Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.SAND2016-7915C.

7th US/German Workshop on Salt Repository Research, Design, and Operation

Salt Images

Compiled by Laura A. ConnollySandia National Laboratories

Washington, DC September 7-9, 2016

Dr. Enrique Adolfo Biurrun

Born in western Argentina on September 8, 1950. Died in

Aachen, Germany onMarch 25, 2016

2

DBE

3

DBE

4

DBE

Ramon Gasull, Johanna Wolf, Dr. Thilo von Berlepsch, Dr. Enrique Biurrun, Dr. Andree Lommerzheim 5

DBE

6

DBE

DBEDr. Joachim Engelhardt made impressive photos of salt minerals:

Halite - The crystals grew due to the dissolution of bischofite (magnesiumchlorid- hexahydrate) in a sodium chloride saturated solution.

The height of the crystal aggregate is about 20 mm.

Four shots are taken with a Canon 350D camera and an EF-S 60 mm macro lens.

The data were used to calculate a picture with an extended depth of focus.

7

8

DBEDr. Joachim Engelhardt made impressive photos of salt minerals:

Halite - The crystals grew due to the dissolution of bischofite (magnesiumchlorid-hexahydrate) in a sodium chloride saturated solution.

The height of the crystal aggregate is about 20 mm.

Four shots are taken with a Canon 350D camera and an EF-S 60 mm macro lens.

The data were used to calculate a picture with an extended depth of focus.

The following figures present:

results of computer topographical analyses (XCT) andnano-tomography (FIB-nT) of compacted crushed rock salt samples

Objective:visualization of the remaining pore space

Wilhelm Bollingerfehr

DBE 9

Visualization of two XCT data sets of a compacted crushed rock salt sample.a) 3D reconstruction of the analyzed volume.b) 3D reconstruction of pore space (green) and the anhydrite mineral with bright image contrast

(grey).c) Reconstruction of anhydrite distribution.

DBE

10

Michael Jobmann compiled results of• computer topographical analyses (XCT) and• nano-tomography (FIB-nT) of compacted crushed rock salt samples

Visualization of two XCT data sets of a compacted crushed rock salt sample.

a) 3D reconstruction of the analyzed volume.

b) 3D reconstruction of pore space (green) and the anhydrite mineral (grey).

11

DBEMichael Jobmann compiled results of• computer topographical analyses (XCT) and• nano-tomography (FIB-nT) of compacted crushed rock salt samples

Visualization of the FIB-nT data set of a compacted crushed rock salt sample. a), b) and c) 3D reconstructions of the analyzed volume documenting the granular pore geometry.d) 3D reconstruction of pore space.

Visualization of the FIB data set of a compacted crushed rock salt sample.a) 3D reconstructions of the analyzed

volumeb) 3D reconstruction of pore space

showing a macropore and numerous in plane fluid inclusions.

c) 3D reconstruction of pore space documenting that the micropores or fluid inclusions are aligned in planes (i.e. sub-grain boundaries). 12

DBEMichael Jobmann compiled results of• computer topographical analyses (XCT) and• nano-tomography (FIB-nT) of compacted crushed rock salt samples

Uwe Düsterloh TU Clausthal

13

BGR salt scientists: About three generations of salt experts covering geology, laboratory, numerical modeling, and safety assessment. From left to right: Otto

Schulze, Udo Hunsche, Werner Gräsle, Michael Langer, Maximilian Pusch, Sandra Fahland, Stefan Heusermann, Manfred Wallner, Jörg Hammer, Dieter Stührenberg.

BGR 14

Lothar Hartwig, retired last year. He performed all of the drilling and sample preparation to exacting precision.

GRS 15

Coaxial salt concrete – Salt sample with salt paste in the annulus after drying

GRS 16

Coaxial salt concrete – Salt sample after compressive loading and brine injection

GRS 17

BGRStack über 400 µm

Fluid inclusion in WIPP-halite filled with brine and crystals of polyhalite. Stacked image with z = 400 µm.

18

BGRAlteration of anhydrite in a matrix of WIPP-halite with replacement of anhydrite by polyhalite.

19

Pseudomorphs of anhydrite and halite after gypsum in WIPP-salt.The former swallowtails are still visible, but replaced by anhydrite and halite.

BGR 20

BGRStack über 1 mm

Fluid inclusions in WIPP-halite filled with brine and gases. Stacked image with z = 1000 µm.

21

BGRStack über 1,3 mm

22

Fluid inclusion in WIPP-halite filled with brine, crystals of anhydrite and polyhalite and gases. Stacked image with z = 1300 µm.

BGR

23

Stack über 160 µm

Bunches of polyhalite at the contact to halite on top of an aggregate of clay and polyhalite in WIPP-salt. Stacked image with z = 160 µm.

BGRStack über 300 µm

Bunches of polyhalite at the contact to halite on top of an aggregate of polyhalite in WIPP-salt. Stacked image with z = 300 µm. 24

BGRStack über 900 µm

Cutout of fluid inclusions in a so called “Chevron” in WIPP-Halite filled with brine and crossed by a crack due to preparation. Stacked image with z = 900 µm.

25

BGRPseudomorphic corona of polyhalite after anhydritein a matrix of halite from Bokeloh (Germany).

26

BGR

Pseudomorphosis of polyhalite after anhydrite in a matrix of halite from Bokeloh (Germany).

27

BGRStack über 400 µm

Grain boundaries of halite crystals decorated with fluid inclusions of brine and hydrocarbons from the main rocksalt in Gorleben (Germany). Stacked image with z = 400 µm.

28

BGR

Grain boundaries of halite crystals decorated with branched and planar fluid inclusions of brine and hydrocarbons from the main rocksalt in Gorleben (Germany). Stacked image with z = 480 µm.

Stack über 480 µm 29

BGR

Grain boundaries of halite and cracks in halite decorated with branched fluid inclusions of brine, gases and hydrocarbons from the main rocksalt in Gorleben (Germany). Stacked image with z = 400 µm.

Stack über 600 µm 30

BGRColorful cropped pieces of anhydrite and a hypidiomorphic crystal of dolomite in halite from the mainrocksalt in Gorleben (Germany).

31

BGRStack 2 - Kopie

Same image as the one below. The detail area of the third image of this group is marked here.

32

BGRStack 2 - Kopie

Fluorescing hydrocarbons at the grain boundaries of halite and anhydrite crystals from the main rocksalt in Gorleben (Germany). Stacked image with z = about 200 µm.

33

BGR

Gas bubble in a large brine filled fluid inclusion (5000 µm) from WIPP-halite.

34

Polyphase gas bubble in a brine filled fluid inclusion from WIPP-halite.

BGR35

BGRPseudomorphosis of anhydrite after swallowtails of gypsum in WIPP-salt.

36

Bird-shaped aggregate of polyhalite in a brine filled fluid inclusion from WIPP-halite.

BGR37

BGR38

Deformed fibers of anhydrite (anhydrite after gypsum) in halite from WIPP.

Cavities in polyhalite from WIPP-salt filled with large, idiomorphic needles of polyhalite surrounded by halite.

39BGR

Deep-view to a brine filled fluid inclusions (3000 µm) within WPP-halite. The square-shaped, white inclusions are filled with packed abrasive dust.

40BGR

Frank Hansen and Enrique Biurrun in Washington, DC

41

Frank Hansen, Enrique Biurrun, Andrew Orrell, Walter Steininger, and Hans Code 42

Ernie Hardin, Kris Kuhlman, Frank Hansen, Geoff Freeze at Asse, 2013

43

Marty Molecke at WIPP Room B: Heated waste package performance testing 44

Darrell Munson at center pillar in Room H (heated axisymmetric

pillar) at WIPP

45

Entrance to Room Q (isothermal brine inflow test) after removal of tunnel boring machine at WIPP

46

Entrance to Room Q (isothermal brine inflow test) after removal of tunnel boring machine at WIPP

47

Darrell Munson in Room A2: 18-W/m2 DHLW mockup at WIPP

48

Darrell Munson and Doug Blankenship in Room H (heated pillar) after installation of heaters and insulation at WIPP

49

Darrell Munson and Rudy Matalucci at center pillar in Room H (heated50axisymmetric pillar) before installation of heaters and insulation at WIPP

Marty Molecke. Drums and empty brine pool in 51Room J (overtest TRU waste demonstration) at WIPP

Entrance to Room Q (isothermal brine inflow test) 52with final seal installed at WIPP

Wendell Weart at WIPPHeated horizontal emplacement boreholes (Room T)

53

Wendell Weart showing orange marker band in WIPP

54

Wendell Weart at WIPP

55

Cliff Howard examining salt using headlamp at WIPP 56

Common vertical fractures at pillar corner WIPP

57

Marty Molecke at WIPP Materials Interface Interactions Test

58

Prof. Dr. Karl-Heinz Lux TU Clausthal

59

Melissa Mills, SNL

60

SEM photomicrograph of WIPP salt, reconsolidated unvented at 250°C and 20 MPa of confining pressure, showing a tight triple- junction and residual moisture isolated in occluded pores.

Ewoud Verhoef, Deputy Director of COVRA

I look forward to hosting the 8th

US/German Workshop to be held at COVRA’s premises in Nieuwdorp, the Netherlands in September 2017. During the workshop, there is opportunity to visit the storage facilities and ‘stand on’ our Dutch high-level heat-generating waste.

61

Erika Neeft, COVRA

Thickness Zechstein salt Netherlands: The thickest salt occurrences on Earth are of marine origin. In the Netherlands, salt deposits mainly occur in Permian and Triassic intervals. For geological disposal, there is a focus on salt of Permian age (260-254 million years old) which attains greatest thickness and belongs to the Zechstein Group.

Hart J, Prij J, Vis G-J, Becker DA, Wolf J, Noseck U, Buhmann D: Collection and analysis of current knowledge on salt-based repositories, OPERA-PU- NRG221A, 2015

62

Erika Neeft, COVRASalt domes Netherlands: The salt domes have been extracted from the thickness map, by assuming a minimum thickness of rock salt in a salt dome of 1300 m. Also indicated on this map are the locations (in green) where salt is present within 1500 m below the surface and thicker than 300 m.

63

Erika Neeft, COVRADepth top Zechstein Group in the Netherlands: The deep underground distribution of Zechstein Group was investigated in OPLA (Dutch acronym for Research program for Disposal Onshore: 1982-1993). In OPERA (Dutch acronym for Research program into Geological Disposal of radioactive waste: 2011-2016), the depth maps of the top and base of the Zechstein group have been constructed on existing, but recently updated data which are based on interpreted seismic data (2D and 3D) and borehole data.

64

65

IfGThe miner preparing his drilling machine for large block coring (Cabanasas mine, Spain) is Michael Wiedemann.

IfG: Salt Dump Zielitz

66

Bedded salt specimen used for direct tension test (rocksalt with anhydrite intercalations, core diameter: 100mm)– Potash mine Zielitz (Saxony-Anhalt, Germany)

IfG67

IfG

68

Salt Dump at the former potash mine Teutschenthal (Saxony-Anhalt, Germany), looking west from the shaft building

IfG Convergence 1

69

IfG Convergence 2

70

IfG: Drift lining – Red salt clay 71

IfG Historical salt mining

72

IfG: Old potash drift 73

IfG: Old potash drift 2 74

IfG Permeation Fluereszenz

75

IfG: Springen Versuchsort 76

IfG: The drift seal Morsleben 77

The technician preparing the large salt specimen (from a rock salt block recovered from the Bernburg salt mine) on the "Karussel-lathe" is Josef Fink, now retired.

78

IfG Sampling

79

Till Popp, IfG

Michael Wiedemann, a mining engineer who drilled at very strange climate conditions a hydro-frac borehole within the large "borehole" at the in-situ test site of IfG in the Merkers mine.

80

IfG Testkaverne 3

81

Dave SevougianFrank Hansen, American Cemetery, Luxembourg, Sep 2009

82

Klaus Wieczorak, GRS

83

Frank Hansen, Thilo von Berlepsch, Christi Leigh, Wilhelm Bollingerfehr, Walter Steininger

5th US/German Workshop in Santa Fe, New Mexico

84

Frank Hansen, Thilo von Berlepsch, Christi Leigh, Wilhelm Bollingerfehr, Walter Steininger

5th US/German Workshop in Santa Fe, New Mexico

Frank Hansen, Thilo von Berlepsch, Christi Leigh, Wilhelm Bollingerfehr, Walter Steininger

5th US/German Workshop in Santa Fe, New Mexico

85

Shannon Casey, Frank Hansen, LeAnn Mays, Christi Leigh, Dina Howell 5th US/German Workshop in Santa Fe, New Mexico

86

Structural geology of the Upper Rio Grande5th US/German Workshop in Santa Fe, New Mexico

87

5th US/German Workshop in Santa Fe, New Mexico (did not pay registration fee)

88

Upper Rio Grande basalt flow5th US/German Workshop in Santa Fe, New Mexico

89

Field trip panorama5th US/German Workshop in Santa Fe, New Mexico

90

Water in the Rio Grande5th US/German Workshop in Santa Fe, New Mexico

91

Rochelle Icenhower, Ingo, Sandra, Jörg, Till, John Icenhower: 5th US/German Workshop Field Trip

92

Frank, Jaap, ?, Stuart, Maximilian, ?: 5th US/German Workshop Field Trip

93

Jens, Nina, Christi, Klaus, Ralf, Lupe, ?, ?, and Jörg: 5th US/German Workshop Field Trip

94

LeAnn, Michael, Walter, Wilhelm, Norbert, Nancy: 5th US/German Workshop Field Trip

95

5th US/German Workshop in Santa Fe, New Mexico

96

Steve Bauer and Frank Hansen5th US/German Workshop in Santa Fe, New Mexico

97

Pillsbury Dough-Boy, Steven J. Bauer and Frank Hansen.Friends, colleagues, researchers, and Aggies

5th US/German Workshop in Santa Fe, New Mexico

98

Frank Hansen, Andrew Orrell, Freiberg, Germany6th US/German Workshop on Salt Repository Research, Design and Operation

99

Dave Sevougian, Frank Hansen, Andrew Orrell TU Bergakademie Freiberg Reiche Zeche

6th US/German Workshop on Salt Repository Research, Design and Operation

100

Frank Hansen, Andrew OrrellTU Bergakademie Freiberg Reiche Zeche

6th US/German Workshop on Salt Repository Research, Design and Operation

101

Microscopic Evidence of Grain Boundary Moisture During Granular Salt Reconsolidation

Rock salt is a favorable medium for nuclear waste disposal because of its low permeability and plastic behavior. Granular salt is likely to be used as back-fill material and a seal system component. In these applications, it is expected that granular salt will reconsolidate to a low permeability comparable to the intact native salt and completely encase the waste.Understanding the consolidation process dependency on stress state, moisture availability, and temperature is important for predicting long-term repository performance.

BackgroundAs granular salt consolidates, the initial void reduction is due to brittle processes of grain rearrangement and cataclastic flow. Eventually, grain boundary processes and crystal-plastic mechanisms control additional porosity reduction. Reconsolidation of granular salt is accomplished by a series of processes and mechanisms, which includes dislocation glide, cross slip, climb, and annealing/recrystallization. When present, fluid assists in grain boundary processes and enhances consolidation. Documentation of deformation mechanisms within consolidating granular salt and particularly at grain boundaries is essential to establish effects of moisture and the reliance of consolidation on stress and temperature.

ExperimentalMine-run granular salt from the Waste Isolation Pilot Plant (WIPP) and Avery Island was used to create cylindrical samples which were consolidated at 250°C and confining pressures up to 20 MPa. The granular salt was placed in copper and malleable soldered lead tubes with caps. For the samples presented here, three different conditions were used: top cap venting to the atmosphere, no vented caps, and top cap venting to the atmosphere with 1% moisture added to the salt.Samples were placed in a pressure vessel where a surrounding fluid was heated to 250°C, allowing thermal expansion of the unconfined specimen. Isostatic tests were conducted by simultaneously increasing confining and axial pressures. Shear testing has also been conducted.

Microstructures illustrated here are typical of ongoing research. All tests at 250°C resulted in high fractional density, low porosity, and tight cohesion evidenced by fracture through the crystal structure rather than at grain boundaries. Unvented reconsolidation retains moisture at grain boundaries as found ubiquitously on scanning electron photomicrographs revealing an inhomogeneous distribution of canals and pores. This observation contrasts significantly with the vented samples, which had virtually no remaining grain boundary moisture and had visible escaping steam during reconsolidation testing. All samples shown here were impermeable; however, unvented samples retained occluded porosity. Fluid inclusion migration and hydrous mineralogy were sufficient to promote fluid aided processes in WIPP salt, but is somewhat obscured at temperatures employed here.

Future WorkThis work comprises one component of a research program to better understand coupled thermal- mechanical-hydrologic behavior of reconsolidating granular salt. The goal is to assist in estimating the rate of consolidation under different conditions by an experimental program, including ongoing laboratory experiments, microstructural observations, and pore structure characterization. Future experiments will be conducted at lower temperatures. The completed work will provide data and parameters for a constitutive model that can be incorporated into numerical simulations. These numerical models will be used to make predictions of long-term repository performance.

Observational TechniquesAfter testing a diamond-wire saw was used to cut ends of the samples, which were used to make impregnated petrographic sections and freshly broken aggregated grains. In the aggregate, grain boundary processes such as pressure solution can be observed. Observational approaches include optical and scanning electron microscopy. Microstructure is highlighted by etching techniques whereby the sample is either swiped quickly with a damp Kim wipe or agitated in a solution of methanol saturated with PbCl2 for a few seconds and stopped by submersion in butanol.

WIPP-01 Vented No additional moisture

WIPP-02 Unvented No additional moisture

Avery Island- 01

Vented No additional moisture

Avery Island- 02

Vented Additional 1% moisture

3-D image of unvented sample with occluded residual moisture poresalong tight grain boundaries.

Intersection of grains at near orthogonal orientation with tight grain boundary achieved by crystal plasticity.

Residual fluid canals on grain boundaries.

Sharp crystal surface lacking evidence of moisture.

Fracture surface through crystal indicating tight cohesion. Note intersected fluid inclusions.

Tight triple junction with canals of resided moisture displaying occluded pores.

Thin section surface in reflected light etched with swipe of water revealing simultaneous recrystallization, internal grain recovery, and high energy grain boundaries.

Water-etched thin section surface in reflected light showing triple- junction with recrystallized area in center and small subgrains decorating tight grain boundaries.

Minor residual porosity. Cleavage fracture (left) and grain boundary fracture (right).

Evidently tight grain boundary, but not high cohesion.Occluded fluid droplets and canals on cubic grain boundary at slightly higher magnification

Grain boundary fracture on left and cleavage fracture on right. Tight cohesion with minor residual porosity.

Upper grain fractured through the crystal structure; lower grain fractured on boundary. Minor residual porosity.

Residual fluid inclusions along healed boundary.

Acknowledgements: This material is based upon work supported under a Department of Energy Nuclear Energy University Programs Graduate Fellowship. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94L85000.

Melissa Mills1, Frank Hansen2, Stephen Bauer2, John Stormont1

1Department of Civil Engineering, University of New Mexico, Albuquerque, NM 871312Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185

Motivation Microstructural Observations Results & Conclusion

Water-etched thin section surface in reflected light showing multiple grain boundaries. Recrystallized area with smaller subgrains emanating through rest of crystal structure.

Thin section with water-etched surface in reflected light displaying large recrystallized area as well as high energy grain boundaries.

Use 3-D glasses to view 3-D SEM image

102

SALT MECH VIII South Dakota School of Mines andTechnology - 2015 103

Dynamically compacted salt grains

104

Reconsolidated crushed salt exhibiting pressure solution redeposition processes

105

RESPEC: Instrumented salt sample

106

RESPEC: Test system schematic

107

RESPEC:Instrumentation

108

RESPEC: Instrumentation schematic

109

RESPEC: Hollow cylinder of domal salt from Avery Island

110

RESPEC:Instrumented salt

sample

111

RESPEC: Hollow cylinder of domal salt from Avery Island

112

Brine inflow experiment at WIPP called Room Q 113

Road header mining at WIPP

114

Alpine miner at WIPP

115

Jim Nowak at WIPP Room B: Heated116brine borehole inflow experiment

Darrell Munson at WIPP Room G:117

Geomechanical convergence experiment

Compacted crushed salt block manufacturing at WIPP

118

Installation of compacted crushed salt block at WIPP: Small scale seal testing

119

Marty Molecke at WIPP Room J: Waste drum overtest experiment

120

121Mining Room H (Heated Pillar) at WIPP

122

Photo by Michael Bühler taken in Morsleben during the technical tour of the 5th WS showing our colleagues Abe

and Enrique. Group front row from left: Gloria Kwong (OECD/NEA), Christi Leigh (SNL), Abe van Luik (DOE),

Enrique Biurrun (DBE), Lupe Arguello (SNL); Back row from left: Ralf Mauke (BfS), Andreas Hampel (Consultant), Prof.Stahlmann (TU Braunschweig), Markus Stacheder (PTKA).

Abraham "Abe" Van Luik Born in Nijmegen, The

Netherlands on December 16, 1944.

Died in Faywood, New Mexico on July 9, 2016.

123

124