preparation of 1100 60co calibration sources

Raf Van Ammel, Katarzyna Sobiech-Matura, Guillaume Lutter

JRC-Geel contribution to

WP5 Task 1 deliverable

5.1.1. of the MetroDecom

project

Preparation of 1100 60Co calibration sources

2016

EUR 28123 EN

This publication is a Technical report by the Joint Research Centre, the European Commission’s in-house science

service. It aims to provide evidence-based scientific support to the European policy-making 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 which might be made

of this publication.

Contact information

Name: Raf Van Ammel

Address: JRC Geel, Retieseweg 111, 2440 Geel, Belgium

E-mail: [email protected]

Tel.: +32-(0)14-571 267

JRC Science Hub

https://ec.europa.eu/jrc

JRC103167

EUR 28123 EN

ISBN 978-92-79-62200-7

ISSN 1831-9424

doi:10.2789/787831

© European Atomic Energy Community, 2016

Reproduction is authorised provided the source is acknowledged.

All images © European Atomic Energy Community 2016

How to cite: Raf Van Ammel, Katarzyna Sobiech-Matura, Guillaume Lutter; Preparation of 1100 60Co calibration

sources; EUR 28123 EN; 10.2789/787831

2

Table of contents

FOREWORD ................................................................................ 3

ABSTRACT .................................................................................. 4

1. Introduction ...................................................................... 5

2. Production of the sources .................................................... 6

2.1 Source holders .......................................................... 6

2.2. Preparation of the 60Co solution .................................. 7

2.3. Preparation of the sources using a precision pattern dispenser ............................................................. 8

3. Calibration of the sources ................................................... 11

3.1 Measurement set-up ................................................. 11

3.2 Measurements ......................................................... 12

3.3 Results .................................................................... 13

3.3.1 Aluminium pill point sources .......................... 13

3.3.2 CMI source holders. ...................................... 15

4 Conclusion......................................................................... 26

REFERENCES ............................................................................. 27

LIST OF ABBREVIATIONS AND DEFINITIONS ................................. 28

LIST OF FIGURES ....................................................................... 29

LIST OF TABLES ......................................................................... 30

3

Foreword

MetroDecom (ENV54), Metrology for decommissioning of nuclear facilities, is a European

Metrology Research Programme (EMRP) project carried out by 15 partners to address

the needs of the nuclear decommissioning process. This is done by developing and

implementing new measurement techniques, instruments, standards and reference

materials, and by ensuring knowledge transfer to stakeholders. The project is divided in

five Work Packages (WP):

WP1 Characterisation of waste materials present on decommissioning sites

WP2 Measurement facility for waste segregation

WP3 Implementation of free release measurement facility on decommissioning site

WP4 Radioactive waste repositories monitoring

WP5 Development of reference materials and standard sources

The Work Package 5, coordinated by the Physikalisch-Technische Bundesanstalt (PTB),

consists of 4 different tasks.

Task 1 Reference materials and standard sources for segregation of materials and for

free release measurements (lead by Cesky Metrologicky Institut (CMI))

Task 2 Reference materials and standard sources for radiochemical analysis (lead by

National Physics Laboratory (NPL))

Task 3 Gaseous reference materials (lead by NPL)

Task 4 Reference materials and standard sources for surface contamination monitors

(lead by Institut National de Cercetare Dezvoltare pentru Fizica si Inginerie Nucleara

(IFIN))

The JRC-Geel Radionuclide Metrology Sector (RN) is involved in WP5 Task 1 and Task 2.

This report summarises the work carried out for deliverable 5.1.1. in task 1 of WP5.

4

Abstract

JRC-Geel is a partner in the EMRP project named MetroDecom, Metrology for

decommissioning nuclear facilities. The project focusses on the different aspects of

metrology applied in the field of decommissioning of nuclear facilities. The commitments

of the Radionuclide Metrology Sector of JRC-Geel (RN) were to conduct part of the work

to be carried out in WP5 Development of reference materials and standard sources. In

Task 1 reference materials and standard sources for segregation of materials and for

free release measurements needed to be produced and characterised.

From a standard solution a mother dilution was made to obtain a solution with an

activity concentration of around 100 Bq per 20 μL. The solution was dispensed in the

cavity of 1120 metallic source holders making use of a precision pattern dispenser. After

evaporation of the liquid, the cavity of the CMI source holders was mechanically closed.

Before and during the source preparation, check sources in the shape of aluminium pills

were produced in order to monitor the stability of the activity concentration of the

mother solution.

The activity of all the sources was determined by gamma-ray spectroscopic

measurements using a NaI-well detector. Some outliers were identified and 1100

sources with certified activity content were selected and made available for further use

in Work Package 2 of the project.

On the basis of the activity calculations it can be stated that sources were successfully

prepared according to the specifications and will be used as calibration standards for the

calibration of a free release measurement facility to measure radioactive waste. They

can also be used as calibration standard for the calibration of waste segregation

facilities.

One of the deliverables in the task was to develop a reference material for the calibration

of a free release facility and testing facility for segregation of waste. The sources are in

the form of 1100 steel and 1100 plastic balls with point sources of 152Eu and 60Co inside.

The task of RN was to produce and standardise the 1100 60Co point sources in a form of

metal holders containing around 100 Bq of 60Co each. These metallic source holders can

be inserted in metallic or plastic balls in order to simulate contaminated waste. The

sources were successfully produced using an precision pattern dispenser, and

standardised by measuring them in the 20.3 X 20.3 cm NaI-well detector. The

standardised sources together with the certificate stating their activities were made

available for further use in the project.

5

1. Introduction

MetroDecom (ENV54), Metrology for decommissioning of nuclear facilities, is a European

Metrology Research Programme (EMRP) project carried out by 15 partners to address

the needs of the nuclear decommissioning process. This is done by developing and

implementing new measurement techniques, instruments, standards and reference

materials, and by ensuring knowledge transfer to stakeholders. The project is divided

into five Work Packages (WP):

WP1 Characterisation of waste materials present on decommissioning sites

WP2 Measurement facility for waste segregation

WP3 Implementation of free release measurement facility on decommissioning site

WP4 Radioactive waste repositories monitoring

WP5 Development of reference materials and standard sources

The Work Package 5, coordinated by the Physikalisch-Technische Bundesanstalt (PTB),

consists of 4 different tasks.

Task 1 Reference materials and standard sources for segregation of materials and for

free release measurements (lead by Cesky Metrologicky Institut (CMI))

Task 2 Reference materials and standard sources for radiochemical analysis. (lead by

National Physics Laboratory (NPL))

Task 3 Gaseous reference materials (lead by NPL)

Task 4 Reference materials and standard sources for surface contamination monitors

(lead by Institut National de Cercetare Dezvoltare pentru Fizica si Inginerie Nucleara

(IFIN))

The Radionuclide Metrology sector of JRC-Geel is involved in WP5 Task 1 and Task 2.

This report describes the work carried out in Task 1 deliverable 5.1.1, which consisted

of:

1) The production of 1100 60Co point sources in special designed sources holders. The aimed activity per sources is 100 Bq.

2) The calibration of the sources by measuring them in a NaI-well detector.

After the calibration of the sources they were made available to be used as calibration

sources of the free release measurement facility and testing facility for the segregation

of waste.

6

2. Production of the sources

2.1 Source holders

For the use of the calibration sources in combination with 1100 steel and plastic balls

special designed metal source holders were produced. The empty source holders were

produced in a mechanical workshop. It consists of three parts, a bottom part with thread

on the outside at the bottom and at the top, a top part with thread at the inside at the

bottom and a cavity at the top, and a fitting to close the cavity (cfr. Figure 1). The

source holders of this type are called hereafter CMI source holders.

Figure 1: Pictures of the metal source holders with and without metal fitting on top.

In the cavity in the top part a small amount of liquid was dispensed (left picture). When

the liquid was dried up a metallic fitting was mechanically inserted (right picture) using a

press to seal the source cavity. The so-prepared sources can be screwed into steel or

plastic balls as shown in Figure 2.

Figure 2: Insertion of the source holder in a steel ball.

7

2.2. Preparation of the 60Co solution

The 60Co mother solution was prepared from an activity standard solution having an

activity concentration of 2.48 (0.02) MBq·g-1 (1 September 2016, [1]). From the

standard solution 0.132 g was gravimetrically transferred into a glass solvent reservoir.

To this solvent reservoir, 65.2 g 0.1 M HCl containing 20 mg CoCl2/L of carrier was

added to obtain a final concentration of about 5000 Bq·g-1 60Co. The solvent reservoir

was closed and the solution was homogenised by shaking it for 2 hours. After

homogenisation 3 check point sources, in the shape of aluminium pills (Figure 3) were

gravimetrically prepared and measured in the NaI-well detector. During the preparation

of the sources the concentration of the mother solution was checked between the

productions of the batches of samples by preparing Aluminium pill check point sources.

Figure 3: Aluminium pill check source.

A schematic overview of the source preparation is shown in Figure 4.

Figure 4: Schematic overview of the source preparation.

8

2.3. Preparation of the sources using a precision pattern dispenser

The aimed activity of each of the 1120 sources was 100 Bq. From the mother solution 20

μL was dispensed in the cavity of each source holder. In order to do this in a

reproducible and automated way a precision pattern dispenser was used (Figure 5). With

this instrument liquid can be dispensed in a reproducible way. The dispenser consists of

a tower mounted on an axis. Inside the tower a syringe can be mounted (Figure 6).

Figure 5: View on the precision pattern dispenser.

9

Figure 6: Syringe mounted in the tower.

The syringe is mounted in such a way that the step motor in the tower can perform

precise movements of the plunger. Therefore the pre-set amount of liquid is dispensed in

a very reproducible way. A 50 μL syringe was used to dispense the 20 μL 60Co solution in

the 1120 CMI source holders.

10

The tray holder contained a tray in which 70 source holders were mounted (Figure 7).

Figure 7: View on the tray filled with 70 source holder.

The tray was placed on a tray holder which was suspended on the axis of the dispenser

on a support. Besides the tray support also a solvent reservoir and an arm containing

the waste vials were suspended to on the axis. The position of all the objects including

positions of the 70 source holders in the tray were set in the software controlling all the

mechanical movements. In the software a single protocol was created to dispense the

liquid in the 70 sources holders.

In order to dispense the 20 μL in each of the 70 source holders in the tray, the syringe

moved to the solvent reservoir containing the mother solution and took out 24 μL. Then

it moved to the waste vial where 2 μL was dispensed to make sure that the needle is

completely filled with liquid. After dispensing in the waste vial, the syringe moved to the

to the first source holder and dispensed the 20 μL liquid in its cavity. Than it moved

back to the waste vial were the syringe was completely emptied. The syringe moved

back to the solvent reservoir and repeated the same sequence dispensing the liquid in

the second source holder. This sequence was repeated 70 times to fill all the source

holders in the tray. In order to avoid drops hanging at the end of the needle of the

syringe, the solvent reservoir and the waste vial were closed with soft septa cleaning the

needle of the syringe whenever the septum was punched. The process of dispensing 70

times in the different holders took around 30 minutes.

After dispensing 20 μL in each of the 70 source holders, the tray was taken out and a

second tray was put on the support and another batch of 70 sources was produced. After

filling the CMI source holders in both trays they were put under an infrared lamp for

drying. When dry, the cavity of the source holder was sealed by inserting a metal fitting

in the cavity using a handheld mechanical press. In total 1120 sources were produced on

6 days. During the first 5 days 140 sources per day were prepared. On the 6th day, 140

were produced in the morning and the same amount was produced in the afternoon.

After each day the septa of both the solvent reservoir and waste vial were changed.

11

During the changing of the septum of the solvent reservoir, an aluminium pill point

source was made to check the 60Co concentration of the mother solution throughout the

whole source preparation. After production, all the sources were checked for external

contamination. The results showed there was no activity at the outside the sealed cavity.

3. Calibration of the sources

3.1 Measurement set-up

All the sources were measured in a 20.3 X 20.3 cm NaI well detector. The depth of the

cavity is 13.4 cm and its diameter 2.54 cm. The detector is surrounded with a 10 cm of

lead, lined with 1 mm of tin and 2 mm of copper. To avoid accidental contamination in

the well, all our samples were measured in a cylindrical Plexiglas sample holder (Figure

8).

The signals generated in the NaI crystal are collected in a photomultiplier tube, sent to

the a preamplifier and amplifier, and fed in a single channel analyser. The lower level

threshold of the single channel analyser is set at 50 keV. To all signals above the

threshold a dead time of 20 μs is added. The homemade data acquisition software

registers all the pulses above the lower level threshold as well as the real time and live

time of the system. The bin-width for all acquisitions was 2.5 channels/keV.

Figure 8: NaI well detector top view and insertion of a source in the holder.

The Full Energy Peak (FEP) efficiencies for the 60Co gamma-rays were calculated using

EGSnrc Monte Carlo program [2] using data from:

the dimensions of the samples

the sample matrix

manufacturer’s information on measurable dimensions of the NaI detector

The Monte Carlo simulations assume that the gamma-ray emissions are isotropic and

uncorrelated. Summing coincidences were calculated using the same program.

The efficiency for 60Co in the aluminium pills is 97.3 %, in the CMI source holder it is

97.5 %. A typical 60Co spectrum is shown in Figure 9.

12

3.2 Measurements

All the sources were measured individually. The CMI source holders were measured for

300 s, while the aluminium pill check sources were counted for at least 3600 s to acquire

enough counts in the spectrum to reduce the associated statistical uncertainty.

Figure 9: 60Co spectrum of CMI source acquired with the NaI well detector.

In between the measurements background spectra were collected. The spectra of the

sources were corrected for background taking an average of the closest background

spectra (before and after the measurement). A typical background spectrum is shown in

Figure 10. Channel/keV)

Figure 10: Background spectrum acquired with the NaI well detector.

0

1

2

3

4

5

0 400 800 1200 1600 2000 2400 2800

co

un

t rate

(s

-1)

Energy (keV)

0

0.01

0.02

0.03

0.04

0.05

0.06

0 400 800 1200 1600 2000 2400 2800

co

un

t rate

(s

-1)

Energy (keV)

13

3.3 Results

3.3.1 Aluminium pill point sources

The activity of the sources was calculated at the reference date of 1 September 2016

00:00 h.

As the mother solution was gravimetrically prepared from an activity standard the

activity concentration was also calculated from the activity and the mass of the standard

and the diluent used. The calculated concentration activity is 5049 (34) Bq·g-1.

Table 1 provides the measured activity values of the aluminium pills produced during the

source preparation campaign. The first measurement was done shortly after the

production of each source. The second measurements were all performed on one day.

The obtained data are in good agreement with each other and with the values obtained

from the activity standard.

Table 1: Measurement of the 60Co check sources.

1st measurement 2nd measurement

Activity

(Bq·g-1)

abs

uncert.

Activity

(Bq·g-1)

abs

uncert.

Co60Al1601 5037.5 4.9 5033.3 6.4

Co60Al1602 5035.1 7.2 5030.4 8.6

Co60Al1603 5034.5 4.9 5034.7 6.3

Co60Al1604 5033.5 3.5 5035.1 3.5

Co60Al1605 5041.8 7.2 5049.0 7.0

Co60Al1606 5033.4 4.7 5033.8 4.9

Co60Al1607 5038.8 7.6 5042.5 6.7

Co60Al1608 5035.6 5.9 5031.3 5.8

Co60Al1609 5042.5 4.5 5044.0 5.3

Co60Al1610 5042.5 5.7 5035.7 5.7

Average 5037.5 5037.0

Stdev 3.7 6.1

The first three sources in the table were made just after the solution was prepared and

homogenised. The following sources were made each time the septum of the solvent

reservoir was changed. Figure 11 shows no trend in the activity concentrations meaning

that the activity concentration was stable during the whole source preparation campaign

thus no evaporation took place.

14

Figure 11: Activity of the check sources in chronological order.

5020.0

5025.0

5030.0

5035.0

5040.0

5045.0

5050.0

5055.0

5060.0

0 1 2 3 4 5 6 7 8 9 10

Acti

vit

y (

Bq

.g-1

)

# source

1st measurement 2nd measurement

average 1st average 2nd

15

3.3.2 CMI source holders.

In total 1120 sources were produced. All the sources were measured for 300 s. During

the 300 s, around 40000 gross counts (statistical uncertainty = 0.5 %) were acquired in

the spectrum. After corrections for background (average of the closest background

spectra) and decay corrections the activities were calculated for each source. The overall

average background count rate was 32.3 ± 0.3 s-1.

After the measurement of all the sources a long background was acquired in runs of

3600 seconds. The results are displayed in Figure 12 and confirmed the high stability of

the background count rate having an average count rate of 32.31 s-1 with a standard

deviation of 0.18 s-1.

Figure 12: Variations in the background count rate.

Tables 2 to 9 give an overview of the results obtained from the measurements. One

table per batch of 140 sources was made (one day production, except for the last day

where two batches were produced on the same day). The average activity and the

standard deviation were calculated per batch. There was no trend observed between the

activity of the sources within a batch neither between average activity of the subsequent

batches. The overall average activity of the 1120 sources is 100.2 Bq, with a standard

deviation of 0.85 Bq. To make the most extreme values visible in the table, sources with

an activity outside ± 2.5 standard deviation from the average are coloured in red. These

15 outliers were remeasured and 8 measurements gave a result within ± 2.5 standard

deviation from the average. In order to obtain an even more homogeneous batch of

1100 sources and as we had produced 20 sources extra, the 7 outliers from the 1100

were replaced by 7 sources out of the last 20. Figure 13 gives an overview of the activity

of all the 1120 sources in the chronological order as they were produced.

32

32.1

32.2

32.3

32.4

32.5

32.6

32.7

0 10 20 30 40 50 60

co

un

rate

(s

-1)

# run

16

Table 2: Overview of the activity of the sources produced on day 1.

Day 1: average activity 100.22 Bq Std. Dev. 1.22 Bq

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

1 100.88 36 99.09 71 101.68 106 99.82

2 100.24 37 101.17 72 100.70 107 99.02

3 101.54 38 100.71 73 100.63 108 100.42

4 101.25 39 99.34 74 100.16 109 100.90

5 101.51 40 100.97 75 101.15 110 99.81

6 99.83 41 99.64 76 99.54 111 99.93

7 100.35 42 99.86 77 101.03 112 99.76

8 92.57 43 100.62 78 100.39 113 100.55

9 100.37 44 101.20 79 99.84 114 100.18

10 95.48 45 99.35 80 101.45 115 100.35

11 100.59 46 100.04 81 100.43 116 99.45

12 100.27 47 100.68 82 99.40 117 99.31

13 101.58 48 99.75 83 100.94 118 100.41

14 100.23 49 99.99 84 99.90 119 100.81

15 100.77 50 100.55 85 99.80 120 101.07

16 101.60 51 100.87 86 100.46 121 100.12

17 99.18 52 101.64 87 100.99 122 99.76

18 100.52 53 100.85 88 99.82 123 100.73

19 100.92 54 100.68 89 100.97 124 100.86

20 100.35 55 100.47 90 101.70 125 100.25

21 99.75 56 99.72 91 100.31 126 99.43

22 101.78 57 101.23 92 100.29 127 98.89

23 101.44 58 100.93 93 100.28 128 100.60

24 98.96 59 100.43 94 99.48 129 99.66

25 100.94 60 100.86 95 99.84 130 100.17

26 100.52 61 100.99 96 99.81 131 100.13

27 100.88 62 100.87 97 99.16 132 99.67

28 99.77 63 101.47 98 99.73 133 99.83

29 99.67 64 100.17 99 92.82 134 101.12

30 101.86 65 100.69 100 99.82 135 100.33

31 101.01 66 100.84 101 100.21 136 100.86

32 99.31 67 99.56 102 99.18 137 99.17

33 99.13 68 100.18 103 101.39 138 99.48

34 100.65 69 100.99 104 101.04 139 100.01

35 100.37 70 101.02 105 100.18 140 100.20

17



#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

141 100.67 176 101.25 211 100.36 246 100.10

142 101.20 177 99.94 212 99.53 247 100.64

143 100.92 178 101.02 213 101.25 248 99.92

144 100.74 179 99.80 214 99.80 249 100.82

145 100.53 180 99.91 215 100.60 250 99.90

146 100.18 181 99.82 216 100.44 251 101.10

147 99.54 182 100.59 217 100.25 252 100.36

148 100.14 183 101.08 218 100.14 253 100.64

149 100.61 184 99.75 219 101.33 254 100.35

150 100.64 185 101.10 220 100.89 255 100.98

151 99.83 186 100.49 221 99.13 256 100.55

152 100.52 187 99.27 222 100.76 257 99.99

153 101.59 188 99.82 223 99.92 258 99.97

154 101.95 189 100.91 224 98.86 259 100.00

155 100.44 190 101.12 225 100.01 260 101.79

156 101.18 191 100.79 226 99.91 261 100.86

157 100.01 192 99.31 227 99.71 262 99.59

158 100.54 193 100.10 228 99.29 263 100.55

159 99.71 194 100.21 229 99.55 264 100.13

160 99.67 195 99.53 230 99.95 265 100.95

161 100.93 196 101.00 231 100.45 266 100.55

162 101.48 197 99.51 232 100.31 267 100.74

163 100.39 198 100.23 233 99.86 268 101.08

164 100.60 199 100.02 234 100.13 269 98.02

165 99.93 200 99.88 235 99.96 270 100.05

166 100.58 201 98.76 236 99.95 271 100.03

167 100.37 202 100.10 237 99.73 272 100.89

168 100.29 203 100.30 238 99.74 273 101.20

169 101.02 204 100.80 239 100.89 274 100.46

170 100.21 205 100.89 240 99.42 275 99.61

171 99.01 206 100.90 241 99.71 276 101.18

172 100.05 207 99.78 242 99.80 277 101.43

173 100.18 208 101.05 243 100.35 278 101.04

174 99.88 209 99.97 244 100.66 279 99.64

175 100.00 210 100.55 245 99.39 280 100.39

18



#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

281 99.63 316 99.77 351 101.75 386 101.09

282 101.13 317 101.07 352 100.28 387 99.21

283 99.72 318 99.28 353 100.40 388 99.91

284 99.53 319 99.67 354 100.22 389 100.35

285 101.02 320 101.37 355 100.65 390 99.81

286 100.84 321 100.23 356 99.06 391 100.75

287 100.38 322 100.07 357 100.81 392 100.35

288 100.54 323 99.95 358 100.83 393 99.97

289 100.11 324 100.51 359 100.54 394 98.95

290 100.81 325 100.41 360 100.40 395 101.77

291 99.09 326 100.04 361 100.40 396 99.88

292 101.23 327 100.92 362 100.45 397 100.58

293 99.47 328 100.88 363 100.47 398 100.15

294 99.61 329 101.37 364 99.28 399 99.53

295 100.18 330 100.28 365 99.49 400 101.50

296 100.63 331 99.83 366 99.91 401 99.63

297 100.07 332 100.20 367 100.35 402 100.54

298 100.04 333 99.56 368 99.81 403 99.42

299 100.41 334 100.92 369 99.86 404 101.19

300 99.98 335 99.90 370 100.57 405 100.12

301 100.02 336 100.34 371 100.37 406 100.58

302 100.54 337 100.16 372 100.45 407 100.25

303 100.74 338 100.55 373 100.40 408 100.40

304 100.34 339 101.05 374 100.87 409 100.90

305 100.13 340 100.45 375 99.27 410 100.72

306 100.52 341 101.41 376 100.51 411 101.43

307 100.78 342 100.86 377 100.62 412 100.40

308 102.21 343 101.80 378 100.09 413 100.44

309 99.50 344 99.90 379 99.97 414 100.10

310 100.60 345 100.26 380 97.49 415 99.98

311 99.28 346 100.33 381 101.02 416 99.96

312 99.19 347 100.29 382 100.54 417 101.07

313 100.12 348 100.49 383 99.58 418 100.86

314 100.21 349 100.53 384 100.54 419 100.69

315 99.94 350 101.22 385 100.64 420 99.81

19



#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

421 99.41 456 101.30 491 100.28 526 99.84

422 99.71 457 100.60 492 100.46 527 101.11

423 99.75 458 99.83 493 100.24 528 100.14

424 100.78 459 100.91 494 100.99 529 99.42

425 100.75 460 99.70 495 100.32 530 100.89

426 100.50 461 99.37 496 100.55 531 102.42

427 101.27 462 100.45 497 100.23 532 100.74

428 100.39 463 98.90 498 100.00 533 100.74

429 100.56 464 100.19 499 102.10 534 100.87

430 99.53 465 101.64 500 99.58 535 100.48

431 99.67 466 100.72 501 98.86 536 99.90

432 101.09 467 99.44 502 100.78 537 100.68

433 100.33 468 100.81 503 100.03 538 99.65

434 102.71 469 100.85 504 102.29 539 100.65

435 100.72 470 101.19 505 100.71 540 100.52

436 99.99 471 100.06 506 99.97 541 100.86

437 100.61 472 101.33 507 101.26 542 100.25

438 99.83 473 99.52 508 99.33 543 99.40

439 100.14 474 100.09 509 100.71 544 99.96

440 100.61 475 100.24 510 100.26 545 99.72

441 100.68 476 100.40 511 99.98 546 100.59

442 100.36 477 99.56 512 101.54 547 100.27

443 101.24 478 100.22 513 100.72 548 101.14

444 100.42 479 99.70 514 101.30 549 98.95

445 100.26 480 100.20 515 101.18 550 99.62

446 99.62 481 100.18 516 99.84 551 100.04

447 100.04 482 100.00 517 100.21 552 100.28

448 100.39 483 99.77 518 101.05 553 99.88

449 99.21 484 99.62 519 100.54 554 99.76

450 100.41 485 99.58 520 99.82 555 99.96

451 99.91 486 101.43 521 100.51 556 100.63

452 100.34 487 100.22 522 100.21 557 100.98

453 99.49 488 99.92 523 99.35 558 100.00

454 99.49 489 100.97 524 100.56 559 101.27

455 101.97 490 100.47 525 99.84 560 99.00

20



#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

561 99.91 596 99.79 631 102.34 666 100.19

562 100.28 597 100.12 632 102.51 667 99.15

563 99.95 598 100.18 633 101.12 668 99.76

564 99.43 599 101.68 634 100.90 669 100.76

565 99.38 600 100.64 635 101.57 670 100.08

566 100.24 601 100.82 636 101.14 671 100.79

567 99.53 602 101.05 637 99.45 672 100.11

568 101.51 603 100.19 638 100.88 673 100.73

569 99.86 604 100.47 639 101.08 674 99.86

570 100.41 605 100.55 640 101.01 675 98.68

571 100.06 606 101.02 641 100.77 676 100.55

572 101.52 607 101.56 642 99.80 677 99.28

573 101.21 608 101.95 643 101.44 678 99.77

574 100.27 609 100.74 644 100.36 679 100.61

575 100.82 610 102.08 645 100.32 680 101.04

576 99.66 611 100.39 646 99.31 681 101.71

577 101.87 612 101.09 647 98.96 682 99.37

578 101.69 613 100.45 648 99.90 683 100.12

579 100.45 614 100.47 649 99.57 684 101.23

580 101.68 615 99.99 650 100.23 685 101.22

581 100.87 616 101.81 651 99.48 686 101.09

582 101.52 617 99.89 652 99.21 687 100.97

583 99.91 618 101.42 653 99.69 688 100.08

584 101.00 619 100.49 654 99.14 689 99.85

585 101.67 620 100.95 655 101.13 690 99.71

586 99.96 621 100.19 656 100.67 691 99.30

587 100.53 622 101.23 657 100.66 692 99.19

588 101.03 623 101.95 658 100.49 693 100.08

589 99.42 624 99.89 659 100.34 694 101.06

590 99.94 625 99.72 660 100.62 695 100.25

591 100.78 626 99.99 661 99.49 696 99.87

592 99.32 627 100.61 662 100.87 697 100.01

593 100.92 628 101.31 663 101.95 698 101.10

594 100.39 629 100.66 664 100.09 699 101.81

595 100.39 630 99.83 665 98.89 700 100.51

21



#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

701 100.21 736 99.53 771 99.87 806 98.72

702 101.66 737 100.71 772 100.57 807 98.80

703 100.19 738 101.81 773 98.75 808 98.60

704 100.56 739 100.01 774 100.30 809 101.34

705 100.78 740 100.48 775 96.58 810 100.00

706 100.09 741 100.33 776 100.24 811 99.82

707 99.78 742 99.92 777 100.34 812 101.68

708 100.57 743 99.48 778 99.04 813 98.31

709 99.53 744 100.17 779 99.71 814 98.13

710 100.54 745 100.55 780 99.01 815 100.00

711 100.78 746 99.99 781 98.40 816 101.46

712 100.80 747 99.87 782 99.69 817 100.63

713 100.38 748 100.12 783 100.32 818 101.45

714 99.09 749 100.37 784 98.95 819 99.33

715 101.21 750 99.46 785 99.62 820 99.20

716 100.14 751 100.86 786 99.48 821 99.25

717 101.82 752 99.24 787 99.43 822 100.05

718 100.01 753 99.76 788 98.35 823 99.04

719 100.03 754 100.85 789 100.11 824 101.54

720 100.02 755 99.90 790 101.85 825 99.00

721 100.13 756 100.85 791 102.20 826 99.80

722 99.97 757 100.12 792 100.11 827 99.43

723 99.85 758 100.13 793 102.82 828 100.26

724 100.24 759 99.81 794 105.04 829 99.55

725 100.70 760 100.08 795 101.07 830 99.51

726 100.84 761 102.00 796 100.16 831 98.64

727 101.15 762 99.74 797 99.92 832 100.31

728 100.38 763 100.01 798 99.42 833 100.28

729 100.65 764 98.95 799 98.81 834 99.70

730 101.27 765 99.46 800 100.66 835 99.98

731 99.59 766 100.89 801 100.08 836 99.53

732 99.69 767 99.52 802 99.04 837 98.49

733 100.88 768 99.15 803 100.44 838 100.10

734 101.30 769 100.03 804 99.16 839 99.86

735 100.18 770 100.03 805 99.64 840 100.74

22

Table 8: Overview of the activity of the sources produced on day 7, 1st batch.

Day 7/1: average activity 100.05 Bq Std. Dev. 0.76 Bq

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

841 100.90 876 100.57 911 100.78 946 99.79

842 100.21 877 101.91 912 101.29 947 99.21

843 100.80 878 99.10 913 98.84 948 100.17

844 100.47 879 101.28 914 100.23 949 99.72

845 100.64 880 100.52 915 100.73 950 99.76

846 99.42 881 101.35 916 99.64 951 99.06

847 100.48 882 100.99 917 100.70 952 101.35

848 99.65 883 99.63 918 100.96 953 100.49

849 101.55 884 99.06 919 98.78 954 99.65

850 100.94 885 100.21 920 99.31 955 100.50

851 100.58 886 100.14 921 100.14 956 99.15

852 99.96 887 99.15 922 99.44 957 101.77

853 101.45 888 98.92 923 99.86 958 98.95

854 100.85 889 100.13 924 99.70 959 99.62

855 101.07 890 99.64 925 100.12 960 100.69

856 99.76 891 100.40 926 100.35 961 99.57

857 100.95 892 100.67 927 100.05 962 99.69

858 98.63 893 99.28 928 100.12 963 99.51

859 100.53 894 98.04 929 99.95 964 99.03

860 99.41 895 99.92 930 100.37 965 100.14

861 99.82 896 99.81 931 99.52 966 100.51

862 100.11 897 101.15 932 100.83 967 99.62

863 99.98 898 98.90 933 99.01 968 98.97

864 100.29 899 100.12 934 99.96 969 99.76

865 99.82 900 100.43 935 99.38 970 100.24

866 99.94 901 99.36 936 99.09 971 100.06

867 100.48 902 99.57 937 99.35 972 99.30

868 101.53 903 99.81 938 100.80 973 100.21

869 100.34 904 98.70 939 100.84 974 101.71

870 99.27 905 100.63 940 99.88 975 99.96

871 99.25 906 100.59 941 99.69 976 99.94

872 101.14 907 99.36 942 100.62 977 101.37

873 99.69 908 100.39 943 100.20 978 99.46

874 100.15 909 101.09 944 100.36 979 100.30

875 99.07 910 98.79 945 99.70 980 99.08

23

Table 9: Overview of the activity of the sources produced on day 7, 2nd batch.

Day 7/2: average activity 99.76 Bq Std. Dev. 0.71 Bq

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

#

source

Activity

(Bq)

981 101.26 1016 101.75 1051 100.72 1086 100.62

982 100.19 1017 99.76 1052 99.39 1087 99.89

983 100.20 1018 100.01 1053 99.10 1088 100.00

984 100.92 1019 99.96 1054 98.93 1089 100.62

985 99.72 1020 99.78 1055 99.80 1090 98.83

986 99.75 1021 98.84 1056 99.19 1091 99.92

987 100.18 1022 98.95 1057 100.25 1092 100.29

988 99.38 1023 99.48 1058 99.14 1093 99.55

989 99.60 1024 97.81 1059 100.07 1094 100.47

990 100.06 1025 100.54 1060 100.06 1095 100.02

991 101.25 1026 99.35 1061 100.25 1096 98.07

992 100.75 1027 100.40 1062 99.39 1097 100.22

993 99.44 1028 100.15 1063 99.71 1098 99.43

994 99.65 1029 99.84 1064 100.13 1099 98.38

995 100.81 1030 99.07 1065 99.24 1100 100.46

996 100.77 1031 99.71 1066 99.29 1101 98.81

997 100.38 1032 100.67 1067 100.16 1102 100.37

998 99.89 1033 99.45 1068 100.23 1103 100.04

999 99.68 1034 99.40 1069 100.26 1104 99.86

1000 98.80 1035 99.80 1070 99.85 1105 98.49

1001 98.56 1036 99.14 1071 100.19 1106 99.76

1002 99.80 1037 100.02 1072 99.71 1107 101.07

1003 99.60 1038 100.28 1073 98.82 1108 99.60

1004 99.72 1039 97.72 1074 100.83 1109 99.79

1005 100.02 1040 99.31 1075 100.45 1110 100.94

1006 98.51 1041 99.86 1076 99.84 1111 99.63

1007 98.53 1042 98.87 1077 98.52 1112 99.04

1008 98.66 1043 99.96 1078 100.29 1113 99.95

1009 98.74 1044 99.01 1079 100.87 1114 99.67

1010 98.72 1045 100.84 1080 100.41 1115 99.25

1011 100.32 1046 99.63 1081 100.52 1116 98.76

1012 99.47 1047 99.63 1082 99.50 1117 100.35

1013 100.09 1048 100.05 1083 99.99 1118 99.63

1014 99.19 1049 99.63 1084 99.85 1119 98.89

1015 100.30 1050 100.22 1085 99.90 1120 99.65

24

Figure 13: Overview of the activity of all 1120 CMI sources.

25

Figure 144 shows the results of source 1039, measured in 80 following runs of 300s

without any interruption between the runs. The calculated results using the same

background subtraction have an average activity of 99.37 Bq with a standard deviation

of 0.72 Bq.

Figure 14: Consecutive measurements of source #1039 in runs of 300s.

97.00

97.50

98.00

98.50

99.00

99.50

100.00

100.50

101.00

101.50

102.00

0 10 20 30 40 50 60 70 80

Acti

vit

y (

Bq

)

# run

26

4 Conclusion

In ENV54 Metrodecom Work Package 5 Task 1, the RN sector of JRC-Geel had to produce

1100 metallic source holders containing an activity of 100 Bq 60Co each. These metallic

source holders can be inserted in metallic or plastic balls in order to simulate

contaminated waste.

The activity of all the sources was determined by gamma-ray spectroscopic

measurements using a NaI-well detector. Some outliers were identified and 1100

sources with certified activity content were selected and made available for further use

in Work Package 2 of the project.

On the basis of the activity calculations it can be stated that sources were successfully

prepared according to the specifications and will be used as calibration standards for the

calibration of a free release measurement facility to measure radioactive waste. They

can also be used as calibration standard for the calibration of waste segregation

facilities.

27

References

[1] Calibration certificate PTB 6.11 2013-1117 [2] WI-D-00015 version 3 (2015.03) 4pi-gamma counting with a NaI well detector [3] Kawrakow and DWO Rogers. “PIRS-701: The EGSnrc Code System: Monte Carlo Simulation of Electron and Photon Transport” Ionizing Radiation Standards (NRC, Ottawa, Ontario,2003), 2003.

28

List of abbreviations and definitions

Bq – Bequerel

CMI – Cesky Metrologicky Institut

EMRP – European Metrology Research Programme

FEP - Full Energy Peak

IFIN – Institut National de Cercetare Dezvoltare pentru Fizica si Inginerie Nucleara

JRC-Geel – Joint Research Institute Geel site (Belgium)

MetroDecom – Metrology for decommissioning of nuclear facilities

NPL – National Physics Laboratory

PTB – Physikalisch-Technische Bundesanstalt

RN – Radionuclide Metrology Sector of JRC-Geel

WP – Work Package

29

List of figures

Figure 1: Pictures of the metal source holders with and without metal fitting on top. ..... 6

Figure 2: Insertion of the source holder in a steel ball. ............................................... 6

Figure 3: Aluminium pill check source. ..................................................................... 7

Figure 4: Schematic overview of the source preparation. ............................................ 7

Figure 5: View on the precision pattern dispenser. .................................................... 8

Figure 6: Syringe mounted in the tower. .................................................................. 9

Figure 7: View on the tray filled with 70 source holder. ............................................ 10

Figure 8: NaI well detector top view and insertion of a source in the holder. ............... 11

Figure 9: 60Co spectrum of CMI source acquired with the NaI well detector. ................ 12

Figure 10: Background spectrum acquired with the NaI well detector. ....................... 12

Figure 11: Activity of the check sources in chronological order. ................................. 14

Figure 12: Variations in the background count rate. ................................................. 15

Figure 13: Overview of the activity of all 1120 CMI sources. ..................................... 24

Figure 14: Consecutive measurements of source #1039 in runs of 300s. ................... 25

30

List of tables

Table 1: Measurement of the 60Co check sources..................................................... 13

Table 2: Overview of the activity of the sources produced on day 1. .......................... 16






Table 8: Overview of the activity of the sources produced on day 7, 1st batch. ............ 22

Table 9: Overview of the activity of the sources produced on day 7, 2nd batch. ........... 23

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2

doi:10.2789/787831

ISBN 978-92-79-62200-7

LC

-NA

-28123-E

N-N

JRC Mission

As the Commission’s

in-house science service,

the Joint Research Centre’s

mission is to provide EU

policies with independent,

evidence-based scientific

and technical support

throughout the whole

policy cycle.

Working in close

cooperation with policy

Directorates-General,

the JRC addresses key

societal challenges while

stimulating innovation

through developing

new methods, tools

and standards, and sharing

its know-how with

the Member States,

the scientific community

and international partners.

Serving society Stimulating innovation Supporting legislation

preparation of 1100 60co calibration sources

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