Environment Laboratories, MonacoDepartment of Nuclear Sciences & Applications

IAEA-465 (BALTIC SEA SEDIMENT) STATUS:

CONTRIBUTION OF HELCOM MORS EG and

CONTRACTING PARTIES TO CERTIFY REFERENCE

MATERIALS FOR RADIONUCLIDES IN MARINE

ENVIRONMENTAL STUDIES

Pham M.K., Osvath I., Harms A.

IAEA-Environmental Laboratories, Monaco

Environment Laboratories, MonacoDepartment of Nuclear Sciences & Applications

Sampling – Bulk material

Preparation of the material (freeze-dried, sieved, homogenization, bottling, irradiation)

Homogeneity test for radionuclides (naturals and anthropogenic)?

Samples dispatched – measurement campaign

Feedback data to NAEL

Data evaluation - feedback the preliminary results to participants for comments

Final report for inter-laboratory run,

DiplomaSamples sent to expert laboratories

Certification process – calculation of “property value” and its uncertainty

Objectives met?

No

Yes

Homogeneityconfirmed?

Yes

Certified reference material

Improvement possible?

Continuation of measurement campaign at NAEL

No

Yes

Material cannot becertified

No

Yes

Recheck homogeneity at NAEL

No

General schema for certification process of reference materials realized at RML-NAEL-IAEA.

Environment Laboratories, MonacoDepartment of Nuclear Sciences & Applications

Sediment sample (IAEA-465), collected by HELCOM-MORS from Baltic Sea. Station JML

TOTAL DEPTH: 82m, St. JML

POS: (N59º34.91, E023º37.608)

Persons taking the sample: Pekka Kosloff, Pekka Kotilainen

Description of the material (IAEA-465, Baltic Sea Sediment)

• 225 kg wet sediment were sampled by box corer (20 × 20 cm) on 26August 2012, at 82 m depth in the Baltic Sea (at 59° 34.91’ N, 23° 37.61’E; station JML of the RV Aranda August 2012 cruise for the HELCOMCOMBINE program)..

• The sediment was first dried in open air to 108 kg and subsequently inheating cabinets at 85 °C leaving a total dry mass of 60 kg.

• The sample was then ground into a powder, using a micronizationtechnique, homogenized by mixing under nitrogen atmosphere,bottled and sealed in polyethylene flasks (50 g units) and coded asIAEA-465 (for a total of 960 bottles).

• All bottles were sterilized at 28 kGy (60Co) at an irradiation facility(Synergy Health, France). The moisture content of the sample wasfound to be approximately 1.9% by drying 1g of sample at 105 °C to aconstant mass.

Homogeneity tests• Two most important technical consideration in the certification of RMs:

Material homogeneity and stability (ISO 35, 2006, Reference materials – General and statistical principles for certification).

• Test of homogeneity for Between–bottles and Within-bottle:

Number of bottles used for homogeneity test: 3x15 bottles (for total 960 bottles) taken randomly for the test.• Method used for homogeneity study should have very good repeatability and

selectivity.• Analyses done by competent technicians in the lab (consumed a lot of time and

human resources).• Homogeneity test performed for:

Radionuclides: – The number of Radionuclides used for test as

many as possible, as each radionuclide has adifferent biogeochemical behaviour in theenvironment.

Other components - Trace metals- Elemental compositions

Homogeneity tests (cont’d)Homogeneity test done for :• 40K, 137Cs, 214Bi, 226Ra, U isotopes and 239+240Pu

Techniques used:• High-resolution low-background gamma-spectrometry, • alpha-spectrometry, • Inductively Coupled Plasma - Mass Spectrometry (ICP-MS), and• Accelerator Mass Spectrometry (AMS).

Weight used:• 1st test for between bottles for 3 x 15 bottles, using 5g of sample for

alpha-spectrometry, and 40 g for gamma-spectrometry.• 2nd test for within-bottles heterogeneity test was done for another 10

aliquots of 10 g of sample for gamma-emitters, and 0.3 g of materialfor Pu isotopes determination using (AMS) as well as for Uraniumisotopes using (ICP-MS) technique.

• 3rd test for 20 aliquots of from 20 different bottles (20 g of samples),counted by gamma spectrometry.

Homogeneity tests (cont’d)IAEA-465, test of homogeneityCs-137

Sample Number

No4

46

No5

61

No2

50

No3

71

No9

21

No9

0

No8

41

No2

29

No7

81

No3

No1

37

No1

20

No6

11

No4

89

No8

01

0.90

0.95

1.00

1.05

1.10

St. dev.

St. dev.

95% conf. lim.

95% conf. lim.Mean

Rel

ativ

e va

lue

Homogeneity tests (cont’d)Table 1 – Homogeneity uncertainty 20 samples of IAEA-465

Nuclide u bb (%) u meas (%) u int (%) u hom (%)137Cs 1.5 1.0* 1.1 1

40K 1.1 1.7* 1.2 0

where u bb (%) is relative standard deviation between bottles (or uncertainty of the between-bottle hetegeneity)u meas (%) is uncertainty of measuerementu int (%) is repeatability of the measurementu hom (%) is homogeneity uncertainty of xx (20) samples taken randomly from a total of 960 bottles (a combine uncertainty of ubb and umeas)* represents value used to calculate u hom

(uc(bb) or uhom) is a combined uncertainty of the between-bottle heterogeneity (ubb) and the measurement variation (umeas)

Sample dispatch and data feedback• 26 selected participants received samples on May 2016• 26 feedback, the last one received at the end of March 2017• Sending out the draft report to participants for their comments and

correction if any.

HELCOM-MORS participants:

• Denmark (DTU Nutech,Technical University of Denmark): DM• Finland (STUK – Radiation and Nuclear Safety Authority): FI• Germany (6 participants from Germany, some belong to HELCOM

contracting party: (i) Johann Heinrich von Thünen-Institut (GE (i)), Institut für Fischereiökologie, (ii) Federal Maritime and Hydrographic Agency (FMHA) (GE (ii)) and (iii) Landesmessstelle für Radioaktivität (GE (iii))

• Poland (3 participants from Poland, two belong to HELCOM: (i) Central Laboratory for Radiological Protection (PO (i)) and (ii) Institute of Meteorology and Water Management, Maritime Branch (PO (ii))

• IAEA

Sample dispatch and data feedback

• Detail report requested from participating laboratories:•• (1) average weight of sample used for analysis;• (2) number of analyses;• (3) massic activity (Bq kg-1) corrected for blank, background, etc.;• (4) estimation of the combined uncertainties;• (5) description of chemical procedures and counting equipment;• (6) standard solutions used for analysis;• (7) chemical recoveries (if any), counting time and decay

corrections.• The reference date for reporting activities was set-up (sampling date-

26th August 2012).

Criteria for assigning values and uncertainties_ISO Guide 13528

• The obtained data were first checked for compliance with the certificationrequirements, and then for their validity based on technical reasoning.

• All accepted set of results were used for robust statistical calculation.Robust statistics as described in ISO Guide 13528 (ISO, 2005) were usedfor the determination of the assigned values, where the robust mean androbust standard deviations were calculated as per Algorithm A as describedin Annex C.1 of ISO 13528.

• A certified value was assigned when at least 5 independent results wereavailable and the relative expanded uncertainty was less than 15 %. Thenumber 15 % chosen based on the homogeneity test of differentradionuclide, and would reach maximum 20% for activities lower than 1Bq kg-1

• For the radionuclides where these criteria were not fulfilled, the robust meanand relative expanded uncertainties were given only as information values.

Criteria for assigning values and uncertainties_Cont’d

• These criteria were fulfilled for:

40K, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 228Th, 230Th, 232Th, 234Th, 234U, 235U, 238U, 239+240Pu and 241Am (alpha technique only)

• and the information values are given to otherradionuclides 238Pu and 241Am (both gamma andalpha techniques used).

Environment Laboratories, MonacoDepartment of Nuclear Sciences & Applications

Data distribution for Cs-137 in IAEA-465

137Cs (IAEA-465)

Laboratories

18 9 19 21 24 20 17 13 22 11 23 14 7 18 25 3 6 16 10 5 15 12 22 8 4 1

Bq kg

-1

50

60

70

80

90

100

110

120

130

140

150

160

GE (iii)

GE (ii)

GE (i)

DM

FI

PO (i)

PO (ii)

IAEA

Environment Laboratories, MonacoDepartment of Nuclear Sciences & Applications

Data distribution for Pu-239+240 in IAEA-465

239+240Pu (IAEA-465)

Laboratories

26 2 23 9 13 17 12 5 10 6 22 18 22 4 20 1 16 25 27 21

Bq kg

-1

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

IAEA

DM

PO (i)

GE (iii)

GE (ii)

GE (i) FI

Environment Laboratories, MonacoDepartment of Nuclear Sciences & Applications

Data distribution for Am-241 in IAEA-465

241Am (IAEA-465)

Laboratories

17 1 9 6 12 20 26 17 11 10 12 8

Bq k

g-1

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

2.4

2.6

2.8

3.0

Environment Laboratories, MonacoDepartment of Nuclear Sciences & Applications

Massic activities in the natural uranium and thorium series in IAEA-465 (Reference

date is 26th August 2012)

36%

232Th 62.4 ± 5.0

Bq kg-1

228Ra 65.7 ± 4.4 Bq kg-1

228Th 67.4 ± 8.7 Bq kg-1

224Ra 53 ± 8.5 Bq kg-1

208Tl 63.1 ± 7.0 Bq kg-1

238U 87 ± 6 Bq kg-1

234U 88.6 ± 5.7 Bq kg-1

230Th 71.6 ± 9.7 Bq kg-1

226Ra 54.2 ± 3.1 Bq kg-1

210Pb/210Po 189 ± 8 Bq kg-1

Uranium series

Thorium series

TABLE 19. SUMMARY OF CERTIFIED VALUES FOR IAEA-465 (Reference date: 26 August 2012, unit: Bq kg-1)

Radionuclide Certified valuea

[Bq kg-1]

Expanded uncertaintyb

[Bq kg-1] Nc

40K 1073 51 24

137Cs 107 4 26

210Pb(210Po)d 189 8 24

226Ra 54.1 3.1 15

228Ra 65.7 4.4 15

228Th 67.4 8.7 8

230Th 71.6 9.7 5

232Th 62.4 5.0 10

234Th 88.8 9.4 8

234U 88.6 5.7 11

235U 4.01 0.23 14

238U 87.0 6.1 18

239+240Pu 2.18 0.06 20

241Am (alpha)e 0.95 0.04 7

Note: Tables 19–20:

a The value is the robust mean (estimated in accordance with the ISO 13528) of accepted sets of data, each set being obtained by different laboratory. The certified values are reported on dry mass basis and are traceable to the SI.

b Expanded uncertainty with a coverage factor k=2 estimated in accordance with the ISO 13528. c Number of accepted data for evaluation. d 210Pb and 210Po were considered as in equilibrium. e 241Am certified value for only alpha measurement method.

TABLE 20. SUMMARY OF INFORMATION VALUES FOR IAEA-465 (Reference date: 26 August 2012, unit: Bq kg-1)

Radionuclide Information valuea [Bq kg-1]

Expanded uncertaintyb [Bq kg-1] Nc

238Pu 0.073 0.013 14 241Am 1.07 0.21 12

IAEA-465 STATUS• Draft report has been sent to participants for their

comments and corrections if any.

• Corrected report and certificated sheet will be submitted to the IAEA-RMCC for reviewing processes.

• Final report will be printed in Vienna and CRM to be released for MS use, foreseen next year.

Acknowledgments

• The authors are indebted to numerous colleagues who contributed numerous measurements on the material.

• Special acknowledgement is given to the HELCOM-MORS for providing the Baltic Sea sediment.

• The IAEA is grateful to the Government of the Principality of Monaco for the support provided to its Environment Laboratories.

SOME CONCLUSIONSThe production of a new certified reference material is a longprocess:

• Covering the identification of needs,• Sample collection,• Pre-treatment, physical homogenization, bottling, homogeneity

test,• Distribution to laboratories,• Evaluation of data, preliminary reporting,• Additional analyses by expert laboratories, certification of

material (including the determination of proper values and theiruncertainties),

• And finally issuing the RMs/CRMs. More than 45 referencematerials have been produced, including a wide range ofmarine sample matrices and radionuclides.

List of CRMs have been produced last 20 years at RML

Code Matrix Origin AnalytesUnits on Stock in Vienna

Units on Stock in Monaco

IAEA-437 Mussel Mediterranean Sea Radionuclides 170 30

IAEA-418 Water Mediterranean Sea 129I 144 20

IAEA-384 Sediment Fangataufa lagoon Radionuclides 500 43

IAEA-414 Fish flesh Irish and North Seas Radionuclides 554 28

IAEA-385 Sediment Irish Sea Radionuclides 1600 160

IAEA-443 Water Irish Sea Radionuclides 130 15 (5 liters)

IAEA-446 Fucus/Seaweeds Baltic Sea Radionuclides 750 145 (100g)

TOTAL 3848 441

List of CRMs candidate to be produced at RML

Code Matrix Origin AnalytesUnits on Stock in Vienna

Units on Stock in Monaco

IAEA-410 Sediment Bikini Atoll Radionuclides 150

IAEA-412 Sediment Pacific Ocean Radionuclides 175

IAEA-465 Sediment Baltic Sea Radionuclides 960

New material needed: fish, molluscsIf opportunity arises, support and collaboration much appreciated!

Latest development for IAEA CRMs production at RML

• Accreditation for CRMs following ISO 34, ISO 35, ISO/IEC 17025

• First step for gamma spectrometry ISO 18589-3 (soil), ISO 10703 (water)…ISO 11929 (determination of the characteristic limits: Decision threshold, LLD, Int. Conf….)

IAEA need:• Pu-241 analysis in reference fish sample

being re-certified.

It would be appreciated if:

• Anyone from HELCOM-MORS could do it?• Or know any colleague from other

institutes/organisations could do it?• Thank you