3.4 DST Heating Schedule -- Workshop Discussions3.4 DST Heating Schedule -- Workshop Discussions...

3.4 DST Heating Schedule -- Workshop Discussions

Discussions were held during the June 8, 2001 workshop regarding the scheduled heatershut-off for the Drift Scale Test. The test will surpass four years of heating afterDecember 3, 2001. Workshop participants agreed that power to the canister and wingheaters are shut-off at the end of four years, indicating the start of a cooling phase.Results from recent thermal calculations were presented that predict heated drift walltemperatures of about 80 degrees C after 3 years of cooling. These predictedtemperatures are discussed in detail in the following section.

Principal Investigators representing each of the coupled process models presented theirideas and opinions regarding heater shut-off. No one advocated extending the heatingphase beyond the original 4-year plan. The thermal-chemical process group requested 1or 2 new core holes for investigating the geochemical properties of the rock in andaround the boiling zone at the time of shut-off. Core from these holes will undergo anultracentrifuge water extraction process with support from the USGS. The thermal-hydrologic process group recommended extending the date of heater shut-off by a monthbecause more frequent monitoring of moisture movement through the rock, immediatelyupon cooling, wouldn't be hampered by holiday shutdown of the ESF. The thermal-mechanical group was interested in installing 5 tiltmeters in holes surrounding the heateddrift. Tiltmeters would monitor expected movement in the rock following heater shut-off. This group also requested more frequent observations of the heated drift crown tolook for cracking or greater volume of loose rock held in the welded wire mesh. Theseobservations would be made from the viewing window at the bulkhead or from imagesrecorded with the remote camera.

Thermal Test Progress Report #7 October 2001s5

3.5 Predictive Simulations of the Cooling Phase in the Drift Scale Test

The heating cycle in the Drift Scale Test (DST), which is expected to continue for fouryears, is scheduled to end on December 3, 2001. It is therefore expedient at this time toperform predictive simulations about the cooling phase of the DST. These predictivesimulations delineate the spatial and temporal evolution of the thermal-hydrological (TH)processes during the cooling phase and help to determine what useful data can becollected during the same. The results from these predictive simulations were presentedduring the 12th Thermal Test Workshop at Las Vegas, Nevada, on June 7th and 8th, 2001.

Predictive simulations for the cooling phase of the DST are based on the same conceptualmodel as has been used for simulating the heating phase. This model uses the integralfinite-difference TOUGH2 simulator along with a dual-permeability conceptualization ofthe interactions between the rock matrix blocks and the fractures embedded in them. Thewing heaters in this model are incorporated as high-permeability conduits. At the time ofperforming the predictive simulations for the cooling phase, the DST was at 39 months ofheating. Since the cooling phase is to begin only after 48 months of heating, the heatingphase was allowed to continue till 48 months with the heating power available at the endof the 39 months (March 2001) of heating.

These predictive simulations are expected to provide us with guidelines for schedulingthe active testing during the cooling phase of the DST. One important issue during thisphase is to find out the rate at which the rock cools once the heaters are switched off.Another important TH issue that needs to be considered is the duration of the two-phasezone (evidenced by 'heat-pipe signatures) during cooling. This will provide evidence ofTH coupling. These predictive simulations are also to demonstrate the expected changesin moisture redistribution both in the fractures and in the matrix rock blocks. While thechanges in fracture liquid saturation will guide the scheduling of air-permeability testing,the changes in matrix liquid saturation will govern the frequency of geophysicalmeasurements.

To determine the rate at which the rock will cool off in the DST following heater switch-off, we first show the simulated contours of temperatures at four years of heating in theplane of hydrology boreholes 57-61 (see Figure 24). Observe that borehole 60, incomparison to the other boreholes in this group, is intersected by the maximum numberof temperature contours, in other words, the temperature gradient is steepest alongborehole 60. Therefore the sensors in this borehole are likely to register maximumchanges in temperature during cooling. Thus, a study of the simulated temperatures inborehole 60 may give us an indication of how fast the rock is going to lose heat. Inaddition, we will investigate the temperature history in RTD borehole 160 and at the driftwall. Borehole 160 is a horizontal hole running parallel to the wing heaters. Historically,this borehole and the drift wall, due to their proximity to the source of heat, haveregistered the maximum temperatures. These will therefore be good locations formonitoring the drops in temperature during the cooling phase.

In Figures 25a and 25b, we show the simulated temperature history at the drift surfaceduring the cooling phase. Figure 25a shows the temperature at the drift surface as a

Thermal Test Progress Report #7 56 October 2001

function of time during cooling, while Figure 25b shows the drop in temperature at thedrift surface from its pre-cooling value at the drift surface. Temperature at the driftsurface decreases rapidly during the initial phases of cooling, before reaching anasymptotic rate of decline. For example, after one year of cooling, the drift surfacetemperature has declined by 1200C, whereas the drop is only 140°C after two years ofcooling. Note also that, after two years of cooling, the temperature at the drift surface isexpected to be well below the nominal boiling point of water. Similar trends are observedin the simulated temperatures from borehole 160. Figures 26a and 26b are similar toFigures 25a and 25b, respectively, except that here the results are for selected sensors inborehole 160. Sensor 17 in borehole 160 was recording the maximum temperature duringheating. This sensor exhibits the fastest rate of decline in temperature during cooling.After two years of cooling, all the sensors in borehole 160, including sensor 17, areexpected to be below the nominal boiling point. The drop in temperature in varioussensors of hydrology borehole 60 follows a similar pattern (see Figures 27a-b). In short,after two years of cooling, even the locations with maximum pre-cooling temperaturesare predicted to decline below 1 00°C.

In addition, note that there is no evidence of heat-pipe signature as temperatureapproaches boiling during cooling in any of the selected boreholes. This is because, incontrast to the situation during heating, no vapor is produced during cooling. This impliesthat, except at the immediate onset of cooling, little movement of water in the fractures isexpected during the cooling phase of the DST. To illustrate, contours of fracture liquidsaturation at onset of cooling (Figure 28a) and at 3 months (Figure 28b), 6 months(Figure 28c) and 12 months (Figure 28d) since initiation of cooling are shown in Figures28a-d. During the heating phase at the DST, there was a build-up of condensate outsidethe dry-out zone surrounding the Heated Drift and the wing heaters. At the initiation ofcooling, this accumulated condensate drains through the fractures. Due to this rapiddrainage at the start of cooling, liquid saturation in the fractures in the pre-coolingcondensate zones decreases rapidly (within the first year or so). This has a direct impacton air-permeability testing. It is expected that, because of the decreasing liquid saturationin the fractures, air-injection testing will exhibit an increase in permeability during thefirst year since initiation of cooling. After that time, no appreciable increase in air-permeability values will be noticeable. However, these increases in air-permeabilityvalues are expected to be detected by testing in only the boreholes above the HeatedDrift, as these boreholes will be located in the drying zone during the first year ofcooling. The boreholes below the Heated Drift will not provide much informationregarding increases in air-permeability values, as drying below the Heated Drift happensoutside the range of these boreholes. Contours of liquid saturation in the matrix areshown in Figures 29a-d. While Figure 6a shows the matrix saturation at the beginning ofcooling, Figure 29b, 29c, and 29d show the same at one year, two years and four years ofcooling, respectively. As expected, liquid saturation in the matrix remains almostunchanged throughout the cooling phase at the DST. During cooling, rewetting of thedry-out zone, at the edge of the condensate zone, may happen through capillary suction.Since water movement in the fractures is very limited during cooling, such rewetting, aslow process in itself, of the rock matrix is expected to be very limited in nature. Sincegeophysical measurements are volume-averaged methods, such small, localized changes


in matrix saturation may be difficult to capture by these measurements. Thus, it isanticipated that geophysical measurements may not produce much new informationduring cooling. However, we recommend that geophysical surveys be carried outfrequently during the first year since initiation of cooling. The frequency of survey can bereduced after that time period.

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Figure 24. Contours of Simulated Temperature in the Plane of Hydrology Boreholes 57-61 at theEnd of 48 Months of Heating in the DST.

Thermal Test Progress Report #7

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Thermal Test Progress Report #7 61

Temperature

October 2001

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Figure 29. (Continued) Simulated Contours of Liquid Saturation in the Matrix at (c) Two YearsAfter Beginning of Cooling and (d) Four Years After Beginning of Cooling.


[NTENTIONALLY LEFT BLANK


4 Thermal-Hydrological Processes

Discussions of thermal-hydrological processes are included in the following foursections. Section 4.1 presents information regarding the field thermal tests. Section 4.2presents the ground penetrating radar, Section 4.3 discusses thermal-hydrological modelvalidation, and Section 4.4 examines data from borehole 79 in the context of temperatureand fluid movement as impacted by neutron logging.

4.1 Field Thermal Tests - The Effect of Heat on the Movement of Water

The movement of water is one of the most important processes to be investigated in thesite characterization of a potential nuclear waste repository at Yucca Mountain, Nevada.Understanding the process of the water movement under the influence of the radioactivedecay heat of the nuclear waste will enhance the accuracy of predicting hydrological andchemical conditions in emplacement drifts and the transport of radioactive nuclides fromthe emplacement drifts to the accessible environment. The potential repository horizon inYucca Mountain is a partially saturated Topopah Spring tuff formation, which is highlyfractured, densely welded, with variable porosity of lithophysal cavity. The potentialrepository horizon will reside in both non-lithophysal and lithophysal units of theTopopah Spring tuff formation. It has been estimated that the pore space in the rock isabout 90% saturated with pore water in the non-lithophysal unit, and about 70% saturatedin the lithophysal unit.

The conceptual model of the effect of the heat on the movement of water is that the heatevaporates the pore water into vapor; the water vapor flows from the matrix into near-byfractures following pressure gradients. The vapor will take the least resistant paths byflowing in fractures. The water vapor will condense into liquid water in the fractures atthe cooler regions. The condensate may be imbibed into the matrix or flows alongfractures under the influence of gravity. Dependent on the combined effects of gravityand fracture orientation, the condensate may be shed away from the heat source or flowstoward the heat source. The condensate that is shed away from the heat source will nolonger be available for subsequent phase of the thermal-hydrological process. Thecondensate that is imbibed into the matrix will increase the water saturation level of therock matrix, which will affect the TH process during the later period of the heating phase.The condensate that flows back toward the heat source may be evaporated/boiled again,and another cycle of vapor flow, condensation, and condensate flow will start again.

In the Drift Scale Test (DST), the heat-driven water movement is monitored by variousmeans. The change of water saturation in the rock mass caused by the water movementis measured by geophysical methods, such as neutron logging, ground-penetrating radar(GPR), and electrical resistance tomography (ERT). Temperature is sensitive to the flowof vapor and water, therefore can be used as an indicator of the water movement. Airpermeability in fractures can be used to infer the variation of water content in fractures,

Thermal Test Progress Report #767Otbr20 Thermal Tet Progres Report6# October 2001

assuming that the variation of fracture aperture due to the rock deformation is notsignificant.

4.1.1 Temperature as a Diagnostic of the Water Movement

In the DST, temperature is measured in the Heated Drift (HD), in the rock mass inresistance temperature device (RTD) boreholes, and in the rock mass in the multiple-point borehole extensiometer (MPBX) boreholes. Because the RTD boreholes are sealed,the temperatures measured in them are more representative of the real temperatures in therock mass. The temperature measured in the RTD boreholes is used in this discussion ofthe heat-driven water movements. There are 28 Temperature (RTD) boreholes in theDST (CRWMS, 1998, Table 4-1). Among those, two are parallel to the axis of theHeater Drift, at about 7 m horizontally from the center of HD, and about 3.5 m above thewing heater plane. Twenty six of the Temperature boreholes are radial to the HD. Thetemporal variation and spatial distribution of the temperature measured in those radialboreholes are used in this discussion of the inferred water movements. In those radialtemperature boreholes, RTDs are installed at a spacing of 30 cm and are numbered I to67, starting from near the collar of each borehole.

Figure 30 shows the temperature measured at RTDs 1 to 7 as a function of elapsed dayssince the heating in borehole#144, which is at 12 m from the bulkhead and oriented 450away from the Access Observation Drift (AOD). This figure is used as an example toillustrate the effects of heat transfer and moisture movement on the temperature.Temperatures measured in other radial boreholes behavior similar to that shown in Figure30. The curve RTD-1 in Figure 30 shows the typical temperature-time curve of heatconduction in a partially saturated medium. The temperature rises fast with time at thebeginning due to a large thermal gradient between the heat source and RTD-1. Thetemperature increasing rate decreases with time because of many factors. The majorcontributing factors include: (1). The thermal gradient decreases with time when thethermal front progresses further from the heat source and expands. (2). Enhancedevaporation of the pore water at elevated temperatures creates a cooling effect. Thetemperature-time curve shows an inflection point at temperature slightly above 100°C.This increase in the temperature rising rate is caused by factors such as the arrival ofadditional heating from the wing heaters, decreasing in thermal conductivity of the rockmass due to drying, etc. Later, the temperature increasing rate decreases again becausethe further decrease of the thermal gradient. The temperature-time curves RTD-2 toRTD-7 show the effect of water movement on the temperature. When more water isavailable, the effect of water movement, such as evaporation and/or flow, on temperaturewill be great so that the temperature rising rate is significantly reduced around the boilingpoint of water. The temperature rising rate may be reduced to near zero if the amount ofwater is great enough so that rapid evaporation and/or flow of vapor can remove almostall of the energy supplied by the heaters. Later on, when most of the water is removed attemperatures above the boiling point of water, the temperature rises in the same way asthat due to thermal conduction only. The number of RTDs in each borehole that involvewith such rapid evaporation process, and the duration of each such RTDs to be involved


in such rapid evaporation process are indicators of either the amount of water in the rockmass or the rate that water can be supplied to the region.

The rapid evaporation/boiling process is shown in the temperature measured in all of thetemperature boreholes. However, the intensity of the process, the spatial extent of theprocess, and the temporal duration of such process vary from borehole to borehole. Theevaporation process may reach the extent that the temperature in a significant region(involves more than two RTDs) along one borehole may be maintained at a near constantlevel at any instance. This kind of spatial energy balance occurs in many boreholes withvariable extents. This phenomenon was reported in Figure 18 of Thermal Test ProgressReport #6 (PR-6) (BSC, 2001).

In some boreholes the amount of water, or the supply of water, is great enough to keepthe temperature at certain locality at very close to constant for an extended period of time.This constant level of temperature is defined as the boiling point of water. It wasreported in PR-6 that the boiling point of water in some of the temperature boreholessystematically decreased with increasing distance from the heaters (BSC, 2001, Figure19). Further analysis of the temperature data indicates that this phenomenon occurs inboreholes #137, #138, #144, #158, and #159. This phenomenon of variation of theboiling point of water with distance from the heat source may be due to the variation ofion concentration in the water due to rock-water interaction. This phenomenon seems tobe localized. In addition, the range of the boiling point of water varies from borehole toborehole. For example, in borehole #158, which is a vertically up borehole at 23 m fromthe bulkhead, the boiling point of water ranges from about 97.5 to 101°C; in borehole#159, which is a 45 degree upward borehole at 23 m from the bulkhead, the boiling pointof water ranges from about 95.5 to 98.5°C.

The spatial extent and the temporal duration of the rapid evaporation/boiling process isused to assess the availability of water in the regions toward AOD (the region betweenthe HD and the AOD) and from AOD (the region on the other side of the HD). At themid HD region (at 23 m from the bulkhead) the to-AOD region seems to have more waterthan the from-AOD region. But near the ends of the HD (at 12 m from the bulkhead and39 m form the bulkhead) the from-AOD region seems to have more water than the to-AOD region. These are illustrated by the following figures.

Figures 31, 32, 33, and 34 show the temperature-time curves in boreholes #138 and #144respectively. Both boreholes #138 and #144 are the 45-degree upward boreholes at about12 m from the bulkhead. Borehole #138 is in the to-AOD region; borehole #144 is in thefrom-AOD region. These figures show that more RTDs in borehole #144 (RTD-7 andabove, as shown in Figure 32) were involved in the rapid evaporation process than inborehole #138 (RTD-14 and above, as shown in Figure 31). And the duration of theprocess in borehole #144 (e.g. more than 360 days at RTD-21, as shown in Figure 33) islonger than that in borehole #138 (e.g. less than 200 days at RTD-21, as shown in Figure32). Figures 35 to 39 show the temperature-time curves in borehole #140 and #142respectively. Both boreholes #140 and #142 are the 45-degree downward boreholes at 12m from the bulkhead. Borehole #140 is in the to-AOD region; borehole #142 is in the


from-AOD region. These figures show that the number of RTDs in borehole #140 (RTD-5 to RTD-9, as shown in Figures 35 and 36) involved in the rapid evaporation process arefewer than that in borehole #142 (RTD-19 to RTD-30, as shown in Figures 37 to 39). Insummary, at 12 m from the bulkhead, the region to-AOD has less water available tosustain the rapid evaporation process than the region from-AOD.

Figures 40 to 45 show the temperature-time curves in borehole #159 and #165. Bothboreholes #159 and #165 are 45-degree upward boreholes at about 23 m from thebulkhead. Borehole #159 is in the to-AOD region; borehole #165 is in the from-AODregion. These figures show that more RTDs in borehole #159 (RTD-21 to RTD-36, asshown in Figures 40 to 43) than in borehole #165 (RTD-21 to RTD-29, as shown inFigures 44 and 45) are involved in the rapid evaporation/boiling process. This is anindication that more water was available in the upper to-AOD region than in the upperfrom-AOD region at 23 m from the bulkhead. Figures 17 to 23 show the temperature-time curves in boreholes #161 and #163, both are 45-degree down-ward boreholes atabout 23 m from the bulkhead. There are more RTDs in borehole #161 (as shown inFigures 46 to 49) than in borehole #163 (as shown in Figures 50 to 52) involved in therapid evaporation process. This is an indication that below the heater plane at 23 m fromthe bulkhead, the to-AOD region seems have more water available than in the from-AODregion. In summary, at 23 m from the bulkhead, the temperature-time curves show thatthere is more water available in the to-AOD region than in the from-AOD region.

At 39 m from the bulkhead the temperature-time curves are shown in Figures 53 to 67.In the upper region, there seem to have fewer RTDs in borehole #171 (as shown inFigures 53 to 55) than in borehole #175 (as shown in Figures 56 to 59) involved in therapid evaporation/boiling process. Borehole #171 is in the to-AOD region, whileborehole #175 is in the from-AOD region. In other words, in the region above the heaterplane at 39 m from the bulkhead, the to-AOD region seems to have less water availablethan the from-AOD region. On the other hand, below the heater plane, there are moreRTDs in borehole #172 (as shown in Figures 60 to 64) than in borehole #174 (as shownin Figures 65 to 67) involved in the rapid evaporation/boiling process. Borehole #172 isin the to-AOD region; and borehole #174 is in the from-AOD region. Therefore, in theregion below the heater plane at 39 m from the bulkhead, the to-AOD region seems tohave more water available than the from-AOD region.

In summary, the availability of water to sustain a rapid evaporation/boiling process varieswith distance from the bulkhead. The availability of water depends on initial moisturecontent and the rate at which water can be supplied to a region. In the region above theheater plane, less water was available in the to-AOD region than in the from-AOD regionat 12 and 39 m from the bulkhead. The reverse is true at 23 m from the bulkhead. In theregion below the heater plane, more water was available in the to-AOD region than in thefrom-AOD region at 23 and 39 m from the bulkhead. The reverse is true at 12 m fromthe bulkhead. Some sort of water movement in a scale greater than the DST may havecaused this variation of the availability of water.


4.1.2 Integrated Interpretation of Geophysical Methods of Monitoring WaterMovement

The geophysical methods used to monitor the spatial distribution and the temporalvariation of moisture content are ground-penetrating radar (GPR), electrical resistancetomography (ERT) and neutron logging. Water movement is inferred from the measuredspatial distribution and temporal variation of the moisture content. In this report all of thegeophysical measurement results are presented as referenced to the pre-heat moisturecontent. Therefore only the changes in the moisture content due to the heating ispresented. The boreholes used for conducting GPR, ERT, and neutron logging are listedin CRWMS (1998). At the Thermal Test Workshop the GPR results were not availableto be incorporated with the results of ERT and neutron logging yet, therefore werepresented separately.

Ground-Penetrating Radar Results

GPR in the DST is conducted in the neutron logging boreholes originated from the AOD,which are boreholes #64 to #68, and boreholes #47 to #51. As shown in CRWMS(1998), boreholes #47 to #51 form an array intersecting the HD at a distance about 6.4 mfrom the bulkhead, and boreholes #64 to #68 intersect the HD at about 26.5 m from thebulkhead. Generally speaking, the GPR results show drying in regions near the heaters,and increasing moisture content outside of the drying regions. This is in generalagreement with the ERT and the neutron logging results, as will be shown later. Due tothe high temperature, GPR in boreholes #64 to #68 were not conducted after October 27,1999. This is unfortunate because boreholes #64 to #68 covers the mid portion of theHD, which is influenced less by end effects.

Figures 68 to 70 show some examples of the GPR results. Figure 68 shows the GPRresults measured in boreholes #65 to #68 on October 27, 1999. This was the lastmeasurement conducted in this array of boreholes. The circle in this figure represents theHD. Borehole #65 is the highest borehole in this figure, and borehole #68 is the lowestone. There was no measurement conducted in borehole #64, which is the highestborehole in this array, and is above borehole #65. Figure 68 illustrates that the heatingmoves water radially from the heat source. The image in Figure 68 is the changes insaturation, from +0.3 to -0.6. Figures 69 and 70 show the variation of the change insaturation between April 14, 2000 and February 6, 2001, as measured by GPR inboreholes #49 to #51. Borehole #49 is immediately above the HD, which is representedby a circle, and boreholes #50 and #51 are below the HD. There was no measurementconducted in boreholes #47 and #48, which are above borehole #49. The changes in thesaturation change between 4/14/00 (Figure 69) and 2/06/01 (Figure 70) are the increase inthe drying region to the side below the HD, decreasing the extent of increasing saturationdirectly below the HD, and increasing the region of increasing saturation near the AOD.The GPR data seem to show a greater extent of drying than the neutron data. Because ofthe sparse spatial coverage of the GPR measurement, not much more information aboutthe water movement can be obtained from the measurements.

Thermal Test Progress Report #771Otbr20 Thermal Test Progress Report7# October 2001

ERT and Neutron Logging Results

ERT is conducted in 8 planes in the DST: two vertical planes from the AOD to the HDintersecting the HD at 4.6 and 25 m from the bulkhead, three vertically up planes parallelto the HD axis, and three vertically down planes parallel to the HD axis. The threevertically up planes origin at the crown of the HD, and cover the distance ranges 2.7 to12, 12 to 23 and 23 to 39 m from the bulkhead respectively. The three vertically downplanes origin at the invert of the HD, and cover the same distances as the vertically upplanes. As shown in CRWMS (1998), there are twelve neutron boreholes in the DST.Ten of those boreholes (#47 to #51, and #64 to #68) origin from the AOD, and form twovertical arrays intersecting the HD at 6.4 and 26.5 m from the bulkhead respectively. Theboreholes in these two arrays are shared by GPR, as mentioned above. Neutron loggingis also conducted in two horizontal boreholes parallel to the HD axis, at about 3.5 mabove the mid wing heater plane (holes #79 and #80). In this analysis, the ratio of theERT and the neutron data obtained at about the same time, with respect to their pre-heatdata, are plotted in a same figure. Because the neutron logging is more frequent than theERT, neutron data obtained at about the same time as the ERT is selected to be plottedwith the ERT data. The result ratio images are shown in Figures 71 to 87. In thesefigures a ratio I means no change in the moisture content; a ratio of greater than 1 meansincreasing in moisture content; and a ratio of less than 1 means losing moisture. It shouldbe noted that the neutron borehole arrays and the ERT planes origin from the AOD areoff-set by about 1.5 to 1.8 m along the AOD axis. A neutron borehole array is about 1.5to 1.8 m farther away from the bulkhead than its nearby ERT plane.

Figures 71 to 87 show both spatial and temporal variations of the moisture ratio asmeasured by ERT and neutron logging, as the heating goes on. Early in the heating phasean extended drying region developed in the transverse ERT plane (the ERT planeoriginates at the AOD and perpendicular to the HD) closer to the bulkhead (Figures 71and 72). This may be related to the moisture loss through the bulkhead, because thetemperature in the transverse plane at mid point of the HD is greater than that closer tothe bulkhead. This drying region extended by 3/16/98 (Figure 72), and the moisturecontent increased in regions above and below it. Both ERT and neutron show theincrease in the moisture content. By 4/22/98 (Figure 73) the drying became more normalas would be expected from the heating. In other words, by 4/22/98 the region at the midpoint of the HD showed more drying than that closer to the bulkhead, as would beexpected. The moisture in the regions both above and below the heaters are increased.But the region below the heaters shows greater increase in moisture. This condition wasmaintained for a couple of months until 7/22/98, when the region above the heaters at themid point of the HD seemed to have greater increase in moisture (Figures 75).

Later when the drying near the heaters progressed, the increase of moisture becameevident everywhere outside of the drying region, with especially significant increase inmoisture in the region below the heaters closer to the bulkhead (Figures 76 to 81). Thenby 6/1/99 (Figure 82) most of the increasing moisture in the region between the AOD andthe HD at 4.6 m from the bulkhead was gone; increasing moisture still existed in theregion above the wing heaters, between the AOD and the HD at 25 m from the bulkhead;and increasing moisture also existed in the regions directly above and below the HD.


These conditions stayed through 9/29/99 (Figure 83). By 11/02/99 (Figure 84) themoisture in the regions above and below the wing heaters, between the AOD and the HDhad increased; the same occurred in the region directly below and above the HD, at adistance greater than 25 m from the bulkhead. By 1/21/00 (Figure 85) the increasingmoisture in the region between the AOD and the HD at 25 m from the bulkhead wasgone; the moisture increase above and below the HD still existed; and there was anincrease in moisture below the wing heater at 4.6 m from the bulkhead. By 9/26/00 andthrough 2/5/01 (Figures 86 and 87) the only region where increasing moisture existedwas above the HD at a distance greater than 25 m from the bulkhead.

The variations of the moisture content with respect time as shown by the ERT/neutrondata, and the spatial variation in the moisture as indicated by the temperature data (asshown above) may be due to heterogeneity in the rock mass or a larger scale moisturemovement.

4.1.3 References

BSC, 2001, Thermal Test Progress Report #6, Bechtel SAIC Company, LLC, Las Vegas,NV 89144.

CRWMS, 1998, Drift Scale Test As-Built Report, BABOOOOO-01717-5700-00003, TRWEnvironmental Safety System Inc. Las Vegas, NV.


Temporatur2 In hole144, at 12 m from the bulkhead, 45 degroo from AOD.

22

200

b -0

ionF -

t00

20

20

10 400 "00 00 ooo

Ela,,sed Time, day'200

Figure 30. Temperature at RTDs 1-7 in borehole #144 as a function of time.

Temperature in hol1,038, at 12 m fom the bulkhead, 45 degre to AOD.

180

ill

140

120

K0

E 80V

60

40

20

60

elapse Time, dvy

Figure 31. Temperature-time curves in borehole #138 show that rapid evaporation process startsat RTD-14.


'' C/o.p

Temperature in hole#138, at 12 m fom the bulkhead, 45 degre to AOD.

140

120

100

i ro

2 60

40

20

0 200 400 rho Wu0 "oQ0 1200Elapsed Time, day

Figure 32. The temperature-time curves in borehole #138 show the duration of the rapidevaporation process. At RTD-21 the duration is almost 200 days,

Tampe,ture in hoieWM44. at 12 m from the bulkhead, 45 degree fn2m AOD.

218

160

140

120

k100H

40

20

0

029 400 0o "000 1000 120oElapsed Time, day

Figure 33. The temperature-time curves in borehole #144 show that the rapid evaporationprocess starts at RTD-7.


Temperature in h2l.#144, at 12 m ftrom the bulkhead, 45 degre2 from AOD.

140

120

100

Ii 80

r0

40

20

00 200 40 00, 000 I'l0

Elp,e.d Time, day

Figure 34 The temperature-time curves in borehole #144 show the duration of the rapidevaporation process at RTD-21 is greater than 360 days.

Temperature in hole40, at 12 m from the bulkhead, 45 depgee to AOD.

200

"i

"I

140

o 120

i29 100

60

40

20

0

Elapsed Time., day



0

12W0

9/

076 October 2001

ITempeatur In hoie#140, at 12 m frm the bUlkhed, 45 degme t AOD

200 40 600

Elapsed Time, day

1"Io 1200

Figure 36. The temperature-time curves in borehole #140 show that the almost constanttemperature curhes end at RTD-9.

Temperature in hoIo#142, at 12 at from the bulkhead, -45 degree from AOD.

0I200 40 "00 aoo 1o 121Elipsed Time, aty

Fig ure 37. The temperature-time curves in borehole #142 show that the almost constanttemperature starts at RTD-19.

)0


tD

IDP

120

120

Ia

60

20

0

IS0

140

120

It 80

E

60

40

20

77 October 2001

Temperatu in hoIe142 at 12 m from the bulkhead, 45 degme from AOD

140

120

- 60

60

40

20

0 200 400 "I eOO Iwo "IElapsed TI., day

Figure 38. The temperature-time curves in borehole #142 show the well-defined almost constanttemperature at RTD-22 to RTD-28

Temperature In hole142, rt 12 m from the bulkhead, -4 degree from AOD.

1'2

100

80

60C

S

20

o 2t 400 6r 'IO 1000 1200

Elapsed Time, day

Figure 39. The temperature-time cuanes in borehole #142 show the almost constant temperatureoccurs at RTD-29 and RTD-30 so far, and may be more later.


0

.

72 October 2001

Temptalturm in hole#1s9, at 23m fomm the bulkhead, 45 dagree to AOD.

160

140

1 0

I I

eaS

E

20

0 200 4o r00 "I moo 12r

Elapsed Time., dy


Temperature in hole#l59, at 23 m from the bulkhead, 45 degree to AOD.

140

120

800

I'

20

4uu

E apsed Time., day

8LoU 1000 '20

Figure 41. Well-defined almost constant temperature curves at RTD-22 to RTD-28 in borehole#159.


IRTD 224

o -RTD-24

RTD 25,-RTD-28

I ---- 2s

79 October 2001

Temperatu in hole159, at23 m frm. the bulkhead, 45 degree to AOD.

I2I

Ip

Rn

I

E

40

20

0 200 400 0 r 1"0

Elapsed Time, day12p

Figure 42. The well-defined almost temperature curves in borehole #159 occur at RTD-29 toRTD-35.

Temperature in hoJe,159, at 23 m fom the bulkhead, 45 degree to AOD

100

80

o 60

40

20

0

2nn 400 000

Elnped Ti.., day800 1I 00

Figure 43. The well-defined almost constant temperature curye in borehole #159 occurs at RTD-36, and may be more later.


a

F.

.

1200

ciltt

Tempeaturm In hole#165, at 23 m from the bulkhead, 45 degre from AOD.

160

1,,

120

leoIT3SwF-

60

40

20

o200 40o am rs0 1,m 120

Elap,od Time, dy

Figure 44. The rapid evaporation process in borehole #165 may be developing at RTD-21, but thetemperature is not quite almost constant.

Temperatur in hde#1 6s, at 23 m ftm the bUh head, 45 degr fYrom AOD.

140-

120

80

O

40

20

400-

5r 60 700 t00 WI0 1m0 I100 1200Elapsed Time, day

Figure 45 The temperature-time curves in borehole #165 are not as flat as those in borehole#1 59.


0/-5

Tempentur in hle3#161, It2 m1m fr the bulkhead, 45 degee to AOD.

260

160

140

o12

2 160

aSM

F- S

60

I0

0 260 400 6WO 800 l/W

Ebp2ed Time., dS

Figure 46. The temperature-time curves in borehole #161 show that the almost constanttemperature occurs at RTD-6 and RTD-7.

Temperatur i hoI#161, at 23 m from the bulkhead, 45 degre to AOD.

200

180

160

140

o 120

- 0

60

40

20

0

1200

PemEbDS.: TimT. dw

Figure 47. The almost flat temperature-time curves in borehole #161 occur at RTD-11 to RTD-14:

0Thermal Test Progress Report #7 82 fOctober 2001

Temperature in holD161, It 23 m frnm the bulkhead, -4 degre to AOD.

160

140

120

100

2 00

EH

60

10

40 600 mo 100o 1200EIapsed Time. dy

Figure 48. The almost constant temperature in borehole #161 occurs at RTD-16 to RTD-22.

Tempeature in hole#161, at 23 m from the bUlkhead, 45 degre to AOD.

ISO

1,,

140

120

E60

60

10

20

0

rEipsed Time, day

Figure 49 The almost constant temperature in borehole #161 occurs at RTD-27 to RTDn29.


Tempeatum in hdT3163, at 23 m from the bulkhead, -4 degmr from AOD.

200

"I

160

i40

o 120

a2 100a

EI1 0

60

40

20

0 u0 400 600 SW I'l 1200Eul.Ad Ti.i, dA.

Figure 50. Rapid-evaporation process in borehole #163 develops at RTD-14. But thetemperature-time curve is not very flat.

Temperatur in hcle163, at 23 m firom the bulkhead, t4 degre frmm AOD.

iso

140

120

0

E

100

so

60

40

20

0

Ela.sed Time, day

Figure 51 The temperature-time curves in borehole #163 are quite flat at RTD-16 to RTD-21.


0

2d f)ctober 20101

Temperturel n hole,163. ,t23 m from the bulkhead, 45 degee from AOD.

10

120

leo

* 80

C

40

20

no Te 200 ErpsodTime, day o RP r E

Figure 52. The temperature-time curves in borehole #163 at RTD-22 and RTD-23 have almostflat segments.

Tmetuein holo#*171, at 39m from the bulkhead, 45 degree to AOD.

180

140

120rt

S 80

40

20

0o aoo ve EUpse0040 aoo 80 1000 1200

Elapsed 5In., day

Fig ure 53. The temperature-time curves in borehoe# #171 show that the rapid evaporationprocess starts at RTD-1 3.


Cl?

Temperature in holeE171, at 39m from the bulkhead, 45 degree t0AOD.

140

120

100

UtE 80a

30

40

0 200 400 600 80 I0o 10I

Elapsed Time, day

Figure 54. The temperature-time curves in borehole #171 at RTD-15 to RTD-21 have flatsegments.

Tempert ure in holb3171, It 3sm firm the bulkhead, 45 deuree to AOD.

100

30

(3

aa!

60

40

20

I0 200 40600 $0 1 M) 1200

Elapse lTime, day

Figure 55. The temperature-ti me curves in borehole #171 at RTD-22 and RTD-23 show almostconstant temperature periods.


0

0

c-c

Temperature in hdeX#175, at 39m from the bulkhead, 45 degree from AOD.

200 40 600 rO r"IElapsed Time, day

1200

Figure 56. The temperature-time curves in borehole #175 show rapid evaporation process startsat RTD-5i

Temperatre in 1,ol#175, It SSm from the blulkhead, 45 degree from AOD,

"IS

I60

140

E1200

•102 80

60

20

El..sed Time, ay

Figure 57. Thetemperatures in borehole #175 at RTD-8 to RTD-14 show flat regions indicatingrapid evaporation.


680

140

c'120

E

- 80

60

40

20

Cu_-

Temperatur In hol#17s, at 39m frm the bUlkhead, 45 degre from AOD.

440

120

e 8°

f

40

20

0 200 400 P00 t00 Iwo I200Eflpaed Time, day

Figure 58. The temperature-time curves in borehole #175 show that the rapid evaporationprocess involves RTD-15 to RTD-21.

Temperature i hOle#175, at 39m from the blukhead, 45 degre, from AOD

100

80

- 40

20

0

0 200 4W 6, Bo0 1000 1200Feapsd Ti.a, day

Figure 59. The temperature-time curves in borehole #175 show well-defined flat regions at RTD-22 to RTD-28.

T'hemal Test Progress Report #7 88 October 2001

0

is

Ctz�

Temperature in holer172, at 39m from the bulkhead, 45 deDgee to AOD.

200

-RTD 2l

RTD- I 160- RTD- 4

140 - bT0-7/- 120

0

E

60

20

o 200 40 600 ar 1000 120Elapsed Time, daY

Figure 60. The temperature-time curves in borehole #172 show that the rapid evaporationprocess starts at RTD-4,

Tempteratur in hoIe#172, at 3sm from the buIkhe d, 45 deree t, AOD.

re -RTD8-RTD-9

140 RTD-1l 1___________

1RTD12-NT-IS

120 -RTO-14

C)

b 80

40

20

0 200 400 to 8r 1l000 1200Elapsed Time, day

Figure 61. The temperature-time curves show that the rapid evaporation process involves allRTDs, RTD-8 to RTD-14, shown in here


Temperature in ho1, 172, at 3sm frOm the bu khead, 45 degr7e to AOD.

160

140

120

10

I 80

E10

60

40

I0

I 200 4o 60) eMO ill

Elaps,d Ti,me, day

Figure 62. The temperature-time curves in borehole #172 show that RTD-16 to RTD-21 areinvolved in the rapid evaporation process.

Temperature in hole#172, at 3sm fom the bulkhead, 45 de=ee to AOD.

"I

ill

80

0

5260

IOF-

40

20

600

Elapse. Time, day

Figure 63. The temperature-time curves in borehole #172 at RTD-22 to RTD-28 show the effectof the rapid evaporation process.


0

1 0

090 Ocrtober 2001

Temperture in hole=172, t 39m frm the bulikhead, 45 degre to AOD.

00

ao

.. 60

E0

40

20

0400 600 800 1000

Elap.d Time., day

1200

Figure 64. The temperature-time curves in borehole #172 show that at least RTD-29 to RTD-31are involved in the rapid evaporation process.

Temperature in, hl1 74, at 39m from the bUlkhead, 45 deDgre 1fm AOD.

200

18

160

40

o 120C

a

40

20

1200Elase Time, day

Figure 65. The temperature-time curve at RTD-7 in borehole #174 starts to show the effect ofrapid evaporation.


CAS

Tempeature in hole#174, at 39s from the bulkhead, 45 degr. from AOD

ISO

160

e i

.40

Cr,p

a

60

40

20

0 200 4"0 GM ar0 1000 1200Elapsed Time, day

Figure 66. The temperature-time curves in borehole #174 at RTD-8 to RTD-14 show the effect ofrapid evaporation

Temperature in hOID174, at 39m fomm the bulkhead, 45 degree from AOD.

140

120

100

I3

-go

E60

40

20

I0 200 4nn 600 600 1000 1200

Elapsed Time, daY

Figure 67. The temperature-time curves in borehole #174 at RTD-15 and RTD-16 show the effectof rapid evaporation.

sThermal Test Progress Report #7 92 October 2001

YUCCA MTM DRIFT SCALE HEATER TEST tGPF RESLTS

WEl s EE�-e7-es 5 OCBER D. IWsO3- .. 10

50

rM I4 SAlUSA101

Figure 68. GPR results in boreholes #65 to #68. This figure shows the difference between theOctober 27, 1999 measurements and the pre-heat baseline on October 29, 1997

YUCCA MTN DRIFT SCALE HEATFF TEST (WR RESLaTS)

WELLS 5140-0S - Ph! 04114() 10 10,2SA'-3 .-1 O t l ~ 4 0 5 t

0z-2g

CRA#V I SATIAt0I

Figure 69. The GPR results in boreholes #49 to #51. This figure shows the difference betweenthe measurements on April 14, 2000 and the pre-heat baseline on October 29, 1997


en~

YUCCA MTN DRIFr SCALE HEATER TEST (CiR RESULTS)

WELLS 51-60-48 P7 - MRE 0/0/01 - 10M/97-30 -25 -20 . II 1 0 I IC

I

-°. 04AE IN SA1JM°TION °

Figure 70. The GPR results in boreholes #49 to #51. This figure shows the difference betweenthe measurements on February 6, 2001 and the pre-heat baseline on October 29,1997.

Figure 71. The ERT and neutron results in the DST. This figure shows the ratio of the watercontent measurements on 2/17/98 to that of the pre-heat baselines.


0

II-

94 October 2001

Figure 72. The ERT and neutron results in the DST. This figure shows the ratio of the watercontent measurements on 3/16/98 to that of the pre-heat baselines.

Figure 73. The ERT and neutron results in the DST. This figure shows the ratio between thewater content measurements on 4/22/98 to that of the pre-heat baselines.


.


Figure 75. The ERT and neutron results in the DST, This figure shows the ratio between thewater content measurements on 7/22/98 to that of the pre-heat baselines.


C-_30




03/

0

Figure 78 The ERT and neutron results in the DST. This figure shows the ratio between thewater content measurements on 11/24/98 to that of the pre-heat baselines.

Figure 79. The ERT and neutron results in the DST. This figure shows the ratio between thewater content measurements on 1/11199 to that of the pre-heat baselines.


Cj '

Figure 80 The ERT and neutron results in the DST This figure shows the ratio between thewater content measurements on 3/01/99 to that of the pre-heat baselines.



C53

Figure 82. The ERT and neutron results in the DST. This figure shows the ratio between thewater content measurements on 6101199 to that of the pre-heat baselines.

Figure 83 The ERT and neutron results in the DST. This figure shows the ratio between thewater content measurements on 9/29/99 to that of the pre-heat baselines.


C3%

Figure 84. The ERT and neutron results in the DST. This figure shows the ratio between thewater content measurements on\1 1107/99 to that of the pre-heat baselines.

Figure 85. The ERT and neutron results in the DST. This figure shows the ratio between thewater content measurements on 1/21/00 to that of the pre-heat baselines


(35


0

Figure 87. The ERT and neutron results in the DST. This figure shows the ratio between thewater content measurements on 2/5/01 to that of the pre-heat baseiines


c3(p

3.4 DST Heating Schedule -- Workshop Discussions3.4 DST Heating Schedule -- Workshop Discussions...

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