Laboratory Measurements of the Coefficient of Thermal Expansion of Olkiluoto Drill Core Samples

Transcription

1 Working Report Laboratory Measurements of the Coefficient of Thermal Expansion of Olkiluoto Drill Core Samples Urban Åkesson April 212 POSIVA OY FI-2716 OLKILUOTO, FINLAND Tel Fax

2 Working Report Laboratory Measurements of the Coefficient of Thermal Expansion of Olkiluoto Drill Core Samples Urban Åkesson Swedish Cement and Concrete Research Institute April 212 Working Reports contain information on work in progress or pending completion.

3 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 2-6 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 1-6 mm/mm C, and the wet density between 2,61 and 2,82 kg/m 3. 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.

4 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 2-6 C. Tulokset kertovat, että lämpölaajeneminen on lähes lineaarista ja lämpölaajenemiskerroin tutkituilla näytteillä vaihtelee välillä 3,2 14,4 x 1-6 mm/mm C ja märkätiheys välillä kg/m 3. Pegmatiitti-graniiteilla on hieman alhaisempi lämpölaajenemiskerroin ja märkätiheys kuin gneisseillä. Avainsanat: Lämpölaajenemiskerroin, Olkiluoto, laboratoriomittaus, kairasydännäyte, märkätiheys

5 1 TABLE OF CONTENTS ABSTRACT TIIVISTELMÄ INTRODUCTION... 2 EQUIPMENT... 3 EXECUTION Description of the specimens Testing RESULTS Description of the specimens and presentation of the results Summary of results REFERENCES... 31

6 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 21 and was completed in May 21. ONK-PP167 ONK-PP199 ONK-PP224 ONK-PP225 ONK-PP m -437 m Figure 1-1. The locations of the ONKALO drillholes for determination of thermal expansion coefficients.

7 3 2 EQUIPMENT The following equipment has been used for the laboratory measurements: Extensometer (DEMEC inv no 12266) for measurement of the thermal expansion. The uncertainty of the extensometer is ± 3.97 x 1-6 mm/mm (strain), which equals an uncertainty of a single measurement of the coefficient of thermal expansion of ±.2 x 1-6 mm/mm o C for a temperature difference of 2 degrees C. Reference bar in invar steel for calibrate the extensometer. Heating chamber (inv no 12284) with an accuracy of ±.7 ºC at 8 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 27).

8 4 3 EXECUTION Determination of the coefficient of thermal expansion was made in accordance with SKB s method description SKB MD version 2. (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 ) and perpendicular (foliation 9) to the core axis. Sample ID Drillhole ID Drillhole depth (m) Rock type code 3784 ONK-PP VGN (foliation 9) 3785 ONK-PP VGN (foliation 9) 3786 ONK-PP PGR 3787 ONK-PP PGR 3788 ONK-PP DGN 3789 ONK-PP DGN 379 ONK-PP DGN 3791 ONK-PP PGR 3792 ONK-PP PGR 3793 ONK-PP VGN (foliation ) 3794 ONK-PP VGN (foliation ) 3795 ONK-PP VGN (foliation ) 3796 ONK-PP DGN 3797 ONK-PP DGN 3798 ONK-PP DGN 3799 ONK-PP PGR 38 ONK-PP VGN (foliation ) 381 ONK-PP VGN (foliation ) 382 ONK-PP PGR 383 ONK-PP VGN (foliation 9) 384 ONK-PP VGN (foliation 9) 385 ONK-PP VGN (foliation 9)

9 5 3.2 Testing The execution procedure followed the prescription in SKB MD 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 2 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 2, 4 and 6 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 2-6 ºC.

10 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/m 3. The coefficient of thermal expansion was determined between 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 Thermal expansion (mm/mm) 3784 Figure 4-1. Diagram showing the thermal expansion of specimen 3784 between 2 and 6 ºC, Figure 4-1 shows a picture of the specimen 3784 and a diagram for the thermal specimen 3784 was measured to be 13.2 x 1-6 mm/mm ºC and the specimen had a wet density of 2,78 kg/m3.

11 7 Specimen 3785 Thermal expansion (mm/mm) 3785 Figure 4-2. Diagram showing the thermal expansion of specimen 3785 between 2 and 6 ºC, Figure 4-2 shows a picture of the specimen 3785 and a diagram for the thermal specimen 3785 was measured to be 8.4 x 1-6 mm/mm ºC and the specimen had a wet density of 2,72 kg/m 3.

12 8 Specimen 3786 Thermal expansion (mm/mm) 3786 Figure 4-3. Diagram showing the thermal expansion of specimen 3786 between 2 and 6 ºC, Figure 4-3 shows a picture of the specimen 3786 and a diagram for the thermal specimen 3786 was measured to be 3.2 x 1-6 mm/mmº C and the specimen had a wet density of 2,61 kg/m 3. Clear non-linear behaviour was noticed in the results.

13 9 Specimen Figure 4-4. Diagram showing the thermal expansion of specimen 3787 between 2 and 6 ºC, Figure 4-4 shows a picture of the specimen 3787 and a diagram for the thermal specimen 3787 was measured to be 7.8 x 1-6 mm/mm ºC and the specimen had a wet density of 2,65 kg/m 3.

14 1 Specimen Figure 4-5. Diagram showing the thermal expansion of specimen 3788 between 2 and 6 ºC, Figure 4-5 shows a picture of the specimen 3788 and a diagram for the thermal specimen 3788 was measured to be 8.3 x 1-6 mm/mm ºC and the specimen had a wet density of 2,69 kg/m 3.

15 11 Specimen Figure 4-6. Diagram showing the thermal expansion of specimen 3789 between 2 and 6 ºC, Figure 4-6 shows a picture of the specimen 3789 and a diagram for the thermal specimen 3789 was measured to be 8.7 x 1-6 mm/mm ºC and the specimen had a wet density of 2,72 kg/m 3.

16 12 Specimen Figure 4-7. Diagram showing the thermal expansion of specimen 379 between 2 and 6 ºC, Figure 4-7 shows a picture of the specimen 379 and a diagram for the thermal specimen 379 was measured to be 8.6 x 1-6 mm/mm ºC and the specimen had a wet density of 2,71 kg/m 3.

17 13 Specimen Figure 4-8. Diagram showing the thermal expansion of specimen 3791 between 2 and 6 ºC, Figure 4-8 shows a picture of the specimen 3791 and a diagram for the thermal specimen 3791 was measured to be 8.3 x 1-6 mm/mm ºC and the specimen had a wet density of 2,64 kg/m 3.

18 14 Specimen Figure 4-9. Diagram showing the thermal expansion of specimen 3792 between 2 and 6 ºC, Figure 4-9 shows a picture of the specimen 3792 and a diagram for the thermal specimen 3792 was measured to be 1.8 x 1-6 mm/mm ºC and the specimen had a wet density of 2,63 kg/m 3. Minor non-linear behaviour was noticed in the results.

19 15 Specimen Figure 4-1. Diagram showing the thermal expansion of specimen 3793 between 2 and 6 ºC, Figure 4-1 shows a picture of the specimen 3793 and a diagram for the thermal specimen 3793 was measured to be 1.8 x 1-6 mm/mm ºC and the specimen had a wet density of 2,75 kg/m 3. Minor non-linear behaviour was noticed in the results.

20 16 Specimen Figure Diagram showing the thermal expansion of specimen 3794 between 2 and 6 ºC, Figure 4-11 shows a picture of the specimen 3794 and a diagram for the thermal specimen 3794 was measured to be 14.4 x 1-6 mm/mm ºC and the specimen had a wet density of 2,79 kg/m 3. Minor non-linear behaviour was noticed in the results.

21 17 Specimen Figure Diagram showing the thermal expansion of specimen 3795 between 2 and 6 ºC, Figure 4-12 shows a picture of the specimen 3795 and a diagram for the thermal specimen 3795 was measured to be 11. x 1-6 mm/mm ºC and the specimen had a wet density of 2,82 kg/m 3.

22 18 Specimen Figure Diagram showing the thermal expansion of specimen 3796 between 2 and 6 ºC, Figure 4-13 shows a picture of the specimen 3796 and a diagram for the thermal specimen 3796 was measured to be 8.6 x 1-6 mm/mm ºC and the specimen had a wet density of 2,74 kg/m 3.

23 19 Specimen Figure Diagram showing the thermal expansion of specimen 3797 between 2 and 6 ºC, Figure 4-14 shows a picture of the specimen 3797 and a diagram for the thermal specimen 3797 was measured to be 8.5 x 1-6 mm/mm ºC and the specimen had a wet density of 2,75 kg/m 3.

24 2 Specimen Figure Diagram showing the thermal expansion of specimen 3798 between 2 and 6 ºC, Figure 4-15 shows a picture of the specimen 3798 and a diagram for the thermal specimen 3798 was measured to be 6.8 x 1-6 mm/mm ºC and the specimen had a wet density of 2,75 kg/m 3.

25 21 Specimen Figure Diagram showing the thermal expansion of specimen 3799 between 2 and 6 ºC, Figure 4-16 shows a picture of the specimen 3799 and a diagram for the thermal specimen 3799 was measured to be 8.7 x 1-6 mm/mm ºC and the specimen had a wet density of 2,63 kg/m 3.

26 22 Specimen Figure Diagram showing the thermal expansion of specimen 38 between 2 and 6 ºC, Figure 4-17 shows a picture of the specimen 38 and a diagram for the thermal specimen 38 was measured to be 8.5 x 1-6 mm/mm ºC and the specimen had a wet density of 2,71 kg/m 3.

27 23 Specimen ,5 381 Figure Diagram showing the thermal expansion of specimen 381 between 2 and 6 ºC, Figure 4-18 shows a picture of the specimen 381 and a diagram for the thermal specimen 381 was measured to be 7.1 x 1-6 mm/mm ºC and the specimen had a wet density of 2,74 kg/m 3.

28 24 Specimen Figure Diagram showing the thermal expansion of specimen 382 between 2 and 6 ºC, Figure 4-19 shows a picture of the specimen 382 and a diagram for the thermal specimen 382 was measured to be 4.6 x 1-6 mm/mmº C and the specimen had a wet density of 2,62 kg/m 3. Non-linear behaviour was noticed in the results.

29 25 Specimen Figure 4-2. Diagram showing the thermal expansion of specimen 383 between 2 and 6 ºC, Figure 4-2 shows a picture of the specimen 383 and a diagram for the thermal specimen 383 was measured to be 12.3 x 1-6 mm/mm ºC and the specimen had a wet density of 2,74 kg/m 3. Non-linear behaviour was noticed in the results.

30 26 Specimen Figure Diagram showing the thermal expansion of specimen 384 between 2 and 6 ºC, Figure 4-21 shows a picture of the specimen 384 and a diagram for the thermal specimen 384 was measured to be 9.5 x 1-6 mm/mm ºC and the specimen had a wet density of 2,75 kg/m 3.

31 27 Specimen Figure Diagram showing the thermal expansion of specimen 385 between 2 and 6 ºC, Figure 4-22 shows a picture of the specimen 385 and a diagram for the thermal specimen 384 was measured to be 1.6 x 1-6 mm/mm ºC and the specimen had a wet density of 2,76 kg/m 3. Minor non-linear behaviour was noticed in the results.

32 28 In order to investigate the non-linearity the specimen 382 was remeasured. This time additional measuring points were glued on the specimen approximately at 12 degrees angles (see Figure 4-23). Figure Photograph showing how the measuring points were placed on specimen 382. The results of the measurements are shown in Figure 4-24, which indicates that the nonlinear phenomenon is partly due to bending of the drill core. The coefficients of thermal expansion for the measuring points were: 382:1 5. x 1-6, 382:2 4.8 x 1-6 and 382:3 8. x 1-6 mm/mm ºC ,8E 18 1E 4 382;1 382;2 382;3 Figure Diagram showing the thermal expansion of specimen 382 between 2 and 6 ºC, measured from three different sides of the specimen. Mean values are plotted.

33 Summary of results All the results are shown in Table 4-1 and Figure Range of the coefficient of thermal expansion of all specimens is between x 1-6 mm/mm C with mean value being 9. x 1-6 mm/mm C. Pegmatitic granite (range x 1-6 with mean value of 7.2 x 1-6 mm/mm C) has slightly lower values than gneissic rocks (range x 1-6 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 1.8 x 1-6 mm/mm C vs. VGN parallel foliation 1.4 x 1-6 mm/mm C. The results are also in good agreement with the results presented in Huotari & Kukkonen (24). They concluded that the linear thermal expansion coefficient of the Olkiluoto gneiss is 7-1 (1-6 / C) in the temperatures between 2-6 C and this study states the value for gneissic rocks are 7-14 (1-6 / 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 ) and perpendicular (foliation 9) to core axis. Drillhole ID Specimen Rock type code Coefficient of thermal expansion between 2 and 6 ºC (mm/mmºc) Wet density (kg/m 3 ) ONK-PP VGN (foliation 9) 13.2 x 1-6 2,78 ONK-PP VGN (foliation 9) 8.4 x 1-6 2,72 ONK-PP PGR 3.2 x 1-6 2,61 ONK-PP PGR 7.8 x 1-6 2,65 ONK-PP DGN 8.3 x 1-6 2,69 ONK-PP DGN 8.7 x 1-6 2,72 ONK-PP DGN 8.6 x 1-6 2,71 ONK-PP PGR 8.3 x 1-6 2,64 ONK-PP PGR 1.8 x 1-6 2,63 ONK-PP VGN (foliation ) 1.8 x 1-6 2,75 ONK-PP VGN (foliation ) 14.4 x 1-6 2,79 ONK-PP VGN (foliation ) 11. x 1-6 2,82 ONK-PP DGN 8.6 x 1-6 2,74 ONK-PP DGN 8.5 x 1-6 2,75 ONK-PP DGN 6.8 x 1-6 2,75 ONK-PP PGR 8.7 x 1-6 2,63 ONK-PP VGN (foliation ) 8.5 x 1-6 2,71 ONK-PP VGN (foliation ) 7.1 x 1-6 2,74 ONK-PP PGR 4.6 x 1-6 2,62 ONK-PP VGN (foliation 9) 12.3 x 1-6 2,74 ONK-PP VGN (foliation 9) 9.5 x 1-6 2,75 ONK-PP VGN (foliation 9) 1.6 x 1-6 2,76

34 3 The wet density of gneissic rocks 2,745 kg/m 3 (mean value) is higher than for pegmatitic granite 2,63 kg/m 3 (mean value). 2,85 2,8 VGN fol 9 Wet density (kg/m3) 2,75 2,7 2,65 PGR DGN VGN fol 2,6 2,55,E+ 2,E 6 4,E 6 6,E 6 8,E 6 1,E 5 1,2E 5 1,4E 5 1,6E 5 Coefficient of thermal expansion between 2 and 6 C (mm/mm C) Figure The results for the coefficient of thermal expansion (mean values) and wet density of the tested specimens.

35 31 REFERENCES Huotari, T. & Kukkonen I. 24. Thermal expansion properties of rocks: Literature survey and estimation of thermal expansion coefficient for Olkiluoto mica gneiss. Posiva Oy, Working Report Åkesson, U. 27. Forsmark site investigation, Boreholes KFM5A and KFM6A, Extensometer measurement of the coefficient of thermal expansion of rock. SKB Report P-7-33.