetrically prepared from 147Pm, 204Tl, 90(Sr+Y) standard solutions

- emission rate calibration is made using sets of sources measured directly in the upper half of the proportional counter.

- response values - determined for various source dimensions, up to 250 mm x 250 mm.M.Sahagia et al. Proceedings, IRPA 9 Congress, 1996, vol 3, pp.34-36 Vienna, Austria

Methods and Equipment for preparationof radioactive sources

• Sources and solutions for absolute (primary) standardization- Radioactive solutions and gravimetric dilutions for other solutions.- Sources for absolute standardization: solid VYNS sources for coincidence

method and LSC vials. - Traditional work: a METTLER M5 micro and an analytical balance. - Recent purchase: a set of METTLER TOLEDO certified balances, types:

MX/M (micro) and XS204/M.

• Radioactive standards for users- various types of radioactive solutions - solid radioactive sources, covering the main part of Romanian necessities:

alpha spectrometric sources, large area beta sources sets of gamma sources, of types: (i) point sources; (II)

volume solid sources, with matrices: water equivalent, soil, zeolite for various volume samples measurement.

M.Sahagia et al. ICRM1991, Nucl.Instr. And Meth. A312(1992)236-239

Metrology services and assurance of traceability:• Organization of national comparisons- Environmental type, mononuclide samples, 2 comparisons, 134Cs, 137Cs, 152Eu, M.Sahagia et al. Nucl. Instr. And Meth. A339(1994)38-42- Radiopharmaceuticals: 131I (1994 and 2007), 57Co (1998), 99mTc (1998 and

scheduled 2008). M.Sahagia et al. Proceedings, IRPA9 Congress, 1996, Vienna, Vol.3 pp.497-499

• Metrology services  As a B RML authorized and attested laboratory, RML performs - legal metrological check and calibration of equipment - standardizes radioactive sources for users (RML products, or imported).

• Accreditation by the national body, RENAR.- whole documentation for accreditation - submitted to RENAR- pre-assessment evaluation , according to EN ISO/IEC 17025-2005, by Mike J

Woods, IRMC Ltd., U.K. - RENAR evaluation of the documents and implementation - this year. - process is under way, with the accomplishment of corrective actions.

International cooperation

• Participation at international comparisons for absolute and relative standardization

• Membership in international organizations

• Bilateral and multilateral projects

Participation at international comparisons for absolute and relative standardization

• BIPM comparisons since 1962 - 60Co sources. • Adoption of the CIPM-MRA (Mutual Recognition

Arrangement) and establishment of the Annex B, Key Comparison Data Base (KCDB), RML is part of the program.

• Key comparisons registrations: (i) BIPM.RI(II)-K1: 110mAg, 133Ba, 60Co, 134 Cs , 131I . (ii) CCRI(II)-K2: 241Am, 109Cd,139Ce, 134Cs,137Cs, 152Eu, 55Fe,

125I , 192Ir, 54Mn, 32P, 75Se, 89Sr, 204Tl, 65Zn. (iii) EUROMET RI(II)-K2: 169Yb , 124Sb (under analysis)• Supplementary comparisons, organized by the IAEA CCRI(II)-S4 “Radionuclides activity measurement in

environmental samples of water, soil and grass” (2006); CCRI(II)-S5 “TENORM” (2007); CCRI(II)-S6 - 131I (2006) and 57Co (planned 2008)

Conclusions from comparisons

• Classification of results:

- Very satisfactory results- our result being considered for the calculation of the KC Reference Value (KCRV), 60Co, 152Eu,192Ir, 133Ba, 131I ( SIR 2007-2009 approval); results with small deviation from the mean: 54Mn, 65Zn, 55Fe, 204Tl

- Good results, registered in KCDB, but not in KCRV (134Cs, 241Am) - Not satisfactory - 125I. We identified the error sources and developed a

new, coincidence, standardization method.

• The program allowed us:- to validate our methods for absolute and relative standardization, - to establish the equivalence of the primary Romanian Activity standards

at the level of the CIPM-MRA, - to promote 37 Calibration and Measurement Capability (CMC) files,

for radioactivity, which were approved by all Regional Metrology Organizations

Membership in international organizations

•IFIN-HH - Member of the International Committee for Radionuclide Metrology (ICRM) since 1980- RML participated regularly, starting with 1991, at ICRM conferences and presented scientific papers. - Dr. Enric Leon Grigorescu served as ICRM - Vicepresident, during 1990 -1994 -Dr. Maria Sahagia is in the nominating commission, 2001-2009.

Recognizing the active participation in international comparisons and RML publication list• The Consultative Committee for Ionizing Radiations, Section Measurement of Radionuclides [CIPM-CCRI(II)], accepted IFIN-HH, as a full member, in 2004, besides other 18 Metrology Institutes and 8 Observers

In this quality, we presented reports at the 2005 and 2007 meetings and updated regularly the publication list.

Bilateral and multilateral collaboration

Bilateral:

CEA-DIMRI(DETECS/LNHB)-France

PTB-Germany

ENEA- Italy

Multilateral:

EC of Excellence – IDRANAP

IAEA- CRPs

Bilateral projects• Collaboration with LNHB-FranceCollaboration Agreement, concluded by the CEA-DIMRI (DETECS)/ LNHB – France and IFIN-HH, 1993, in force until 2010Very fruitful, all IFIN-HH, RML members worked in the LNHB and French colleagues in IFIN-HH.Common papers published:-X and gamma-ray spectrometry: A. Luca et al., Appl.Radiat.Isot. 52(2000)481-486, 56(2002)173-180, 58(2003)607-610; Appl.Radiat.Isot. 60(2004)233-237- LSC-TDCR: A.C. Razdolescu and P. Cassette, Appl.Radiat.Isot. 60(2004)493-498; -gas and LSC counting: D. Stanga et. al., Appl.Radiat.Isot. 64(2006)1203-1206, P. Cassette, M. Sahagia et al., Appl.Radiat.Isot. 64(2006)1465-1470; -LSC-TDCR using channel photomultipliers: C. Ivan et al., ICRM2007, Capetown, SA, Appl.Radiat.Isot. ref 4007. New directions developed at RML: LSC-TDCR method, Tritium gas measurement, High performance gamma-ray spectrometry and Nuclear Decay Data Evaluation, Radon standardization, Use of CPMs for LSC-TDCR.

Bilateral collaboration-continued

• IFIN-HH, RML benefited of a common calibration of the CENTRONIC IG12/20A Ionization Chamber at PTB-Germany, in 2001

• Collaboration with ENEA- Italy was accomplished by three ENEA fellowships, 2001- 2002: Source preparation, Coincidence counting, Surface sources measurement.

Multilateral projects

• European Commission’s Center of Excellence InterDisciplinary Research and Applications Based on Nuclear and Atomic Physics (IDRANAP), Contr. ICA1-CT-2000-70023/12.

- Radionuclide Metrology Laboratory participated as the WP 7 - RML members worked mainly at LNHB, on thematics: Decay Data evaluation, LSC-TDCR, Gas counting. - Colleagues from LNHB-France, RC POLATOM-Poland, ENEA-Italy,

Institute of Hungarian Academy -Center Debrecen, worked in RML, in the fields: LSC-TDCR, Coincidence counting, Positron emitters obtaining and standardization.

- RML members and his visitors had an important scientific contribution at the Conference: Applications of High Precision Atomic and Nuclear Methods (HIPAN 2002 ) Neptun, Romania, 2002:

9 participants from WP7, 9 papers presented-published in Conference Proceedings, Romanian Academy Editor, 2005

Multilateral Projects - continued

• International Atomic Energy Agency (IAEA) Coordinated Research Projects (IAEA-CRP)

- CRP E2.10.05 “Harmonization of quality practices for nuclear medicine radioactivity measurements” Contract ROM/12921/ 2004-2008 “Assurance of traceability, IAEA, IFIN-HH, hospitals, for nuclear medicine measurements”.

RML contribution - Participated at : two international comparisons 131I, 57Co (under way)- Organized a national (2007) and an international (2008), Ankara-Turkey

University-Medical Faculty 131I comparisons;

99mTc comparison - 2008 scheduled; - Participated at IAEA-TRS 454/2006,Quality Assurance for Radioactivity

Measurement in Nuclear medicine and other documents’ elaboration.

- CRP F42.006 „Updated Decay Data Library for Actinides” Contract ROM /13341/2005-2008: „Improved decay data for important actinides”, with details to be presented by Dr. Aurelian Luca

Conclusions• The Radionuclide Metrology Laboratory

developed methods and equipment for absolute standardization

• RML assured the whole traceability chain by offering radioactivity standards and metrology services to Romanian users.

• RML has a long tradition of participation in international activities

• RML validated its standards by participating in international programs of comparisons

THANK YOU!