European Metrology Research Project IND 57 (MetroNORM): Metrology For Processing Materials with High Natural Radioactivity

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1 European Metrology Research Project IND 57 (MetroNORM): Metrology For Processing Materials with High Natural Radioactivity Marie-Martine Bé, CEA(FR); Pierino de Felice, ENEA(IT); Mikael Hult, JRC-IRMM(EU); Simon Jerome, NPL(UK), Franz-Josef Maringer, BEV/PTP(AT); Monika Mazánová, ČMI(CZ) and Branko Vodenik, IJS(SI) 60 th RRMC, Knoxville, Tennessee: 27 th -31 st October 2014 Date

2 Features of the EMRP The European Metrology Research Programme aims to - Promote high quality, joint R&D amongst the metrology community in Europe - Address explicit stakeholder needs - Facilitate closer integration of national research programmes. - Reduce duplication and increase impact. - Involve researchers and organisations other than the NMIs, DIs and JRC - Principal goal is to accelerate innovation and competitiveness Value to NMI community nominally 70m p.a. of which 50% contributed by EU

3 MetroNORM Need for the project - Naturally occurring radionuclides are present in many natural resources - Exploitation leads to exposure to Naturally Occurring Radioactive Materials (NORM) in products, by-products, residues and wastes, some of which may be produced in large quantities. - Handling/processing such materials implies the need to determine the nuclides present and their activity concentrations as accurately as possible - Requirement for for reference materials to validate radioanalytical procedures, measurement strategies and data processing. Runs from 1-Sep-2013 to 31-Aug-2016

4 MetroNORM Partners - BEV/PTP Austria - CEA France - CIEMAT Spain - ČMI Czech Republic - ENEA Italy - IJS Slovenia - IST Portugal - JRC-IRMM EU - MIKES Finland - MKEH Hungary - NPL UK - NRPA Norway - STUK Finland - BOKU Austria - SURO Czech Republic

5 Work Packages Reference Materials and Sources (ČMI) Development of in situ measurement systems and sampling methods (NPL) Standardisation of measurement procedures (IRMM/NPL) Improvement of NORM-related decay data (CEA) On site/in situ testing (IJS) Creating impact (ENEA) Coordination and project management (BEV/PTP)

6 WP1 Reference materials (ČMI) Task 1.1 Specification of reference materials and standard sources Task 1.2 Reference materials and standard sources for laboratory measurements Task 1.3 Reference materials and standard sources for in situ measurements Task 1.4 Standardisation of reference materials and sources

7 WP1 Reference materials (ČMI) Task 1 Specification of materials - Target industry sectors: Extraction of rare earths, Niobium/tantalum ore processing, TiO 2 pigment production, Phosphate processing industries, Construction materials, Metal processing and smelting, Water production, Recycling industries, and Oil and natural gas industries.

8 WP1 Reference materials (ČMI) Selection of at least 4 materials - Grouped as follows Group 1: Group 2:(i) (ii) (iii) (iv) Group 3: Group 4: Residue/waste from Ta/Nb ore processing Residue/waste from phosphogypsum processing Ash of the type used in building Residue/waste from TiO 2 production Tuff used in building Filters, resins and from water purification. Scale from the oil industry.

9 WP1 Reference materials (ČMI) Evaluation of materials - Divided between participants IRMM: Ferro-niobium oxide slag G1 ČMI: Residue/waste from TiO 2 production G2 ČMI: Coal ash used in building G2 ENEA: Tuff used in building G2 IRMM: Residue/waste from phosphogypsum processing G2 NPL: Building aggregate G2 ČMI: IONEX resin from water industry G3 NPL: FeO(OH)/MnO 2 sludge from water industry G3 NPL: Oil wastes G4

10 WP1 Reference materials (ČMI) Reference sources - For γ-spectrometry Mixed nuclide source for detector calibration Reference materials detailed above - For α-spectrometry Electroplated sources (usual type) of U nat and 226 Ra Larger sources for portable system Calibration - Absolute Coincidence counting for constituents of mixed γ sources Solid angle counting for reference α sources - Relative Reference materials Larger α sources

11 WP2 Measurement systems (NPL) Task 2.1 Development of in situ measurement systems and sampling methods Task 2.2 Development of a sampling device for laboratory analysis Task 2.3 Systems for 220 Rn (Thoron) measurement

12 WP2 Measurement systems (NPL) Technologies - The device needs to be portable - Measurements are non-destructive - Designing new equipment is impractical, since technologies already exist Constrains the choice to a γ-ray detectors (measurement of α- and β-emissions is possible, but uninformative) Self-contained device is preferable (portability excludes the use of LN 2 cooled germanium detector) Choices are a γ-ray detector, operating at room temperature. NaI(Tl) crystals, LaBr 3 (Ce) crystals, (Cd,Zn)Te CeBr 3, or SrI 2 - On the basis of performance, availability and state of development, the recommendation is that LaBr 3 (Ce) crystals are the optimum choice

13 WP2 Measurement systems (NPL) Drawback of LaBr 3 :Ce - Naturally occurring lanthanum consists of 0.09% 138 La which is radioactive and decays by electron capture and beta emission (see fig 1) and produces gammas at kev and kev.

14 WP2 Measurement systems (NPL) Ba (k α, β = 32.19, kev) Ce ( kev) α-particles from 4n+3 series Ce ( kev) Counts Energy / kev

15 WP2 Measurement systems (NPL) Data processing - Determination of activities by dividing spectrum into regions and using matrix inversion to derive activities 40 K; 138 La; 176 Lu 228 Ra- 228 Ac; 228 Th- 208 Tl 238 U- 234m Pa; 226 Ra- 214 Po; 210 Pb- 210 Po; 235 U- 231 Th; 231 Pa; 227 Ac- 207 Tl;; 87 Rb, 147 Sm, 230 Th and 234 U not possible - Assumption that combined unknown spectrum is a direct superposition of fundamental spectra of the component elements. nn 11 nn 11 nn 1jj nn 1 nn 1jj aa 1 mm 1 αα 1 + αα 2 αα jj = = nn ii1 nn ii1 nn iiii nn ii1 nn iiii aa jj mm jj

16 WP2 Measurement systems (NPL) Hand held prototype - System being developed at INFN (Italy)

17 Measuring surface contamination using ADONIS α-detector MCA and computer in a backpack Data transfer to remote expert support (reachback)

18 Testing background MCA-box (preamp.+battery+mca) Detector Laptop (toughpad)

19 220 Rn/ 222 Rn progeny in a glassfibre air filter (no collimation) 212 Bi, 218 Po 218 Po 212 Po β and γ 6.0 MeV 7.7 MeV 8.8 MeV

20 To be done Testing operation of the equipment in a laboratory - STUK sources - NPL source Testing data transfer to reachback - Field testing Data visualization in reachback Scientific reporting

21 WP2 Measurement systems (NPL) NORM industry sampling - Oil industry responses suggest: Samples received from oil industry include mixture of scale/or wax and oil in various proportions complicated by mixed matrices: scale, water, sand, wax, oil Some RPAs go for sampling of drummed waste for sentencing, but issues with inhomogeneity - Sampling/assay: Crush, sieve, homogenise and prepare sources under: Ambient conditions Low moisture atmosphere to avoid inconsistency with water content Automations (sample changers) are recommended Consistent measurement volumes

22 WP2 Measurement systems (NPL) Sample preparation method - Measurements by γ-spectrometry are clear from ČMI recommendations - Propose techniques developed in MetroRWM for preparation of radiochemical analysis samples: Crush, sieve and homogenise samples: Fuse with KATANAX system LiBO 2 /LiB 2 O 7 /LiBr flux Residual solids removed with PEG and HF/HNO 3

23 WP2 Measurement systems (NPL) Thoron - Design of a production chain of 220 Rn in a vacuum set-up (introduction of 222 Rn is also possible) - Design of a measurement system of thoron by α spectrometry of a volume source - Modeling of the measurement set-up to calculate its detection efficiency for a volume source by using a simulation code - Development of a measurement system making possible the on-line determination on a calibration bench of the 220 Rn activity (collaboration with IRSN) - Comparison with γ spectrometry

24 WP2 Measurement systems (NPL) Design of a production chain of 220 Rn: Vacuum line

25 WP2 Measurement systems (NPL) Design of a production chain of 220 Rn: parts of the chain Temperature pressure and humidity control 228 Th source Measurement volume Decay products: - solid elements (isotopes of Po, Pb, Bi) produced by α or β disintegrations - positively charged - trapped on the detector with an electric field Polarization of the detector High voltage power supply for the electric field

26 WP2 Measurement systems (NPL) Results of optimized simulations: Electric field Flow rate Path of charged particles

27 WP2 Measurement systems (NPL) Design of a production chain of 220 Rn: First spectrum - The spectrum allows the determination of 216 Po activity and the determination of 220 Rn activity. Linear spectrum Logarithmic spectrum

28 WP2 Measurement systems (NPL) Thoron Chamber at INMRI-ENEA - Thoron exits from the vessel and naturally diffuses into the chamber: fan used to achieve an uniform concentration inside the chamber - Thoron concentration is measured by a Durridge RAD7 monitor: based on electrostatic collection of radon and thoron decay products on a silicon detector - Measurements are carried out in separate windows: A 218 Po/ 212 Bi B 216 Po C 214 Po D 212 Po - The collection efficiency for 218 Po and 214 Po appear to be the same, and knowledge of the 212 Bi branching ratio allows the deconvolution of 218 Po/ 212 Bi

29 WP2 Measurement systems (NPL) Durridge RAD7 monitor 228 Th source producing 220 Rn

30 Task 2.3 Thoron: 220 Rn 70 Po216 Po212 Bi212+Po Po218+Bi212 Po214 Po cpm cpm time (h) time (h) Count rate for 220 Rn decay product with RAD7 Count rate for 220 Rn and 222 Rn decay product with RAD7

31 WP3 Standardisation of procedures (IRMM) Task 3.1 Identification of key methods Task 3.2 Standardisation of laboratory procedures Task 3.3 Standardisation of in situ procedures

32 WP3 Standardisation of procedures (IRMM) Data collected on analysis procedures across the EU Direct mailing Information collated and analysed Report due end November 2014

33 WP4 Decay data Task 4.1: 238 U (4n+2) decay series Task 4.2: 235 U (4n+3) decay series Task 4.3: Task 4.4: 138 La NORM-specific measurement problems

34 WP4 Decay data Radium Lack of data and wide spread of reported values Radium-226 α-particle emission intensities measured twice: Bastin-Scoffier, G., Leang, C.F. and Walen, R.J., J.Phys., 24, 854, (1963) LaMont, S.P., Gehrke, R.J., Glover, S.E. and Filby, R.H., J.Radioanal.Nucl.Chem., 248, 247, (2001) Radium-226 γ-ray emission intensities have 5 contributing values at 186 kev: Contributing values vary by ~2.6% Daughter radionuclides show similar, if not wider variation. Radium-226 X-ray emission Uncertainties of ~2-3%

35 WP4 Decay data Lead Wide spread of reported values Lead-210 γ-ray emission intensities have 4 contributing values at 46 kev: Contributing values vary from 4.24 to 4.8% Lead-210 X-ray emission Uncertainties of ~2-3%

36 WP4 Decay data Uranium-235 et seq - Complex data set Uranium-235 γ-ray emission intensities reasonably well known: Uncertainties for main lines ± ~0.6% (k=1) Precision needed in order to correct for 226 Ra interference Protactinium-231 γ-ray emissions complicated by interferences from 227 Ac onwards chain Low abundance Contributing values discrepant in some cases Data is sparse and old

37 WP4 Decay data Thorium Standardised by 4πLS-γ with digital data acquisition and CIEMAT/NIST efficiency tracing - Half life measured - Measurement of γ-ray emission probabilities in progress Radium Standardised by 4πLS-γ with digital data acquisition and CIEMAT/NIST efficiency tracing - Half life measured - Measurement of γ-ray emission probabilities in progress

38 WP4 Thorium-227 Standardisation - Was standardised by 4πLS-γ with digital data acquisition and CIEMAT/NIST efficiency tracing Half-life (stated as (9) days in ENSDF) - Separated from 227 Ac parent and 223 Ra (et seq.) daughters - Decay of 227 Th monitored via: 50.1 kev γ-ray, summed peak area of the and kev γ-rays, and kev γ-ray - Value measured to be (25) days - Only direct measurement that has been made - Followed over 75 days (~4 half-lives) - Paper drafted (Collins, Pearce, Pommé and Jerome) γ-ray emissions measurement in progress

39 WP4 Radium-223 Standardisation - Separated material (from 227 Ac and 227 Th parents) used - Was done by 4πα-γ, 4πβ-γ, 4πLS-γ, TDCR - All techniques gave consistent results - Ionisation calibration figure derived for equilibrated 223 Ra - Paper drafted (Keightley, Pearce, Fenwick, Collins, Ferreira, Johansson) Half-life (stated as (3) days in DDEP) - Decay of 223 Ra monitored via: Continuous ionisation chamber measurements - Consistent with DDEP value - Will publish with 227 Th half-life in same paper γ-ray emissions measurement in progress

40 WP4 Decay data Actinium Lack of data Actinium-227 difficult to accumulate in large amounts until recently Spread of up to ±10% on γ-ray emissions from daughter nuclides Measurement challenging, due to low activities in past Problems revealed by increasing medical use of 223 Ra

41 WP4 Decay data 4n+3 decay chain: 231 Pa to 207 Pb - Lack of data only small amounts available until 2000 Many interfering γ-rays Half lives rarely measured (measurement of 211 Pb half life at NPL first since 1965 and 1939) Complex decay Plan to climb up the decay chain 223 Ra: 227 Th: 227 Ac: 231 Pa:

42 WP4 Decay data Lanthanum Rare nuclide Lanthanum-138 has a half-life of years and forms ~0.09% of natural lanthanum Specific activity of lanthanum ~0.83 Bq/g Impossible to accumulate in large amounts Curse and blessing for LaBr 3 :Ce detectors raises background, but also acts as an internal calibration nuclide Spread of up to ±5 to 10% on γ-ray emissions Measurement challenging, due to low activity

43 WP5 On site/in situ testing (IJS) Task 5.1: Task 5.2: Starts 2015 Specification of verification criteria and procedures On site/in situ verification of measurement systems and procedures

44 Conclusions WP1: WP2: WP3: WP4: WP5: Materials specified measurement in progress Equipment and techniques identified and being implemented First report due on standardising and verifying procedures Data measured for 223 Ra and 227 Th. 227 Ac, 231 Pa, 235 U, 226 Ra, 210 Pb and 138 La to follow Not started yet

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