Evaluation of the 2017 EC Proficiency Test on 131I, 134Cs and 137Cs in maize powder.
Date: 2020-04-30
Institutions: Joint Research Centre
Subjects: animal feedingstuffs, food additive, food contamination, maize, manufactured feedingstuffs, research report

 Evaluation of the 2017 EC 
Proficiency Test on 131I, 134Cs and 
137Cs in maize powder 

Katarzyna Sobiech-Matura,              
Guillaume Lutter,                              
Raf van Ammel,                                         
Gerd Marissens,                                                                                      
Håkan Emteborg,                        
Mikael Hult                                          

2020  

EUR 30142 EN 

 
 
 
 
 
 
 
This publication is a Technical report by the Joint Research Centre (JRC), the European Commission’s science 
and knowledge service. It aims to provide evidence-based scientific support to the European policymaking 
process. The scientific output expressed does not imply a policy position of the European Commission. Neither 
the European Commission nor any person acting on behalf of the Commission is responsible for the use that 
might be made of this publication. For information on the methodology and quality underlying the data used in 
this publication for which the source is neither Eurostat nor other Commission services, users should contact 
the referenced source. The designations employed and the presentation of material on the maps do not imply 
the expression of any opinion whatsoever on the part of the European Union concerning the legal status of any 
country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. 

Contact information 
Name: Katarzyna Sobiech-Matura 
Address: Retieseweg 111, 2440 Gel, Belgium 
Email: katarzyna.sobiech-matura@ec.europa.eu 
Tel.: +32 14 571290 

EU Science Hub 
https://ec.europa.eu/jrc 

JRC118790 

EUR 30142 EN 

PDF 

ISBN 978-92-76-17330-4 

ISSN 1831-9424 

doi: 10.2760/54966 

Luxembourg: Publications Office of the European Union, 2020  

© European Atomic Energy Community, 2020 

The reuse policy of the European Commission is implemented by the Commission Decision 2011/833/EU of 12 
December 2011 on the reuse of Commission documents (OJ L 330, 14.12.2011, p. 39). Except otherwise noted, 
the reuse of this document is authorised under the Creative Commons Attribution 4.0 International (CC BY 4.0) 
licence (https://creativecommons.org/licenses/by/4.0/). This means that reuse is allowed provided appropriate 
credit is given and any changes are indicated. For any use or reproduction of photos or other material that is 
not owned by the EU, permission must be sought directly from the copyright holders. 

All content © European Atomic Energy Community  

How to cite this report: Katarzyna Sobiech-Matura, Guillaume Lutter, Raf van Ammel, Gerd Marissens, Håkan 
Emteborg, Mikael Hult,  Evaluation of the 2017 EC Proficiency Test on 131I, 134Cs and 137Cs in maize powder, EUR 
30142 EN, Publications Office of the European Union, Luxembourg, 2020, ISBN 978-92-76-17330-4, doi 
10.2760/54966, JRC118790 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Contents 

Acknowledgements ................................................................................................ 1 

Abstract ............................................................................................................... 2 

1  Introduction ...................................................................................................... 3 

2  The EC Proficiency Test 2017 .............................................................................. 4 

2.1  Reference material ....................................................................................... 4 

2.2  Participating laboratories .............................................................................. 4 

2.3  Reporting of results...................................................................................... 4 

2.4  Timetable of the PT ...................................................................................... 5 

3  Material preparation and reference values ............................................................ 6 

3.1  Reference material ....................................................................................... 6 

3.2  Reference material characterisation ............................................................... 7 

3.2.1  Homogeneity ....................................................................................... 8 

3.2.2  Short-term stability .............................................................................. 8 

3.2.3  Reference values ................................................................................. 9 

4  Methods used by the participating laboratories ............................................................ 10 

4.1  Moisture content ........................................................................................ 10 

4.2  Measurements ........................................................................................... 11 

4.2.1  Techniques, instrumentation and quality system .................................... 11 

4.2.2  Sample preparation ............................................................................ 11 

4.2.3  Sample positioning ............................................................................. 12 

4.2.4  Efficiency calibration .......................................................................... 12 

4.2.5  Analysis and calculation software ......................................................... 13 

4.2.6  Corrections ....................................................................................... 13 

4.2.7  Nuclear data ..................................................................................... 14 

4.2.8  Background measurements ................................................................. 14 

4.2.9  Detection limit calculation ................................................................... 14 

5  Reported results .............................................................................................. 15 

6  Evaluation of the results ................................................................................... 16 

6.1  Scores ...................................................................................................... 16 

6.1.1  z score ............................................................................................. 16 

6.1.2  Zeta (ζ ) score ................................................................................... 16 

6.1.3  En score ............................................................................................ 17 

6.2  Evaluation ................................................................................................ 17 

6.3  PomPlots .................................................................................................. 23 

6.4  Possible influencing parameters ................................................................... 26 

7  Conclusions .................................................................................................... 27 

i 

List of abbreviations and definitions ....................................................................... 29 

List of figures ...................................................................................................... 31 

List of tables ....................................................................................................... 32 

Annexes ............................................................................................................. 33 

Annex 1. Letter of invitation for laboratory nomination ......................................... 33 

Annex 2. Invitation to laboratories for registration ............................................... 35 

Annex 3. Sample dispatch information ............................................................... 37 

Annex 4. Sample accompanying letter ................................................................ 38 

Annex 5. Instruction for moisture content determination ...................................... 40 

Annex 6. Communication of preliminary results ................................................... 42 

Annex 7. List of participating laboratories (countries in alphabetical order) ............. 47 

Annex 8. Questionnaire .................................................................................... 59 

Annex 9. Results of the laboratories (routine reporting) ........................................ 87 

Annex 10. Results of the homogeneity study ....................................................... 91 

Annex 11. Results of the short-term stability study .............................................. 95 

Annex 12. The PomPlot .................................................................................... 97 

Annex 13. REMPES file example ........................................................................ 99 

ii 

Acknowledgements 

First of all the authors wish to thank all 120 participating laboratories listed in Annex 7. 
This  work  would  not  have  been  possible  without  their  active  participation  in  this 
proficiency test. 

The  authors  would  also  like  to  thank  Thierry  Branger  (CEA,  France),  Iolanda  Osvath 
(IAEA, Monaco) and Sandor Tarjan (IAEA, Austria) for their contributions to the reference 
value determination. 

Thanks  to  the  colleagues,  Jean  Charoud-Got,  John  Seghers  and  Hanne  Leys,  from  the 
Reference  Materials  Unit  of  the  JRC  Geel  for  their  help  in  the  preparation,  mixing  and 
filling the material in the bottles.  

The  authors  would  also  like  to  thank  Marc  De  Cort  of  JRC  Ispra  and  Vesa  Tanner,  Alan 
Ryan and Michael Hübel of EC DG ENER for the good and smooth collaboration. 

Thanks  to  the  colleagues  Viktor  Jobbagy,  for  keeping  an  experienced  eye  on  the  entire 
project,  Heiko  Stroh  for  his  help  during  the  measurements,  Petya  Malo  for  assistance 
during  distribution  of  the  PT  reference  material  and  Ulf  Jacobson  for  preparing  the 
REMPES file. 

We would like to give a special thanks to Timos Altzitzoglou for his valuable advice during 
the planning phase. 

Authors 

Katarzyna  Sobiech-Matura,  Guillaume  Lutter,  Raf  van  Ammel,  Gerd  Marissens,  Håkan 
Emteborg, Mikael Hult  

1 

 
Abstract 

A proficiency test (PT) on the measurements of 131I, 134Cs and 137Cs in maize powder was 
organised  by  European  Commission  Directorate-General  (EC  DG)  Joint  Research  Centre 
in Geel on request of the EC DG for Energy. This PT was an integral part of the EC's work 
of realising verification of Member State's  obligations  towards Article 35 of the  Euratom 
Treaty.  It  is  part  of  the  quality  control  programme,  which  JRC  Geel  is  coordinating  in 
order  to  assess  the  quality  of  the  results  collected  in  the  Radioactivity  Environmental 
Monitoring (REM) database.   

The  PT  reference  material  was  prepared  by  spiking  blank  maize  powder.  The  samples 
were  sent  to  123  laboratories  of  which  120  laboratories  submitted  their  results.  The 
results of the PT were evaluated according to ISO 13528:2015. The zed (z) and zeta (ζ) 
and En scores were calculated.  

The z scores of the reported results for  131I were acceptable for 92% of laboratories. For 
both  134Cs  and  137Cs  they  were  acceptable  for  94%  laboratories.  The  ζ  scores  were 
satisfactory for 66%, 56% and 68% of results for 131I, 134Cs and 137Cs respectively.  

2 

 
1  Introduction 

Within the framework of the European Atomic Energy Community (Euratom) Treaty and 
derived European legislation, Member States (MS) of the European Union are obliged to 
perform measurements of the radioactivity levels in their environment. The results shall 
be  reported  to  the  European  Commission  (EC).  The  Radioactivity  Environmental 
Monitoring (REM) group of the EC DG JRC collects, validates and publishes the reported 
data.  In  order  to  verify  the  performance  of  the  monitoring  laboratories  and  to  ensure 
comparability of reported results, regular proficiency tests (PTs) are organised by the EC. 
Since 2003, the EC DG Joint Research Centre Geel (JRC Geel) is organising the PTs. The 
past  ten  PTs  are  summarised  in  a  recent  report  by  Hult,  Jobággy  and  Sobiech-Matura 
(2019).  The 
the  REMON  website: 
https://remon.jrc.ec.europa.eu/Services/Proficiency-Tests  

reports  are  also  available 

from 

full 

The  physical  properties  as  well  as  the  radioactivity  levels  of  JRC  Geel  PT  reference 
material  are  generally  closer  to  the  real  samples  measured  in  monitoring  laboratories 
than calibration standards. Therefore, they give a realistic estimate of the performance of 
these laboratories in their routine monitoring tasks.  

This report describes in detail the PT organised in 2017. It covers the production of the 
reference  material,  the  analytical  methods  used  to  establish  the  reference  value,  the 
treatment of the reported data and provided details regarding the procedures used to the 
evaluation  and  comparison  of  the  individual  results  with  the  reference  values.  The 
performance  of  individual  laboratories  was  evaluated  according  to  ISO  13528:2015 
(2015).  

3 

 
2  The EC Proficiency Test 2017 

The aim of this PT was to verify the performance of EU Member States (MS) monitoring 
laboratories for the determination of the massic activity of  131I,  134Cs and  137Cs in maize 
powder.  

2.1  Reference material 

Maize  powder  was  produced  using  commercially  available  maize  grains.  It  was  spiked 
with radioactive solutions of  131I,  134Cs and  137Cs. A bottle containing no less than 100 g 
of  spiked  powder  was  sent  to  each  participating  laboratory.  Details  on  the  reference 
material production and reference values determination can be found in Chapter 3. 

2.2  Participating laboratories 

In  total,  123  laboratories  registered  to  participate  in  this  PT.  The  laboratories  were 
mainly national research institutes, authorities and radioactivity monitoring laboratories. 
From  EU  MS,  112  laboratories  were  nominated  by  the  national  representatives  in  the 
Euratom  Treaty  Art.  35/36  Expert  Group.  Ten  laboratories  from  accession  and 
pre-accession countries (AC) and one laboratory from Switzerland also registered in this 
PT. These laboratories were invited as they report their monitoring results to EURDEP.  

In total 120 laboratories (109 from EU MS, 10 from AC and 1 from Switzerland) reported 
results. The list of all participating laboratories is shown in Annex 7. Since anonymity is a 
requirement in the PTs according to ISO 17043 (2010) the identity of the laboratories is 
not shown in this compilation of the results. The laboratory numbers used throughout the 
data  evaluation  in  this  report  are  not  related  to  the  order  of  listing  the  participants  in 
Annex 7.  

Laboratories  that  submitted  the  results  in  this  PT  have  different  functions  –  48 
laboratories  are  only  monitoring  radioactivity  in  the  environment,  whereas  61  combine 
this function with others, like research and development (31 laboratories), monitoring of 
nuclear  facilities  (7  laboratories)  or  both  (11  laboratories).  Four  laboratories  carry  out 
only research and development activities and 7 laboratories have different functions, like 
for example disaster management, food monitoring or civil protection.   

Table 0-1. The origin of participating laboratories. 

Nominated  laboratories 
from EU Member States 

EU Pre-accession 
Countries 

Other  Total 

Sample sent 

112 

Results submitted 

109 

Source: JRC Geel 

2.3  Reporting of results 

10 

10 

1 

1 

123 

120 

Participants  were  instructed  to  report  the  results  and  the  associated  uncertainty  as 
massic  activity  normalised  to  dry  mass  (Bq/kg  d.m.).  The  organiser  recommended 
performing  the  moisture  content  determination  on  small  subsamples  that  shall  not  be 
used for the radionuclide analysis to avoid the loss of the 131I in the radionuclide analysis 
sample.  The  participants  were  instructed  to  take  these  subsamples  from  the  bottles  at 
the  same  time  as  the  samples  for  radionuclide  analysis.  The  recommended  method  for 
moisture  content  determination  was  the  oven-drying  procedure  (Annex  5).  The  detailed 
description of the method was sent together with the sample accompanying letter (Annex 
4). 

4 

 
The  reference  date  for  all  results  was  1  June  2017  00:00:00  UTC.  The  Monographie 
BIPM-5  vol.  3,  7  and  8  (2006,  2013  and  2016)  was  recommended  as  source  of  nuclear 
decay  data  to  be  used  in  the  analysis.  This  data  arise  from  the  Decay  Data  Evaluation 
Project  (DDEP),  which  is  recommended  by  the  ICRM  (International  Committee  for 
Radionuclide  Metrology)  as  the  first  choice  of  decay  data  to  be  used  in  radiometric 
analyses. 

The  results  were  reported  via  a  web-based  tool  called  MILC  (developed  by  JRC  Geel), 
which served also as  the tool for  a questionnaire.  Participants were asked to answer all 
relevant questions regarding the measurement procedures used. Information given in the 
questionnaire  enables  a  more  detailed  evaluation  of  the  PT  results.  It  helps  also  to 
discover  sources  of  possible  discrepancies  and  gives  an  overview  of  the  methods  used 
among the laboratories.  

For the first time in a  REM PT supporting Article 35, the possibility to perform so-called 
"emergency reporting" was introduced. The participants were asked on a voluntary basis 
to  report  their  results  within  48  hours  after  receipt  of  the  PT  reference  material.  These 
results  were  not  formally  reported  to  national  authorities  or  DG  ENER.  They  will  be 
discussed  in  a  separate  publication.  For  the  routine  reporting  the  laboratories  had  two 
months  to  report  after  receiving  the  material.  These  results  are  reported  to  the 
laboratories national authority and DG ENER. 

2.4  Timetable of the PT 

29/03/2017 

Invitation letter (Annex 1) sent to the national representatives to 
nominate laboratories in their countries 

28/04/2017 

Nominations from the national representatives collected 

11/05/2017 

Invitation  letter  sent  to  the  non-EU  laboratories  from  countries 
reporting to EURDEP 

10-31/05/2017 

Registration of laboratories 

01-09/06/2017 

Material  and  additional  information  on  the  PT  sent  to  the 
participants via express mail 

02-14/06/2017 

Laboratories submit their emergency results to the JRC Geel 

02/06-28/07/2017 

Laboratories submit their routine results and questionnaire to the 
JRC Geel 

25/10/2017 

Preliminary  evaluation  of  reported  results  sent  to  participants 
(Annex 6) 

31/1-2/2/2018 

Workshop and follow-up training 

05/03/2018 

Distribution  of  laboratory's  final  PT  results  via  a  new  MS 
Excel-based tool (REMPES) 

5 

 
 
  
 
 
 
 
  
 
 
3  Material preparation and reference values 

3.1  Reference material 

The reference material used as a test item in this PT was blank maize powder spiked with 
radioactive  solutions  of  131I,  134Cs  and  137Cs.  Due  to  the  short  half-life  of  131I  (8  days), 
spiking  was  the  only  available  method  for  producing  this  PT  material.  The  Reference 
Materials Unit of the JRC Directorate F located at  JRC  Geel performed the processing of 
the material. 

The bulk raw material consisted of 75 kg of maize grains available on the local market as 
animal feed. It was purchased  from a commercial supplier in Belgium. The maize grains 
were  placed  in  metallic  drums  and  cooled  down  in  liquid  nitrogen  (-196  °C).  Once  cold, 
they  were  milled  using  a  vibrating  cryogenic  mill  (KHD  Humboldt  Wedag,  Köln, 
Germany). After the processing a total amount of 64.7 kg  of powder  was collected. The 
powder  was  sieved  at  room  temperature  over  a  250  μm  stainless  steel  mesh  (Russel 
Finex  Industrial  sieve  Model  17300,  London,  United  Kingdom)  connected  to  an 
ultrasonication probe (Russel Finex Vibrasonic 2000, London, United Kingdom). The fine 
fraction  represented  57.10  kg  and  the  coarse  fraction  7.15  kg.  The  coarse  fraction  was 
re-milled and re-sieved as previously described. The fine fraction of the re-milled coarse 
fraction (7.13 kg) was added to the 57.10 kg of the fine fraction obtained from the first 
milling/sieving  sequence.  The  total  fine  fraction  (64.3  kg)  was  then  placed  in  a  200  L 
metallic  drum.  It  was  mixed  for  two  hours  with  a  DynaMIX-CM200  mixer  (WAB,  Basel, 
Switzerland). The mixed powder was then split in 7 different plastic drums containing ca. 
10 kg of powder each. The material was stored at +4 °C.  

Figure 1 Maize grains processing (cooling, milling and sieving). 

Source: JRC Geel 

6 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
For  the  spiking,  503.26  g  of  blank  maize  powder  was  placed  in  a  rotary  evaporator 
powder flask of 2 L total volume. Then 600 mL of ethanol was added to obtain a slurry in 
the flask. The radioactive solutions of  131I,  134Cs and  137Cs were gravimetrically added to 
the slurry using  pycnometers (Canis, Canada) and an analytical balance (Mettler Tolledo 
type AT21). The activity of the  solutions used  for  spiking was determined by  measuring 
gravimetrically  made  point  and  volume  sources.  These  sources  were  prepared  at  the 
same time as the spiked maize powder. 

The  flask  containing  the  slurry  was  placed  in  a  rotary  evaporator  (Hei-VAP,  Heidolph, 
Germany) and rotated for 10 hours at room temperature. Mixing continued for 20 more 
hours during evaporation of ethanol. In order to retrieve the powder form of the material 
the water bath of the device was heated up to 65 °C and the pressure in the system was 
lowered to 500 mBar.  In the vertical condenser water  at 3 °C was circulated. When the 
powder  was  dried,  it  was  transferred  from  the  rotary  evaporator  powder  flask  to  a  2  L 
polypropylene  container  with  a  screw  cap.  The  powder  was  mixed  together  with  6 
porcelain balls in a Turbula shaker-mixer (T2F, Glen Mills, USA) for 4 hours.  

The spiked powder was transferred to a polypropylene drum containing 19.79 kg of blank 
maize  powder.  The  content  of  the  drum  was  mixed  in  a  DynaMIX-CM200  mixer  (WAB, 
Basel, Switzerland) for  4 hours. After mixing, the powder was bottled in 250 mL amber 
glass  bottles  containing  at  least  100  g  each.  The  bottles  were  closed  with  a  screw  cap 
with a break-ring.  

Since  the  homogeneity  of  so-prepared  material  was  not  satisfactory  an  additional  step 
was introduced. All available material was collected again in a plastic drum. It was cooled 
down  in  liquid  nitrogen  (-196  ºC)  and  milled  in  Cryogenic  Mill  (CryoMill,  Retsch, 
Germany). Additional mixing in DynaMIX-CM200 mixer (WAB, Basel, Switzerland) for 4 h 
was  applied.  After  this  additional  homogenisation,  the  powder  was  as  previously 
described bottled into 161 new amber 250 mL glass bottles.  

The  moisture  content  of  the  material  after  bottling  was  determined  according  to 
procedure sent to the participants together with the PT material. The moisture content of 
the final product was (12.85 ± 0.02)%.  

3.2  Reference material characterisation 

The  characterisation  of  the  PT  reference  material  was  performed  by  four  laboratories 
(IAEA  Monaco,  IAEA  Seibersdorf,  CEA  Saclay  and  JRC  Geel).  All these  laboratories  used 
2-3  bottles  of  the  PT  reference  material.  They  reported  one  mean  value  obtained  by 
measuring  different  samples  covering  all  received  bottles.  The  reported  values  for  each 
laboratory used for calculations can be found in Table 2.  

7 

 
 
Table 0-2. Measurement results and uncertainty reported by the laboratories used for the 
reference value calculations (k=1). 

Laboratory 
name 

IAEA 
Seibersdorf 

IAEA 
Monaco 

131I 

134Cs 

137Cs 

40K 

Activity 
(Bq/kg 
d.m.) 

unc. 
(Bq/kg 
d.m.) 

Activity 
(Bq/kg 
d.m.) 

unc. 
(Bq/kg 
d.m.) 

Activity 
(Bq/kg 
d.m.) 

unc. 
(Bq/kg 
d.m.) 

Activity 
(Bq/kg 
d.m.) 

unc. 
(Bq/kg 
d.m.) 

184 

7.0 

913 

23 

550 

14 

88 

7.0 

190 

10 

885 

14 

534 

9.0 

107 

7.0 

CEA Saclay  190 

11 

911 

JRC Geel 

197 

6.0 

921 

Source: JRC Geel 

50 

28 

561 

563 

30 

17 

103 

5.5 

105 

7.0 

The  homogeneity  and  short-term  stability  (under  the  transport  conditions)  of  the 
analytes  in  the  reference  material  used  were  assessed  at  JRC  Geel.  The  study  was 
executed in accordance with the ISO Guide 35 (2015).  

3.2.1  Homogeneity 

Ten  bottles  of  the  PT  reference  material  for  the  homogeneity  study  were  selected  in  a 
random  stratified  manner  covering  the  whole  batch.  Three  samples  of  20  g  were 
prepared  from  each  bottle.  All  samples  were  measured  on  the  same  high-purity 
Germanium  (HPGe)  detector  under  the  same  measurement  conditions.  The  relative 
standard  deviation  of  all  measurements  was  1.8%,  0.8%  and  1.0%  for  131I,  134Cs  and 
137Cs respectively. One-way ANOVA calculations were performed using SoftCRM software 
(Bonas,  et  al.,  2003).  The  relative  uncertainty  contribution  due  to  inhomogeneity  (ubb) 
was  estimated  by  calculation  of  ubb*  (Linsinger,  et  al.,  2001).  The  results  of  the 
measurements and the calculations are shown in Annex 10 and the relative components 
of uncertainty resulting from inhomogeneity equal to 0.6%, 0.3% and 0.3% for 131I, 134Cs 
and  137Cs  respectively. These values  were used  to calculate the total uncertainty on the 
reference values.   

3.2.2  Short-term stability 

The  short-term  stability of the  PT  reference  material was assessed  at two temperatures 
(40  and  60  °C).  Samples  stored  at  room  temperature  were  used  as  reference.  Four 
bottles  were  selected  in  a  randomly  stratified  manner  to  study  the  stability  at  each 
temperature. All bottles were weighted on one balance at the beginning of the study and 
at  the  time  of  the  second  measurement.  They  were  all  measured  on  the  same  HPGe 
detector at the beginning of the study. Four bottles per temperature were stored in two 
ovens  set  at  40  °C  and  60  °C  respectively.  Two  bottles  were  stored  at  the  reference 
temperature.  One  bottle  was  taken  out  of  each  oven  after  1,  2,  3  and  4  weeks.  It  was 
cooled down to room temperature and measured  on the  same detector under the same 
measurement  conditions  as  at  the  beginning  of  the  study.  The  net  count  rate  was 
calculated for both measurements. A linear regression was fitted to the net count rates of 
the  measurement  results  for  each  test  temperatures.  A  Student  t-test  described  in  the 
ISO  Guide  35  (2015)  was  used  to  evaluate  whether  the  slope  of  the  linear  regression 
curve  is  significantly  different  from  zero.  For  all  tree  radionuclides  and  for  both 
temperatures there was no significant statistical trend. Therefore, in accordance with ISO 

8 

 
13528  (2015),  the  component  of  uncertainty  due  to  instability  (usts)  was  not  taken  into 
account for the calculation of uncertainty of the reference value.  

3.2.3  Reference values 

The reference values, given in Table 0-3, are composed of the reference values (xpt) and 
an  expanded  uncertainty  (𝑈(𝑥𝑝𝑡)).  The  reference  value  (xpt)  for  each  radionuclide  was 
calculated  based  on  power-moderated  mean  (PMM)  approach  (Pommé  &  Keightley, 
2015). The standard uncertainty of the reference value (𝑢(𝑥𝑝𝑡)) was calculated according 
to the following equation: 

𝑢(𝑥𝑝𝑡) =   √𝑢𝑐ℎ𝑎𝑟

2 + 𝑢ℎ𝑜𝑚

2

where 

𝑢𝑐ℎ𝑎𝑟 is the uncertainty from the power-moderated mean calculated for the results of the 

characterisation study;  

𝑢ℎ𝑜𝑚 is the uncertainty component associated with reference material heterogeneity.  

The expanded uncertainty (𝑈(𝑥𝑝𝑡)) was calculated according to the following equation: 

𝑈(𝑥𝑝𝑡)   = 𝑘 ∙ 𝑢(𝑥𝑝𝑡) 

where 

𝑘 = 2 (corresponding to a level of confidence of about 95%). 

(1) 

The reference values for 131I, 134Cs and 137Cs are further on used for the evaluation of the 
results reported by the PT participants. The reference value for 40K is only informative. 

Table 0-3. Reference values of massic activity xpt with expanded uncertainties U(xpt) (k = 2) for 
the PT reference material at the reference date (1 June 2017 00:00:00 UTC).  

Radionuclide 

xpt ± U(xpt) (Bq/kg d.m.) 

131I 

134Cs 

137Cs 

40K (*) 

191 ± 8  

901 ± 23 

547 ± 14  

 101 ± 9 

(*) The value for 40K is only informative. 

Source: JRC Geel 

9 

 
 
 
 
                                                               
 
 
 
 
 
 
 
 
 
 
4  Methods used by the participating laboratories 

Participants  in  this  PT  could  freely  choose  the  measurement  method,  although it  should 
preferably be their routine procedure for measuring 131I, 134Cs and 137Cs in environmental 
matrices.  They  were  asked  to  report  for  each  radionuclide  the  specific  activity  per  dry 
mass  of  the  spiked  maize  powder.  Participants  could  also,  on  a  voluntary  basis,  report   
specific activity results per dry mass for 40K in the PT reference material. 

The  reporting  of  the  results  was  realised  via  a  web-based  platform  called  MILC,  where 
participants were also asked to fill in a questionnaire.  The information in this chapter is 
extracted from the files obtained from MILC. 

4.1  Moisture content  

All results of massic activity had to be normalized to dry mass. It was recommended to 
determine  the  moisture  content  in  separate  small  samples  not  used  for  other  analysis. 
The  description  of  the  recommended  oven  drying  method  for  the  moisture  content 
determination  was  sent  to  participants  together  with  the  PT  material  (Annex  5).  In  this 
way,  the  influence  of  differences  resulting  from  moisture  content  determination 
procedures  were  minimised.  The  mean  value  of  moisture  content  reported  by  the 
participants  equalled  to  12.14%,  which  was  close  to  the  reference  value  of  (12.85  ± 
0.02)%. The reported results varied from 0.123% to 89.48%. In one third of the cases, 
the relative difference  between the  reference  value and reported value for the  moisture 
content  varied  more  than  20%.  It  has  to  be  noted  however  that  the  discrepancies  may 
be  resulting  from  misunderstanding  the  question,  i.e.  the  reported  value  0.123%  may 
mean 12.3%, and the value 89.48% may refer to the dry mass content (wet mass being 
10.52%).  For  21  participating  laboratories  moisture  content  determination  in  food 
samples  is  not  routinely  performed.  Those  laboratories  had  problems  with  proper 
determination of the moisture content. One laboratory (8) informed about difficulties due 
to lack of experience and adequate equipment for the drying procedure.  

Seven  laboratories  reported  that  they  did  not  follow  the  provided  oven  drying  method. 
Laboratory 36 dried for a longer time at lower temperature. Their result (10.8 ± 0.4)%, 
was lower than the reference value.  

Laboratories  21  and  54  dried  the  samples  for  15  and  18  hours  respectively  (instead  of 
recommended  1  hour  intervals),  reporting  results  of  (12.5671  ±  0.0035)%  and 
(12.32 ± 0.12)% respectively.  

Laboratory  43  used  different  aliquots  (5 g)  and  the  moisture  content  reported  by  this 
laboratory was also underestimated (8.6 ± 0.18)%.  

Laboratories 64 and 92 used their routine methods (drying overnight at 105 °C) instead 
of  the  recommended  method.  The  moisture  content  reported  by  laboratory  64  was 
underestimated  (9.1  ±  1)%,  but  the  result  reported  by  laboratory  92  was  correct 
(12 ± 1)%.  

Laboratory  114  could  not  perform  the  sample  preparation  for  moisture  content 
determination  at  the  same  time  as  the  measurement  of  the  PT  reference  material.  The 
reported  result  was  correct  (12.14%),  but  an  uncertainty  component  for  moisture 
content determination was not reported by this laboratory.  

Laboratory 115 did not report the moisture content. 

The  applied  correction  factor  for  dry  mass  as  reported  by  the  participating  laboratories 
varied from 0 to 92.8. Laboratories applied different approaches to calculating this factor. 
Most  of  the  laboratories  divided  the  dry  mass  of  the  sample  by  the  wet  mass  of  the 
sample,  resulting in  correction  factor  ranging  from  0.85  to  0.97.  Others  calculated  it  as 
wet mass divided by dry mass, with results ranging from 1.08 to 1.15. Some laboratories 

10 

 
simply  used  the  result  of  moisture  content  determination.  Eleven  laboratories  did  not 
provide a value for the dry mass correction factor. 

4.2  Measurements 

4.2.1  Techniques, instrumentation and quality system 

All  participants  used  gamma-ray  spectrometry  for  determining  the  massic  activities  of 
131I, 134Cs and 137Cs in the samples. One laboratory (number 66) used a NaI(Tl)-detector, 
one  laboratory  (number  98)  used  a  Ge(Li)-detector,  whilst  the  remaining  118 
laboratories  all  used  HPGe  detectors.  The  relative  efficiency  of  HPGe  the  detectors  used 
ranged from 5 to 150%.  

The participants used in this study mostly methods routinely applied in their laboratories 
(91 out of 120). Most of the participants (104 out of 120) routinely measure food or feed 
samples. Out of these 104, 31% measure routinely less than 50 food or feed samples per 
year,  15%  measure  50  to  100  samples  per  year,  33%  measure  100  to  500  samples  of 
this  type  per  year,  12%  measure  500  to  1000,  and  more  than  1000  samples  are 
analysed by 10% of laboratories (Table 0-4). 

Table 0-4 Number of samples per year analysed by laboratories routinely measuring food or feed 
samples 

Number  of  analysed  samples 
per year 

Number of laboratories 

< 50 

50 to 100 

100 to 500 

500 to 1000 

> 1000 

Source: JRC Geel 

32 (31%) 

16 (15%) 

33 (32%) 

12 (12%) 

11 (10%) 

Out  of  the  120  participating  laboratories,  47  are  accredited  according  to  ISO  17025  for 
gamma-ray spectrometry and 28 laboratories are authorised. The ISO 9001 management 
system is applied in 13 laboratories.  

4.2.2  Sample preparation 

The  typical  masses  of  the  samples  routinely  analysed  in  the  participating  laboratories 
using gamma-ray spectrometry varies from 0.01 g to 15 kg. On average it  is 750 g.  In 
most  of  the  laboratories  (104  out  of  120)  pre-treatment  of  samples  is  routinely 
performed (e.g. grinding, mixing, ashing, drying, cutting, calcination).  

The PT material was treated according to the same procedure as a routine sample by 91 
laboratories.  Five  laboratories  applied  a  procedure  to  compact  the  material  and  25 
laboratories homogenised the sample. For 8 laboratories the detector was calibrated to a 
geometry  where  more  material  than  provided  is  required.  Therefore,  to  respect  the 
geometry, they prepared a mixture of the PT material with another type of blank material 
(e.g.  maize  powder,  silicon).  Special  equipment  for  preparation  of  the  PT  material  was 
used by 13 laboratories, mostly for compacting or homogenising the sample. 

The smallest sample mass used for a single measurement was (1.9781  ±  0.0003)  g  by 
laboratory  120.  One  fourth  of  the  laboratories  used  all  of  the  provided  PT  material 

11 

 
(~90-100 g) remaining after preparation of the moisture content determination samples. 
Four laboratories (2, 21, 60, 120) used for a single measurement less material than the 
minimum  prescribed  sample  intake  of  20  g.  This  could  have  influenced  their  results  as 
homogeneity  of  the  PT  reference  material  was  only  guaranteed  down  to  the  sample 
intake of 20 g. 

The  majority  of  laboratories  used  cylindrical  containers,  16  laboratories  used  a  Marinelli 
beaker and 6 a Petri dish. The sample containers were mostly made of plastic; laboratory 
49 used an aluminium container, laboratories 50, 67 and 75 containers made out of other 
metals  and  laboratories  9  and  109  a  glass  container.  Approximately  half  of  the 
laboratories completely filled the measurement container with the sample.  

4.2.3  Sample positioning 

The  sample  was  centred  on  the  detector  by  eye  in  75  laboratories  and  centred  using 
sample  holders  in  36  laboratories.  In  9  other  laboratories  either  a  Marinelli  beaker  was 
used  or  other  methods  were  applied.  Laboratory  42  covered  the  detector  with  parafilm, 
which  was  marked  with  the  diameter  of  the  cylindrical  measurement  containers.  The 
sample  was  placed  directly  on  the  detector  end-cap  by  41  laboratories.  The  rest  of 
participants  reported  a  different  source-detector  distance  from  0.1  to  50 mm,  with  a 
mean of 3 mm and a median of 1 mm.  

4.2.4  Efficiency calibration 

The full energy peak  efficiency calibration of the detector was mostly performed using a 
calibration source of a geometry similar to the PT  reference material measured. Sixteen 
laboratories  used  LabSOCSTM  (Mirion)  and  6  laboratories  Monte  Carlo  simulations. 
Laboratory number 3 indicated that no calibration was performed.  

From  the  answers  it  was  not  possible  to  understand  in  detail  how  every  laboratories 
performed efficiency calibration but Table 5 gives an indication.  

Five laboratories used one or more certified reference material (CRM). It should be noted 
that  the  approach  of  using  CRMs  for  either  obtaining  a  calibration  curve  or  directly  the 
calibration  factors  for  the  radionuclides  of  interest  is  may  result  in  enlarging  the 
measurement uncertainties. It is therefore in many cases not recommended to use CRMs 
in  this  way.  The  uncertainties  of  the  radionuclide  activity  in  CRMs  are  generally  higher 
than  what  can  be  obtained  in  standard  calibration  sources  of  liquids  and  resins.  It  is 
recommended to use CRMs for method validation and testing.  

12 

 
 
 
Table 0-5 Efficiency calibration methods used by the participating laboratories 

Method 

Number 
laboratories 

of 

Comment 

Set  up  calibration  curves  using  volume 
sources  of  relatively  similar  geometry 
from a liquid solution or resin 

50 

Set up calibration curves using a CRM 

5 

One  of  the  two  above  and  additionally 
using geometry transfer method 

38 

LabSOCSTM 

16 

Software  from  manufacturer 
factory-developed 
with 
computer  model  of 
the 
detector 

a 

ISOCSTM 

Monte Carlo simulation 

calibration 

Deriving 
from 
another  PT  material  with  radiocaesium 
and producing an own spiked calibration 
standard for 131I 

factors 

Calibration by external expert 

Source: JRC Geel 

a 

Software  from  manufacturer 
with 
factory-developed 
the 
computer  model  of 
detector  (main  intended  use 
is 
like 
for 
drums) 

large  sources 

Codes:  GEANT  3.0,  MCNP, 
Gespecor, Angle 3, EFFTRAN, 
RadiationHelper  coupled  with 
(based 
DetectorCalibration 
on GEANT4) 

Laboratory using this method 
overestimated results for 131I  

3 

6 

1 

1 

4.2.5  Analysis and calculation software 

The  software  used  for  spectrum  analysis  was  mostly  Mirion's  GenieTM  2000  (74 
laboratories).  Ortec's GammaVision® was used by 34 laboratories. Fourteen laboratories 
used other, sometimes home-made, software. 

Activity  calculation  was  performed  using  GenieTM  2000  software  by  more  than  half  of 
participating  laboratories.  Thirty-one  used  GammaVision®  for  this  purpose  and  14  used 
spreadsheets  for  the  calculations.  Twelve  laboratories  used  other,  sometimes  home-
made, software. 

4.2.6  Corrections 

True coincidence  summing corrections were applied by 80 laboratories. Ten laboratories 
reported  applying  self-attenuation  correction  and  37  geometry  transfer  correction. 
Correction for the decay during the measurement was applied by 84 laboratories.  

13 

 
 
 
 
 
4.2.7  Nuclear data  

The  recommended  source of nuclear data  was  used by 42 laboratories,  out of which 11 
used the Nucléide-Lara library, a website using data from DDEP. Twenty-four participants 
used  the  data  available  in  the  library  of  the  software  used  (GenieTM  2000  or 
GammaVision®).  Five 
the  Lund/LBNL  Nuclear  Data  Search 
(http://nucleardata.nuclear.lu.se/nucleardata/toi/).  The 
tables  of 
reference  data 
Physikalisch-Technische Bundesanstalt (PTB) were used by 4 laboratories. The rest of the 
responding participants used various other sources. Four laboratories (46, 72, 79 and 93) 
provided  an  answer  not  adequate  to  the  question  asked  and  5  laboratories  did  not 
answer this question.  

laboratories  used 

4.2.8  Background measurements 

A background measurement was performed by 115 laboratories. Details on the duration 
of  the  background  measurement  were  not  provided  by  15  laboratories.  Forty-five 
laboratories  measured  the  background  with  an  empty  sample  container.  44  with  an 
empty shield, 18 with a sample container filled with (usually distilled) water in the same 
type  of  container  as  used  for  the  measurement  of  the  PT  reference  material.  Eight 
laboratories measured background with a container filled with a blank organic substance 
- 4 used blank corn flour and 2 cellulose. One laboratory used a solution of agar (known 
to have about 0.8 Bq/g of  40K), which might be the reason for a too high result for  40K. 
One laboratory reported using a blank sample without specifying its type.  

The  length  of  the  background  measurements  varied  from  989  to  2,000,000  seconds 
(equal to 16 min to 23 days).  

4.2.9  Detection limit calculation 

The  laboratories  were  asked  which  method  they  used  to  calculate  the  minimum 
detectable  activity.  Only  30  laboratories  replied.  ISO  11929:2000  was  indicated  by  4 
laboratories, ISO 11929:2010 by 15 laboratories, and the "Currie method" by 6. The rest 
of  laboratories  reported  other  methods  like  calculation  built  in  to  GenieTM  2000  or 
GammaVision®. 

14 

 
5  Reported results 

As explained in Chapter 2.3, for the first time in this series of proficiency tests two types 
of reporting were used – emergency and routine reporting. The emergency reporting will 
be  described  in  detail  in  a  separate  report.  For  the  routine  reporting,  participants  were 
given two months after the sample receipt. The massic activities of  131I,  134Cs and  137Cs 
with  their  corresponding  expanded  uncertainties  and  the  coverage  factor  used  (k) 
reported  in  the  routine  mode  are  presented  in  Annex  10.  The  results  for  40K  are  also 
provided for information purposes only.  

One  laboratory  (37)  noticed  after  the  deadline  of  submission  that  by  mistake  their 
reported  results  were  filled  in  in  the  wrong  order  into  the  reporting  form.  The  results 
reported  before  the  deadline  were  retained,  which  resulted  in  very  big  deviations  from 
the  reference  values.  Another  laboratory  (3)  reported  “0”  as  a  value  for  the  massic 
activity  of  131I.  This  laboratory  has  lost  their  first  analysis  results,  and  the  second 
measurement was performed too late to report 131I.  

15 

 
6  Evaluation of the results 

6.1  Scores 

The  evaluation  of  the  reported  results  was  conducted  according  to  ISO  13528:2015 
(ISO 13528:2015, 2015). The  results were compared to the  reference values presented 
in  

The  reference  values  for  131I,  134Cs  and  137Cs  are  further  on  used  for  the  evaluation  of 
the  results  reported  by  the  PT  participants.  The  reference  value  for  40K  is  only 
informative. 

Table 0-3. Three different scores were  calculated z, ζ and En  score.  The results can 

be found in Annex 10.  

6.1.1  z score 

In  the  calculation  of  the  z  score  the  standard  deviation  for  proficiency  assessment 
(σpt) is used. This parameter was set at 20% of the assigned reference value (xpt), based 
on  the  experience  from  previous  PTs  and  on  what  should  be  expected  that  a  modern 
laboratory today should be able to produce under routine conditions. 

The z score was calculated according to the following equation: 

z =

xi − xpt
σpt

where 

xi   

xpt   

is the participant's results; 

is the assigned reference value. 

The interpretation of the z score is as follows:  

 
 
 

If the participant's result gives | z |  ≤ 2.0, it is acceptable; 
If the participant's result gives 2.0 < | z | < 3.0, it gives a warning signal; 
If  the  participant's  result  gives  | z  |  ≥  3.0,  it  is  unacceptable  and  gives  an 
action signal. 

6.1.2  Zeta (ζ ) score 

In order to assess the agreement of the participants' estimations of uncertainty with 

that of the reference value two additional scores were calculated namely ζ and En score. 

 The  ζ  score  is  taking  into  account  the  standard  uncertainty  (k=1)  of  both  the 
participant's  result  and  the  reference  value  and  is  calculated  according  to  the  following 
equation: 

xi − xpt

ζ =

√u2(xi) + u2(xpt)

where 

u(xi) 

u(xpt) 

is the standard uncertainty of the participant's result;  

is the standard uncertainty of the assigned reference value. 

When uncertainties are correctly estimated according to the Guide to the Expression 
of Uncertainty Measurement (GUM)  (ISO/IEC  GUIDE 98-3:2008, 2008), a measurement 
result  with  its  uncertainty  interval  should  overlap  with  the  reference  value  and  its 
uncertainty.  

16 

 
 
 
The  ζ  score  indicates  whether  a  participant's  result  agree  with  the  reference  value 
within  the  provided  uncertainty  value.  An  unsatisfactory  ζ  score  can  be  related  to 
incorrect  measurement  result,  poor  uncertainty  estimation,  or  both  of  these.  It  is 
interpreted as follows:  

 
 
 

If | ζ |  ≤ 2.0, the participant's result is acceptable; 
If 2.0 < | ζ | < 3.0, the participant's result gives a warning signal; 
If | ζ | ≥ 3.0, the participant's result gives an action signal. 

6.1.3  En score 

To  take  the  expanded  uncertainty  (k=2)  of  the  participant's  result  and  that  of  the 
reference values into account in the analysis of the reported results, a performance test 
using  En  score  was  applied  (ISO,  2015).  The  calculation  of  the  En  score  was  carried  out 
according to the following formula:  

xi − xpt

En =

√U2(xi) + U2(xpt)

where 

U(xi) 

U(xpt) 

is the expanded uncertainty of the participant's result;  

is the expanded uncertainty of the assigned reference value. 

En scores are interpreted as following: 

 

 

If  |En|  <  1,  the  uncertainty  of  the  participant's  result  is  consistent  with  the 
uncertainty of the reference value; 
If |En| ≥ 1, the uncertainty of the participant's result are inconsistent with the 
uncertainty  of  the  reference  value  and  the  sources  of  deviation  should  be 
investigated and corrected. 

6.2  Evaluation  

Overview  of  the  participants  performance  is  presented  in  Table  0-6.  In  addition,  the 
results  of  the  z  and  ζ  scores  are  presented  in  Figs.  2  to  9.  Out  of  the  120  participants 
according to the z score the results were acceptable in 92% for 131I and in 94% for both 
134Cs  and  137Cs.  For  131I,  only  1  laboratory  received  a  warning  signal,  8  laboratories  an 
action signal and 1 laboratory reported a value below the detection limit. In case of 134Cs, 
also  only  1  laboratory  received  a  warning  signal  and  6  an  action  signal,  and  for  137Cs 
there  were  2  laboratories  with  a  warning  signal  and  5  with  an  action  signal.  For  the 
optional 40K, 81% of reported results were acceptable, whereas 7 laboratories received a 
warning signal and 13 an action signal.  

The  absolute  value  of  ζ  score  was  found  to  be  lower  than  2  for  66%  of  participants  for 
131I,  56%  for  134Cs  and  68%  for  both  137Cs  and  40K.  These  laboratories  reported  values 
having uncertainties consistent with the uncertainty of the reference value. In case of En 
score, the number of consistent results was the same as for ζ score.  

17 

 
 
 
Table 0-6 Overview of the laboratories performance. The numbers within brackets are the number of reported results. 

Radionuclide 

𝑧 score 

ζ score 

En score 

acceptable  warning signal  action signal  acceptable  warning signal 

action signal 

consistent 

inconsistent  

92% (110) 

1% (1) 

7% (8) 

66% (79) 

11% (13) 

23% (27) 

66% (79) 

34% (40) 

94% (113) 

1% (1) 

5% (6) 

56% (67) 

7% (9) 

37% (44) 

56% (67) 

44% (53) 

94% (113) 

2% (2) 

4% (5) 

68% (81) 

5% (6) 

27% (33) 

68% (81) 

32% (39) 

81% (85) 

7% (7) 

12% (13) 

68% (71) 

12% (14) 

17% (20) 

68% (71) 

29% (34) 

131I 

134Cs 

137Cs 

40K* 

Source: JRC Geel 

18 

 
e
r
o
c
s

z

4

3

2

1

0

-1

-2

-3

-4

e
r
o
c
s

z

4

3

2

1

0

-1

-2

-3

-4

Figure 2 Results of z score calculations for 131I  

z score I-131

Laboratory

Source: JRC Geel 

Figure 3 Results of z score calculations for 134Cs 

z score Cs-134

Laboratory

Source: JRC Geel 

19 

 
 
 
 
 
4

3

2

1

0

-1

-2

-3

-4

7
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
-7

e
r
o
c
s

z

e
r
o
c
s

z

Figure 4 Results of z score calculations for 137Cs 

z score Cs-137

Laboratory

Source: JRC Geel 

Figure 5 Results of z score calculations for 40K 

z score K-40

Laboratory

Source: JRC Geel 

20 

 
 
 
 
 
 
s
e
r
o
c
s

ζ

7
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
-7

s
e
r
o
c
s

ζ

7

6

5

4

3

2

1

0

-1

-2

-3

-4

-5

-6

-7

Figure 6 Results of ζ score calculations for 131I 

zeta (ζ) score I-131

Laboratory

Source: JRC Geel 

Figure 7 Results of ζ score calculations for 134Cs 

zeta (ζ) score Cs-134

Laboratory

Source: JRC Geel 

21 

 
 
 
 
e
r
o
c
s

ζ

e
r
o
c
s

ζ

7

6

5

4

3

2

1

0

-1

-2

-3

-4

-5

-6

-7

7

6

5

4

3

2

1

0

-1

-2

-3

-4

-5

-6

-7

Figure 8 Results of ζ score calculations for 137Cs 

zeta (ζ) score Cs-137

Laboratory

Source: JRC Geel 

Figure 9 Results of ζ score calculations for 40K 

zeta (ζ) score K-40

Laboratory

Source: JRC Geel 

22 

 
 
 
6.3  PomPlots 

Another tool to display the results is a PomPlot. Detailed information regarding this graph 
can  be  found  in  (Spasova,  et  al.,  2007).  If  the  reported  result  and  its  uncertainty  are 
correctly assessed by the laboratory, the result on the graph should be found in between 
the  green  lines  (=1).  The  laboratories  with  results  close  to  the  top  of  the  pyramid, 
between  the  green  lines  (=1),  reported  the  most  accurate  results  with  small 
uncertainties  (see  Annex  12).  The  MAD  is  the  Median  of  the  Absolute  Deviation  and  is 
used  as  it  is  a  robust  measure  of  the  typical  statistical  spread  of  the  data  set,  which  is 
useful  for  normalising  the  axes  in  the  PomPlot.  D  is  the  deviation  from  the  reference 
value and u is the standard uncertainty of the laboratory and the reference value. 

The PomPlots based on the results of this PT are presented in Figures 10 to 13. For  131I 
most  of  the  results  are  gathered  in  the  centre.  There  are  however  some  results  falling 
outside the red lines (=3). There is also a group of laboratories with high uncertainties 
(u/MAD>1.5). For 134Cs there are many laboratories with too low results (left part of the 
graph, outside the green, blue and red lines). The same group of laboratories also seem 
to  underestimate  their  uncertainties  (u/MAD<0.7).  The  results  are  similar  for  137Cs 
except that there is not a distinct group on the left hand side of the plot as in the case of 
134Cs. Also for 40K it can be noted that some laboratories underestimate the uncertainties 
and that more laboratories have too high results than too low.  

23 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 10 PomPlot of the 131I results. Green, blue and red solid lines indicate ζ scores. The 
reference value is presented as a red square, the participants' results are presented as blue 
diamonds 

-8

-6

-4

-2

D/MAD
0

2

4

6

8

0

1

2

3

4

D
A
M
u

/

Source: JRC Geel 

Figure 11 PomPlot of the 134Cs results. Green, blue and red solid lines indicate ζ scores. The 
reference value is presented as a red square, the participants' results are presented as blue 
diamonds 

-8

-6

-4

-2

D/MAD
0

2

4

6

8

0

1

2

3

4

D
A
M
u

/

Source: JRC Geel 

24 

 
 
Figure 12 PomPlot of the 137Cs results. Green, blue and red solid lines indicate ζ scores. The 
reference value is presented as a red square, the participants' results are presented as blue 
diamonds 

-8

-6

-4

-2

D/MAD
0

2

4

6

8

0

1

2

3

4

D
A
M
u

/

Source: JRC Geel 

Figure  13  PomPlot  of  the  40K  results.  Green,  blue  and  red  solid  lines  indicate  ζ  scores.  The 
reference  value  is  presented  as  a  red  square,  the  participants'  results  are  presented  as  blue 
diamonds 

-8

-6

-4

-2

0

2

4

6

8

D/MAD

0

1

2

3

4

D
A
M
u

/

Source: JRC Geel 

25 

 
 
6.4  Possible influencing parameters 

Based  on  the  reported  results  and  answers  to  the  questionnaire  an  analysis  of  possible 
reasons  for  errors  and  areas  of  improvement  are  identified.  This  includes  looking  at 
parameters  such  as  application  of  true  coincidence  summing  corrections,  accreditation 
and experience of laboratories in measurement of food or feed samples. 

For 131I, there was no relation between the z scores below -3 and lack of true coincidence 
summing correction. For 134Cs, only 1 laboratory with z score below -3 and 1 with z score 
above  3  used  more  than  one  γ-ray  line  and  did  not  apply  true  coincidence  summing 
correction.  The  remaining  laboratories  with  unacceptable  results  according  to  z  score 
used  only  one  γ-ray  line,  used  more  than  one  γ-ray  line  and  applied  true  coincidence 
summing  correction  or  did  not  provide  any  information  regarding  the  number  of  γ-ray 
lines  used.  This  indicates  that  the  procedures  applied  for  the  efficiency  calibration 
calculation and/or true coincidence summing corrections should be revised.  

Eleven out of 16 laboratories with z score above 2 for 40K had also z score for 134Cs lower 
than the reference value (z score -0.14 to -3.60). For  134Cs, 2 out of 5 laboratories with 
results lower than the reference value reported for  40K results higher than the reference 
value (z score 1.11 and 4.49) and 2 did not report a result for 40K. This may indicate that 
the  efficiency  calibration  is  not  accurate  enough  for  40K.  If  the  efficiency  calibration 
source  contains  60Co  and/or  88Y  the  true  coincidence  summing  corrections  must  be 
correctly applied in the calculations of efficiencies.    

26 

7  Conclusions 

Overall,  the  results  of  the  participating  laboratories  are  good  and  no  major  problems 
have been discerned. Some more detailed observations are: 

  Although  many  laboratories  (80)  reported  applying  true  coincidence  summing 
corrections,  the  negative  bias  on  the  results  for  134Cs  indicate  that  many 
laboratories  still  fail  to  properly  apply  these  corrections  and/or  include  the 
associated  uncertainty  components  in  the  overall  uncertainty  budget.  The  same 
seems to be true for the efficiency calibration sources (especially those containing 
60Co). This is further made clear by the 40K results that have a positive bias, which 
is likely to be caused by either failing to perform proper true coincidence summing 
correction  on  certain  radionuclides  in  the  calibration  source  or  improper 
background subtraction. 

  Some  laboratories  use  CRMs  for  setting  up  calibration  curves.  This  is  not  always 
suitable. A calibration source must have low uncertainty, which is not always the 
case with CRMs as some are aimed for method validation and testing. 

  Some laboratories use Monte Carlo calculations for absolute efficiency calculation, 
which  can  be  treacherous,  as  a  computer  models  tends  to  be  accurate  only  for 
very specific samples. Even a small error in a model can result in incorrect results. 
Measuring the sample  at a distance of 2-8 cm (depending on a  count rate)  from 
the detector could reduce the effect of small errors in Monte Carlo calculations.  

  A recurrent problem is the underestimation of uncertainties. This can be seen by 

the slightly worse results of ζ score compared to the z scores.  

  Awareness of correct decay data is increasing but some laboratories still use data 
from sources that are not updated with the latest high quality evaluations. In this 
case the effect is however of minor importance. 

  The too low amount of sample material that was used by some laboratories could 
possibly  have  influenced  some  results.  The  prescribed  minimum  sample  intake 
shall be respected.   

27 

 
References 

Bonas, G., Zervou, M., Papaeoannou, T. & Lees, M., 2003. ‘SoftCRM’: A New Software for 
the Certification of Reference Materials. Accreditation and Quality Assurance, 8(3-4), pp. 
101-107. 

Hult, M., Jobbágy, V. & Sobiech-Matura, K., 2019. Radioactivity monitoring: How the JRC 
verifies  results  from  monitoring  within  the  European  Union,  Luxembourg:  Publication 
Office of the European Union. 

ISO  13528:2015,  2015.  Statistical  methods 
interlaboratory  comparisons,  Geneva,  Switzerland:  International  Organisation 
Standardization. 

in  proficiency  testing  by 
for 

for  use 

ISO  17043:2010,  2010.  Conformity  assessment  —  General,  Geneva,  Switzerland: 
International Organisation for Standardization. 

ISO  Gide  35:2015,  2015.  Reference  materials  –  Guidance  for  the  characterisation  and 
the  assessment  of  the  homogeneity  and  stability  of  the  material,  Geneva,  Switzerland: 
International Organisation for Standardization. 

ISO/IEC  GUIDE  98-3:2008,  2008.  Uncertainty  of  measurement  -  Part  3:  Guide  to  the 
expression  of  uncertainty 
in  measurement,  Geneva,  Switzerland:  International 
Organisation for Standardization. 

Linsinger, T. et al., 2001. Homogeneity and stability of reference materials. Accreditation 
and Quality Assurance, Volume 6, pp. 20-25. 

Monography BIPM-5: Table of radionuclides, v.3, 2006.  

Monography BIPM-5: Table of radionuclides, v.7, 2013.  

Monography BIPM-5: Table of radionuclides, v.8, 2016.  

Pommé, S. & Keightley, J., 2015. Determination of a reference value and its uncertainty 
through a power-moderated mean. Metrologia, pp. S200-S212. 

Spasova,  Y.,  Pommé,  S.,  Wätjen,  U.  &  W,  2007.  Visualisation  of  interlaboratory 
comparison results in PomPlot. Accreditation and Quality Assurance, pp. 623-627. 

28 

 
 
 
List of abbreviations and definitions 

AC 

pre-accession countries 

ANOVA 

analysis of variance 

BIPM 

Bureau International des Poids et Mesures 

Bq 

CEA 

CRM 

Becquerel, SI derived unit of radioactivity  

Commissariat à l’énergie atomique et aux énergies alternatives 

Certified Reference Material 

DDEP 

Decay Data Evaluation Project 

d.f. 

DG 

degrees of freedom 

Directorate General 

d.m. 

dry mass 

EC 

EU 

European Commission 

European Union 

EURATOM 

European Atomic Energy Community 

EURDEP 

European Radiological Data Exchange Platform 

F 

Fcrit 

GUM 

HPGe 

IAEA 

ICRM 

ISO 

JRC 

k 

kg 

MAD 

MILC 

MS 

test statistic used in one way ANOVA analysis 

value of the F statistic at the threshold probability α of mistakenly 
rejecting a true null hypothesis 

Guide to the Expression of Uncertainty in Measurement 

high-purity germanium  

International Atomic Energy Agency 

International Committee for Radionuclide Metrology 

International Organization for Standardization 

Joint Research Centre 

coverage factor 

kilogram 

median of the absolute deviation 

Management of Interlaboratory Comparisons software 

member states (of the European Union) 

29 

MSB 

MSW 

PMM 

PT 

PTB 

REM 

SS 

Sbb 

Swb 

between-bottle variance 

within-bottle variance 

power-moderated mean 

proficiency testing 

Physikalisch-Technische Bundesanstalt 

Radioactivity Environmental Monitoring 

sum of squares 

between bottles standard deviation 

within bottles standard deviation 

StDev 

standard deviation 

ubb 

ubb* 

uchar 

uhom 

Upt 

upt 

xpt 

uncertainty contribution due to inhomogeneity 

estimation of uncertainty contribution due to inhomogeneity 

uncertainty  from  the  power-moderated  mean  calculated  for  the 
results of the characterisation study 

uncertainty  component  associated  with 
heterogeneity (this report equal to ubb*) 

reference  material 

expanded uncertainty of the reference value 

uncertainty of the reference value 

reference value 

30 

 
 
 
List of figures 

Figure 1 Maize grains processing (cooling, milling and sieving). ................................. 6 

Figure 2 Results of z score calculations for 131I ........................................................19 

Figure 3 Results of z score calculations for 134Cs ......................................................19 

Figure 4 Results of z score calculations for 137Cs ......................................................20 

Figure 5 Results of z score calculations for 40K ........................................................20 

Figure 6 Results of ζ score calculations for 131I ........................................................21 

Figure 7 Results of ζ score calculations for 134Cs ......................................................21 

Figure 8 Results of ζ score calculations for 137Cs ......................................................22 

Figure 9 Results of ζ score calculations for 40K ........................................................22 

Figure 10 PomPlot of the 131I results. Green, blue and red solid lines indicate ζ scores. 
The reference value is presented as a red square, the participants' results are presented 
as blue diamonds .................................................................................................24 

Figure 11 PomPlot of the 134Cs results. Green, blue and red solid lines indicate ζ scores. 
The reference value is presented as a red square, the participants' results are presented 
as blue diamonds .................................................................................................24 

Figure 12 PomPlot of the 137Cs results. Green, blue and red solid lines indicate ζ scores. 
The reference value is presented as a red square, the participants' results are presented 
as blue diamonds .................................................................................................25 

31 

 
 
List of tables 

Table 1. The origin of participating laboratories. ....................................................... 4 

Table 2. Measurement results and uncertainty reported by the laboratories used for the 
reference value calculations (k=1). .......................................................................... 8 

Table 3. Reference values of massic activity xpt with expanded uncertainties U(xpt) 
(k = 2) for the PT reference material at the reference date (1 June 2017 00:00:00 UTC).
 ........................................................................................................................... 9 

Table 4 Number of samples per year analysed by laboratories routinely measuring food 
or feed samples ....................................................................................................11 

Table 5 Efficiency calibration methods used by the participating laboratories ..............13 

Table 6 Overview of the laboratories performance. The numbers within brackets are the 
number of reported results. ...................................................................................18 

32 

 
Annexes 

Annex 1. Letter of invitation for laboratory nomination 

33 

 
 
34 

 
 
Annex 2. Invitation to laboratories for registration 

35 

 
 
36 

 
 
Annex 3. Sample dispatch information 

Subject: EC PT on I-131, Cs-134 and Cs-137 in maize powder - samples dispatch  

Thu 01/06/2017 15:23 

Dear colleague, 

Your  laboratory  is  registered  for  the  EC  PT  on  I-131,  Cs-134  and  Cs-137  in  maize 
powder.  We  have  started  dispatching  the  samples  today  and  due  to  a  large  number  of 
participants we will continue with the shipment during the following days. 

The parcel will contain:  

  a bottle with spiked maize powder,  
 
  a letter with your password key required for the routine reporting of results. 

instruction for moisture content determination,  

The reporting of laboratory results will be done in two ways: 

  Emergency reporting (voluntary), the results of which will remain anonymous 

and are collected as a part of a scientific study. This reporting will be collected up to 
48 h from the moment of sample receipt by filling in the attached excel file and 
sending it back to the e-mail address: JRC-GEE-REM-COMPARISONS@ec.europa.eu. 
The most important is the Tab nr. 2 (results), but we will be grateful if you could 
fill in also the other information.  

  Routine reporting (mandatory) the results of which will be revealed to relevant 

authorities and used for performance evaluation. The reporting of the results is done 
via the following URL: https://web.jrc.ec.europa.eu/ilcReportingWeb and will be 
opened from 5 June 2017 to 28 July 2017. To report your results, you will need 
your password key which is unique to this proficiency test and your laboratory. 
Please find the attached pdf file with instructions for the routine reporting. 

Should you have any question, please feel free to contact us at: 

Email: JRC-GEE-REM-COMPARISONS@ec.europa.eu 

Looking forward to hearing from you,  

Yours sincerely, 

Katarzyna Sobiech-Matura                                            Petya Malo 

Project Coordinator                                                      Logistic Assistant 

European Commission 
DG Joint Research Centre 
Directorate G - Nuclear Safety & Security 

Unit G2 - Standards for Nuclear Safety, Security and Safeguards 

Retieseweg 111 
B-2440 Geel, Belgium 
+32 14 571290 
JRC-GEE-REM-COMPARISONS@ec.europa.eu 

http://ec.europa.eu/dgs/jrc 

37 

 
  
 
 
Annex 4. Sample accompanying letter 

38 

 
39 

 
Annex 5. Instruction for moisture content determination 

40 

 
41 

 
 
Annex 6. Communication of preliminary results 

42 

 
43 

 
 
44 

 
  
45 

 
46 

  
Annex  7.  List  of  participating 

laboratories  (countries 

in 

alphabetical order) 

AUSTRIA 

Austrian Agency for Health and Food Safety (AGES) 
STRA 
Spargelfeldstraße 191 
1220 Vienna 

Austrian Agency for Health and Food Safety (AGES) 
Radon and Radioecology  
Wieningerstrasse 8  
4020 Linz 

BELGIUM 

IRE-ELIT  
LMR  
Avenue de l'Espérance 1  
6220 Fleurus 

SCK•CEN  
EHS-LRM  
Boeretang 200  
2400 Mol 

BOSNIA-HERZEGOVINA 

Institute for Public Health of Federation of Bosnia and Herzegovina 
Radiation Protection Centre 
Marsala Tita 9 
71000 Sarajevo 

BULGARIA 

Executive Environment Agency  
Regional Laboratory - Pleven  
Storgoziya District PBox:525  
"Measures and Measuring Devices", RO Building, floor 4 
5800 Pleven 

Executive Environment Agency  
Regional Laboratory - Vratza 
Exarh Josif 81 
3000 Vratza 

Executive Environment Agency  
Regional Laboratory – Montana 
"Jlius Irasek" Str. 4 
3400 Montana 

Executive Environment Agency 
Blvd. Tzar Boris III, 136 
1618 Sofia 

National Center of Radiobiology and Radiation Protection (NCRRP) 
Radiation Protection 
Georgi Sofiiski Blvd. 3 
1606 Sofia 

47 

 
 
 
 
 
 
 
 
 
 
Regional Health Inspectorate of Burgas 
Control of radiation 
Alexandrovska str.120 
8000 Burgas 

CROATIA 

Institute for Medical Research and Occupational Health 
Radiation Protection Unit 
Ksaverska cesta 2 
10000 Zagreb 

Ruđrer Bošković Institute 
Laboratory for radioecology  
Bijenička cesta 54 
10000 Zagreb 

CYPRUS 

State General Laboratory of Cyprus 
Kimonos Str. 44 
1451 Nicosia 

CZECH REPUBLIC 

Statni ustav radiacni ochrany, v.v.i. 
Hradec Kralove 
Pileticka 57 
500 03 Hradec Kralove 

National Radiation Protection Institute (SÚRO) 
Monitoring 
Bartoškova 28 
140 00 Prague 

DENMARK 

Technical University of Denmark 
Center for Nuclear Technologies 
Frederiksborgvej 399, Building 201 
4000 Roskilde 

ESTONIA 

Environmental Board Republic of Estonia 
Radiation Safety Department 
Kopli 76 
10416 Tallinn 

University of Tartu 
Institute of Physics 
W. Ostwaldi Str 1 
50411 Tartu 

FINLAND 

STUK - Radiation and Nuclear Safety Authority 
VALO 
Laippaite 4 
00880 Helsinki 

48 

 
 
 
 
 
 
 
 
 
 
 
 
FRANCE 

Institut de Radioprotection et de Sureté Nucléaire (IRSN) 
STEME 
31 rue de l'Ecluse,  
BP 40035 
78116 Le Vésinet 

GERMANY 

Max Rubner-Institute (MRI) 
Safety & Quality of Milk &Fish 
Hermann-Weigmann-Strasse 1 
24103 Kiel 

GREECE 

Aristotle University of Thessaloniki  
Nuclear Technology Laboratory  
Egnatia street 
54124 Thessaloniki  

HUNGARY 

National Food Chain Safety Office  
Food and Feed Safety Directorate  
Fogoly utca 13-15 
1182 Budapest 

University of Pannonia 
Institute of R & R 
Egyetem str. 10 
8200 Veszprém 

National Public Health Institute 
Anna street 5 
1221 Budapest 

Government Office for Gyor-Moson-Sopron County 
National Public Health 
Josika Street 16 
9024 Gyor 

Hungarian Academy of Sciences Centre for Energy Research 
29-33 Konkoly T M 
1121 Budapest 

Government Office of the Capital City Budapest 
Nemetvölgyi 37-39 
1124 Budapest 

Hungarian Defence Forces CBRN Area Control Centre (MH GAVIK) 
Radiological Laboratory 
Jaszberenyi ut 39-45 
1106 Budapest 

IRELAND 

Environmental Protection Agency 
Radiation Monitoring 
3 Clonskeagh Square, Clonskeagh Road 

49 

 
 
 
 
 
 
 
 
 
 
 
Dublin 14 Dublin 

ITALY 

ARPA Lombardia 
CRR Milano 
Via Filippo Juvara 22 
20129 Milan 

ARPA Lombardia 
CRR sede di Bergamo 
via Clara Maffei 4 
24121 Bergamo 

ARPACAL 
RC - Physical Laboratory 
Via Troncovito SNS 
89135 Reggio Calabria 

ARPAS - Agenzia Regionale per la Protezione dell'Ambiente della Sardegna 
DTS-CMVA Agenti Fisici 
Viale F. Ciusa 6 
09131 Cagliari 

ARPA Sicilia 
S.T. Catania 
Via Carlo Ardizzone, 35 
95124 Catania 

Arpa Sicilia 
Struttura Territoriale Palermo 
via Nairobi 4 
90129 Palermo 

Istituto Zooprofilattico Sperimentale Lazio e Toscana "M.Aleandri" 
Produzioni Zootecniche 
Via Appia Nuova, 1411 
00178 Rome   

Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata 
CRN Radioattività, S.C.Chimica 
Via Manfredonia, 20 
71121 Foggia 

ARPA Molise 
CRR Molise 
Contrada Selva Piana snc 
86100 Campobasso 

ARPA Lazio 
Sezione Provinciale di Latina 
Via G. Carducci, 7 
04100 Latina 

ARPA Lazio 
Sezione provinciale di Viterbo 
Via Montezebio 17 
01100 Viterbo 

50 

 
 
 
 
 
 
 
 
 
 
 
 
A.R.P.A.Cal - Agenzia Regionale per la protezione dell'Ambiente della Calabria 
Cosenza - Lab. Fisico 
L. da Vinci n° 49/51 
87040 Castrolibero 

ARPA Valle d'Aosta 
Environmental Radioactivity 
Loc Grande Charrière 44 
11020 Saint-Christophe 

A.R.P.A.B. - Centro Regionale Radioattività 
Dipartim. Provinc. di Matera 
via dell'Industria snc 
75100 Matera 

ARPA  FVG  (Environmental  Protection  Agency  of  Friuli  Venezia  Giulia  -  North-East 
Italy) 
Radiation Protection Center 
Via Colugna, 42 
33100 Udine 

ARPA Piemonte 
Dipartimento Radiazioni 
Via Jervis 30 
10015 Ivrea (TO) 

I.S.P.R.A.  -  Italian  National  Institute  for  the  Environmental  Protection  and 
Research 
Radiometric Measurement Lab 
via di Castel Romano, 100 
00128 Rome 

ARPAV 
DRL - UO CRA-CRR 
Via Alberto Dominutti 8 
37135 Verona 

ARPA Marche 
U.O. Radioattività Ambientale 
via Colombo, 106 
60127 Ancona 

APPA TN - Local Environmental Protection Agency 
Settore Laboratorio 
via Lidorno, 1 
38123 Trento 

Environmental Protection Agency - Tuscany Region 
Radioattività e Amianto 
via Ponte alle Mosse 211 
50144 Florence 

Arpa Piemonte 
Struttura Semplice Siti Nucleari 
Via Trino 89 

51 

 
 
 
 
 
 
 
 
 
 
 
 
13100 Vercelli 

ARPA Umbria 
Servizio Radiazioni Ionizzanti 
Via Pievaiola 207 B-3 
06132 Perugia 

ARPAE Emilia-Romagna 
CTR Radioattività ambientale 
via XXI Aprile 48 
29121 Piacenza 

Agenzia Regionale per la Tutela dell'Ambiente - ARTA Abruzzo 
Distretto Prov. di Pescara 
Via Guglielmo Marconi, 51 
65126 Pescara 

ARPA Puglia 
BARI 
Via Oberdan 18/E 
70126 Bari 

LATVIA 

Institute of Food Safety, Animal Health and Environment - "BIOR" 
Lejupes Street 3 
1076 Riga 

LITHUANIA 

National Food and Veterinary Risk Assessment Institute 
Radiology 
J.Kairiukscio st.10 
08409 Vilnius 

Radiation Protection Centre 
Expertise and Exposure Monitor 
Kalvariju 153 
08221 Vilnius 

LUXEMBOURG 

Ministère de la Santé - Direction de la Santé 
Division de la Radioprotection 
Villa Louvigny, Allée Marconi 
2120 Luxembourg 

MALTA 

Environmental Health Directorate 
Public Health Laboratory 
Merchant street 
VLT1179 Valletta 

MONTENEGRO 

LLC Center for Ecotoxicological Research Podgorica 
Radionuclide analytics Unit 
Put Sarla de Gola 2 
81000 Podgorica 

52 

 
 
 
 
 
 
 
 
 
 
 
 
 
NETHERLANDS 

RIKILT Wageningen University & Research 
Contaminants 
Akkermaalsbos 2 
6708 WB Wageningen 

POLAND 

Central Mining Institute 
Centre for Environmental Radio 
Plac Gwarkow 1 
40-166 Katowice 

Central Laboratory for Radiological Protection 
Dosimetry Department 
Konwaliowa St. 7 
03-194 Warszawa 

AGH University of Science and Technology 
Faculty of Physics and ACS 
Al. Mickiewicza 30 
30-059 Krakow 

Institute of Nuclear Physics (IFJ PAN) 
Radzikowskiego 152 
31-342 Krakow 

National Centre for Nuclear Research 
LPD 
A. Soltana 7 
05-400 Otwock 

PORTUGAL 

Instituto Superior Técnico 
Laboratório de Proteção e Segurança Radiológica 
Estrada Nacional 10 (km 139,7) 
2695-066 Bobadela LRS 

ROMANIA 

Environmental Protection Agency Dolj 
SSRM Craiova 
Calea Bucuresti 150 
200349 Craiova 

Environmental Protection Agency 
Splaiul Muresului FN 
310132 Arad 

Environmental Protection Agency Constanta 
300 Mamaia B-dul, Room nr.19, (C.M.R. "Dobrogea" Building) 
900581 Constanta 

Environmental Protection Agency Iasi 
Calea Chisnaului nr.43 
700179 Iasi 

53 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Environmental Protection Agency Maramures 
Radioactivity Station 
Iza street nr 1° 
430073 Baia Mare 

National Environmental Protection Agency 
Radioactivity Laboratory 
294 Splaiul Independentei 
060031 Bucharest 

National Institute of Public Health - Regional Center of Public Health Cluj 
Radiation Hygiene 
Pasteur 6 
400349 Cluj Napoca 

National Institute of Public Health-Regional Center Iasi 
Radiation Laboratory 
Victor Babes 14 
700465 Iasi 

Institute for Hygiene and Veterinary Public Health 
Chemistry and Radioactivity 
Campul Mosilor no. 5, sector 2 
021201 Bucharest 

SERBIA 

Vinča Institute of Nuclear Science 
Chemical Dynamics Department 
Mike Petrovića Alasa 12-14 
11351 Belgrade 

Vinča Institute of Nuclear Science 
Laboratory 011 
Mike Petrovića Alasa 12-14 
11351 Belgrade 

Vinča Institute of Nuclear Science 
Radiation and Envir.Protection 
Mike Petrovića Alasa 12-14 
11351 Belgrade 

Institute for the Application of Nuclear Energy-INEP 
Banatska 31b 
11080 Belgrade 

ANAHEM d.o.o 
Mocartova 10 
11160 Belgrade 

SLOVAKIA 

Slovenské elektrárne, a.s. 
Závod Atómové elektrárne Mochovce 
935 39 Mochovce 

54 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Atómové elektrárne Bohunice 
Off-site radiation monitoring 
Okružná 14 
91701 Trnava 

VUJE, Inc. 
Okružná 5 
91864 Trnava 

Public Health Authority of the Slovak Republic 
Radiation Protection 
Trnavská cesta 52 
82102 Bratislava 

Regional Public Health Authority 
Radiation Protection 
Cesta k nemocnici 1 
97556 Banska Bystrica 

Regional Public Health Authority 
Ipelska 1 
04001 Kosice 

Ministry of Interior 
Control chemical laboratory 
Príboj 559 
97613 Slovenská Ľupča 

Ministry of Interior  
Control Chemical Laboratory 
Ku kachlickarni 653/9 
04423 Jasov 

Ministry of Deffence 
CBRN Battalion 
Safarikova 109 
04801 Roznava 

State Veterinary and Food Institute 
Ref. Lab. Environmen. Radioact. 
Tr. A. Hlinku 2, RI-pavilon SPU 
94976 Nitra 

Faculty of Mathematics, Physics and Informatics Comenius University Bratislava 
Nuclear Physics and Biophysics 
Mlynská dolina F1 
84248 Bratislava 

SLOVENIA 

ZVD Zavod za Varstvo pri Delu D.D. 
CFM 
Chengdujska Cesta 25 
1260 Ljubljana Polje 

Jozef Stefan Institute 

55 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Jamova cesta 39 
1000 Ljubljana 

SPAIN 

Laboratorio de Radiactividad Ambiental 
Energy Independencia 13 
33004 Oviedo 

Universitat Politecnica de Catalunya 
Institut Tecniques Energetique 
Av. Diagonal 647, Edifici ETSEIB, Campus Sud 
08028 Barcelona 

University of the Balearic Islands 
Environ. Radioactivity Lab. 
Cra. Valldemossa km 7.5 
07122 Palma de Mallorca 

University of Granada 
Inorganic Chemistry 
Radiochemistry Environmental Laboratory 
Faculty of Sciences, Av. Fuentenueva, s/n 
18077 Granada 

University of Extremadura 
LARUEX, Dpt Applied Physics 
LARUEX, Faculty of Veterinary, Avda. Universidad, s/n 
10003 Cáceres 

University of Extremadura 
Physics 
Physics Av. w/n 
06006 Badajoz 

University of the Basque Country 
Nuclear Engin. & Fluid Mech. 
Escuela de Ingenieria – Bilbao, Alameda de Urquijo, s/n 
48013 Bilbao 

University of Málaga 
Applied Physics II, Lab. Radiactividad Ambiental 
Facultad de Ciencias-Químicas, Campus de Teatinos s/n 
29071 Málaga 

Barcelona University 
Lab. Radiologia Ambiental 
Martí i Franquès, 1-11 3ª 
08028 Barcelona 

Universidad de Sevilla 
Física Aplicada II 
Av. Reina Mercedes 2 
41012 Sevilla 

UPM-E.T.S.I.Caminos 
Laboratorio Ingeniería Nuclear 
Profesor Aranguren s/n 

56 

 
 
 
 
 
 
 
 
 
 
 
28040 Madrid 

Universitat Politecnica de Valencia 
Lab. Radiactividad Ambiental 
Camino de Vera, s/n  Edificio 5 I 
46022 Valencia 

Escuela Universitaria Politécnica de Ferrol 
Laboratorio de Radiactividad Ambiental, UDC 
Química 
Avenida 19 de Febrero s/n 
15405 Ferrol 

Universidad de La Laguna 
SEGAI 
Laboratorio Fisica Medica. Facu 
Aprtado 456, La Laguna 
38200 Tenerife 

University of Zaragoza, Faculty of Sciences 
Theoretical Physics, Nuclear A 
Pedro Cerbuna 12 
50009 Zaragoza 

Universidad de Salamanca 
LRI-DATACION 
Edificio I+D+i Calle espejo S/N 
37008 Salamanca 

Laboratorio de Radiactividad Ambiental-Universidad de Valencia 
Edificio Jerónimo Muñoz, Avenida Dr. Moliner, 50 
46100 Burjassot (Valencia) 

CIEMAT 
Environmental Dept. 
Avenida Complutense 40, E70.P0.09 
28040 Madrid 

SWEDEN 

Swedish Radiation Safety Authority 
Solna strandväg 122 
17154 Solna 

Swedish Defence Research Agency 
Cementvägen 20 
90182 Umeå 

SWITZERLAND 

CERN 
The Occupational Health & Safety and Environmental Protection (HSE) Unit  
24-E-003 
1217 Meyrin 

TURKEY 

Cekmece Nuclear Research and Training Center 
Radioactivity Measurement Unit 

57 

 
 
 
 
 
 
 
 
 
 
 
Rad  Birimi,  Yarimburgaz  mah.,  Nukleer  Arastirma  Merkezi  Yolu,  No:10,  Halkali 
Kucukcekmece 
34303 Istanbul 

Turkish Atomic Energy Authority - Sarayköy Nuclear Research and Training Center 
Saray Mah. Atom Cad. No:27, Kazan Ankara 
06983 Ankara 

UKRAINE 

Ukrainian Hydrometeorolodical Institute (UHMI) 
ERMD  av. Nauki, 37 
03028 Kyiv 

UNITED KINGDOM 

Public Health England 
RHED, CRCE Glasgow 
155 Hardgate Road 
G51 4LS Glasgow 

Centre for Environment, Fisheries and Aquaculture Science (CEFAS) 
Radioanalytical Services 
Pakefield Road 
NR33 0HT Lowestoft 

58 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annex 8. Questionnaire 

59 

 
 
60 

 
 
 
 
61 

62 

 
 
63 

64 

 
65 

66 

67 

68 

69 

70 

71 

72 

73 

 
74 

75 

76 

77 

78 

79 

80 

81 

 
82 

83 

84 

 
85 

86 

 
 
 
 
Annex  9.  Results  of  the  laboratories  (routine  reporting).  For  each  laboratory  reported massic  activity 
and expanded uncertainty (U) is provided, as well as results of z and ζ scores calculations 

4 

352 

78 

42 

7.93 

53.4 

26 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 

16 

17 

18 

19 

20 

21 

22 

23 

24 

25 

26 

Lab 
code 

Massic 
activity of 
131I (Bq/kg 
d.m.) 

z 
score 

ζ score  Massic 

U  

activity of 
134Cs (Bq/kg 
d.m.) 

z 
score 

ζ score  Massic 

U  

activity of 
137Cs (Bq/kg 
d.m.) 

z 
score 

ζ score 

Massic 
activity of 
40K (Bq/kg 
d.m.) 

231 

243 

0 

152 

1.05 

1.36 

8.48 

0.39 

-5.00 

-47.75 

-1.02 

-5.11 

881 

954 

784 

846 

-0.11 

-1.71 

0.29 

0.30 

-0.65 

-2.88 

-0.31 

-2.30 

528 

710 

464 

510 

4 

104 

46 

43 

-0.17 

-2.61 

110 

1.49 

3.11 

-0.76 

-3.45 

-0.34 

-1.64 

- 

- 

- 

U  

5 

266 

0 

13 

U  

4 

- 

- 

- 

239.63 

9.85 

1.29 

7.66 

966.07 

0.36 

5.35 

688.08 

10.78 

1.29 

15.97 

2863.52 

81.62 

186.2 

192 

218.6 

7.8 

22 

13 

22.3 

1.7 

-0.13 

-0.41 

806.4 

0.03 

0.72 

0.13 

2.33 

815 

1097.0 

-0.52 

-3.25 

535.9 

-0.48 

-4.95 

525 

109.5 

1.09 

3.50 

735.5 

-4.80 

-44.80 

31.0 

2.5 

-4.83 

-75.21 

18.0 

33.8 

38 

71.2 

2.1 

-0.10 

-0.61 

-0.20 

-1.09 

96.2 

339 

1.72 

5.20 

131.0 

-4.84 

-74.74 

57.3 

15.8 

42 

20.5 

7.3 

192.98 

30.24 

0.05 

0.13 

905.42 

78.11 

0.02 

0.11 

549.45 

57.15 

0.02 

0.08 

101.12 

22.88 

180 

186 

192 

17 

15 

23 

191.83 

13.83 

164 

201 

102 

190.4 

197.2 

186 

181 

329.45 

182.0 

73.27 

206 

1454.60 

27 

22 

6 

13.2 

12.7 

28 

26 

76.54 

18.2 

12.86 

25 

- 

-0.29 

-1.17 

-0.13 

-0.59 

0.03 

0.02 

0.08 

0.10 

-0.71 

-1.92 

0.26 

0.85 

-2.33 

-17.80 

-0.02 

-0.08 

0.16 

0.83 

-0.13 

-0.34 

-0.26 

-0.74 

3.62 

3.60 

-0.24 

-0.91 

857 

890 

882 

867.17 

920 

698 

432 

862.7 

927.8 

845 

897 

61.47 

766.0 

-3.08 

-15.55 

545.93 

0.39 

1.14 

931 

72 

88 

35 

25 

50 

55 

9 

38.1 

39.8 

175 

100 

25.30 

76.6 

32.91 

101 

-0.24 

-1.16 

-0.06 

-0.24 

-0.11 

-0.91 

523 

532 

533 

40 

53 

22 

-0.22 

-1.13 

100 

-0.14 

-0.55 

-0.13 

-1.07 

- 

99 

22 

- 

12 

-0.19 

-1.99 

545.16 

15.28 

-0.02 

-0.18 

118.86 

15.06 

0.11 

0.69 

-1.13 

-6.81 

-2.60 

-37.98 

-0.21 

-1.72 

0.15 

1.17 

-0.31 

-0.63 

-0.02 

-0.08 

557 

482 

292 

536.0 

557.3 

531 

539 

28 

35 

7 

35.1 

26.9 

75 

68 

0.09 

0.64 

-0.59 

-3.45 

102 

167 

-2.33 

-32.58 

- 

-0.10 

-0.58 

0.09 

0.68 

-0.15 

-0.42 

-0.07 

-0.23 

79.34 

101.6 

109 

133 

6 

12 

- 

20.9 

8.0 

18 

60 

-4.66 

-49.11 

26.03 

14.64 

-4.76 

-51.44 

123.28 

30.84 

-0.75 

-3.38 

530.0 

53 

-0.16 

-0.62 

196.0 

-1.97 

-17.69 

498.82 

30.17 

-0.44 

-2.90 

123.10 

0.17 

0.58 

571 

53 

0.22 

0.88 

105.9 

19.6 

12.7 

8.8 

33.08 

- 

12161.5 

901.325 

62.49  24.98 

8641.50 

384.18 

73.99  42.11 

12588.30 

1660.6 

87 

 
27 

28 

29 

30 

31 

32 

33 

34 

35 

36 

37 

38 

39 

40 

41 

42 

43 

44 

45 

46 

47 

48 

49 

50 

51 

52 

53 

54 

55 

56 

57 

58 

59 

60 

187 

151 

178 

196.6 

202 

170 

184.41 

174.0 

190 

197 

545.3 

198.9 

174.56 

140.59 

204 

197.70 

195 

520 

228 

193 

190 

196 

24 

18 

14 

68.2 

41.1 

40 

-0.10 

-0.32 

-1.05 

-4.06 

-0.34 

-1.61 

0.15 

0.29 

0.16 

0.53 

-0.55 

-1.03 

880 

748 

797 

952.4 

901 

800 

112 

76 

78 

85.9 

182 

50 

-0.12 

-0.37 

-0.85 

-3.85 

-0.58 

-2.56 

0.29 

0.00 

1.16 

0.00 

-0.56 

-3.67 

528 

499 

534 

591.9 

547 

470 

64 

50 

49 

61.9 

110 

30 

-0.17 

-0.58 

-0.44 

-1.85 

-0.12 

-0.51 

0.41 

0.00 

1.41 

0.00 

-0.70 

-4.65 

- 

60 

98 

112.3 

100 

74 

- 

10 

11 

24.2 

21.7 

10 

28.53 

-0.17 

-0.44 

826.14 

24.27 

-0.42 

-4.48 

580.03 

38.23 

0.30 

1.62 

214.83 

66.98 

9.2 

20 

28 

68.1 

43.0 

14.0 

5.57 

24 

21.7 

56 

151 

54 

56.35 

22 

20 

-0.45 

-2.79 

-0.03 

-0.09 

0.41 

890 

957 

870 

0.16 

9.27 

0.21 

10.33 

195.7 

0.36 

895.2 

26 

90 

122 

24.8 

75 

-0.06 

-0.63 

0.31 

1.21 

-0.17 

-0.50 

512 

563 

522 

-3.91 

-41.70 

865.6 

-0.03 

-0.15 

546.5 

16 

50 

73 

99.8 

48.6 

-0.32 

-3.29 

0.15 

0.62 

-0.23 

-0.67 

2.91 

0.00 

6.32 

-0.02 

-0.43 

-2.04 

807.80 

47.98 

-0.52 

-3.50 

481.73 

27.62 

-0.60 

-4.22 

-1.32 

-10.34 

694.41 

0.34 

0.18 

0.10 

8.61 

0.97 

0.05 

1.03 

0.58 

0.14 

4.35 

1.36 

0.09 

-0.03 

-0.09 

0.13 

0.46 

813 

922.23 

882 

936 

1179 

812 

890 

880 

8.43 

25 

-1.15 

-16.87 

473.91 

-0.49 

-5.18 

528 

135.2 

0.12 

0.31 

550.24 

300 

44 

101 

59.5 

80 

90 

-0.11 

-0.13 

0.19 

1.54 

1.41 

5.37 

-0.49 

-3.45 

-0.06 

-0.26 

-0.12 

-0.45 

560 

534 

622 

509 

540 

535 

-0.67 

-9.13 

101.05 

-0.17 

-1.67 

100 

7.78 

18 

71.1 

140 

28 

81 

0.03 

0.12 

0.09 

0.18 

-0.12 

-0.83 

0.69 

1.82 

25.5 

-0.35 

-2.24 

70 

55 

-0.06 

-0.20 

-0.11 

-0.42 

121 

- 

104 

- 

102.5 

99.44 

116.71 

71 

- 

57 

- 

107 

94 

17 

- 

15 

- 

15.4 

16.98 

16.27 

17 

16.4 

53 

- 

8 

- 

21 

14 

1882.57 

152.09 

44.28  22.21 

7779.27 

576.84 

38.17  23.83 

5781.48 

158.57 

47.85  65.77 

5852.79 

126.36 

182 

167 

123 

23 

19 

17 

202.19 

7.71 

213 

163.0 

21 

9 

-0.23 

-0.74 

-0.63 

-2.33 

-1.78 

-7.24 

0.29 

0.58 

2.01 

1.96 

877 

761 

574 

770.28 

835 

-0.73 

-4.65 

704.0 

102 

76 

46 

-0.14 

-0.47 

-0.78 

-3.53 

-1.81 

-12.72 

526 

533 

385 

62 

55 

44 

-0.19 

-0.65 

-0.13 

-0.49 

-1.48 

-7.02 

112 

117 

70.8 

30.97 

-0.73 

-6.78 

561.66 

22.24 

0.13 

1.12 

167.51 

67 

35 

-0.37 

-1.86 

546 

-1.09 

-9.41 

482.0 

45 

25 

-0.01 

-0.04 

-0.59 

-4.54 

152 

- 

40 

14 

13.1 

41.03 

82 

- 

177.3830 

32.9894 

-0.36 

-0.80 

732.0204 

52.7555 

-0.94 

-5.87 

512.3045 

62.5416 

-0.32 

-1.08 

101.1189 

12.2762 

194 

223.7 

158.61 

192 

17 

61.0 

4.07 

19 

0.08 

0.86 

0.32 

1.06 

879 

1012 

44 

274 

-0.12 

-0.89 

0.62 

0.81 

541 

620 

22 

169 

-0.05 

-0.46 

0.67 

0.86 

-0.85 

-7.22 

609.84 

15.13 

-1.62 

-21.15 

427.96 

10.47 

-1.09 

-13.62 

110 

118.5 

68.43 

0.03 

0.10 

897 

90 

-0.02 

-0.09 

535 

54 

-0.11 

-0.42 

95 

8.0 

37.1 

14.07 

13 

88 

61 

62 

63 

64 

65 

66 

67 

68 

69 

70 

71 

72 

73 

74 

75 

76 

77 

78 

79 

80 

81 

82 

83 

84 

85 

86 

87 

88 

89 

90 

91 

92 

93 

94 

871.7 

41.59 

-0.16 

-1.23 

604.1 

27.98 

26 

48 

89 

37 

56.9 

51.22 

108 

89.7 

45.50 

28.01 

103 

64 

-0.02 

-0.23 

-0.80 

-5.41 

-0.69 

-2.72 

-0.14 

-1.19 

0.25 

0.08 

1.48 

0.55 

613 

474 

445 

539 

558.16 

557.75 

-0.07 

-0.24 

547 

-0.50 

-1.96 

0.16 

1.13 

493.3 

562.3 

-3.60 

-35.80 

1023 

0.33 

1.14 

-0.27 

-1.44 

692 

527 

26 

29 

51 

58 

96.92 

31.62 

64 

55.2 

31.38 

105.2 

71 

58 

0.52 

0.60 

3.65 

4.47 

-0.67 

-4.53 

-0.93 

-3.86 

105.4 

102 

90 

- 

-0.07 

-0.27 

97.8 

0.10 

0.10 

0.00 

0.23 

0.62 

0.00 

-0.49 

-1.89 

0.14 

4.35 

1.33 

0.89 

8.97 

4.01 

-0.18 

-0.67 

619.72 

124.73 

103 

79.0 

103.92 

191.6 

- 

120 

-0.16 

-0.77 

536 

-0.16 

-1.47 

543.95 

42 

26.8 

-0.10 

-0.50 

127 

-0.03 

-0.20 

0.22 

1.26 

608.76 

37.54 

0.56 

3.08 

103.12 

185.54 

-0.63 

-1.20 

760.31 

68.34 

-0.78 

-3.90 

518.54 

125.28 

-0.26 

-0.45 

91.31 

219.2 

11.70 

215 

169 

157 

197 

264.88 

212.16 

183 

180.3 

202.37 

677.2 

235 

196 

166.88 

204 

190.35 

244.35 

192 

220.32 

206 

195.2 

203 

192 

183 

29 

13 

24 

20 

30.15 

11.19 

24 

21.5 

19.63 

45.54 

22 

32 

39.4 

22 

6.9 

31.22 

22 

19.09 

4 

15 

7 

14 

61 

193.167 

35.156 

0.74 

0.63 

3.98 

1.60 

-0.58 

-2.88 

-0.89 

-2.69 

0.16 

1.93 

0.55 

0.56 

4.74 

3.08 

897 

757 

776 

875 

946.47 

916.31 

-0.21 

-0.63 

888 

-0.28 

-0.93 

810.3 

0.30 

1.07 

929.74 

12.73  21.03 

252.3 

1.15 

0.13 

3.76 

0.30 

961 

852 

0.34 

1.11 

873 

-0.02 

-0.12 

872.47 

1.40 

0.03 

0.77 

0.39 

0.11 

0.31 

0.03 

3.31 

0.09 

2.83 

3.35 

0.49 

2.26 

0.12 

-0.21 

-0.26 

941.09 

882 

854.62 

908 

892 

912 

823 

857 

69 

31.14 

59.25 

95 

9 

24 

14 

54 

-0.11 

-0.39 

534 

51.44 

-0.26 

-1.65 

585.97 

0.04 

0.57 

612 

-0.05 

-0.54 

550.0 

0.06 

0.82 

-0.43 

-2.66 

549 

554 

503 

284 

-0.24 

-0.31 

163.07 

17.2 

-0.73 

-2.94 

787.18 

31.51 

-0.63 

-5.84 

510.22 

199 

200 

195 

193 

188 

193 

189.16 

186 

18 

30 

31 

22 

26 

12 

0.06 

0.21 

0.24 

0.10 

0.05 

0.12 

0.81 

0.58 

0.25 

0.17 

-0.08 

-0.22 

0.05 

0.28 

877.12 

119.788 

-0.13 

-0.39 

531.176 

899 

900 

909 

880 

929 

902 

76 

110 

88 

94 

119 

54 

-0.01 

-0.05 

-0.01 

-0.02 

0.04 

0.18 

-0.12 

-0.43 

0.16 

0.01 

0.46 

0.03 

543 

530 

560 

524 

529 

550 

48.40 

-0.05 

-0.08 

816.69 

30.37 

-0.47 

-4.43 

562.23 

35 

-0.13 

-0.28 

810 

130 

-0.50 

-1.38 

515 

89 

58 

39.32 

9 

18.4 

11 

36 

72 

60.15 

71.76 

52 

60 

35 

62 

68 

34 

19.23 

61 

-0.12 

-0.44 

100 

0.36 

0.59 

0.03 

0.02 

0.06 

1.87 

7.81 

0.26 

0.22 

0.36 

-0.40 

-1.20 

145.06 

120 

100 

101 

140 

97 

-0.34 

-1.19 

97.49 

-0.14 

-0.43 

-0.04 

-0.15 

-0.16 

-0.55 

0.12 

0.69 

-0.21 

-0.72 

-0.16 

-0.52 

0.03 

0.14 

0.16 

1.28 

93.3 

103 

80 

60 

92 

135 

110 

116.96 

-0.29 

-1.02 

91 

13.85 

31 

14 

- 

10.2 

221.43 

19.9 

26 

17.1 

21.50 

60.2 

- 

32 

35.32 

27 

17.28 

64.94 

21 

39.33 

6 

24 

27 

28 

22 

14.53 

39.23 

17 

30 

16 

20 

31 

12 

21.28 

19 

95 

96 

97 

98 

99 

100 

101 

102 

103 

104 

105 

106 

107 

108 

109 

110 

111 

112 

113 

114 

115 

116 

117 

118 

119 

120 

167.15 

210.9 

206.76 

165 

207 

212.08 

178.10 

190.2 

232.8 

184 

200 

201 

188 

194 

143 

195 

175.5 

196 

210.45 

197 

150 

210.2 

197 

210 

195 

163.0 

21.84 

13.6 

37.25 

33 

9 

30.6 

39.54 

7.8 

10.8 

18 

20 

16 

15 

12 

14 

30 

30.5 

24 

23.65 

22 

15 

42.9 

12.2 

50 

24 

6.4 

-0.62 

-2.05 

716.22 

0.52 

0.41 

2.52 

0.83 

-0.68 

-1.53 

0.42 

0.55 

2.66 

1.33 

986.1 

835.28 

781 

998 

813.18 

50.85 

38.1 

23.83 

109 

34 

37.9 

-1.03 

-6.62 

478.32 

0.47 

3.82 

602.1 

-0.37 

-3.99 

578.51 

-0.67 

-2.15 

0.54 

4.73 

472 

564 

-0.49 

-3.96 

571.63 

-0.34 

-0.64 

850.09 

53.48 

-0.28 

-1.75 

518.56 

-0.02 

-0.14 

1.09 

6.22 

-0.18 

-0.71 

0.24 

0.26 

0.84 

1.12 

-0.08 

-0.35 

0.08 

0.42 

-1.26 

-5.95 

0.10 

0.26 

838.4 

957.2 

863 

884 

879 

888 

888 

611 

876 

-0.41 

-0.98 

767.4 

0.13 

0.51 

0.16 

0.40 

1.56 

0.51 

-1.07 

-4.82 

0.50 

0.16 

0.50 

0.10 

0.88 

0.82 

0.75 

0.32 

793 

821.78 

881 

940 

874.6 

808 

970 

786 

-0.73 

-5.47 

715.4 

11.6 

6.6 

32 

90 

38 

78 

53 

42 

120 

90.7 

50 

-0.35 

-4.86 

0.31 

4.70 

-0.21 

-1.93 

-0.09 

-0.37 

-0.12 

-0.99 

-0.07 

-0.33 

-0.07 

-0.45 

-1.61 

-12.11 

-0.14 

-0.41 

518.0 

653.8 

550 

537 

576 

541 

538 

409 

524 

-0.74 

-2.86 

500.0 

-0.60 

-3.92 

552 

51.61 

-0.44 

-2.80 

574.97 

104 

94 

90.4 

2.46 

100 

16 

25.8 

-0.11 

-0.38 

0.22 

0.81 

547 

550 

-0.15 

-0.57 

575.4 

-0.52 

-8.04 

0.38 

1.34 

-0.64 

-8.21 

570 

590 

524 

33.75 

30.1 

33.26 

66 

13 

33.5 

33 

10.2 

8.2 

20 

55 

24 

42 

32 

28 

72 

62.2 

38 

33.40 

59 

60 

61.6 

2.62 

60 

11 

20.65 

25 

28.65 

13 

19 

58.9 

23.65 

7.8 

13.4 

20 

15 

40 

12 

- 

16 

58 

47 

30 

- 

16 

11 

-0.63 

-3.76 

102.64 

0.51 

0.29 

3.32 

1.77 

-0.68 

-2.21 

0.16 

0.23 

1.78 

1.36 

-0.26 

-1.59 

-0.27 

-3.35 

0.98 

0.03 

13.17 

0.25 

-0.09 

-0.35 

0.27 

2.09 

-0.05 

-0.27 

-0.08 

-0.52 

-1.26 

-8.82 

104 

112.31 

91 

104 

139.5 

109.81 

99.6 

127.8 

99 

98 

117 

104 

- 

78 

-0.21 

-0.63 

169 

-0.43 

-1.47 

0.05 

0.26 

0.00 

0.03 

0.26 

0.21 

0.39 

0.25 

1.54 

0.00 

0.10 

0.90 

3.23 

1.40 

-0.21 

-2.58 

208.5 

144 

- 

93 

102 

102.0 

34.5 

131 

90 

114 

16 

30 

23 

-1.03 

-10.74 

431.0 

45.4 

-1.06 

-4.88 

111.8 

12.6 

90 

Annex 10. Results of the homogeneity study 

Massic activity of 131I (Bq/kg) 

Bottle number 

Replicate 1 

Replicate 2 

Replicate 3 

8 
30 
41 
64 
77 
90 
111 
114 
141 
157 

194.4 
199.7 
196.4 
202.8 
200.3 
207.6 
201.7 
204.7 
204.0 
206.3 

206.9 
201.6 
203.8 
200.8 
205.0 
207.5 
195.2 
203.2 
206.4 
206.7 

201.0 
206.1 
205.0 
202.0 
197.2 
204.2 
206.2 
203.9 
200.5 
203.6 

Mean 
StDev 
Relative StDev 
Source: JRC Geel 

202.8 
3.6 
1.8% 

One way ANOVA calculation for 131I 

SS 

d.f. 

MS 

StDev 

F 

Source of 
Variation 
Between Units 

106.97 

Within Units 

270.27 

Total 

377.24 

11.89  MSB<MSW 

0.88 

13.51 

3.68 

9 

20 

29 

F-crit 
95% 
2.39 

F-crit 
99% 
3.46 

Homogeneity 
Results 

Source: JRC Geel 

Mean 

Sbb 

Sbb  (%) 

Swb 

202.81  MSB<MSW   MSB<MSW  

3.68 

Swb  
(%) 
1.80% 

Ubb* 

1.193 

Ubb* 
(%) 
0.60% 

Differences between units statistically significant? (a=95%): No 

Differences between units statistically significant? (a=99%): No 

91 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Massic activity of 134Cs (Bq/kg) 

Bottle number 

Replicate 1 

Replicate 2 

Replicate 3 

8 
30 
41 
64 
77 
90 
111 
114 
141 
157 

933.4 
937.5 
944.7 
934.0 
947.2 
943.3 
930.4 
930.9 
937.4 
944.8 

932.4 
945.8 
941.6 
939.7 
937.9 
939.9 
921.8 
931.0 
937.4 
937.9 

937.8 
942.8 
925.2 
927.0 
926.2 
950.3 
942.0 
948.0 
938.3 
942.7 

937.6 
7.2 
0.8% 

Mean 
StDev 
Relative 
StDev 
Source: JRC Geel 

One way ANOVA calculation for 134Cs 

SS 

d.f. 

MS 

StDev 

F 

Source of 
Variation 
Between 
Units 
Within Units 

452.265 

1,054.14 

Total 

Homogeneity 
Results 

1,506.40 
Weight.Avg. 

F-crit 
95% 
2.393 

F-crit 
99% 
3.457 

50.252  MSB<MSW 

0.953 

52.707 

7.26 

9 

20 

29 

Sbb 

Sbb  (%) 

Swb 

Swb  
(%) 

Ubb* 

Ubb* 
(%) 

937.638  MSB<MSW   MSB<MSW  

7.26  0.80% 

2.357  0.30% 

Source: JRC Geel 

Differences between units statistically significant? (a=95%): No 

Differences between units statistically significant? (a=99%): No 

92 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Massic activity of 137Cs (Bq/kg) 

Bottle number 

Replicate 1 

Replicate 2 

Replicate 3 

8 
30 
41 
64 
77 
90 
111 
114 
141 
157 

573.4 
574.7 
577.6 
567.4 
577.4 
579.6 
566.6 
578.1 
572.7 
572.7 

574.5 
576.2 
573.7 
575.3 
571.6 
571.4 
558.9 
568.1 
574.3 
576.3 

570.2 
569.3 
576.5 
567.2 
558.7 
577.4 
580.5 
570.6 
564.2 
573.1 

572.3 
5.4 

Mean 
StDev 
Relative StDev  1.0% 
Source: JRC Geel 

One way ANOVA calculation for 137Cs 

SS 

d.f. 

MS 

StDev 

F 

Source of 
Variation 
Between 
Units 
Within Units 

191.516 

667.273 

Total 

Homogeneity 
Results 

858.789 
Weight.Avg. 

F-crit 
95% 
2.393 

F-crit 
99% 
3.457 

21.28  MSB<MSW 

0.638 

33.364 

5.776 

9 

20 

29 

Sbb 

Sbb  (%) 

Swb 

Swb  
(%) 

Ubb* 

Ubb* 
(%) 

572.263  MSB<MSW   MSB<MSW  

5.776  1.00% 

1.875  0.30% 

Source: JRC Geel 

Differences between units statistically significant? (a=95%): No 

Differences between units statistically significant? (a=99%): No 

93 

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Annex 11. Results of the short-term stability study   

Short-term stability in 40°C

)
g
/
s
p
c
(

m
a
r
g
r
e
p
e
t
a
r

t
n
u
o
C

0.007

0.006

0.005

0.004

0.003

0.002

0.001

0

Cs-137

Cs-134

I-131

y = 5E-05x + 0.006
R² = 0.8988

y = 5E-05x + 0.003
R² = 0.8805

y = 3E-05x + 0.0019
R² = 0.701

0

1

2

3

4

Time (weeks)

Source: JRC Geel 

Table A1. Results of measurements for the short-term stability study in 40°C 

Countrate per mass (cps/g) 

Time (weeks) 

Cs-137 

Cs-134 

I-131 

0 

1 

2 

3 

4 

Mean 

Slope 

0.003150299  0.006023900  0.001922051 

0.003373622  0.006454323  0.002119166 

0.003082863  0.005913943  0.001843770 

0.003221634  0.006223087  0.001853515 

0.003315840  0.006367836  0.002201835 

0.003228852  0.006196618  0.001988068 

0.000017909  1.905894495  0.577283629 

Error on the slope  0.000041974  0.122608076  0.246108236 

t 

tcrit 

ustab 

0.426680748  0.58100451 

0.515485962 

5.840909310  5.84090931 

5.84090931 

4.19735E-05  7.8595E-05 

5.70172E-05 

relative ustab (%) 

0.012999516  0.01268346 

0.028679723 

Source: JRC Geel 

95 

 
 
 
 
 
 
 
 
 
 
 
 
Short-term stability test in 60°C

y = 5E-05x + 0.0061
R² = 0.1011

y = 2E-05x + 0.0032
R² = 0.0572

y = 3E-05x + 0.0019
R² = 0.0814

Cs-137

Cs-134

I-131

)
g
/
s
p
c
(

m
a
r
g
r
e
p
e
t
a
r
t
n
u
o
C

0.008

0.007

0.006

0.005

0.004

0.003

0.002

0.001

0

0

1

2

3

4

Time (weeks)

Source: JRC Geel 

Table A2. Results of measurements for the short-term stability study in 60°C 

Countrate per mass (cps/g) 

Time (weeks) 

Cs-137 

Cs-134 

I-131 

0 

1 

2 

3 

4 

Mean 

Slope 

0.00315 

0.00602 

0.00192 

0.00337 

0.00645 

0.00211 

0.00308 

0.00591 

0.00184 

0.00322 

0.00622 

0.00185 

0.00331 

0.00636 

0.00220 

0.00322 

0.00619 

0.00198 

0.00001790 

1.90589449 

0.57728362 

Error on the slope  0.00004197 

0.12260807 

0.24610823 

t 

tcrit 

ustab 

0.426680748  0.58100451 

0.515485962 

5.840909310  5.84090931 

5.84090931 

4.19735E-05  7.8595E-05 

5.70172E-05 

relative ustab (%) 

0.012999516  0.01268346 

0.028679723 

Source: JRC Geel 

96 

 
 
 
 
 
 
 
 
 
 
 
 
Annex 12. The PomPlot 

The  PomPlot,  a  graphical  method,  is  used  for  producing  a  summary  overview  of  the 
participants' results.  It  displays the  relative deviations (D/MAD) of the individual results 
Ai from the  reference value  A0 on the horizontal axis and relative uncertainties (u/MAD) 
on the vertical axis (Fig. A1). For both axes, the variables are expressed as multiples of 
MAD, which is defined as the median of the absolute deviation from the reference value 

𝑀𝐴𝐷 = 𝑀𝑒𝑑𝑖𝑎𝑛|𝐷𝑖|, (𝑖 = 1, … , 𝑛)  

where  

(1) 

Di is the difference between the reported and the reference activity concentration: 

(2) 

where  

Ai 

A0 

activity value reported by laboratory i 

assigned reference value  

The median absolute deviation MAD is used because of its robustness. 

For every data point the uncertainty is calculated as an independent sum of the reported 
combined uncertainties on Ai and A0 

where  

u(Ai) 

  standard uncertainty of activity value reported by Laboratory i (k=1) 

u(A0) 

standard uncertainty of assigned activity reference value for Laboratory i (k=1) 

(3) 

Figure A1. Interpretation of a PomPlot (Spasova et al., 2007) 

Source: JRC Geel 

97 

10AADii0222AuAuucici 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
The ζ-scores, where 

, with values 1, 2 and 3, are represented by diagonal solid 

lines,  creating  the  aspect  of  a  pyramidal  structure.  The  ζ-score  is  a  measure  of  the 
deviation between  laboratory  result and reference value relative to  the total uncertainty 
(ISO,  2015).  The  points  on  the  right-hand  side  of  the  graph  correspond  to  results  that 
are higher than the reference value whereas lower values are situated on the left. When 
the  reported uncertainty is small, the  corresponding point is situated  high in the graph. 
The  most  accurate  results  should  be  situated  close  to  the  top  of  the  pyramid.  Points 
outside of the ζ=±3 lines are probably inconsistent with the reference value. 

98 

uD 
Annex 13. REMPES file example 

99 

 
 
100 

 
 
101 

GETTING IN TOUCH WITH THE EU 

In person 

All over the European Union there are hundreds of Europe Direct information centres. You can find the 
address of the centre nearest you at: http://europea.eu/contact 

On the phone or by email 

Europe Direct is a service that answers your questions about the European Union. You can contact this 
service: 

- by free phone: 00 800 6 7 8 9 10 11 (certain operators may charge for these calls), 

- at the following standard number: +32 22999696, or 

- by electronic mail via: http://europa.eu/contact 

FINDING INFORMATION ABOUT THE EU 

Online 

Information about the European Union in all the official languages of the EU is available on the Europa 
website at: http://europa.eu 

EU publications 
You can download or order free and priced EU publications from EU Bookshop at: 
http://bookshop.europa.eu. Multiple copies of free publications may be obtained by contacting Europe 
Direct or your local information centre (see http://europa.eu/contact). 

 
 
 
 
K
J
-
N
A
-
3
0
1
4
2
-
E
N
-
N

doi: 10.2760/54966 

ISBN 978-92-76-17330-4