laboratory measurements of the coefficient of … measurements of the coefficient of thermal...

POSIVA OY

FI-27160 OLKILUOTO, FINLAND

Tel +358-2-8372 31

Fax +358-2-8372 3709

Urban Åkesson

Apri l 2012

Working Report 2012-14

Laboratory Measurements ofthe Coefficient of Thermal Expansion of

Olkiluoto Drill Core Samples

Apri l 2012

Working Reports contain information on work in progress

or pending completion.

Urban Åkesson

Swedish Cement and Concrete Research Inst i tute

Working Report 2012-14

Laboratory Measurements ofthe Coefficient of Thermal Expansion of

Olkiluoto Drill Core Samples

Laboratory Measurements of the Coefficient of Thermal Expansion of Olkiluoto Drill Core Samples ABSTRACT The coefficient of thermal expansion and the wet density has been determined on 22 specimens from the ONKALO drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226, Olkiluoto, Finland. The coefficient of thermal expansion has been determined in the temperature interval 20-60 ºC. The results indicated that the thermal expansion was almost linear, and the coefficient of thermal expansion for the investigated specimens range between 3.2 and 14.4 x 10-6 mm/mm C, and the wet density between 2,610 and 2,820 kg/m3. The granite pegmatite has slightly lower coefficient of thermal expansion and wet density than gneissic rocks. Keywords: Coefficient of thermal expansion, Olkiluoto, laboratory measurements, rock core samples, wet density.

Kiven lämpölaajenemiskertoimen laboratoriomääritykset Olkiluodon kairasydännäytteistä TIIVISTELMÄ Kiven lämpölaajenemiskerroin ja märkätiheys on määritetty Olkiluodon 22 kairasydännäytteistä. Näytteet ovat ONKALOn tutkimusrei’istä ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 ja ONK-PP226. Lämpölaajenemiskerroin on määritetty lämpötilaväliltä 20 - 60 °C. Tulokset kertovat, että lämpölaajeneminen on lähes lineaarista ja lämpölaajenemiskerroin tutkituilla näytteillä vaihtelee välillä 3,2 – 14,4 x 10-6 mm/mm C ja märkätiheys välillä 2610 - 2820 kg/m3. Pegmatiitti-graniiteilla on hieman alhaisempi lämpölaajenemiskerroin ja märkätiheys kuin gneisseillä. Avainsanat: Lämpölaajenemiskerroin, Olkiluoto, laboratoriomittaus, kairasydännäyte, märkätiheys

1

TABLE OF CONTENTS ABSTRACT TIIVISTELMÄ

1 INTRODUCTION ................................................................................................... 2

2 EQUIPMENT ......................................................................................................... 3

3 EXECUTION ......................................................................................................... 43.1 Description of the specimens ....................................................................... 43.2 Testing ......................................................................................................... 5

4 RESULTS .............................................................................................................. 64.1 Description of the specimens and presentation of the results ...................... 64.2 Summary of results .................................................................................... 29

REFERENCES ............................................................................................................. 31

2

1 INTRODUCTION The purpose of this report was to determine the coefficient of thermal expansion and the wet density of intact rock cores from the Olkiluoto drillcore samples. The testing comprised of 22 rock specimens from the ONKALO drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226. The locations of the drillholes are shown in Figure 1-1. The specimens were sampled by Posiva Oy, and sent to the Swedish Cement and Concrete Research Institute in Borås, Sweden who performed the test. Testing commenced in April 2010 and was completed in May 2010.

Figure 1-1. The locations of the ONKALO drillholes for determination of thermal expansion coefficients.

ONK-PP167

ONK-PP199 ONK-PP224 ONK-PP225 ONK-PP226

-290 m

-437 m

3

2 EQUIPMENT The following equipment has been used for the laboratory measurements:

Extensometer (DEMEC inv no 102266) for measurement of the thermal expansion. The uncertainty of the extensometer is ± 3.97 x 10-6 mm/mm (strain), which equals an uncertainty of a single measurement of the coefficient of thermal expansion of ± 0.2 x 10-6 mm/mm oC for a temperature difference of 20 degrees C.

Reference bar in invar steel for calibrate the extensometer.

Heating chamber (inv no 102284) with an accuracy of ± 0.7 ºC at 80 ºC for heating up the specimens.

A covered plastic box filled with water for keeping the specimens water saturated.

The equipment was same as used for SKB’s thermal expansion property measurements at Oskarshamn and Forsmark sites (see e.g. Åkesson 2007).

4

3 EXECUTION Determination of the coefficient of thermal expansion was made in accordance with SKB’s method description SKB MD 191.002-version 2.0 (SKB internal controlling document). The Swedish Cement and Concrete Research Institute performed the tests. 3.1 Description of the specimens The specimens from the drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226 were sampled on various depths in the drillholes. Table 3-1 shows the identification mark, sampling level and rock type description of each specimen. Table 3-1. Identification mark, drillhole ID, sampling position and rock type of each specimen. Rock type abbreviations: VGN is veined gneiss, DGN is diatexitic gneiss and PGR pegmatitic granite. The veined gneisses are divided in two groups by the foliation angle; parallel (foliation 0) and perpendicular (foliation 90) to the core axis. Sample ID Drillhole ID Drillhole depth (m) Rock type code 3784 ONK-PP167 1.95-2.49 VGN (foliation 90) 3785 ONK-PP167 4.42-4.98 VGN (foliation 90) 3786 ONK-PP199 10.33-10.75 PGR 3787 ONK-PP199 47.45-48.03 PGR 3788 ONK-PP224 1.93-2.46 DGN 3789 ONK-PP224 3.64-4.15 DGN 3790 ONK-PP224 5.00-5.48 DGN 3791 ONK-PP224 7.42-8.07 PGR 3792 ONK-PP224 9.24-9.85 PGR 3793 ONK-PP224 13.39-13.75 VGN (foliation 0) 3794 ONK-PP224 16.75-17.3 VGN (foliation 0) 3795 ONK-PP224 27.97-28.50 VGN (foliation 0) 3796 ONK-PP225 0.83-1.46 DGN 3797 ONK-PP225 3.54-4.05 DGN 3798 ONK-PP225 4.70-5.26 DGN 3799 ONK-PP225 9.62-10.22 PGR 3800 ONK-PP225 19.26-19.72 VGN (foliation 0) 3801 ONK-PP225 19.72-20.18 VGN (foliation 0) 3802 ONK-PP225 29.00-29.56 PGR 3803 ONK-PP226 2.93-3.50 VGN (foliation 90) 3804 ONK-PP226 20.56-21.03 VGN (foliation 90) 3805 ONK-PP226 23.45-23.88 VGN (foliation 90)

5

3.2 Testing The execution procedure followed the prescription in SKB MD 191.002 and the following steps were performed: Item Activity 1 The specimens were cut according to the marks on the rock cores. 2 Two measuring points with a distance of 200 mm were glued on the specimens. 3 The specimens were photographed in JPEG format. 4 The specimens were water saturated for seven days. 5 The wet density was determined. 6 The coefficient of thermal expansion was determined. The thermal expansion was

measured at 20, 40 and 60 ºC. On each temperature level was three to five measurements done with 24 h intervals in order to know that the expansion was completed for each temperature level. The coefficient of thermal expansion was determined between 20-60 ºC.

6

4 RESULTS The results of the coefficient of thermal expansion and wet density determinations of core samples from the drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226 are presented here. The temperature of the water used for the water saturation was 21.5 ºC and the density of the water was 997 kg/m3. The coefficient of thermal expansion was determined between +20- +60 ºC to cover the rock temperature range equivalent to the disposal process. 4.1 Description of the specimens and presentation of the results Specimen 3784

Figure 4-1. Diagram showing the thermal expansion of specimen 3784 between 20 and 60 ºC, mean values plotted. Figure 4-1 shows a picture of the specimen 3784 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3784 was measured to be 13.2 x 10-6 mm/mm ºC and the specimen had a wet density of 2,780 kg/m3.

3784

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

n(m

m/m

m)

7

Specimen 3785


3785

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

n(m

m/m

m)

8

Specimen 3786

Figure 4-3. Diagram showing the thermal expansion of specimen 3786 between 20 and 60 ºC, mean values plotted. Figure 4-3 shows a picture of the specimen 3786 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3786 was measured to be 3.2 x 10-6 mm/mmº C and the specimen had a wet density of 2,610 kg/m3. Clear non-linear behaviour was noticed in the results.

3786

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

n(m

m/m

m)

9

Specimen 3787


3787

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

10

Specimen 3788


3788

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

11

Specimen 3789


3789

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

12

Specimen 3790


3790

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

13

Specimen 3791


3791

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

14

Specimen 3792

Figure 4-9. Diagram showing the thermal expansion of specimen 3792 between 20 and 60 ºC, mean values plotted. Figure 4-9 shows a picture of the specimen 3792 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3792 was measured to be 10.8 x 10-6 mm/mm ºC and the specimen had a wet density of 2,630 kg/m3. Minor non-linear behaviour was noticed in the results.

3792

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

15

Specimen 3793


3793

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

16

Specimen 3794


3794

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

17

Specimen 3795


3795

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

18

Specimen 3796


3796

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

19

Specimen 3797


3797

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

20

Specimen 3798


3798

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

21

Specimen 3799


3799

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

22

Specimen 3800


3800

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

23

Specimen 3801


3801

0

0,00005

0,0001

0,00015

0,0002

0,00025

0,0003

0,00035

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

24

Specimen 3802

Figure 4-19. Diagram showing the thermal expansion of specimen 3802 between 20 and 60 ºC, mean values plotted. Figure 4-19 shows a picture of the specimen 3802 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3802 was measured to be 4.6 x 10-6 mm/mmº C and the specimen had a wet density of 2,620 kg/m3. Non-linear behaviour was noticed in the results.

3802

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

25

Specimen 3803

Figure 4-20. Diagram showing the thermal expansion of specimen 3803 between 20 and 60 ºC, mean values plotted. Figure 4-20 shows a picture of the specimen 3803 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3803 was measured to be 12.3 x 10-6 mm/mm ºC and the specimen had a wet density of 2,740 kg/m3. Non-linear behaviour was noticed in the results.

3803

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

26

Specimen 3804


3804

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

27

Specimen 3805


3805

0

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Temperature C

Ther

mal

expa

nsio

nm

m/m

m

28

In order to investigate the non-linearity the specimen 3802 was remeasured. This time additional measuring points were glued on the specimen approximately at 120 degrees angles (see Figure 4-23).

Figure 4-23. Photograph showing how the measuring points were placed on specimen 3802. The results of the measurements are shown in Figure 4-24, which indicates that the non-linear phenomenon is partly due to bending of the drill core. The coefficients of thermal expansion for the measuring points were: 3802:1 5.0 x 10-6, 3802:2 4.8 x 10-6 and 3802:3 8.0 x 10-6 mm/mm ºC.

Figure 4-24. Diagram showing the thermal expansion of specimen 3802 between 20 and 60 ºC, measured from three different sides of the specimen. Mean values are plotted.

1E 04

1,8E 18

0,0001

0,0002

0,0003

0,0004

0,0005

0,0006

20 40 60

Ther

mal

expa

nsio

nm

m/m

m

3802

3802;1

3802;2

3802;3

29

4.2 Summary of results All the results are shown in Table 4-1 and Figure 4-25. Range of the coefficient of thermal expansion of all specimens is between 3.2 – 14.4 x 10-6 mm/mm C with mean value being 9.0 x 10-6 mm/mm C. Pegmatitic granite (range 3.2 – 10.8 x 10-6 with mean value of 7.2 x 10-6 mm/mm C) has slightly lower values than gneissic rocks (range 7.1 – 14.4 x 10-6 with mean value of 9.7 mm/mm C) (Figure 4-25). The foliation does not seem to affect the expansion properties, since the mean values are practically the same; VGN perpendicular foliation 10.8 x 10-6 mm/mm C vs. VGN parallel foliation 10.4 x 10-6 mm/mm C. The results are also in good agreement with the results presented in Huotari & Kukkonen (2004). They concluded that the linear thermal expansion coefficient of the Olkiluoto gneiss is 7-10 (10-6/°C) in the temperatures between 20-60 °C and this study states the value for gneissic rocks are 7-14 (10-6/°C). Table 4-1. Summary of the results for the coefficient of thermal expansion (mean values) and wet density of the tested specimens. Rock type abbreviations: VGN is veined gneiss, DGN is diatexitic gneiss and PGR pegmatitic granite. The veined gneisses are divided in two groups by the foliation angle; parallel (foliation 0) and perpendicular (foliation 90) to core axis.

Drillhole ID Specimen Rock type code Coefficient of thermal expansion

between 20 and 60 ºC (mm/mmºC)

Wet density (kg/m3)

ONK-PP167 3784 VGN (foliation 90) 13.2 x 10-6 2,780 ONK-PP167 3785 VGN (foliation 90) 8.4 x 10-6 2,720 ONK-PP199 3786 PGR 3.2 x 10-6 2,610 ONK-PP199 3787 PGR 7.8 x 10-6 2,650 ONK-PP224 3788 DGN 8.3 x 10-6 2,690 ONK-PP224 3789 DGN 8.7 x 10-6 2,720 ONK-PP224 3790 DGN 8.6 x 10-6 2,710 ONK-PP224 3791 PGR 8.3 x 10-6 2,640 ONK-PP224 3792 PGR 10.8 x 10-6 2,630 ONK-PP224 3793 VGN (foliation 0) 10.8 x 10-6 2,750 ONK-PP224 3794 VGN (foliation 0) 14.4 x 10-6 2,790 ONK-PP224 3795 VGN (foliation 0) 11.0 x 10-6 2,820 ONK-PP225 3796 DGN 8.6 x 10-6 2,740 ONK-PP225 3797 DGN 8.5 x 10-6 2,750 ONK-PP225 3798 DGN 6.8 x 10-6 2,750 ONK-PP225 3799 PGR 8.7 x 10-6 2,630 ONK-PP225 3800 VGN (foliation 0) 8.5 x 10-6 2,710 ONK-PP225 3801 VGN (foliation 0) 7.1 x 10-6 2,740 ONK-PP225 3802 PGR 4.6 x 10-6 2,620 ONK-PP226 3803 VGN (foliation 90) 12.3 x 10-6 2,740 ONK-PP226 3804 VGN (foliation 90) 9.5 x 10-6 2,750 ONK-PP226 3805 VGN (foliation 90) 10.6 x 10-6 2,760

30

The wet density of gneissic rocks 2,745 kg/m3 (mean value) is higher than for pegmatitic granite 2,630 kg/m3 (mean value).

Figure 4-25. The results for the coefficient of thermal expansion (mean values) and wet density of the tested specimens.

2,550

2,600

2,650

2,700

2,750

2,800

2,850

0,00E+00 2,00E 06 4,00E 06 6,00E 06 8,00E 06 1,00E 05 1,20E 05 1,40E 05 1,60E 05

Wet

dens

ity

(kg/

m3)

Coefficient of thermal expansion between 20 and 60 C (mm/mm C)

VGN fol 90°

PGR

DGN

VGN fol 0°

31

REFERENCES Huotari, T. & Kukkonen I. 2004. Thermal expansion properties of rocks: Literature survey and estimation of thermal expansion coefficient for Olkiluoto mica gneiss. Posiva Oy, Working Report 2004-04. Åkesson, U. 2007. Forsmark site investigation, Boreholes KFM05A and KFM06A, Extensometer measurement of the coefficient of thermal expansion of rock. SKB Report P-07-33.

laboratory measurements of the coefficient of … measurements of the coefficient of thermal...

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