INTERNATIONAL ATOMIC ENERGY AGENCY

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2 1/4 INTERNATIONAL ATOMIC ENERGY AGENCY AGENCY'S LABORATORIES, A 444 SEIBERSDORF, AUSTRIA TEL NO.: ; FAX NO.: ; AQCS@.ORG Department of Nuclear Sciences and Applications Physics, Chemistry and Instrumentation Laboratory Chemistry Unit / AL / 15 Final Report on the Proficiency Test of the Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA) Network Abdulghani Shakhashiro, Zbigniew Radecki, Alexander Trinkl, Umberto Sansone, Thomas Benesch Seibersdorf, August 5 Almera Final Report

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4 Page 3 CONTENTS 1. ABSTRACT ACKNOWLEDGMENT INTRODUCTION OBJECTIVE OF THE ALMERA PROFICIENCY TEST PARTICIPANTS OF THE ALMERA PROFICIENCY TEST MATERIALS AND METHODS Preparation of standard and spiking solutions Mixed alpha emitting radionuclides solution for spiking soil samples 1,, 3 and standard solution sample Sr solution for spiking soil samples 1,, 3 and 9 Sr standard solution sample Mixed gamma emitting radionuclides solution for spiking soil sample Preparation of solution of mixed carriers Spiking procedure for soil samples 1,, 3 alpha emitting radionuclides and 9 Sr Spiking procedure for soil sample 7- gamma emitting radionuclides Sample blank preparation Mixed gamma emitting radionuclides standard solution: sample 8 (ampoules) RESULTS AND DISCUSSIONS Target values and uncertainties Gamma emitting radionuclides Alpha emitting radionuclides and 9 Sr PERFORMANCE CRITERIA EVALUATION CRITERIA PERFORMANCE EVALUATION REPORTS SORTED BY LABORATORY Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

5 Page 4/4 1.9 Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : 5-A Laboratory : Laboratory : Laboratory : Laboratory : 55- A Laboratory : Laboratory : Laboratory : Laboratory : 6-A Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : 65-A Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : Laboratory : SUMMARY OF PERFORMANCE EVALUATION SORTED BY RADIONUCLIDE Am-41, measured by Gamma Spectrometry in Standard Solution Am-41, measured by Gamma Spectrometry in Spiked Sample Co-57, measured by Gamma Spectrometry in Standard Solution Co-57, measured by Gamma Spectrometry in Spiked Sample Co-6, measured by Gamma Spectrometry in Standard Solution Co-6, measured by Gamma Spectrometry in Spiked Sample Cs-134, measured by Gamma Spectrometry in Standard Solution Cs-134, measured by Gamma Spectrometry in Spiked Sample Cs-137, measured by Gamma Spectrometry in Standard Solution Cs-137, measured by Gamma Spectrometry in Spiked Sample Zn-65, measured by Gamma Spectrometry in Standard Solution Zn-65, measured by Gamma Spectrometry in Spiked Sample Am-41 in Standard Solution Am-41 in Spiked Sample Am-41 in Spiked Sample Am-41 in Spiked Sample Pu-38 in Standard Solution Pu-38 in Spiked Sample Pu-38 in Spiked Sample Pu-38 in Spiked Sample Pu-39+4 in Standard Solution

6 Page Pu-39+4 in Spiked Sample Pu-39+4 in Spiked Sample Pu-39+4 in Spiked Sample Pu-41 in Standard Solution Pu-41 in Spiked Sample Pu-41 in Spiked Sample Pu-41 in Spiked Sample Sr-9 in Standard Solution Sr-9 in Spiked Sample Sr-9 in Spiked Sample Sr-9 in Spiked Sample CONCLUSIONS AND RECOMMENDATIONS REFERENCES ANNEX A: LIST OF PARTICIPANTS ANNEX B: HANDLING INSTRUCTIONS AND REPORTING FORMS FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

7 Page 6/4 Final Report on the Proficiency Test of the Analytical Laboratories for the Measurement of Environmental Radioactivity (ALMERA) Network 1. ABSTRACT This report presents the statistical evaluation of results from the analysis of 1 radionuclides in 8 samples within the frame of the First Proficiency Test of Analytical Laboratories for the Measurement Environmental RAdioactivity (ALMERA) organized in 1- by the Chemistry Unit, Agency's Laboratory in Seibersdorf. The results were evaluated by using appropriate statistical means to assess laboratory analytical performance and to estimate the overall performance for the determination of each radionuclide. Evaluation of the analytical data for gamma emitting radionuclides showed that 68% of data obtained a Passed final score for both the trueness and precision criteria applied to this exercise. However, transuranic radionuclides obtained only 58% for the same criteria. Gamma Overview Emitters of performance on determination of gamma emitting radionuclides Trueness criteria failed 4% Precision criteria failed 1% Final Score failed 3% 76% 9% 68% Overview of performance on determination of transuranic (TRU) radionuclides Transuranic radionuclides Precision critetia Trueness criteria Final Score failed 6% failed % failed 4% 74% 8% 58%. ACKNOWLEDGMENT This work is a result of team work of the Chemistry Unit staff, Agency's Seibersdorf Laboratory, special thanks to Ms. Karin Will for her assistance in editing the report.

8 Page 7 3. INTRODUCTION ALMERA (Analytical Laboratories for the Measurement of Environmental Radioactivity) is a laboratory network to provide a world-wide emergency assistance coverage for environmental radioactivity measurements. ALMERA was formally established in 1999 when the International Atomic Energy Agency () issued a request to its Member States to nominate laboratories for membership. The membership of ALMERA is always open to new candidates who must be officially nominated by their government. ALMERA currently consists of 84 laboratories drawn from 5 countries, whose goal is to provide accurate radionuclide analysis in environmental samples for Member States in the event of an accidental or intentional release of radioactivity. It will be counted on by the world to support the s activities in the event of any future accidental or intentional release of radioactivity as a result of negligent, criminal or terrorist activities. The Agency's Laboratory in Seibersdorf and its Marine Environment Laboratory in Monaco are members of the network. The Chemistry Unit of the Physics, Chemistry and Instrumentation Laboratory in Seibersdorf is the central co-ordinator of the network's activities and provides technical assistance to help the laboratories to improve their readiness in case of need. The network consists of a core team from the and one or more regional teams selected for their ability to meet performance requirements, training, inter-comparison of emergency measurement capabilities and rapid access to member countries in their region. It was created to respond to a specific need and does not affect the co-operation arrangements defined in any bilateral and/or multilateral agreements between States. In order to remain as an active ALMERA member, a primary requirement is the successful participation in the proficiency tests, specifically organized for ALMERA on a regular basis, to monitor and demonstrate the performance and analytical capabilities of the network members. One of the goals of these proficiency tests is to monitor and demonstrate improvements in the accuracy (trueness and precision) and the international comparability of measurements of radionuclides in environmental samples over time by the members. Inadequate performance in an ALMERA proficiency tests precludes the member from participating in any related international activities until adequate performance is demonstrated in subsequent proficiency tests. This report presents the results of a laboratory proficiency test organized in 1 using spiked soil samples, to evaluate the analytical performance of the laboratory members of ALMERA. In this study, laboratory means of up to 1 radionuclides from 53 laboratories are compared with target values. Outliers were identified by using HISTO program [5], which was developed by the Chemistry unit in Seibersdorf. The participants results were evaluated against acceptance criteria for trueness and precision. The laboratories performance are presented and corrective action are proposed where necessary. 4. OBJECTIVE OF THE ALMERA PROFICIENCY TEST The aim of this proficiency test was to evaluate the analytical performance of ALMERA network participants in analysing a mineral matrix spiked with man made radionuclides. FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

9 Page 8/4 5. PARTICIPANTS OF THE ALMERA PROFICIENCY TEST The first ALMERA Proficiency Test was organised by the free of charge to the ALMERA Network members. 53 laboratories from 37 countries from five continents agreed to participate and reported measurement results. The geographical distribution of the laboratories reporting analytical results is shown in figure (1). ANNEX A shows the complete list of participants. Geographic Distribution of Participants in the first ALMERA Proficiency Test Middle East Africa 11% % Americas 6% Australia % Asia 19% Total Europe 6% Figure (1): The geographical distribution of the laboratories reporting analytical results 6. MATERIALS AND METHODS The following PT design was adopted: Two sets of samples were prepared; each consisted of spiked soil samples and the relevant standard solutions. The first set contained three equal samples of soil (samples 1,, 3 each 5g) spiked with a mixture of 38 Pu, 39+4 Pu, 41 Am and 9 Sr radionuclides, one ampoule with a standard solution of Pu+Am radionuclides (Sample 4) and one ampoule with 9 Sr standard solution (sample 5). The second set contained spiked soil (sample 7, 5g ) and an ampoule with a standard solution (sample 8) of the relevant radionuclides; in addition to a blank soil (sample 6, 5g) this set was designed for gamma-spectrometric measurements. The standard solution contained the above radionuclides at activity concentrations three orders of magnitude higher than in the solid samples to facilitate the detector efficiency check. The participants were asked to choose which set of samples (or both) they were willing to analyse. They received the chosen set, together with handling instructions and the reporting forms (see annex B). For spiked soils (samples 1,, 3 and 4) analysts were obliged to analyze the entire sample, as these samples were not homogenized after spiking. Each sample had its own code, which consisted of four digits, the first two digits to code the sample type, and the third and fourth digits for laboratory coding. The description of these samples is shown in Table 1:

10 Page 9 Table 1- Radionuclide composition of PT samples Sample code Description Radionuclides 1 Spiked soil Spiked soil 3 Spiked soil 4 Standard solution 5 38 Pu, 39 Pu, 4 Pu, 41 Pu, 39+4 Pu, 41 Am, 9 Sr 38 Pu, 39 Pu, 4 Pu, 41 Pu, 39+4 Pu, 41 Am 9 Sr standard solution 9 Sr 6 Blank - 7 Spiked soil 8 γ emitters standard solution 57 Co, 6 Co, 65 Zn, 134 Cs, 137 Cs, 41 Am A soil from China was used to prepare a spiked mineral matrix with gamma-emitting radionuclides, actinides and 9 Sr at different levels. The matrix of Chinese soil was characterised and a number of samples of this soil were prescreened for man-made gamma-emitting radionuclides prior to spiking. The results have shown that the material is free from man-made radionuclides, except for 137 Cs, which was present at the 3±.15Bq/kg activity concentration level. Before using the soil for spiking, it was sieved and passed through a.4mm sieve to collect the appropriate mesh size fraction. Eighteen sub-samples of the soil material were taken from a batch at random for the determination of 9 Sr, 38 Pu, 39+4 Pu, 41 Pu and 41 Am activities in the matrix. The results showed that all these radionuclides are present in the material, however the levels of activity that were spiked into the soil were at least two orders of magnitude above the endogenous level. 6.1 Preparation of standard and spiking solutions Mixed alpha emitting radionuclides solution for spiking soil samples 1,, 3 and standard solution sample 4. The original alpha emitting radionuclides certified standard solution was comprising a mixture of 38 Pu, 39 Pu, 4 Pu, 41 Pu and 41 Am, and was purchased from POLATOM, Poland, in The spiking solution and the standard solution for the ampoules were obtained by mixing appropriate amounts of the certified standard solutions with M nitric acid. The dilution scheme and the resulting activities are given in (Table ). The spiking solution was used to spike soil samples (1,, 3). All dilutions were prepared gravimetrically, using an analytical balance which weighed to the fifth decimal place. FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

11 Page 1/4 Table : The dilution scheme and resulting activities of alpha emitting radionuclides II Dilution of TRU standard solution Nuclide Activity ±U Activity ±U ±U 1-Jan Jan-1 [Bq/g] [Bq/g] [Bq/g] [Bq/g] [%] 38 Pu % 39 Pu % 4 Pu % 39+4 Pu % 41 Pu % 41 Am % I Working solution and target activities of sample 4: TRU standard solution (in ampoules) Mass of II Dilution solution Diluted with M HNO 3 to Nuclide Activity ±U [g] [g] [Bq/g] [date] [Bq/g] Pu Jan % 39 Pu Jan % 4 Pu Jan % 39+4 Pu Jan % 41 Pu Jan % 41 Am.14 1-Jan % I Working solution and target activities of sample 4: TRU standard solution (in ampoules) after decay correction T 1/ Decay correction factor Nuclide Activity ±U [years] [Bq/g] [date] [Bq/g] [%] Pu Jan-1.8.% Pu Jan-1.88.% Pu Jan % Pu Jan % Pu Jan % Am Jan % II Working solution (for spiking soil samples 1,, 3) Mass of I Working solution Diluted with M HNO 3 to Nuclide Activity ±U [g] [g] [Bq/g] [date] [Bq/g] Pu.69 1-Jan % 39 Pu Jan % 4 Pu Jan % 39+4 Pu Jan % 41 Pu Jan % 41 Am Jan % II Working solution (for spiking soil samples 1,, 3) after decay correction T 1/ Decay correction factor Nuclide Activity ±U [years] [Bq/g] [date] [Bq/g] [%] Pu Jan % Pu Jan-1.17.% Pu Jan % Pu Jan-1.91.% Pu Jan % Am Jan %

12 Page 11 TRU radionuclides target activities (in soil samples 1,, 3) Spiking of soil samples Target activities in soil ±U Mass of II Working solution Standard uncertainty Nuclide [Bq/sample] [date] [Bq/sample] [%] [g] [%] % 38 Pu Jan % 39 Pu Jan % 4 Pu Jan % 39+4 Pu Jan % 41 Pu Jan % 41 Am Jan % T 1/ Nuclide Target activity in soil ±U Decay correction factor [years] [Bq/sample] [date] [Bq/sample] [%] Pu Jan % Pu Jan % Pu Jan % Pu Jan % Pu Jan % Am.69 1-Jan % Continued Table : Dilution scheme and resulting activities of alpha emitting radionuclides Sr solution for spiking soil samples 1,, 3 and 9 Sr standard solution sample 5 The original 9 Sr certified standard solution was purchased from NIST (USA) in A fraction of this solution was diluted approximately fold using a.1m HCl solution that contained stable strontium and yttrium (5 µg/ml of each element) as holdback carriers (I dilution). The final solution for spiking soil samples was obtained by two successive dilutions (5x and 63x) of the above (I dilution), using the same acid and carriers mixture. Table 3: Dilution scheme and the activities of 9 Sr in samples 1,, 3 and 5 Standard solution A o [Bq/g] 494 A 1 [Bq/g] U [Bq/g] U [Bq/g] 7638 t o 13-Mar-95 t 1 1-Jan-1 T 1/ [y] 8.79 t [d] 11 1σ [y].6 I Dilution I Dilution Mass of standard solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] Sr Mar Jan I Working solution I Working solution and target activity for sample 5 (ampoules) Mass of I Dilution solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] [%] Sr Mar % Jan-1.6.8% II Working solution II Working solution (for spiking soil) Mass of I Working solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] [%] Sr Mar %.34 1-Jan-1.1.8% Spiking of soil samples Target activities in samples 1,, 3 (spiked soil) Mass of II Working solution Standard uncertainty Nuclide Activity U [g] [%] [Bq/sample] [date] [Bq/sample] [%] FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK.3% Sr Mar % Jan-1.4.3%

13 Page 1/4 The (I working) solution obtained in the first dilution step of (I dilution) (5x), was designated as the standard solution-sample 5. Its activity concentration was 1.9±.6 Bq/g on the reference date ml portions of this solution were dispensed into glass ampoules. The ampoules were weighed initially and after two weeks to check their integrity. The participants were requested to confirm the latter by an independent weight check upon receipt of the samples Mixed gamma emitting radionuclides solution for spiking soil sample 7 The solution was obtained by mixing appropriate amounts of certified standard solutions of selected radionuclides with the carrier solution (Table 5) as to obtain the desired activity concentrations for each radionuclide. All dilutions were prepared gravimetrically, using an analytical balance which weighed to the fifth decimal place. The dilution scheme and activities of mixed gamma emitting radionuclides solution are given in (Table 4) below. Table 4: Dilution scheme and the activities of mixed gamma emitting radionuclides solution for spiking soil sample 7 Dilutions of 65 Zn standard Standard solution A o [Bq/g] 469 A 1 [Bq/g] 5153 U [Bq/g] 83 U [Bq/g] 93 t o -Nov-98 t 1 1-Jan-1 T 1/ [d] 44.6 t [d] 773 1σ [d].6 I Dilution Mass of standard solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] Zn Jan-1.9 II Dilution: mixed gamma solution for spiking soil sample 7 Mass of I Dilution solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] [%] Zn Jan % Dilutions of 57 Co standard Standard solution A o [Bq/g] 5379 A 1 [Bq/g] 734 U [Bq/g] 33 U [Bq/g] 45 t o 1-Nov-98 t 1 1-Jan-1 T 1/ [d] t [d] 781 1σ [d].9 I Dilution Mass of standard solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] Co Jan-1 1. II Dilution: mixed gamma solution for spiking soil sample 7 Mass of I Dilution solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] [%] Co Jan-1.4.8%

14 Page 13 Dilutions of 6 Co standard Standard solution A o [Bq/g] 534 A 1 [Bq/g] 4414 U [Bq/g] 14 U [Bq/g] 17 t o 19-Nov-98 t 1 1-Jan-1 T 1/ [d] 195. t [d] 774 1σ [d].37 I Dilution Mass of standard solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] Co Jan-1. II Dilution: mixed gamma solution for spiking soil sample 7 Mass of I Dilution solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] [%] Co Jan % Dilutions of 134 Cs standard Standard solution A o [Bq/g] 5386 A 1 [Bq/g] 59 U [Bq/g] 65 U [Bq/g] 134 t o 13-Nov-98 t 1 1-Jan-1 T 1/ [d] 754. t [d] 78 1σ [d].37 I Dilution Mass of standard solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] Cs Jan II Dilution: mixed gamma solution for spiking soil sample 7 Mass of I Dilution solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] [%] Cs Jan-1.9.8% Dilutions of 137 Cs standard Standard solution A o [Bq/g] 4159 A 1 [Bq/g] 398 U [Bq/g] 616 U [Bq/g] 59 t o 1-Nov-98 t 1 1-Jan-1 T 1/ [d] 1983 t [d] 783 1σ [d] 11 I Dilution Mass of standard solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] Cs Jan-1. II Dilution: mixed gamma solution for spiking soil sample 7 Mass of I Dilution solution Diluted with.1m HCl to Nuclide Activity U [g] [g] [Bq/g] [date] [Bq/g] [%] Cs Jan % Continued Table 4: Dilution scheme and the activities of mixed gamma emitting radionuclides solution for spiking soil sample 7 FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

15 .46 Page 14/4 Continued Table 4: Dilution scheme and the activities of mixed gamma emitting radionuclides solution for spiking soil sample Preparation of solution of mixed carriers The stock solution was prepared by dissolving the indicated amounts of the respective salts in water, 1 ml of M hydrochloric acid was added and diluted with water to ml to obtain concentrations of.5 mg/ml of each salt. The weights and dilutions are given in (Table 5). This solution was added to each gamma emitting radionuclides spiking solution and to the mixed standard solution, to give a final concentration of.1 mg/ml for each carrier. Table 5: Solution of mixed carriers Element Salt Molecular weight Amount of salt taken [g] Amount of element present [g]. * Element concentration in carriers solution [mg/ml] Pb Pb(NO 3 ) Cd Cd(NO 3 ). 4H O Ba Ba(NO 3 ) Cs CsCl Mn MnCl Zn ZnCl Co Co(NO 3 ). 6H O Y YCl 3. 6H O Spiking procedure for soil samples 1,, 3 alpha emitting radionuclides and 9 Sr.5 ml (.4937 g ±.18%) of 9 Sr solution (II working) solution and.5 ml (.568 g ±.43%) of mixed alpha emitting radionuclides solution (II working) were pipetted into ml plastic scintillation vials containing 5. g of Chinese soil. The containers were left open for several days to dry the soil. No effort was made to homogenize the samples as they are intended for one application in which the whole amount of material will be used Spiking procedure for soil sample 7- gamma emitting radionuclides.5 ml (.5863 g ±.3%) of the spiking solution for soil were introduced into polypropylene containers and diluted with 8 ml of methanol. A portion of Chinese soil (5 g ±.1 g) was weighed to the second decimal place and transferred to the jar with the spiking solution. The liquid-to-solid ratio was determined experimentally such that the whole

16 Page 15 amount of liquid was absorbed by the soil and the whole amount of soil became uniformly moistened. The samples were set aside for a few days to dry under ambient conditions and then kept in an oven at 7 C for days to become completely dry. They were then equilibrated with ambient humidity for 5 days before sealing. After such treatment the residual moisture content was found to be.4 ±.%, which means that the initial moisture content of the untreated sample (.3 ±.1%) is comparable to the moisture content of the spiked one Sample blank preparation The Sample Blank contained 15g of unspiked soil, which can be used to take one, or more, appropriately sized aliquot(s) for blank determination Mixed gamma emitting radionuclides standard solution: sample 8 (ampoules) A fraction of the certified standard solution was diluted approximately fold using a.1m HCl solution and.1 mg/ml of each carrier (I dilution solution). Then the final solution for filling the ampoules was obtained by mixing appropriate amounts of the above (I dilution solution) using the same acid and carriers mixture. Ten millilitre portions of the final solution were dispensed into glass ampoules which were immediately flame-sealed to prevent loss due to evaporation. The ampoules were weighed initially and after two weeks to check their integrity. The participants were requested to perform an independent weight check upon receipt of the samples as in para Target activities and combined uncertainties of sample 8 are shown in (Table 6) Table 6: Target activities and combined uncertainties of sample 8. Sample Unit 57 Co 6 Co 65 Zn 134 Cs 137 Cs 41 Am 8 [Bq/kg] 668± ±58 374±69 474±4 1±3 166±33 7. RESULTS AND DISCUSSIONS: 7.1 Target values and uncertainties: Gamma emitting radionuclides FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK (Reference date1/1/ 1). The target values were calculated from the certified activity values assigned to each radionuclide, taking into account the successive dilution steps, the mass of spiking solutions and the amount of matrix being spiked. All dilutions were done by weighing, the combined weighing uncertaintiess were all bellow.1% and could therefore be neglected. The target values for all radionuclides in the soil and mixed standard solution, together with the respective uncertainties are presented in (Table 7). The combined standard uncertainty includes three major components: uncertainty of spiking solution, uncertainty originating from imperfect homogenisation and one arising from variability of moisture content in samples. The two latter sources are the largest contributors to the overall uncertainties which are, nevertheless, gratifyingly small for all radionuclides used in the PT.

17 Page 16/4 Radionuclide Activity u(a) u(hom) Dry weight ratio u(dw) Sample mass u(sample mass) Activity ±U(combined) Bq/sample % Bq/sample % % g Bq/kg d.w. % 65 Zn %.75.4% 97.8%.5% % 57 Co %.1.4% 97.8%.5% % 6 Co %.19.4% 97.8%.5% % 134 Cs %.13.4% 97.8%.5% % 137 Cs %.187.4% 97.8%.5% % 41 Am %.1.4% 97.8%.5% % Table 7: Target activities and combined uncertainties (on dry weight) of gamma emitting radionuclides used for evaluation of spiked soil sample 7 (Reference date: 1 January 1) Alpha emitting radionuclides and 9 Sr Target values for these radionuclides were obtained by calculating the successive gravimetrical dilutions of the original starting certified standard solutions. The target activities for alpha emitting radionuclides and 9 Sr are listed in (Table 8). The accompanying uncertainties are small and are dominated by calibration uncertainty of the standard solutions. The combined uncertainty expressed as the square root of the sum of variances of all known sources of uncertainty according to Eurachem/CITAC Guide []. The value of combined uncertainty is intended to represent, at the level of one standard deviation, the combined effect of uncertainty components associated with the gravimetric preparation. Reference date: 1 January 1 Sample Unit 9 Sr 38 Pu 39+4 Pu 41 Pu 41 Am 1,, 3 Bq/sample.1677± ±.73.77±.16.5±.11.69±.15 4 Bq/g -.114±.3.44± ± ±.47 5 Bq/g 1.9± Bq/g Blank Table 8: Target values and combined uncertainties for samples 1,, 3, 4, 5, Homogeneity of gamma emitters in soil The method of spiking soil sample was developed in the Agency's Laboratories in Seibersdorf and was demonstrated to yield reliable and reproducible results within 1-4% for all radionuclides tested. In this work, and after spiking, the samples were thoroughly shaken for approx. 6 min. Each 5 g sample was measured to ensure that the material could be considered sufficiently homogeneous for the purpose of this exercise. In one series of experiments, materials from one bottle of each kind of spiked samples was divided into five equal parts and each part was subjected to gamma-spectrometric analysis for one day. Preliminary results, provide experimental evidence that satisfactory within-bottle homogeneity has been attained for all radionuclides in soil for sub-samples weighing 5 g or more. Between bottle homogeneity study was not necessary since each bottle was a single gravimetrical spike and then each bottle was also individually homogenised. The value of between bottle heterogeneity uncertainty is limited to weighing uncertainty. It was estimated

18 Page 17 that combined weighing uncertainties were all bellow.1% and could therefore be neglected. 8. PERFORMANCE CRITERIA In order to provide the optimal evaluation of the analytical performance of the participants it was decided to evaluate both the trueness and the precision of the reported analytical data. Therefore, three different statistical parameters were calculated for each analytical data and an individual evaluation report was issued and sent to each participant. The individual report pointed the following evaluation parameters: A) Relative bias: To evaluate the bias of the reported results, the relative bias between the s value and the value was calculated and expressed as a percentage: Value Value Re lative bias = 1% (1) Value B) The Z-Score value: calculated according to the following equation: z Score Value = Value σ () The target value for the standard deviation (σ) is as follows: For the spiked samples: (a). x Value for Pu-41, (b).15 x Value for Sr-9, Pu-38, Pu-39+4 and Am-41, For the standard solution: (a).1 x Value for Pu-41, (b).1 x Value for Sr-9 (c).8 x Value for Pu-38, Pu-39+4 and Am-41. For the spiked sample (a).15 x Value for Zn-65 and Am-41, (b).1 x Value for Co-57, Co-6, Cs-134 and Cs-137. For the standard solution (a).1 x Value for Zn-65 and Am-41 (b).7 x Value for Co-57, Co-6, Cs-134 and Cs-137. C) The U test Score: The value of the U test score calculated according to the following equation: u test Value Value = (3) Unc. + Unc. FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

19 Page 18/4 The calculated U test value is compared with the critical values listed in the t-statistic tables to determine if the reported result differs significantly from the expected value at a given level of probability: The advantage of U test that it takes into consideration the propagation of measurement uncertainties, this is especially useful when evaluating results which may overlap with the reference interval. It should be noted that the choice of the significance level is subjective. For this proficiency test we have set the limiting value for the u-test parameter to.58 to determine if a result passes the test (u <.58). 9. Evaluation criteria The participants results were evaluated against the following evaluation criteria for Trueness and precision and assigned the passed or rejected accordingly. A result must pass both criteria to be assigned the final of passed. 1. Trueness: result passes if Value Value + (4).58 Unc Unc. Precision (dependent on the activity level): the result passes if: Unc Value Unc + Value 1% (5) is (a) < % for Pu-41 in spiked samples (b) < 15 % for Sr-9, Pu-38, Pu-39+4 and Am-41 in spiked samples (c) < 1 % for Pu-41 in the standard solution (d) < 1 % for Sr-9 in the standard solution (c) < 8 % for Pu-38, Pu-39+4 and Am-41 the standard solution. (e) < 15% for Zn-65 and Am-41 in the spiked sample, (f) < 1% for Co-57, Co-6, Cs-134 and Cs-137 in the spiked sample and Zn-65 and Am-41 in the standard solution, (g) < 7% for Co-57, Co-6, Cs-134 and Cs-137 in the standard solution.

20 Page Performance Evaluation Reports Sorted by Laboratory: The evaluation results according to the adopted criteria, were summarised in an individual report and sent to every participating laboratory. In this chapter the summary of these reports along with the raw data are listed under the laboratory code, which is known only to the PT provider and the laboratory. Reference date for all data is 1 January Laboratory : 1 9 Sr Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 11 Bq Bq Bq Bq/g Bq/g Status Value Value.58 Unc + Unc [%] Status passed 4.4 passed passed 1.. passed 3.7 passed passed passed 6.6 passed passed passed.9 passed passed Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 11 Bq Bq Bq Bq/g Bq/g Status [%] Status passed 8.6 passed passed 1..8 passed 8.6 passed passed passed 16.8 failed rejected passed 4.8 passed passed FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

21 Page /4 Summary of Performance Evaluation Report Sorted by Laboratory Continue Laboratory : Pu Sampl e Data Reported Results Relative u-test / Unit bias z-score score ratio 11 Bq Bq Bq Bq/g Bq/g Status [%] Status passed 6.4 passed passed passed 7. passed passed passed 7.3 passed passed passed 3.9 passed passed Spiked matrix (Sample 17) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg d.w.] [Bq/kg d.w.] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co failed.7 passed rejected 6 Co. 3.7 passed 4.5 passed passed 65 Zn failed 8.7 passed rejected 134 Cs passed 4.9 passed passed 137 Cs.8.9 passed 3.5 passed passed 41 Am passed 3.8 passed passed

22 Page 1 Summary of Performance Evaluation Report Sorted by Laboratory Continue Laboratory : 1 Standard solution (Sample 18) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg] [Bq/kg] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co failed 1. passed rejected 6 Co failed 1.6 passed rejected 65 Zn failed 5. passed rejected 134 Cs failed.7 passed rejected 137 Cs failed 1.7 passed rejected 41 Am failed.1 passed rejected FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

23 Page /4 Summary of Performance Evaluation Report Sorted by Laboratory 1. Laboratory : Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 111 Bq Bq Bq Bq/g Bq/g - - < Status [%] Status passed 6.6 passed passed passed 6.8 passed passed passed 7.1 passed passed passed 6.3 passed passed Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 111 Bq Bq Bq Bq/g Bq/g - - < Status [%] Status passed 6. passed passed passed 6. passed passed passed 6.4 passed passed failed 6. passed rejected

24 Page 3 Summary of Performance Evaluation Report Sorted by Laboratory Laboratory : 11 Spiked matrix (Sample 117) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg d.w.] [Bq/kg d.w.] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co.1.8 passed 6.4 passed passed 6 Co passed 8.7 passed passed 65 Zn passed 3.3 failed rejected 134 Cs passed 9.4 passed passed 137 Cs passed 8.4 passed passed 41 Am passed 7.8 passed passed FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

25 Page 4/4 Summary of Performance Evaluation Report Sorted by Laboratory 1.3 Laboratory : 1 9 Sr Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 11 Bq Bq Bq Bq/g Bq/g Status [%] Status passed 5.8 passed passed passed 5.8 passed passed passed 5.8 passed passed passed 6. passed passed Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 791 Bq Bq Bq Bq/g Bq/g Status [%] Status passed 6.1 passed passed passed 1.9 passed passed passed 6.1 passed passed passed 5.8 passed passed

26 Page 5 Summary of Performance Evaluation Report Sorted by Laboratory Continue Laboratory : Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 791 Bq Bq Bq Bq/g Bq/g Status [%] Status passed 5.8 passed passed passed 9. passed passed passed 5.9 passed passed passed 5.4 passed passed Reported Background:.4 cpm Reported Detection Limit: not reported 41 Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 791 Bq.5.11 Not reported Bq.5.11 Not reported Bq.5.11 Not reported Bq/g Not reported Bq/g - - Not reported Am Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 791 Bq Not reported Bq Not reported Bq Not reported Bq/g Not reported Bq/g - - Not reported FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

27 Page 6/4 Summary of Performance Evaluation Report Sorted by Laboratory Continue Laboratory : 1 Spiked matrix (Sample 17) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg d.w.] [Bq/kg d.w.] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co. 4. passed 9. passed passed 6 Co passed 6.3 passed passed 65 Zn 1..6 passed 7.3 passed passed 134 Cs. 3. passed 6.4 passed passed 137 Cs passed 6.5 passed passed 41 Am failed 6.9 passed rejected Standard solution (Sample 18) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg] [Bq/kg] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co passed 5.4 passed passed 6 Co passed 5. passed passed 65 Zn passed 6.3 passed passed 134 Cs 67 8 passed 5.4 passed passed 137 Cs passed 5.5 passed passed 41 Am passed 5.9 passed passed

28 Page 7 Summary of Performance Evaluation Report Sorted by Laboratory 1.4 Laboratory : Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 131 Bq Bq Bq Bq/g Bq/g - - < Status [%] Status passed 9.1 passed passed passed 6.4 passed passed passed 6.4 passed passed passed 8.7 failed rejected Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 131 Bq Bq Bq Bq/g Bq/g - - < Status [%] Status passed 7.6 passed passed passed 8.7 passed passed passed 4.9 passed passed passed 7.9 passed passed FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

29 Page 8/4 Summary of Performance Evaluation Report Sorted by Laboratory Continue Laboratory : Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 131 Bq.5.11 Not reported Bq.5.11 Not reported Bq.5.11 Not reported Bq/g Not reported Bq/g - - Not reported Am Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 131 Bq Not reported Bq Not reported Bq Not reported Bq/g Not reported Bq/g - - Not reported Spiked matrix (Sample 137) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg d.w.] [Bq/kg d.w.] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co passed.4% failed rejected 6 Co passed 3.7% passed passed 65 Zn failed 5.6% passed rejected 134 Cs 3..3 failed 4.7% passed rejected 137 Cs failed 3.5% passed rejected 41 Am passed.1% failed rejected

30 Page 9 Summary of Performance Evaluation Report Sorted by Laboratory Continue Laboratory : 13 Standard solution (Sample 138) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg] [Bq/kg] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co failed 6.5% passed rejected 6 Co failed 3.6% passed rejected 65 Zn failed 9.% passed rejected 134 Cs failed 7.7% failed rejected 137 Cs failed.3% passed rejected 41 Am failed 4.9% passed rejected FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

31 Page 3/4 Summary of Performance Evaluation Report Sorted by Laboratory 1.5 Laboratory : 16 Spiked matrix (Sample 167) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg d.w.] [Bq/kg d.w.] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co.9.4 passed 5.1% passed passed 6 Co.1 4. passed 4.7% passed passed 65 Zn passed 1.3% passed passed 134 Cs.3.3 failed 3.9% passed rejected 137 Cs passed 3.8% passed passed 41 Am passed 8.3% passed passed Standard solution (Sample 168) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg] [Bq/kg] [%] 1σ 57 Co Co Zn Cs Cs Am NK energy below efficiency definition Status [%] Status 57 Co passed 6.4% passed passed 6 Co passed 4.% passed passed 65 Zn passed 4.5% passed passed 134 Cs passed 3.7% passed passed 137 Cs passed 5.4% passed passed 41 Am

32 Page 31 Summary of Performance Evaluation Report Sorted by Laboratory 1.6 Laboratory : 17 9 Sr Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 171 Bq Bq Bq Bq/g Bq/g Status [%] Status failed 4.8 passed rejected passed 4.9 passed passed passed 5. passed passed passed 5.1 passed passed Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 171 Bq Bq Bq Bq/g Bq/g E-6 3.E Status [%] Status passed.7 passed passed passed.6 passed passed passed.3 passed passed passed.3 passed passed FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

33 Page 3/4 Summary of Performance Evaluation Report Sorted by Laboratory Continue Laboratory : Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 171 Bq Bq Bq Bq/g Bq/g E-5 6.E Status [%] Status passed.5 passed passed passed.5 passed passed passed.3 passed passed passed. passed passed Pu Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 171 Bq.5.11 Not reported Bq.5.11 Not reported Bq.5.11 Not reported Bq/g Not reported Bq/g - - Not reported Am Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 171 Bq Not reported Bq Not reported Bq Not reported Bq/g Not reported Bq/g - - Not reported

34 Page 33 Summary of Performance Evaluation Report Sorted by Laboratory Continue Laboratory : 17 Spiked matrix (Sample 177) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg d.w.] [Bq/kg d.w.] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co passed.8 passed passed 6 Co passed.9 passed passed 65 Zn passed 3.6 passed passed 134 Cs passed.8 passed passed 137 Cs passed 3. passed passed 41 Am passed 4.4 passed passed Standard solution (Sample 178) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg] [Bq/kg] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co passed 1.1 passed passed 6 Co passed 1. passed passed 65 Zn passed.1 passed passed 134 Cs passed 1.1 passed passed 137 Cs 113 passed 1.6 passed passed 41 Am passed.4 passed passed FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK

35 Page 34/4 Summary of Performance Evaluation Report Sorted by Laboratory 1.7 Laboratory : 18 9 Sr Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 181 Bq Bq Bq Bq/g Bq/g Status [%] Status failed 7.8 passed rejected failed 7.9 passed rejected failed 7.8 passed rejected failed 1.3 failed rejected

36 Page 35 Summary of Performance Evaluation Report Sorted by Laboratory 1.8 Laboratory : 19 9 Sr Sample Data Reported Results Relative u-test / Unit bias z-score score ratio 191 Bq Bq Bq Bq/g Bq/g Status [%] Status passed 13.6 passed passed passed 14.4 passed passed passed 13.9 passed passed failed 3.8 passed rejected Spiked matrix (Sample 197) Data Reported Results Relative u-test / Analyte Value Uncertainty * Value Uncertainty * bias z-score score ratio [Bq/kg d.w.] [Bq/kg d.w.] [%] 1σ 57 Co Co Zn Cs Cs Am Status [%] Status 57 Co failed 5.3 passed rejected 6 Co 7.1. failed 4. passed rejected 65 Zn failed 7.7 passed rejected 134 Cs failed 4.6 passed rejected 137 Cs 9..6 failed 4. passed rejected 41 Am failed 7.7 passed rejected FINAL REPORT ON THE PROFICIENCY TEST OF ALMERA NETWORK